Comparative advantage and efficacy of natural products for polycystic ovary syndrome

Abstract

Background

Natural products including Korean Medicine, Traditional Chinese Medicine and Campo medicine have been suggested to be suitable for polycystic ovary syndrome (PCOS), which is known to be a multifactorial disease, since current treatment for PCOS focuses on the amelioration of symptoms with adverse effects.

Aim of the study

In this review, the ethnopharmacology and mechanisms of natural remedies including herbs, herbal formulation and acupunctures are introduced, providing a comprehensive insight for its advantage on PCOS.

Materials and methods

We conducted a comprehensive literature search using PubMed, MEDLINE, and Google Scholar databases. Search terms included combinations of “polycystic ovary syndrome,” “PCOS,” “natural product,” “herbal medicine,” “phytotherapy,” “acupuncture,” and “alternative and complementary medicine”.

Results

A total of 2,514 articles were identified. After removing duplicates, we screened titles and abstracts for relevance. Studies were included if they involved: (1) preclinical in vivo or in vitro experiments using natural products in PCOS models; (2) randomized controlled trials (RCTs) or meta-analyses involving herbal, acupuncture, or combined treatments for PCOS; or (3) mechanistic evaluations. A total of 69 studies were selected for full-text analysis. Articles were excluded if they were non-original (e.g., reviews, commentaries), unrelated to PCOS, or did not include natural treatment modalities.

Conclusion

The current status of the potential target pathway of natural products was assigned to three categories: research on the improvement of ovary and uterus quality, fertility and the weight loss for PCOS. However, there is no continuous study from basic research including in vitro and in vivo, and clinical trials. Large scale and more in-depth research are needed to verify their potential benefits for treating PCOS as a new drug.

Introduction

Polycystic ovary syndrome (PCOS), also known as Stein–Leventhal syndrome or hyperandrogenic anovulation [1], is one of the most common endocrine disorders in women who have fertility and even adolescents. Studies have reported that 8–13% of reproductive women are supposed to be affected by PCOS worldwide. It is typically characterized by anovulation, irregular menstrual cycles, hyperandrogenism and obesity. Although the symptoms vary in their phenotype, severity and other factors such as polycystic ovarian morphology, excessive androgen level and ovulation disorders, the hypothalamic-pituitary-ovarian axis dysfunction is thought to play a chief role [2]. The excessive release of gonadotropin from the pituitary gland caused by an imbalance in the hypothalamic-pituitary-ovarian axis results in hypersecretion of luteinizing hormone (LH), which makes follicular fluid forming cystic follicles in the ovaries [3, 4]. A number of arrested follicles in the growing stage become atretic follicles with thin-walled cyst [5], leading to the overproduction of androgens [6]. Additionally, there have been numerous reports that PCOS with obesity has a high risk of developing metabolic disorders such as hyperinsulinemia and cardiovascular diseases. It manifests obesity, hyperinsulinemia and insulin resistance as the indisputable etiological factors with abnormalities in LH and follicle-stimulating hormone (FSH) hormones. The interaction between insulin and LH could upregulate androgen levels via Cytochrome P450 17α-hydroxylase (CYP17A1), a steroidogenic enzyme that converts pregnenolone to dehydroepiandrosterone (DHEA) [7]. For that reason, most PCOS patients with hyperandrogenism has the risk of comorbidities such as obesity, hyperinsulinemia and type II diabetes [8]. Furthermore, recent research has mentioned that PCOS connects with heredity and microbiomes, indicating that the pathophysiology of PCOS is attributed to a complex of genetic variants, environmental matters and individual lifestyle [9].

It is well known that the disease tends to further worsen becoming chronic with complications, if PCOS patients are left untreated. As oligomenorrhea which has the over 35 days gaps between menstruation or irregularities are the main feature of PCOS, infertility problem is the main concerns for women with PCOS. Ovulation inducers are the first recommendation for women with PCOS. Clomiphene citrate has been used as the first-line prescription for anovulatory PCOS [10]. Clomiphene citrate induces a gonadotropin-releasing hormone (GnRH) pulse, leading to the secretion of gonadotropin from the anterior pituitary gland [11]. The other ones currently used are contraceptive pills, metformin and statin. As part of lifestyle modification, there are results that mediterranean diet or ketogenic diet are meaningful for improving PCOS and also Yoga can improve the symptom of PCOS. One of them, metformin has positive effects for PCOS patients who have reproductive axis abnormalities and metabolic disease [12]. However, the clinical usefulness of those treatment remains controversial. There have been several studies that ovulation inducers degrade the quality of ovaries and reduce the thickness of endometrium. Statins is reported to cause serious diseases such as type 2 diabetes, memory loss, and even dementia. In addition, there are no obvious experimental results that statin can decrease the androgen level [13]. These findings point to the needs of treatments which can effectively improve PCOS without adverse effects.

In that sense, natural herbal medicine could be attractive since those are prescribed individually and known to be low risk for treating PCOS. Now, the numerous researches provide insight into the use of medicinal herbs for treating PCOS that govern reproductive function. Gymnema sylvestre, Panax ginseng, Foeniculum vulgare are the common prescription for PCOS patients. Acupuncture treatment that includes SP6 (Sanyinjiao) also has had a great deal of potential for treating PCOS [14]. This present review introduces succinctly the overall information of PCOS and arranges the ongoing investigation of the alternative and complementary therapies including herbal treatment, acupuncture, and a case of cupping therapy for PCOS.

Development of PCOS

PCOS is a complicated hormonal, metabolic, and psychological disorder [3], affecting by genetics, lifestyle, individual characteristics such as habits, and its phenotype [15]. Irregular menstruation cycle, chronic anovulation, hyperandrogenism, and insulin resistance are the serious and common symptoms of PCOS, also hirsutism, acne, and weight gain are manifested [16]. Their symptoms such as the start of the first period or maybe health issues are developed later on in your twenties or thirties. The cause of PCOS still remains unclear, however, conducted studies have suggested the pathogenesis of PCOS. Obesity, insulin resistance (IR), hormone imbalance, epigenetics, excessive oxidative stress and even gut microbiota has been revealed as representative examples of those [17].

Ovulation dysfunction

Chronic anovulation is usually presented as amenorrhea, oligomenorrhea and further developing infertility in PCOS [18]. About 75–80% of PCOS patients are reported to have menstrual abnormalities, oligomenorrhea, and amenorrhea [19]. Ovarian dysfunction of PCOS includes both oligo-ovulation or anovulation and morphological changes of polycystic ovaries, which can be described as a collection of 2–9 mm size of tiny antral follicles [19]. Women with PCOS have a menstrual cycle that is disturbed at several stages and anti-Müllerian hormone (AMH) influences on this cycle in a way that is focused on antral and primordial follicles and regulation of their development into the beginning level [15].

Because of the complicated factors, including abnormal menstrual cycle and anovulation, the number of cysts in the ovary can cause cramps and abdominal pains during periods [15]. In this case, endometrial hyperplasia is strongly related to anovulation. Normal endometrium cycle from remodeling, shedding to regeneration is capable of suitable blastocyst implantation and pregnancy [20]. Well-functioning endometrial receptivity for decidualization and placental changes could be impaired by hyperandrogenism and hyperinsulinemia via reduction of sex hormone-binding globulin (SHBG) [21]. Additionally, constant anovulation has negative effects on estrogen persistence and increases the endometrial proliferation [22]. The abnormalities on hormone levels in PCOS patients alter endometrial environment via fluctuating the cytokine and chemokine [23].

Hormone abnormalities with hyperinsulinemia and hyperandrogenism

Hormonal dysfunction is critical feature in PCOS pathogenesis in a complex of androgen, gonadotropin and IR [24]. Originally, in response to GnRH secretion from hypothalamus, anterior pituitary gonadotrophs secrete the LH and FSH [25]. However, in terms of hyperinsulinemia, it increases GnRH pulse frequency and regulates FSH release [18]. High insulin level leads to a decrease in sex hormone-binding globulin (SHBG), which leads to an increase of testosterone circulation in blood, resulting in hyperandrogenemia. Consecutively, hyperinsulinemia leads to a surge of LH to FSH ratio, and in the end, LH surge prevails over FSH surge, showing that LH/FSH ratio levels are all increasing with PCOS patients. Due to its imbalance, ovarian androgen level increases and it leads to follicular immaturity [18]. Another study mentioned that there is strong correlation with the AMH and LH, LH/FSH ratio levels. Commonly, serum AMH concentration is higher 2–3 times in PCOS patients than healthy people [26]. Hyperandrogenism can stimulate the secretion of AMH from granulosa cells of over-recruit follicles with the alteration of aromatase activity [27, 28].

Obesity and IR

Obesity and IR play a key role in PCOS, appearing to contribute to developing and maintaining PCOS. About 65–70% of PCOS patients are impacted by IR and secondary hyperinsulinemia [15], and a majority of these individuals also struggle with obesity, worsening their IR [22]. The mechanism is still uncertain, but with the high probability, obese women easily have selective IR and hyperinsulinemia [1, 29]. Firstly, too much fat, highly refined carbohydrates and carbonized drinks are the things that young and stressful women with PCOS have usually taken. Those cause raising of insulin levels unhealthy and stimulating androgen receptors out of the ovary, and eventually leading to block of the ovum release from follicles [30]. Obesity-induced excess of androgen can attenuate the activation of thermogenesis in brown adipose tissue and reduces mitochondrial respiration [31]. Additionally, the possible role of NOD-like receptor pyrin domain-containing protein 3 (NLRP3) in the foundation of chronic inflammation of adipose tissue in obesity and IR has been suggested recently. Chronic inflammation is reported to be closely associated with the pathogenesis of PCOS [32]. Hyperandrogenism and oxidative stress in the ovaries triggers NLRP3 inflammasome-activated caspase-1 dependent pyroptosis, and eventually leading to the production of interleukin (IL)-1β and IL-18 [33]. This pathway affects to ovarian dysfunction including cystic follicles, thickened theca cells, and accelerating ovarian fibrosis [34]. Through a meta-analysis, it was found that NLRP3 activation in subcutaneous and visceral adipose tissue was far higher in obese patients [33].

Heredity

Although it was widely spread that PCOS is a life style disease, recent family clustering and twin studies have suggested that PCOS has an obvious heritable component [35]. Fetal acquired factors like AMH and androgen excess might play significant roles in the beginning of PCOS. Mice exposed to high levels of AMH during gestation transmit PCOS-trait to their offspring [36]. Remarkably, all the major diagnostic manifestations of PCOS, including hyperandrogenism, central alterations, oligo-anovulation, and fertility impairments are exhibited from all these offsprings [37]. In terms of genetics, PCOS has been estimated as not a single gene, but complicated genes are related to PCOS. Around 30 genes have been associated with the development of PCOS such as AMH, AMHR2, ADIPOQ, AR and CYP17A1 [38]. Another study has demonstrated that the probability of having PCOS is 50% higher to women whose direct female, such as mother, sister, or aunt have PCOS. Taken together, both hereditary and acquired factors are regarded as the basal factors for PCOS [39].

Gut microbiota

Interestingly, the connection with microbiome and PCOS is being focused these days [1]. Women with PCOS appear to be less diverse and with greater intestinal permeability than in women without PCOS [1]. This dysbiosis appears to play an important role in the development of PCOS [40]. Fewer and less diverse intestinal microorganisms are related to hyperandrogenism and increased levels of systemic inflammation [1]. There are research reports that brain-gut axis might affect the clinical appearance and following complications of PCOS [41]. For this reason, prebiotics, probiotics and synbiotics could be considered as treatment of PCOS to regulate gut microbiota [42].

Diagnosis

There are various methods to diagnose PCOS, meaning that no obvious criteria exist. Irregular menstrual cycle, excess facial hair growth, gain of weight, acne, and infertility are common clinical diagnosis indicators [43]. Rotterdam criteria is regarded as the most recommended criteria for diagnosis of PCOS. According to this criterion, patients are diagnosed with PCOS if they have two or more of the following features. The first feature is hyperandrogenism, which can be assessed biochemically by elevated testosterone levels and increased dehydroepiandrosterone sulfate (DHEAS) or androstenedione (ANSD) [44]. Modified ferriman-gallwey score is clinically used. The second feature is oligo anovulation characterized by menstrual cycles longer than 35 days or fewer than 8 menstrual periods per year. The third feature is polycystic ovarian morphology, which can be identified if there are more than 20 follicles per ovary and if the ovarian volume is greater than 10 cm³, as assessed by transvaginal ultrasound [43].

Since symptoms of PCOS can overlap with those of Cushing’s syndrome, hyperprolactinemia, thyroid disease, and adrenal hyperplasia [1], physical examination and hormone level measurement are also recommended to differentiate these conditions. Through physical examination, cutaneous signs can be noticed such as androgenic alopecia, skin tags, acne, terminal hair development, acanthosis nigricans, and baldness of male pattern in women [17]. Deepening of the voice, muscular mass, or development of clitoromegaly could be other signs for detecting PCOS [17]. Based on the pathophysiology of PCOS, the evaluation of rising in LH to FSH ratio could be a major indicator [15]. Moreover, AMH has been considered as a significant measurement and used as a substitution with ultrasound. It is based on the research that the number of ovarian antral follicles is closely correlated with AMH levels, indicating the potential of AMH as a biomarker of PCOS [45].

In summary, PCOS patients could be classified into phenotype A, B, C, or D based on manifest symptoms (Table 1) [46]. In a study tracked the 312 patients of PCOS for a year, the most common phenotype of the PCOS is type A including hyperandrogenism, PCOs on ultrasound, and irregular cycles. Group A manifests more obesity, IR, hyperandrogenism, and metabolic syndrome, so have a high risk of metabolic disorders and cardiovascular diseases compared to others. Also, group A is more likely to have resistance to clomiphene. This kind of classification helps to understand PCOS profoundly and predict the progression of PCOS for treating patients more effectively [47]. And type B, C, and D are followed respectively.

Table 1.

Classification by Rotterdam criteria

Type	Ovulatory dysfunction	Hyperandrogenism	Polycystic ovaries
A	Y	Y	Y
B	Y	Y	N
C	N	Y	Y
D	Y	N	Y

*Y indicates that the type is relevant to it. N indicates that the type is not relavent to it

Treatment and management of PCOS

Combined oral contraceptive pills (COCPs) consisting 2 active components, an estrogen and a progestogen, target menstrual irregularities and physical manifestations of hyperandrogenism, acne, hirsutism, and androgen-related alopecia as androgen agonists [48]. It typically is able to make the menstrual cycle normal by estrogen and progestogen-induced downregulation of hypothalamus-pituitary axis, resulting in decrease free testosterone concentrations and lowering free circulating androgens [49]. However, continuous taking COCP might increase the risk of venous and arterial thrombosis and elevate C-reactive protein (CRP) levels which cause cardiovascular diseases [50]. Some studies figured out that COCP is associated with disturbing glucose metabolism. For that reason, progestin, a synthetic progestogen that acts as agonist of progesterone, is suggested for PCOS patients based on its anti-androgenic property via competition with androgen receptors of endogenic androgens in hair and skin by hindering the 5α-reductase type I enzyme [51]. Nevertheless, there is also major side effect of this treatment such as gaining weight [52].

Since anovulation is a common symptom of PCOS, ovulation inducer is a well-known treatment of PCOS. Mostly, the first considering drugs for inducing ovulation is “clomiphene citrates”, a partially selective estrogen receptor modulator [8]. Clomiphene citrate treatment has shown that individual pregnancy rates reach around 75% within the initial 3 months [48]. It leads to increased FSH availability and continues follicular growth and LH surge, and then ovulation is followed. Especially, combination of clomiphene and hMG can stimulate human chorionic gonadotropin and in assisted reproduction, therefore, this combination has been regarded as a standard protocol to treat PCOS for a long time [53]. But there are other problems rise, in which various endometrial dysfunctions occurs, affecting fertility [54]. And some people have resistance to clomiphene, to address the problems, aromatase inhibitors are considered as ovulation inducers by increasing the secretion of FSH to stimulate follicular maturation [55].

Apart from ovulation, metformin has been typically used as a substance to decrease blood glucose levels for type 2 diabetes [22]. Several studies have confirmed the effects of metformin, which are normalization of the menstrual cycle and ovulation, and reduction of serum androgen levels on PCOS patients. Additionally, these metabolic advantages can lead to weight loss, and notably, metformin may also induce deduction weight. Metformin can not only amplify insulin sensitivity which can connect to increased proliferation and has a positive effect on dyslipidemia, and also treat skin issues like acanthosis nigricans, acne, and hirsutism [56]. Most PCOS patients have high level of CYP17 due to the theca cell production of hormone which is a precursor of androgen [57]. It was found that metformin directly affects the ovarian theca cells and diminishes the activity of CYP17 [58]. Even those positive effects of metformin, the limitation of use has been highlighted. Because its therapeutic targets focus on the improvement of IR, metformin is not recommended for PCOS patients who don’t have metabolic symptoms [59]. Statins could be one of the alternatives for decline in LH, LH/FSH ratio, testosterone, androstenedione, DHES and prolactin [46]. According to several studies, statin could decline in insulin sensitivity index, total cholesterol, fasting glucose, low density lipoprotein (LDL) cholesterol, triglycerides, and high-sensitivity C-reactive protein. Also, statins reduce ovarian androgen production by preventing the creation of androgen from theca cells and also lower total cholesterol by regulating 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase that is necessary for cholesterol synthesis [46, 60]. However, there was a study conducted with a randomized, double-blind, placebo-controlled design and a 6-month follow-up found that statins are related with glucose metabolism impairment, which can increase the risk of type 2 diabetes mellitus. Since PCOS patients are prone to hinder in glucose metabolism, using statin as PCOS treatment could have negative effects. Moreover, a limitation is that statins do not lower androgen levels or reduce steroidogenic capacity compared to healthy individuals who are on placebo [61]. Furthermore, the most common side effects of statins are headache, difficulty sleeping, flushing of the skin, drowsiness, dizziness, nausea or vomiting, abdominal cramping or pain, bloating or gas, diarrhea, constipation, and rare things are rhabdomyolysis, necrotizing autoimmune myopathy and liver toxicity.

There are clinical case reports that bariatric surgery is the most effective treatment than any other drug treatments in PCOS patients [62]. The study suggested that bariatric surgery promotes significant weight loss, which is associated with improvement in IR, hyperandrogenism, menstrual irregularity, and ovulatory dysfunction [63]. In particulate, 36 PCOS patients who did bariatric surgery achieved weight loss as well as regulate androgen level and ovarian volume and that was confirmed by ultrasound in a study conducted in 2021. Bariatric surgery was found to decrease the gaps between intermenstrual days and produce more ovulations compared to medical therapy. This can be verified using serum progesterone levels and transvaginal ultrasound [63]. Yet, it is controversial whether bariatric surgery is effectively suitable for all of PCOS patients in terms of no-correlation with AMH levels and bariatric surgery, different range of effectiveness depends on circumstances of patient, and complications [64].

Emerging remedies for PCOS

To date, it is widely established that taking medication is the first-line treatment for PCOS patients. COCPs directly lower the free circulating androgens, while metformin and statin ameliorate IR, in which its effects are secondly connected to reduction of androgen secretion from Thecal cells. PCOS women who want to be pregnant could be prescribed clomiphene citrate for stimulation of ovulation. Bariatric surgery is another option to choose for PCOS patients with overweight. However, there has been individual limitation on its use, and some even are fatal. Therefore, the need of alternative and complementary remedies for treating PCOS continues to emerge [65]. Based on the classic theory, herbal treatment addresses the overall health of patients, not just their specific symptoms, in contrast with the fact that current medications for PCOS have primarily focused on symptomatic management [2]. In addition, there is a similarity between the multifactorial pathophysiology of PCOS and the multi-component and multi-target approach of herbal medicine. Accordingly, many studies on alternative and complementary treatment for PCOS are being conducted. From this point of view, due to the characteristic of PCOS symptoms, treatment of PCOS should be dynamic and sustainable, adapting to the changing conditions and expectations of individual patients [65].

Natural remedies, which is mainly based on herbal treatment and acupuncture, provides a safe alternative to the serious side effects of current medication for PCOS. These alternative and complementary approaches are becoming more important for the best treatment of PCOS [65]. To explore the therapeutic potential of natural products for PCOS, we conducted an extensive literature survey focusing on herbal medicine and complementary treatments. Databases including MEDLINE, PubMed, and Google Scholar were queried using combinations of terms such as “polycystic ovary syndrome”, “herbal therapy”, “phytomedicine” and “alternative treatment”. Out of 2,514 initially identified articles, 69 studies were ultimately included in the review based on relevance, study design, and therapeutic focus.

Herbs

Herbal medicine is considered a promising resource for the development of safe treatments for PCOS. The effect of the herb is derived from the active ingredients in it. There are a variety of ingredients in the herb, among which effective active ingredients can treat PCOS (Table 2). For example, Citrinin, an active ingredient in tangerine peel, can inhibit obesity and also improve IR via control of inflammatory responses induced by obesity [65]. Studies have shown that herbal medicines diminished male hormones, recovered female hormones, the estrous cycle and the ovarian morphology as well as ameliorated IR and metabolism of lipids in PCOS with no adverse drug reaction or risks [66]. Recently, using phytoestrogens in many plants has been extensively studied to treat PCOS with no adverse effects [67]. As phytoestrogens are functionally and structurally similar to estrogens [67], they give protective effects on hormonal and metabolic abnormalities [68] and have a lot of health benefits. The mechanism underlying these beneficial effects of herb on PCOS was found to be related with anti-oxidative stress, anti-inflammation, inhibition of apoptosis or autophagy, and reduction of ovarian nerve growth factor (NGF) [66]. As herbs are known for the multiple target characteristics, several hormones could be controlled at the same time, and the increase or decrease levels of hormone also could vary for each experiment. Except for hormonal control, the most frequently mentioned treatment targets include (A) Ovary/cystic abnormality, (B) Decline infertility and (C) Obesity (Fig. 1). (A) includes weight change of ovary/uterus, systematic recovery of ovary/uterus, increase of graafian follicles and antral follicles, decrease of cystic follicles, changes of theca cell thickness, and increase of corpus luteum. (B) includes improved fertility including normalization of the estrous cycle. And (C) includes body weight loss and decrease of body mass index (BMI) level. Here, we introduced the functional efficacy and significant targets of natural herbs with their active compounds for treating PCOS through in vitro and in vivo studies with clinical trials.

Table 2.

List of herb for PCOS

Name	Sample	Experimental Design	Efficacy	Ref.
Labisia pumila var. alata	Labisia pumila var. alata	DHT-induced Wistar rats	- uterine weight ↑ - glucose infusion rate ↑ - plasma resistin levels ↑ - lipid profile ↓ - leptin mRNA expression in adipose tissue ↓	[69]
Matricaira chamomilla L.	Matricaira chamomilla L.	Estradiol valerate-induced Wistar rats	- signs of PCOS in the ovarian tissue ↓ - the cysts had mainly disappeared - the number of dominant follicles ↑ - estradiol and gonadotropins, LH and FSH ↓	[70]
	Chamomile with Urtica dioica L.	DHEA-induced BALB/C mice	- the number of corpus luteum, preantral, and antral follicles ↑ - the number of cystic follicles ↓ - restored estrus cycle - the number of Treg cells ↓ - The expression of MMP9 and TGFβ genes ↓	[71]
		Estradiol valerate-induced Wistar rats	- improvement in serum level of thyroid hormones - disappearance of most thyroid gland pathological changes - estrogen ↓ - MDA ↓ - GPx, CAT and GSH ↑ - the apoptotic death of thyroid cells ↓ - reduction of caspase-3 immuno-expression	[72]
	Matricaira chamomilla L.	Estradiol valerate-induced Wistar rats	- testosterone ↓ - normalized serum lipid profile - antioxidant activity ↑ - p53 expression in kidney glomeruli and tubules ↓ - the expression of the anti-apoptotic gene Bcl2 ↑	[74]
	Chamomile capsule	80 women of childbearing age with PCO (randomized clinical trial)	- testosterone ↓ - normalized serum lipid profile	[73]
Vitex agnus-castus L.	Vitex agnus-castus L.	Letrozole-induced SD rats	- progesterone ↑ - testosterone ↓ - did not affect the estradiol and DHEA levels.	[75]
		Letrozole-induced Wistar rats	- progesterone, estrogen, FSH levels ↑ - testosterone, LH ↓ - normalized expression of KISS-1 gene	[78]
		Letrozole-induced Wistar albino rats	- testosterone, estrogen, LH ↓ - progesterone, FSH ↑  - glucose, insulin ↓ - antioxidant activity ↑ - normalized serum lipid profile	[77]
	vitex-agnus castus with metformin	DHEA-induced SD rats	- FSH and prolactin ↓ - LH ↑ - glucose, cholesterol and triglycerides levels ↓ - antioxidant activity ↑	[76]
Tribulus terrestris L.	Tribulus terrestris L. with Withania somnifera L. Dunal	Letrozole-induced Wistar rats	- FSH level ↑ - LH, estradiol and testosterone levels↓ - serum total cholesterol ↓ - ovarian weight ↓ - uterine weight ↑ - normalized the estrus cycle	[80]
	Nardostachys jatamansi DC with Tribulus terrestris L.	Estradiol valerate-induced SD rats	- estradiol, testosterone levels↓ - progesterone levels ↑ - corpus luteum ↑ - normalized the estrus cycle - regulated ovarian follicular growth	[81]
Symplocos racemose Roxb.	Symplocos racemose Roxb.	Letrozole-induced albino Wistar rats	- estrogen, progesterone levels ↑ - testosterone levels ↓ - ovarian weight ↓ - uterine weight ↑ - cholesterol levels ↓ - recovery of follicle with intact structure of granulosa layer and thecal layer - prevented ovarian cell dysfunction in PCOS to improve fertility - well developed antral follicle with oocyte and antrum	[82]
Origanum majorana L.	Origanum majorana L.	DHEA-induced Albino rats	- NO ↓ - total antioxidant capacity ↑ - serum progesterone, estradiol, FSH ↑ - serum testosterone ↓ - body weight gain ↓ - ovarian cysts number ↓	[83]
		DHEA-induced Wistar rats	- ovary weight (the number of ovarian cysts) ↓ - estradiol ↓ - adiponectin ↑ → insulin sensitivity ↓ - the IL-6 level ↓ - the levels of ovarian SOD, GPx enzymes ↑ - the level of TBARS↓	[84]
Foeniculum vulgare Mill.	Foeniculum vulgare Mill.	Estradiol valerate-induced Wistar rats	- serum estrogen ↓ - serum progesterone ↑ - uterine epithelial thickness ↓ - uterine endometrial thickness ↑	[87]
	aqueous extract of fennel	Estradiol valerate-induced Wistar rats	- mean values of blood urea nitrogen ↑ - histopathological changes of kidney samples	[88]
	Fennel essential oil	30 female students aged range of 20–35 and met the Rotterdam diagnostic criteria for PCOS (double-blinded, randomized controlled study)	- DHEAS ↑ - ovarian follicles number ↓	[85]
	Fennel seed infusion plus a dry cupping	61 patients with oligomenorrhea	- menstrual cycles ↑ - the mean pain severity ↓ - serum estradiol ↓	[86]
Nigella sativa L.	Nigella sativa L. extract	DHEA-induced Wistar rats	- LH, testosterone, estrogen ↓ - FSH, progesterone ↑ - FBG, insulin levels ↓ - SOD, GPX, CAT ↑ - body weight ↓ - the mean number of primordial and primary follicles, secondary and Graffian follicles ↑ - cystic and atretic follicles ↓ - corpus luteum ↑	[89]
Panax ginseng Meyer	Total saponins of red ginseng	Estradiol valerate-induced SD rats	- NGF in the ovaries ↓ - body weight ↓ - cystic follicles ↓ - the numbers of corpora lutea and corpora albicantia ↑	[90]
	Red ginseng water extract	DHEA-induced SD rats	- body and ovary weights ↓ - the number & size of ovarian cysts ↓ - testosterone, estradiol, aromatase levels ↓ - macrophage infiltration ↓ - IL-8, MCP-1, IL-1β, IL-6, iNOS ↓ - EGF, TGF-β↑ - Bad, Cleaved caspase-9, Cleaved caspase-3 ↓ - p-IκBα, p–NF-κB, Nrf2, HO-1, NQO-1 ↓	[91]
	Ginseng extract and metformin	Letrozole-induced Wistar rats	- the number of ovarian cysts and ovarian weights ↓ - serum LH, testosterone and NF-κB levels ↓	[92]
		Letrozole-induced Wistar rats	- estrogen, progesterone ↑ - testosterone, LH ↓ - ovarian follicles ↓ - cystic follicles ↓	[93]
Linum usitatissimum L.	Linum usitatissimum L. hydroalcoholic extract	Estradiol valerate-induced SD rats	- progesterone ↑ - testosterone ↓ - the number of preantral follicles, antral follicles and corpus luteum ↑ - the number of cystic follicles and diameter of antral follicles ↓ - the thickness of granulosa layer ↑ - the thickness of theca layer and tunica albuginea ↓	[95]
	Fenugreek Seeds and Flaxseed	Estradiol valerate-induced Wistar rats	- glucose, insulin, insulin resistance, AST, ALT, GGT ↓ - LH, FSH, ‎testosterone ↓ - progesterone ↑ - body weight ↓ - antioxidant activity ↑ - normalized serum lipid profile - lipid ‎peroxidation ↓	[96]
	Flaxseed oil and Fennel essential oil	Estradiol valerate-induced Wistar rat	- blood insulin hormone ↑ - fasting blood glucose concentration ↓ - their anti-diabetic effects and anti-oxidative properties improved the body mass index and progesterone concentration, and HOMA-IR, HOMA-β, and QUICKI indices	[96]
	polyunsaturated fatty acids from Flaxseed	Estradiol valerate-induced Wistar rats	- normalized serum lipid profile - blood glucose and insulin levels↓ - body weight ↓ - testosterone, LH ↓	[97]
Aloe barbadensis Mill.	The hydro-extract of Aloe	Estradiol valerate-induced Wistar rats	- estrogen ↓ - progesterone ↑	[98]
	Aloe vera gel formulation	Letrozole-induced Charles Foster rats	- plasma triglyceride, LDL cholesterol ↓ - HDL-cholesterol ↑ - normalization of estrous cycle and glucose tolerance - HMG CoA reductase activity ↑	[99]
	Partially purified non-polar phytocomponents from Aloe barbadensis Mill. gel	Letrozole-induced Balb/c mice	- oral glucose intolerance ↓ - fasting insulin level, HOMA-IR ↓ - triglyceride ↓ - exhibited mature follicles, corpora lutea and few cystic and atretic follicles - testosterone ↓ - progesterone ↑ - ovarian AR, Star expression ↓ - ovarian Esr-1, Pgr, Hsd3b1, Cyp19a1 expression ↑	[100]
	Aloe vera gel formulation	Letrozole-induced Charles Foster rats	- restoration of estrous cycle - oral glucose tolerance ↓ - ovary atretic cysts ↓ - ovarian 3β hydroxy steroid dehydrogenase (3β HSD) and 17β hydroxy steroid dehydrogenase (17β HSD) activities ↓	[101]
	Aloe vera	Letrozole-induced Swiss albino mice	- body weight ↓ - the number of estrous cycle ↓ - diestrous ↑ - recovery in the body weight - glucose, cholesterol ↓ - SOD ↓ - LH ↓ - recovery in follicular cyst, medulla, and Graafian follicle	[102]
Mentha piperita L.	peppermint	Letrozole-induced albino Wistar rats	- body weight, ovarian weight ↓ - LH, testosterone ↓ - estrogen ↑ - infertility ↓ - improved PCOS symptoms and ovarian histology	[103]
	spearmint oil	Letrozole-induced Wistar albino rats	- body weight ↓ - testosterone level ↓ ovarian cysts and atretic follicles ↓ - the number of corpus lutea ↑ - Graafian follicles ↑	[106]
	Menta herbal tea	12 patients with PCOS, 9 patients with idiopathic hirsutism	- testosterone ↓ - LH, FSH and estradiol ↑	[104]
	Mentha longifolia syrup	A double-blind, randomized, placebo-controlled, multicenter study 120 women with secondary amenorrhea and oligomenorrhea	- LH ↓ - menstrual cycles ↑	[105]
Glycyrrhiza glabra	licorice	Estradiol valerate-induced NMIR mice	- estradiol ↑ - testosterone, estrogen ↓ - the number of primary, preantral follicles ↑ - the number of preantral, cystic follicles ↓ - corpus luteum ↑ - body weight ↓ - fertilization rate ↑	[107]
	Licorice ethanol extract	Letrozole-induced SD rats	- FSH ↑ - LH/FSH ratio ↓ - mRNA expression levels ↑ - the number of follicular cysts and theca layer thickness ↓ - the number of antral follicles and granulosa cell layer thickness ↑	[110]
	licorice extract	Estradiol valerate-induced NMIR mice	- testosterone and estradiol levels ↓ - the number of oocytes, number of two-cell and blastocysts ↑ - fertilization ↑	[108]
	licorice extract	DHEA-induced BALB/C mice	- the number of ovarian cysts ↑ - restored estrus cycle - TGF-β expression level ↑	[109]
	Spironolactone, licorice	32 women with PCOS (16 received 100 mg spironolactone and 16 spironolactone plus 3.5 g of licorice a day)	- activation of the renin–aldosterone system ↓ - prevalence of metrorrhagia ↓ - body weight ↓ - side effects related to the diuretic activity of spironolactone ↓	[111]
Gymnema sylvestre R. Br.	Gymnema sylvestre R. Br., Pergularia daemia (Forssk.) Chiov)	Estradiol valerate-induced albino Wistar rats	- normalized the estrus cycle	[115]
	Gymnema sylvestre R. Br.	DHEA-induced C57BL6/J mice	- obesity, estrus irregularity ↓ - insulin levels ↓ - testosteron levels, LH/FSH ratios ↓ - FSH, progesterone, estradiol ↑ - AST, ALT l ↓ - triglyceride, cholesterol↓ - IL-6, IL-17, IL-23, TNF-α ↓ - normalized cystic follicles and granulosa cell layer - YAP1-positive cells in the ovary ↓	[118]
	Gymnema sylvestre R. Br., Pergularia daemia (Forssk.) Chiov	Letrozole-induced Wistar rats	- normalized estrus cyclicity - LH, testosterone, estrogen ↓ - FSH and progesterone ↑ - ovary weight ↓ - showed the minimal number of cysts, normal healthy follicles fluid filled antrum ↓ - corpus luteum↑ - normalized serum lipid profile	[113]
	Gymnema sylvestre R. Br.	Letrozole-induced albino Wistar rats	- serum blood glucose ↓ - LH, testosterone ↓ - estrogen, FSH and progesterone ↑ - normalized serum lipid profile - restored estrus cycle - showed normal healthy developing follicles, corpus luteum and few follicular cysts	[112]
	Gymnema sylvestre R. Br.	Letrozole-induced Wistar rats	- restored estrus cycle - LH, testosterone ↓ - estradiol, FSH and progesterone ↑ - insulin resistance ↓ - normalized serum lipid profile - GLUT4 and AMPK mRNA expression in ovarian cells ↑ - showed few follicular cysts, various stages of follicles, and the presence of the corpus luteum	[114]
Cinnamomum zeylanicum	cinnamon	DHEA-induced C57BL/6 mice	- IGF-I level ↓ in plasma and ovary tissue  - IGFBP-1 level ↑ in plasma and ovary tissue - LH, FSH, testosterone ↓ - insulin levels ↓ - insulin resistance ↓ - restored estrus cycle - cystic follicles ↓ - corpora lutea ↑ - body weight ↓	[119]
	cinnamon	84 overweight or obese PCOS patients	- serum fasting blood glucose, insulin, insulin resistance ↓ - body weight ↓ - normalized serum lipid profile serum triglyceride and body mass index ↓	[120]
	cinnamon	45 women with PCOS	- menstrual cycles ↑ - progesterone ↑	[121]
	Hydroalchoholic extract of cinnamon zeylanicum	Estradiol valerate-induced Wistar rats	- blood glucose, insulin, LH, testosterone ↓ - estrogen ↑ - antioxidant activities ↑ - the primary follicles, cystic follicles ↓ - the preantral follicles, antral follicles, corpus luteum ↑	[122]
Curcuma longa L.	Curcumin	Letrozole-induced Wistar albino rats	- progesterone, estradiol ↑ - testosterone ↓ - normalized serum lipid profile - serum glucose and HbA1c levels ↓ - uterine weight ↑ - antioxidant activity ↑ - size of follicles ↑ / corpora lutea and antral follicles ↑	[125]
	Curcumin	Estradiol valerate-induced Wistar rats	- thickness of theca layer ↓ - the number of corpus luteum diameter ↑ - the number of corpus luteum ↑ - the number of cysts and antral follicles ↓ - IL-6 ↓	[126]
	self-nanoemulsifying drug delivery system extract of Curcuma longa L.	Letrozole-induced Wistar rats	- GLUT-4 in muscle cells ↑ - FBG, insulin, and HOMA-IR score ↓ - improved expression of GLUT-4, FBG, Insulin level, and HOMA-IR score via insulin sensitizer activity	[123]
	Turmeric extract	Letrozole-induced Swiss Albino mice	- body weight ↓ - progesterone, estrogen, FSH levels ↑ - LH ↓ - blood glucose, cholesterol, triglyceride levels ↓ - concentration of plasma IL-6 ↓ - plasma adiponectin ↓	[124]

Fig. 1.

Veen diagram visualizing the therapeutic targets of each herb for PCOS. (A) Ovary/Cystic abnormality, (B) Decline infertility and (C) Obesity

Labisia pumila var. Alata

Labisia pumila var. alata is known to have phytoestrogenic effect [69]. It has been a treatment for menstrual irregularities, and a postpartum medicine to induce and promote childbirth for many generations in South Asia [69]. At the end of the experiment, daily oral administration of 50 mg/kg L. pumila var. alata increased weight of the uterus and also improved the lipid profile and insulin sensitivity, while without changes in the weights of the inguinal, parametrial, retroperitoneal and mesenteric adipose tissue depots in DHT-induced PCOS rats [69]. Thus, L. pumila var. alata could be a promising herbal treatment with its phytoestrogenic effects.

Matricaira chamomilla (Matricaria recutita) L

Matricaira chamomilla L., chamomile, is widely used herbal treatment as well as relaxing tea with its anti-spasmolytic and anti-inflammatory effects. Antispasmodic properties of chamomile not only ease menstrual cramps but lessen the probability of premature labor and also stimulates menstruation [70]. These benefits are reported to be attributed to the major ingredients in chamomile, such as flavonoids, phenolic compounds, and phytoestrogens [71]. Even, the extract of Chamomile flowers is revealed to normalize the histological feature of PCOS ovary and assist LH excretion [72]. In a randomized, double-blind, placebo-controlled trial involving PCOS 80 women, daily intake of 370 mg chamomile capsules over 12 weeks led to a significant reduction in serum testosterone levels compared to placebo, indicating its potential as a complementary anti-androgenic therapy [73]. The alcoholic extract of chamomile flowers at the 25, 50 and 75 mg/kg concentrations recovered PCO condition through its impact on the Gamma-aminobutyric acid (GABA) pathway in the LH secretion in estradiol valerate-induced rats. It also increased dominant follicles and cause better endometrial tissue arrangement [70]. Additionally, chamomile’s therapeutic effects are partially mediated through its antioxidant and anti-apoptotic mechanisms, as demonstrated in histological and biochemical analyses [71]. As seen in the other experiment, co-administration of chamomile and Nettle (Urtica dioica L.) and their combination could be an efficient treatment to reduce the negative impacts of PCOS and supplement the immunological and histological improvement [71]. Furthermore, the combination of chamomile and metformin was found to improve hypofunction of thyroid associated with PCOS, through antioxidant and antiapoptotic mechanisms is shown in the histological examinations [72]. Specifically, chamomile was found to reduce kidney damage caused by PCOS [74]. In a rat model of PCOS, oral administration of 200 mg/kg chamomile extract significantly reduced serum LH levels and normalized LH/FSH ratio, while also increasing the number of Graafian follicles in a dose-dependent manner [71]. Through those results, chamomile could attenuate the PCOS-affected follicular ovary by regulating the LH surge secretion.

Vitex agnus-castus L

Leaves of Chaste tree, as known as Vitex agnus-castus L.; VAC have been known to have anti-inflammatory and fertility-enhancing properties. These benefits, which improve fertility and help regulate menstrual cycles [75], indicating that Chaste tree leaves a potential treating herb against PCOS [76]. Above all, Chaste tree, acting through the axis of hypothalamus-pituitary [75], regulates various hormones, especially LH. Those are assumed to be from the components including flavonoids, glycosides [77] and opioid, dopamine and also estrogen receptor ligands [78]. In the study, VAC treatment to letrozole-induced PCOS rats led to modifying the expression of KISS-1 gene in the hypothalamus with the up-regulated progesterone, estrogen and FSH and down-regulated testosterone and LH [78]. As seen at another experiment, VAC fruit might be effective in PCOS by changing the levels of sex hormones to restore balance [75]. And VAC plant extract was shown to have various beneficial effects on anovulation [77] and even the combination of metformin and this herb could improve its action by the synergistic effect [76]. Taken together, VAC is likely to exhibit the adjusting property on HPG axis by regulating balance of KISS-1 and sex hormone in PCOS.

Tribulus terrestris L

Tribulus terrestris L. (TT) is traditionally known to be a sexual activity enhancer. Studies investigating the pharmacological activities of TT focused on the reproductive system for both genders. Especially, TT is reported to promote ovulation, in this regard, the active steroidal saponins have been known to be included in TT [79]. TT is not expected to exert amelioration of PCOS symptoms based on its androgenic action, but there are some reports that TT could change the estrous cycle in practice. The combination with the hydroalcoholic extracts of TT fruits and Withania somnifera L. Dunal (Ashwagandha) roots have a significant effect on anti-androgen which regulates the overall hormone imbalance in PCOS. In addition, the hotness which is the characteristic of the combination is appropriate to infertility and amenorrhea. Additionally, changes in estrous cycle, recovery of ovary/uterus including increase of uterine weight, decrease of ovary weight are observed in letrozole-induced PCOS rats [80]. In another experiment, TT with Nardostachys jatamansi DC. in a form of dried powder showed the anti-androgen effects and remarkable normalization of estrous cyclicity [81].

Symplocos racemosa Roxb

Symplocos racemosa Roxb. is an evergreen tree found in lower hills or plains throughout East and North India, and even in the Himalayas. This herb has been traditionally used in menorrhagia and female reproductive dysfunctions. Stem barks of Symplocos racemosa Roxb. used in aqueous form significantly regulated androgen and estrogen levels. At high dose, 1 g/kg, improvement of fertility, ovarian weight, uterine weight and the ovarian histology, recovery of follicle granulosa layer, thecal layer and hormone imbalance were observed in Symplocos racemosa Roxb.-treated PCOS rats [82].

Origanum majorana

Origanum majorana L., a common name Marjoram, is an aromatherapeutic herb mainly found in Mediterranean countries. The Marjoram plant is traditionally well-known to regulate hormonal imbalance and the menstrual cycle. The main chemical compounds are monoterpene and phenolic acid. Especially among phenolic compounds, thymol and carvacrol are responsible for different biological activities such as antioxidant via scavenging free radicals due to its hydrogen donating ability. As shown in the study, 100 mg/kg of Marjoram extract recovered the serum levels of progesterone, estradiol, testosterone and FSH with body weight loss in DHEA-induced PCOS rats. Additionally, the number of ovarian cysts was significantly reduced and follicular structure in ovaries was normalized by Marjoram administration. In other study, the marjoram treatment attenuated insulin sensitivity by increasing the serum adiponectin level in DHEA-induced PCOS rat [83]. Furthermore, the levels of ovarian superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzymes were significantly regulated in combination with Marjoram and metformin in PCOS rats, indicating that Marjoram showed antioxidant and anti-inflammatory activity against pathogenesis of PCOS [84]. These multiple mechanisms may work synergistically and also improve PCOS symptoms.

Foeniculum Vulgare mill

Foeniculum Vulgare Mill., as known as Fennel, is a well-known Mediterranean aromatic plant used as spice. It is also a medicinal herb that is generally recommended by Iranian traditional practitioners for ovarian health and infertility in women as it has an effect like estrogen [85]. Especially, Fennel seed containing mainly anethole, a phytoestrogen volatile oil, possesses antioxidant and antimicrobial activities [86]. According to the study, Fennel has demonstrated decreased serum estrogen level and epithelial tissue thickness of uterus in estradiol valerate-induced PCOS rats, while the serum progesterone and uterine endometrial thickness were increased [87]. Additionally, the aqueous extract of fennel was found to exert renoprotective effects in PCOS animal models by preventing progressive glomerulosclerosis [88]. Based on those preclinical studies, Fennel essential oil capsules were administrated to PCOS women aged 20–35 for 3 months by a randomized double-blind, placebo-controlled trial. From that study, Fennel has demonstrated to decrease the dehydroepiandrosterone sulphate (DHEAS) and both ovarian follicles number. However, the treatment did not alter the menstruation cycle, hirsutism, BMI and ovarian cyst symptoms, indicating that its efficacy in human studies remains unclear, even though Fennel was found to have protective effects on uterine tissues in PCOS-induced rat models [85]. In Persian medicine, Fennel along with dry cupping have been used to manage oligomenorrhea. Dry cupping is recommended during a monthly period ending in ovulation. In a randomized clinical trial involving 68 PCOS patients, dry cupping therapy combined with daily Fennel seed infusion (3 g/day) for 3 cycles resulted in significant improvements in menstrual regularity and estradiol levels compared to metformin, with no adverse effects reported [86].

Nigella sativa

The seed of Nigella sativa L., known as Black cumin, was used traditionally as treatment for menstrual abnormality, inflammatory and painful disorders. The compounds extracted from N. sativa are thymoquinone, carvacrol, t-anethole, and 4-terpinol and those compounds are reported to have radical scavenging, anti-inflammatory, and antioxidant characteristics. In the experiment, the hydroalcoholic extract of Black cumin seed is used and phytoestrogens are included in the extract as an active compound of Black cumin. According to the experiment, due to the phytoestrogens, Black cumin improved hormone imbalance including decreasing the estrogen and androgen levels with lowered the food intake and weight loss. In letrozole-induced PCOS rats, administration of 600 mg/kg black cumin extract significantly decreased serum testosterone levels and restored estrous cyclicity. Specifically, dose-dependent reduction in body weight and food intake was observed over 28 days [89]. Taken as liquid, diabetic improvement was observed. N. sativa increased the number of graafian follicles and corpus luteum, while it decreased the cystic follicles [89].

Panax ginseng

The roots of Panax ginseng Meyer were traditionally used in eastern Asia for slowing down aging [90], replacing estrogen, and activating estrogen receptors [91]. The main compound of ginseng is known to be ginseng saponins, composed of more than 30 ginsenosides steroid glycosides [92]. A study has revealed that total saponins of red ginseng lowered the number of cystic follicles and ovarian weight, and attenuated nerve growth factor (NGF) expressions in the ovaries, not in brain areas of the pituitary and hippocampus of estradiol valerate-induced PCOS rats. Authors suggested that total saponins of red ginseng affected the NGF expression in the periphery rather than centrally of brain [90]. In addition, red ginseng water extracts significantly inhibited the number and size of ovarian cysts as well as body and ovarian weight in DHEA-induced PCOS rats. Red ginseng exerted the anti-inflammatory and anti-oxidant effects, demonstrated from the results that red ginseng reduced the macrophage infiltration and regulated the pro-inflammatory cytokines and inducible nitric oxide synthase in PCOS ovaries [91]. Also, combination with oral contraceptives and red ginseng extract normalized abnormal ovarian weights, and decreased serum LH level and ovarian cysts in estradiol valerate-induced rats [93]. Furthermore, 500 mg/kg of ginseng extract with 500 mg/kg metformin reversed the decreases of serum estrogen, progesterone and number of cystic ovarian follicles, while increases of serum testosterone and LH levels in letrozole-induced PCOS rats [92].

Linum usitatissimum L

The seed of Flaxseed, Linum usitatissimum L. contains bioactive components that are efficient in protecting some long-term diseases like cancer, diabetes, cardiovascular diseases and cerebrovascular stroke [94]. According to an experiment, Flaxseed hydroalcoholic extract improved the hyperandrogenism and ovarian histomorphometric features disturbed by induction of PCOS [95]. The results from another experiment showed that Flaxseed and Fenugreek each had beneficial effects in improving hyperandrogenism and reducing IR disrupted by PCOS [94]. Flaxseed oil and Fennel essential oil improved the serum glucose, insulin, progesterone concentration, body mass index, and QUICKI indices, and homeostatic model assessment for insulin resistance (HOMA-IR), HOMA-β in PCOS rats due to their anti-oxidative properties and anti-diabetic effects [96]. Interestingly, polyunsaturated fatty acids from Flaxseed or fish oil may have positive effects on glycemic control, hyperinsulinemia, lipid profile and obesity as they have enhanced anti-inflammatory and anti-atherogenicity properties [97].

Aloe barbadensis mill. (Aloe vera)

Aloe, originally Aloe barbadensis Mill. or called Aloe vera, which contains vitamin A, C, and E [98] has long been recognized for its medicinal uses and is well known for its anti-inflammatory, hypoglycemic, lipid lowering, and antioxidant properties [99]. The hydro-extract of Aloe reduced and increased estrogen and progesterone levels in rats respectively. Polysaccharide, an active pharmaceutical ingredient of the Aloe leaves and gel, also shows the well-known medicinal effects mentioned earlier. That is, using Aloe would be useful in treating PCOS and infertility disorders [98]. Meanwhile, an Aloe vera gel formulation has therapeutic value for treating female reproductive disorders, including menopausal problems and menstrual disturbances by providing supportive and beneficial effects on folliculogenesis and ovarian tissue [98, 100]. In addition, a preliminary study showed that Aloe vera gel can exert protective effects against the phenotype of PCOS and also against the related metabolic complication by normalizing steroid status of the ovary and altering major steroidogenic activity [99, 101]. This might be due to the phyto-components such as polyphenols, flavonoids, sterols along with some nutrients in the extract [101]. The specific phyto-component affecting the enzyme system is not identified yet, but in the study, Aloe vera gel directly affects key enzymes such as 3β HSD, reducing enzyme activity and modulating the pathway toward estradiol formation [102]. Also, according to another study, among partially purified non-polar phytocompounds of Aloe vera gel, LP1 and LP3 showed maximum potential to regulate the molecular targets related to PCOS. Oral administration of these greatly alleviated PCOS complications that these may be a replacement of metformin [100]. The other experiment revealed that the active components in Aloe vera gel, polyphenols and phytosterols, are active components that are controlling the hyperglycemic condition [99].

Mentha Piperita L

Peppermint (Mentha piperita L.) is a hybrid mint which cross between spearmint (M spicata L.) and water mint (M. aquatica L.) [103]. Mentha is known to have anti-tumor, anti-inflammatory, and anti-oxidative effects [104]. The main compound of spearmint, Carvone, is significant for treating PCOS [103, 104]. According to several studies, peppermint, used as tea or even syrup [105], is reported to be effective to PCOS patients with hirsutism due to its anti-androgen characteristic, and clinically is prescribed to patients who are infertile because of anovulation and poor oocyte quality [103, 106]. Although side effects derived from spearmint and peppermint are often suggested which includes allergy and iron deficiency anemia [104], the free testosterone and triglyceride were decreased, while LH, FSH and estradiol levels were increased in Menta herbal tea-drunk PCOS hirsutism women [104].

Glycyrrhiza glabra

Licorice (Glycyrrhiza glabra L.) is known to have anti-oxidative, anti-bacterial, anti-fatigue properties. In respect to PCOS, research has shown Licorice has estrogen activity [107]. Dried Licorice root is composed of almost 500 components. The active components of Licorice are glycyrrhizin which is suggested as reducing testosterone levels, anti-inflammatory, lessening the androgen secretion, and glabridin and glabrene which act like estrogen are demonstrated causing increased aromatase activity [108, 109]. According to several experiments with Licorice regarding on PCOS, it acts to restore the menstrual cycle with anti-testosterone effects, and it is more effective to take with other herbs than to take in single [110]. In one study genetically analyzed the type of follicles and reported which phase Licorice affects [110]. In another study, taking sulfadoxine-pyrimethamine, which is effective for hyperandrogenism, with Licorice increased the advantage of sulfadoxine-pyrimethamine and lessens the side effects of sulfadoxine-pyrimethamine which is the ruined menstrual cycle [111]. Except for those effects, weight loss, decrease cystic follicles, increase luteum corpus and fertility rate are mentioned.

Gymnema sylvestre R. Br

Gymnema (Gymnema sylvestre R. Br.) leaf is a medicinal herb widely used as a traditional medicine to treat various diseases, particularly diabetes [112]. In this herb, the key bioactive secondary metabolites, gymnemic acids, consist of saponins, anthraquinones and acidic glycosides act as a dietary supplement [113]. Thanks to these, Gymnema known as “sugar destroyer” [113] has an ability to modulate insulin and increase glucose metabolism [114]. Along with that, as Gymnema also has effects like decreasing body weight, blood triglyceride and cholesterol [112], it was assumed to be used for PCOS treatment [115]. The study showed that using the individual Gymnema significantly changed the estrus and menstrual cycle positively, but only moderately effective when compared to Trellis-vine (Pergularia daemia (Forssk.) Chiov). According to this study, the combination of these herbs appears prospective for developments of phytomedicines to manage and treat PCOS [115]. Also, combinating Gymnema and trellis-vine would have a potent synergistic activity to the hyperinsulinemia, hyperandrogenism, follicular cysts and anovulation in PCOS [113]. Similarly, one study revealed that Gymnema is considered an alternative remedy treating metabolic and reproductive complications in PCOS through the characteristics of regulating IR by improving utilization of glucose [112]. Moreover, another study explained that gymnemic acid at 400 mg/kg enhanced ovarian glucose transporter type 4 (GLUT4) expression and reduced serum insulin levels in a dose-dependent manner, supporting its action via the AMP-activated protein kinase (AMPK) pathway [114]. AMPK importantly plays roles in the regulation of lipid and glucose uptake, in which AMPK activation could regulate the glucose transporter GLUT4 and suppress the cholesterol synthesis, leading to the amelioration of insulin resistance [116]. Hyperandrogenism and hyperinsulinemia environment in PCOS promotes the disrupted glucose uptake and accelerated the lowering of insulin sensitivity [117]. Thus, the activated AMPK and GLUT4 expressions by gymnemic acid sequentially might improve insulin resistance. Meanwhile, the other experiment reported that Gymnema treatment enhanced the mitochondrial architecture of PCOS ovary that is mediated by a major pathogenic gene, yes associated protein 1 (YAP1). In addition, this study provided fresh insights into the improvement of activated mitochondrial structure by the therapeutic intervention of this herb for the clinical PCOS management [118].

Cinnamomum zeylanicum

Cinnamon (Cinnamomum zeylanicum L.) was known for regulating insulin for 20 years ago. Procyanidin polyphenol type-A polymer and Cinnamaldehyde, known as the main compounds of Cinnamon, reduced the glucose tolerance and regulated obesity by inhibiting the accumulation of lipids, respectively [119]. According to an experiment using DHEA-induced PCOS mice, Cinnamon recovered the disrupted estrous cycle, the number of corpora lutea and oocyte. There were significant changes on the total testosterone, ratio of LH/FSH, serum insulin, IGF-1 and IGFBP-1 levels in the 100 mg/kg Cinnamon powder-treated PCOS mice compared to DHEA-induced PCOS mice, indicating that Cinnamomum zeylanicum acts via polyphenol-mediated insulin sensitization and AMPK activation [119]. In another experiment, significant decline in the plasma levels of blood glucose, insulin, LH, FSH, and testosterone with the increase of estrogen level was observed in hydroalchoholic extract of C. zeylanicum in estradiol valerate-induced PCOS rats [120]. The double-blind randomized controlled clinical trial was conducted to investigate whether Cinnamon capsule could alter the biochemical markers regarding PCOS symptoms. 1.5 g of Cinnamon treatment for 8 weeks to PCOS patients significantly inhibited serum fasting blood glucose, insulin, HOMA-IR, total cholesterol and LDL-cholesterol, but increased HDL-cholesterol compared to placebo group [121]. Moreover, another prospective, placebo controlled, double-blinded randomized trial showed that there is improvement on menstrual cyclicity between before and after taking 1.5 g of Cinnamon supplements for 6 months in PCOS women [122].

Curcuma longa L

Curcumin longa L., known as Turmeric, has been considered as anti-cancer, antioxidant, anti-inflammatory, anti-rheumatic and anti-microbial herb for its bioactive effect [123]. Several studies showed that this herb not only has estrogenic effects but also acts as a safe phytochemical which can improve IR by increasing adiponectin circulation. This effect appears to be mediated through enhanced adiponectin signaling, leading to improved insulin sensitivity via AMPK activation and suppression of systemic inflammation [124]. The broad-spectrum biological effects of Turmeric have made it a bright medicine to treat clinical and pathological abnormality in PCOS conditions [125]. Curcumin is a polyphenol from the rhizome of Curcumin longa L. and makes up about 2 to 8% of the turmeric preparations [125, 126]. In the study, Curcumin had many beneficial effects like Clomiphene citrate to treat PCOS conditions and induce ovulation. Curcumin normalized the profile of hormone and lipid, glycemic and antioxidant status besides ovarian morphology [126]. Another study showed that Turmeric which inhibits IL-6, tumor necrosis factor-α and CRP by improving corpus luteum and ovulation, decreasing the follicular sheath, would enhance histological features of PCOS ovary and push it towards the healthy and active ovary [125]. In addition, it was proven the self-nanoemulsifying drug delivery system extract of C. longa enhanced skeletal muscle GLUT-4 expression, reduced fasting insulin, HOMA-IR scores and blood glucose levels in PCOS rat model [123]. According to the other study, adiponectin, a circulating protein created by adipocytes, has been inversely associated with metabolic diseases and PCOS. When changing circulating androgen-adiponectin balance, Turmeric extract mitigates inflammation-related comorbidities and endocrine-metabolic abnormalities relevant to letrozole-induced PCOS [124]. Also, the experiment revealed that the combination of the curcumin and zinc is promising to normalize reproductive hormones. Zinc is implicated in all processes such as an insulin-like tissue, storage and excretion. This value is displayed by reversing changes related to the PCOS [125].

Formulation

Based on the available database and previous studies, a mix of different medicinal plants was proposed due to their pharmacological properties from their phytoconstituents (Table 3). Therefore, using various potent herbs in combination can provide a synergistic and potentiating effect for treating chronic sickness such as PCOS. Each of the herbs targets different clinical PCOS symptoms [2]. Due to the availability, affordability, higher therapeutic efficacy, safety and improvement of patient compliance, global demands for polyherbal formulations are continuously increasing to manage PCOS [114].

Table 3.

List of formulation for PCOS

Name	Constituents	Experimental Design	Efficacy	Ref.
Herbal combination and its syrup formulation	Myrica esculenta, Symplocos racemosa, Mimosa pudica, Cyperus rotundus, Asteracantha longifolia, and Saraca asoca, Aegle marmelos, Berberis aristata whereas Woodfordia fruiticosa and Terminalia arjuna	Letrozole-induced SD rats	- testosterone level ↓ - progesterone level ↑ - triglyceride level ↓ - restoration of folliculogenesis	[127]
Polyherbal syrup	Saraca asoca, Gymnema sylvestre, Pergularia daemia, Cinnamomum zeylanicum, Caesalpinia bonduc, and Withania somnifera	Letrozole-induced albino Wistar rats	- testosterone, LH ↓ - estradiol, progesterone, FSH level ↑ - restored estrus cycle - glucose, insulin sensitivity ↓ - insulin and SHBG levels ↓ - normalized serum lipid profile - ovarian steroidogenic enzymes ↓ - follicular cysts, cystic follicles ↓ - the number of developing follicles, antral follicles and corpus luteum ↑ - showed various stages of follicles	[129]
Herbal syrup	anise, fennel, and celery seed extracts	Letrozole-induced SD rats	- testosterone, LH, FSH, LH/FSH ↓ - estradiol, progesterone ↑ - body weight, ovary weight ↓ - Graafian follicles and Cystic Follicle ↓ - the number of primary, secondary, antral, and corpora lutea ↑	[128]
Polyherbal Capsules	Bauhinia variegata, Emblica officinalis, Terminalia belerica, Terminalia chebula, Commiphora wightii, Cinnamon Cassia, Tribulus Terrestris, Hypericum perforatum, Commiphora molmol, Nigella sativa	Acute and Sub-acute toxicity study (OECD Guidelines) in Wistar rats	- testosterone ↓ - estrogen ↑ - no signs of toxicity when tested during the toxicity studies - normalized histological abnormality	[129]
Combination therapy with Bunium persicum and Foeniculum vulgare capsules	Bunium persicum and Foeniculum vulgare extracts	70 women with PCOS	- LH and DHEAS levels ↓ - menstrual cycles ↑ - the mean number of follicles ↑ hirsutism ↓	[130]
Aloe vera gel formulation	Aloe vera leaves, gel, turmeric, Karaya gum, lemon juice	Letrozole-induced Charles Foster rats	- restored estrus cycle - ovary atretic cysts ↓ - body weight ↓ - improved glucose sensitivity - improved ovarian 3β hydroxy steroid dehydrogenase (3β HSD) and 17β hydroxy steroid dehydrogenase (17β HSD) activities	[101]
	freeze-dried powder of Aloe barbadensis Mill. Gel	Letrozole-induced Balb/c mice	- testosterone ↓ / progesterone ↑ - normalized serum lipid profile - body weight ↓ - glucose intolerance and fasting insulin levels ↓ - restored estrus cycle	[100]
	Aloe vera leaves, gel, turmeric, Karaya gum, lemon juice	Letrozole-induced Charles Foster rats	- normalized serum lipid profile - restored estrus cycle - normalized glucose intolerance, and lipid metabolizing enzyme activities	[99]
	Aloe vera leaves, gel, turmeric Curcuma longa, lemon juice	Letrozole-induced Swiss albino mice	- LH, Testosterone ↓ - FSH ↑ - body weight ↓ - restored estrus cycle - glucose, cholesterol concentration ↓ - displayed follicular cyst, medulla, and Graffian follicle	[102]
Bu-Shen-Tian-Jing Formula, BSTJF	Short-horned Epimedium Herb, Desertliving Cistanche Herb, Largehead Atractylodes Rh, Glossy Privet Fruit, Palmleaf Raspberry Fruit, Semen Cuscutae, Malaytea Scurfpea Fruit, Milkvetch Root, Dan-Shen Root	111 patients with PCOS who undergone in vitro fertilization	- helped to get more retrieved oocytes and fertilized oocytes - the clinical cumulative pregnancy rate, live birth rate, and term delivery rate ↑ - the AMH levels in the follicular fluids ↓	[133]
Combined seeds (Seed cycling)	Flaxseed, sesame seeds, sunflower seeds, and pumpkin seeds	Ninety women with PCOS, between 15 and 40 years	- body weight ↓ - LH, TSH, prolactin ↓ - FSH level ↓ - ovarian cysts ↓	[131]
Chitosan nanocomposites	Chit-TPP (Chitosan-tripolyphosphate), FEC@NBC (Fennel seed extract-chitosan nanobiocomposite)	Estradiol valerate-induced Wistar rats	- LH, testosterone ↓ - FSH ↑ - FBS, insulin ↓ - normalized serum lipid profile	[134]
Pomegranate juice and Synbiotic Pomegranate juice	pomegranate fruit	92 women with PCOS	- Insulin resistance ↓ - BMI, weight, and waist circumference ↓ - testosterone ↓	[132]

Polyherbal syrup

Since the insoluble herbal components evenly distributed in the liquid medium offer better gastric absorption than other oral preparations, the chosen herbs were formulated into a syrup. Honey is used as the syrup base to cover the bitterness of the phytochemicals and because it has properties that normalize the estrous cycle and enhance fertility. This beneficial and extensive therapeutic effect of the manufactured polyherbal syrup is due to a combination of several potent herbs that can act simultaneously on multiple targets to completely relieve PCOS [127].

In a study, both novel herbal combinations and its syrup formulations contain 10 different medicinal plants combined in particular ratio, based on reported therapeutic effects of herbs such as hormonal supplementation (50%), fertility enhancement (25%) and diabetes control (25%). Therefore, this formulation shows recovery of an altered hormonal profile and also restoration of the ovary folliculogenesis. The novel herbal syrup formulation could be an effective remedy to manage PCOS showing the potential to be progressed as an adjuvant treatment with a modern drug. Also, this formulation could effectively alleviate the PCOS-related risks of cardiovascular problems and diabetes [2]. In another study, it primarily works by lowering peripheral and ovarian hyperandrogenism, enhancing insulin sensitivity through activation of the insulin receptor and AMPK, which mediate transcription to translation of the GLUT4 from cytoplasm to ovarian membrane, leading to increase of glucose uptake and promotion of follicular growth and ovulation [127]. In addition, the other study demonstrated that herbal syrup containing Fennel, Celery and Anise could normalize hormone levels and recover ovarian morphology. Therefore, the studied herbal syrup could be a useful therapeutic herbal medicine for PCOS treatment [128].

Polyherbal capsules

Studies suggested that polyherbal capsules could be a boon for treatment of PCOS without any side effects. In one study, the collected herbs in the form of powders, extracts, and granules have a medicinal role and also have been shown to conform with the standard. That is, the herbs are seen to be powerful in PCOS treatment, especially in regulation of hormones and recovery of histological abnormality. Another study revealed that the ingestion of green tea and spearmint leaves could be a valuable herbal holistic interference in the decrease of hirsutism on the body and face. However, to define the definitive consequences for the beneficial effects of these herbal remedies, extensive studies with controlled measurement of all necessary parameters for PCOS and hirsutism are needed [129]. Besides, in one study, the treatment of PCOS women through the combination of Cumin and Fennel extract alleviated levels of LH and DHEAS, decreased hirsutism score and BMI significantly and it also increased menstrual duration. For these reasons, this combination could be utilized cost-effectively and safely to improve symptoms of PCOS [130].

Other formulations

One study suggested that using seed cycling could handle the dominant conditions of PCOS. All the seeds contain antioxidants, omega-3 and omega-6 fatty acids, carbohydrates, protein, fiber, zinc, phosphorus, potassium, magnesium and significant levels of trace minerals which promote normal hormonal levels. Conclusively, seed cycling could improve hormonal disturbance promoting a healthy life [131].

In another study, Pomegranate juice, a rich origin of phytochemicals with potent antioxidant activity such as anthocyanins and ellagic acid can promote the development of probiotic bacteria and generate short-chain fatty acids which have anti-inflammatory effects, improving lipid profiles, glycemic index and obesity by modulating peroxisome proliferator-activated receptors (PPARs). Since there was no adverse effect during this study, adding synbiotics to fruit juice could be a useful option to modulate health and alleviate the danger of metabolic diseases. However, most fruit juice is rich in calories, sugar and low in fibers. Therefore, proper consumption is recommended [132].

In addition, the therapeutic principle of bu-shen-tian-jing formula (BSTJF) used in one study is to strengthen the kidney (in Chinese: Bu-Shen) and fill the essence (in Chinese: Tian-Jing). BSTJF significantly could improve the outcome of in vitro fertilization in PCOS patients by decreasing AMH levels of follicular fluid. However, because of the several potential biases and the small size of the sample, the evidence is restricted [133].

Although the therapeutic effects of herbs on the health issue associated with PCOS complication have been identified, the effectiveness of the phytomolecules targeted delivery by safe and green carriers has not been assessed systematically. Therefore, in this novel study, chitosan-tripolyphosphate was synthesized by the ion gelation method and filled with biomolecules present in the extract of ethanolic Fennel seed. This is why chitosan, which is surface characteristic and mucoadhesive, not only protected the phytomolecules but increased their delivery and stability thanks to the property of chitosan. In conclusion, this study reveals that FEC@NBC (Fennel seed extract-chitosan nanobiocomposite) is the safe and effective bio agent normalizing the levels of hormones and lipid profile, and biochemical changes of PCOS [134].

Acupuncture

The basic principles of acupuncture are as follows: Stimulating the acupuncture needle in the skeletal muscle sends acupuncture-induced signals to the central nervous system (CNS) via supraspinal pathways, where they can exert central effects [135]. The mechanism of acupuncture in the treatment of PCOS differs from determining therapeutic targets (Table 4). Those include changes in the proportion and amount of specific hormones and the death of particular cells. The reporting of acupuncture protocols follows the STRICTA guidelines, including acupoint selection (e.g., SP6), needling depth, frequency, and stimulation method (manual vs. electrical). SP6 is frequently used to regulate β-endorphin pathways implicated in GnRH suppression [136]. As previously mentioned, changes in the proportion and amount of specific hormones are major therapeutic targets. In this case, LH is regulated through selecting GnRH and gonadotropins as therapeutic targets. Above all, β-endorphin plays a key role in this process. β-endorphin is secreted in three types: (1) Within CNS, (2) β-endorphin created in the arcuate nucleus of the medial basal hypothalamus secretes. In addition, (3) pituitary secretes β-endorphin and it flows into the peripheral circulation. In particular, the beta endorphin is created in the hypothalamus project of brainstem nuclei and midbrain. This can influence both autonomic function and sensitivity [135]. Of these three types, both (1) and (2) of β-endorphin have been shown to be regulated by acupuncture. Acupuncture may reduce the level of plasma β-endorphin and upregulate level of hypothalamic β-endorphin [137]. β-endorphin in CNS (1) has tonic suppression on GnRH and succeeding LH release in both direct and indirect way [151]. PCOS patients have elevated plasma levels of β-endorphin (2) [135, 138]. These higher plasma levels of β-endorphin may serve to the pathogenesis, as β-endorphins in the CNS have insufficient inhibition on GnRH [151, 153]. On the other hand, in the case of healthy women undergoing ovulation, levels of β-endorphin in ovarian follicular fluid are much higher than those measured in plasma [136]. Studies have shown acupuncture lowers cortisol concentrations and adjusts β-endorphin in both CNS and plasma production and secretion, influencing the GnRH and gonadotropins releasing [136].

Table 4.

List of acupuncture for PCOS

Name	Experimental Design	Efficacy	Ref.
Acupoint: “Guan Yuan”,“Zi Gong”, “San Yin Jiao”, “Zhong Zi”, “Qi Hai” (using disposable silver needles (Hwato, China, 0.25*25 mm))	DHEA-induced SD rats	- the number of granulosa cells ↑ - apoptosis of ovarian granulosa cells ↓ (through LncMEG3-mediated regulation of miR-21-3p) - improvements in number of mature follicles and corpus luteum structures, AMH secretion, LH secretion, FSH secretion, testosterone secretion and estradiol(E2) secretion	[139]
Acupoint: 14 needles (protocol (Li et al., 2017)) with metformin	a randomized trial enrolling women with PCOS and IR from three hospitals in China	- HOMA-IR ↓ - glucose, AUC↓, FPG↓	[141]
Acupoint: abdominal and hindlimb muscles(somatic segments corresponding to the innervation of the ovaries) Low-frequency EA(12–14 treatments), (0.8 ~ 1.3 mA)	DHT-induced Wistars rats	- proportion of atretic antral follicles ↓ - thickness of the theca interna cell layer in those follicles ↓ - fresh corpora lutea ↑ - DHT-induced changes in the expression of Ngf and Npy mRNA in mesenteric adipose tissue ↓ - the expression of Adrb3 and Ar mRNA ↓	[142]
EA treatment (10–14 treatments)	women with PCOS and oligo-/amenorrhea	− 0.15→0.66 ovulations/woman and month - BMI↓ - WHR↓ - serum testosterone concentration↓ - SHBG ratio ↓ - serum basal insulin concentration↓	[143]

The death of a particular cell is also an important therapeutic target for PCOS. For example, excessive granulosa cell apoptosis in the ovary can cause ovulatory dysfunction and abnormal follicular development. Therefore, suppressing granulosa cell death, clinical symptoms of PCOS, such as IR, hyperandrogenemia, and abnormal follicle development, can be alleviated. Acupuncture promotes granulosa cell proliferation in PCOS and inhibits both late and early cell deaths by downregulating long non-coding RNA MEG3 (LncMEG3) [139]. LncMEG3 is a type of long non-coding RNA (LncRNA). LncRNA is associated with various biologically significant processes such as control of chromatin modification, X chromosome silencing, nuclear transport, transcriptional interference, transcriptional activation, genomic imprinting, dosage compensation, and gene expression [139]. LncMEG3 is expressed in the embryonic development process and in a variety of normal cells, suggesting that LncMEG3 may be closely related to disease development [139]. Additionally, it is well-known that high miR-21 expression is closely related to the inducement of ovarian autocrine and lateral secretion dysfunction and cell death [139]. Expression of abnormal miR-21 in a serum of PCOS patients is involved in PCOS processes, and miR-21 plays a role in the apoptotic response. As a result of experimentation, the expression of miR-21 and LncMEG3 in the PCOS group was higher than the normal group [139]. Analysis of the relationship between LncMEG3 and miR-21-3p expression using the Pearson test revealed a positive correlation between miR-21-3p and LncMEG3 expression [139]. In addition, analysis of the binding sites of LncMEG3 and miR-21-3p showed that LncMEG3 targets [139]. According to the experiment, when MEG3 is silenced, the number of granule cells increases, and apoptosis of granule cells is inhibited [139]. That is because at the initiation process of apoptosis, apoptotic proteins related to mitochondrial membrane translocation are restored. In sum, when MEG3 is in silence or decrease, apoptosis is regulated [139]. A study showed that LncMEG3 expression of ovarian granule cells was significantly decreased in the PCOS with acupuncture group compared to the untreated PCOS group [140]. This suggests that acupuncture can reduce LncMEG3. In conclusion, as acupuncture regulates miR-21, which LncMEG3 mediates, self-death of granule cells is inhibited [139].

Acupuncture Table 1 (AT1) conducted a randomized controlled trial (RCT) on 60 rats with PCOS. The rats were distributed into 6 groups (10 rats per each group): western medicine group, sham acupuncture group, acupuncture group, MEG3-shRNA lentivirus group, small hairpin RNA negative control group and dehydroepiandrosterone PCOS group. In the case of acupuncture group and sham acupuncture group, the acupuncture treatment lasted for 15 days [139]. Acupuncture Table 2 (AT2) conducted a RCT on 342 women with IR and PCOS. The participants were recruited through Rotterdam criteria of 2004 and randomly distributed into three groups: acupuncture + placebo(n = 114), metformin + sham acupuncture(n = 114) and sham acupuncture + placebo(n = 114). In every group, acupuncture or sham acupuncture treatment was given three times a week for 30 min. In total, 48 treatments for 4 months [141]. Acupuncture Table 3 (AT3) conducted a RCT on 49 Wistars. The Wistars were largely divided into two groups: DHT-induced PCOS group (n = 36) and control group (n = 13). And the Wistars of PCOS group were divided into three groups: PCOS + EA group (n = 11), PCOS + exercise group (n = 13) and PCOS group (n = 12). In the case of PCOS + EA group, 12–14 times of low-frequency EA treatments lasted for 4–5 weeks [142]. Acupuncture Table 4 (AT4) conducted non-randomized, longitudinal, prospective study on 24 women aged 24–40 years old with oligo-/amenorrhea and PCOS. In total, 10–14 times of acupuncture treatments lasted for 8–9 months [143].

In the above four experiments, acupuncture treatments have been shown to have positive effects in various indexes. Besides the acupuncture group, the result that sham acupuncture group had improvements in some indexes is also noteworthy [139, 141, 142]. However, there were limitations in directly comparing each study because there are cases in which the subjects were PCOS women and mice, and the generation of Rotterdam Criteria, which is the main criteria for the subjects’ PCOS diagnosis, was also different. In addition, since the acupoints were different, the induction effect was inevitably different.

Taken together, acupuncture could be one of the alternative remedies for treating PCOS. However, not all studies show that acupuncture has a better effect on treating PCOS. Previous study demonstrated that acupuncture is better than metformin at improving glucose metabolism, but it is less effective at increasing insulin sensitivity in women with IR and PCOS compared to metformin [144]. In addition, a study comparing the effects of acupuncture and metformin in obese/overweight women and thin women with IR and PCOS found that acupuncture and metformin showed similar effects in thin women with IR and PCOS, but in those of obese/overweight women, acupuncture was less effective in increasing insulin sensitivity compared to metformin [144].

For that reason, more effective treatments are needed to supplement this, and in fact, it may be possible to combine alternative and complementary treatment with Western medicine. An experiment comparing the metformin group and the metformin with acupuncture group in diabetic patients showed improvements in insulin sensitivity and weight loss in both groups; however, the combination group exhibited significantly greater reductions in BMI levels and weight [145]. Also, experiment using acupuncture with metformin for obesity-type PCOS patients with infertility showed much more effective results in reducing BMI, improving hyperandrogenism and IR, and increasing the rate of pregnancy and ovulation compared with acupuncture alone and acupuncture placebo + metformin [146]. The first experiment showed ‘combination with metformin and acupuncture’ is superior to metformin alone treatment and second experiment showed ‘combination with metformin and acupuncture’ is superior to acupuncture alone treatment. In summary, combination with metformin and acupuncture is more effective than single treatment in improving PCOS.

Conclusions

The current medication for treating PCOS mainly targets anti-androgen effects (COCPs), ovulation induction by estrogen receptor modulation effects (Clomiphene citrate) or aromatase inhibitor (Letrozole), inhibitory effects against insulin resistance (Metformin) and lowering lipid profile effects (Statin). As a result, underlying mechanisms of them are sequentially connected, even though their primary goal is different respectively. In addition, each medication has important considerations for use because of adverse effects, diverse drug responses and lack of universally effective treatment. For that reason, we introduced the effective natural product including herbs and formulation, and acupuncture with their potential action of mode for treating PCOS. Preclinical and clinical researches suggest the reliable evidence that herbal treatment and acupuncture could be efficient treatment techniques with potential. The mechanism of action of the natural medicine includes the regulation of sex hormones, serum lipid profile, insulin resistance, oxidation and inflammation in the ovaries. Single herbs and herbal formulation decrease the testosterone and LH levels, but increase the estrogen, progesterone and FSH level, leading to the normalization of hypothalamic-pituitary-ovarian axis function. Those effects can trigger the body weight loss with the decline in triglyceride and cholesterol levels. And fasting insulin levels with the glucose intolerance might be regulated by natural medicine via AMPK-mediated glucose intake and promotion of follicular growth, leading to ovulation. Also, ovarian SOD, MDA, GPx as oxidative stress markers, and pro-inflammatory cytokines could be attenuated by several natural herbs described in this review.

However, there are weak but a little concerning point. Firstly, even natural products could have unexpected side effects. Studies reported that some patients complained of anorexia and abdominal distension in the Korean herbal medicine group, but patients were able to tolerate these effects and symptoms were also resolved voluntarily. A patient in an herbal medicine group developed itching and skin rash after using cinnamon capsule for 5 days, and the adverse effect disappeared after discontinuing treatment with no intervention [65]. These included mild gastrointestinal discomfort, itching, rash, and rare allergic responses. As similar, oriental herbal medicines caused few adverse events, but the reported side effects did not have a critical impact and were reversible, indicating that oriental herbal medicines are relatively reliable and safe for PCOS treatment. Importantly, all reported events were self-limiting and resolved spontaneously, suggesting a favorable safety profile for natural therapies. Secondly, the studies to investigate the combination of the current medication and herbal medicine with the purpose of reduction of adverse effects or effective dose 50 for PCOS treatment is insufficient in spite of sufficient effects and less side effects. Most of combination studies have only confirmed the effectiveness. Lastly, as the standardized treatment plans have not yet been established, further studies, exploration, and summary are needed. Especially, therapeutic protocol that can be treated according to patients with different symptoms is needed, in regard to pathophysiology of PCOS, learning much about the exact pathophysiology and etiology are major future tasks. In particulate, although the number of in vitro and in vivo studies regarding on natural products have been increasing, the clinical trials for investigating the efficacy and safety of natural medicines are seriously insufficient.

Forwardly, clinical data on treatment using natural medicine should be accumulated and based on that data, large scale study on effects of oriental medicine to PCOS is needed. Also, follow-up studies on more precise mechanisms for each herb, formulation, and acupuncture are needed.

Abbreviations

AMH

Anti-Müllerian hormone

AMPK

AMP-activated protein kinase

ANSD

Androstenedione

AT1

Acupuncture Table 1

AT2

Acupuncture Table 2

AT3

Acupuncture Table 3

AT4

Acupuncture Table 4

BMI

Body mass index

BSTJF

Bu-shen-tian-jing formula

Chti-TPP

Chitosan-tripolyphosphate

CNS

Central nervous system

COCPs

Combined oral contraceptive pills

CRP

C-Reactive Protein

CYP17A1

Cytochrome P450 17α-hydroxylase

DHEA

Dehydroepiandrosterone

DHEAS

Dehydroepiandrosterone sulfate

DHT

Dihydrotestosterone

FSH

Follicle-stimulating hormone

GLP-1Ras

Glucagon like peptide-1 receptor agonists

GLUT4

Glucose transporter type 4

GnRH

Gonadotropin-releasing hormone

HDL

High density lipoprotein

HHOA

Hypothalamus-hypophysis-ovarian axis

HMG-CoA

3-hydroxy-3-methylglutaryl coenzyme A

hMG

Human menopausal gonadotropin

HOMA-IR

Homeostatic Model Assessment for Insulin Resistance

INSR

Insulin receptor

IR

Insulin resistance

IVF

In vitro fertilization

LDL

High density lipoprotein

LH

Luteinizing hormone

LncMEG3

Long non-coding RNA MEG3

LncRNA

Long non-coding RNA

MDA

Malondialdehyde

NGF

Nerve growth factor

NLRP3

NOD-like receptor pyrin domain-containing protein 3

PCOS

Polycystic ovary syndrome

PPARs

Peroxisome proliferator-activated receptors

RCT

Randomized controlled trial

SHBG

Sex hormone-binding globulin

SNEDDS

Self-nanoemulsifying drug delivery system

TT

Tribulus terrestris L

VAC

Vitex agnus-castus L

YAP-1

Yes-associated protein1

Author contributions

JL conceptualized, analyzed and investigated the data and was a major contributor in writing the manuscript. SA, YWK, LYC, DYK analyzed and investigated the data, and writing the manuscript. MHK provided supervision throughout the project. All authors read and approved the final manuscript.

Funding

This paper was supported by Woosuk University.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Clinical trial number

Not applicable.

Competing interests

The authors declare no competing interests.