Molecular Mechanisms of Cancer Prevention by Gooseberry (Phyllanthus emblica)

Abstract

Indian gooseberry (Emblica officinalis Gaertn or Phyllanthus emblica Linn; family Phyllanthaceae) has a recognized history in Indian traditional medicine (Ayurveda). Various therapeutic properties have been attributed to gooseberry as a dietary supplement. Many parts of the plant (fruits, seed, leaves, root, bark, and flowers) possess various activities and are used to treat a range of diseases. This review focuses on the evidence for the cancer-preventive properties of gooseberry, its extracts, and its principal phytochemicals based on studies In Vitro and In Vivo. Most importantly, in multiple rodent models of cancer, treatment with P. emblica was found to prevent tumor incidence, number, and volume at various organ sites. The mechanism(s) implicated in gooseberry-mediated cancer inhibition are diverse and include antioxidants, Phase I and II enzyme modifications, anti-inflammatory action, regulation of the cell cycle, and modulation of oncogenic signaling genes. Studies in humans also indicate that P. emblica can offer various health benefits and synergize with other treatments. This review provides detailed information on the potential use of gooseberry extract as an anticarcinogenic in humans, illuminates the therapeutic applications, and discusses clinical trials.

Introduction

Many plant extracts, as well as chemicals purified from them, have demonstrated medicinal properties, and have been used to develop numerous traditional herbal therapies demand for which is continuously increasing worldwide. More than 110 thousand plant extracts or purified molecules have been screened for their anticancer efficacy since the start of a National Cancer Institute (NCI) screening program (1). Approximately 25 percent of all medications prescribed in the United States were developed from plants (2), including paclitaxel (commonly known by the tradename Taxol) which is derived from the bark of the Pacific yew tree and may be the most widely used anticancer medication. Similarly, gooseberry (Phyllanthus emblica, Emblica officinalis, or Amla) is an important herbal medicine, commonly used in the Ayurvedic and Unani systems of medicine in South Asia and Arab nations. Different parts of the P. emblica tree have various therapeutic applications in these systems of medicine, including: improving the immune system, treating constipation, reducing stomach acidity, treating stomach ulcers, purifying the blood, and treating diarrhea, dysentery, helminthic infections, diabetes, and cancer (3).

P. emblica fruit is the second richest known source of vitamin C (4), as well as having high levels of tannins, alkaloids, polyphenols, vitamins, and minerals. P. emblica contains several biologically-active antioxidant polyphenols, including gallic acid, pyrogallol, emblicanin A and B, pentagalloylglucose, and ellagic acid (Figure 1). Other compounds found in P. emblica include flavonoids, quercetin, kaempferol, sesquiterpenoids, and flavonol, all of which have pleotropic effects on various cellular functions (3, 5, 6). Antioxidants are well established to protect cells from the impact of free radicals and in turn reduce inflammation in the body. Multiple preclinical or clinical studies over the last three decades have shown that gooseberry constituents possess anti-inflammatory, anticancer, anti-microbial, and anti-oxidant effects which protect against neurological disorders, have hepatoprotective and cardioprotective activities, and are cancer-preventive (3, 7–11) (Table 1 and Figure 2). Based on these reported protective activities and therapeutic benefits, P. emblica extracts are prepared and commercialized in many forms, including pickles, candy, jam, squash, juice, and powders; P. emblica is also a primary ingredient in herbal formulations known as Chyavanprash and Triphala (13).

Figure 1.

Main phytochemical constituents and taxonomic tree of Phyllanthus emblica.

Table 1.

Main source and activities of major phytoconstituents present in P. emblica (3, 12).

S. No.	Common name	Anti-oxidant	Anti-inflammatory	Anti-proliferative	Anticancer	Anti-diabetic	Cardio-protective
Whole plant 1	Gallic acid	+	+	+	+	+	+
2	Ellagic acid	+	+		+	+	+
3	Quercetin	+
Fruit
4	Vitamin C	+				+
5	Emblicanin-A & B	+
6	Punigluconin	+
7	Pedunculagin	+
8	Chlorogenic acid	+
9	3,6-di-O-galloyl-D-glucose	+
10	Chebulagic acid	+	+	+		+
11	Corilagin	+
12	L-malic acid 2-O-gallate			+
13	Mucic acid 2-O-gallate			+
14	Coumaric acid	+
15	Myrecetin	+
16	Caffeic acid	+	+	+	+	+	+
Leaf
17	1,2,3,4,6-penta-O-galloylglucose		+
18	Lutelin-4-O-neohesoeridoside		+			+
Root
19	Phyllaemblicin-A, B and C			+
20	Phyllaemblic acid			+

Figure 2.

Pharmacological activities of major phytochemicals present in gooseberry.

Substantial In Vitro and In Vivo data demonstrate that P. emblica extracts possess bioactive components that offer a wide variety of health benefits by modulating various signaling pathways. This review mainly focuses on extracts of P. emblica that prevent cancer development via mechanisms that inhibit tumor initiation and progression (summarized in Tables 2 and 3).

Table 2.

In Vivo chemopreventive effects of gooseberry extract/phytochemical in different rodent models.

S. No.	Animal model	Organ	Carcinogen (Dose/Route/Duration)	Gooseberry extract (Dose/Route/Duration)	Observations	Reference
1	Male ICR mice	Skin	DMBA (390 nmol, topically, single) + TPA (4 nmol, topically, 2x/wk-20 wks)	P. emblica (1, 2 or 4 mg, topically, 2x/wk-20 wks 1 h before TPA application)	Reduction of tumor numbers and volumes	(14)
2	Rats	Liver	N-Nitrosodiethylamine (NDEA; 0.02%, 2.5 ml/rat, oral, 5 day/wk-20 wks)	P. emblica (EO) polyphenol fraction (EOP, 60 mg/kg, oral, 5 day/wk-20 wks)	Decreased the incidence of tumors	(15)
3	Swiss albino mice	Bone marrow	7,12-dimethylben(a) anthracene (DMBA; (50 mg/kg/BW, i.p., single)	P. emblica fruit extract (100, 250, 500 mg/kg BW, oral, 7 day)	Decreased the frequency of bone marrow micronuclei	(16)
4	Wistar rats	Liver	NDEA (0.02%, oral, 5 day/wk-20 wks)	P. emblica extract (50, 125, 250 mg/kg BW, oral, 5 day prior to NDEA till 20 wks)	Decreased the incidence of tumors and liver weight	(17)
5	Albino rats	Liver, testis, and kidneys	Cd as CdCl2 (3 mg/kg BW, i.p., single), 1 h after last dose of P.emblica	P. emblica fruit juice (500 mg/kg BW/5 ml, oral, 8 day)	Reduced mortality and prevented histopathological damage in testis, liver, and kidneys	(18)
6	Swiss albino mice	Skin	DMBA (100 µl, topical, single) + croton oil (1%, topical,3x/wk-16 wks)	P. emblica extract [100 mg/kg BW, oral, a) 7 day before and after DMBA application, b) starting croton oil for 16 wks., and c) starting 7 day before DMBA application till end of the experiment]	Decreased the incidence, yield and burden of tumor, and tumor multiplicity	(19)
7	Swiss albino mice	Bone marrow	B(a)P (50 mg/kg BW, gavage, three dose/wk-17 day after pretreatment of EO extract)	P. emblica extract (5 mg/ml, gavage, three dose/wk-8 day + 3 dose/wk-17 day; on alternate days with B(a)P + 3 day alone post-B(a) P until day 28)	Decreased the carcinogen-induced frequency of chromosomal aberrations and damaged cells	(20)

P. emblica showed significant reduction in tumor incidence, multiplicity and volume in various carcinogen treated rodent models of cancers.

Table 3.

Anti-tumor activity of gooseberry extract In Vivo using rodent models bearing transplanted tumors/xenografts.

S. No.	Animal model	tumor cells/Growth factor; Dose/Route	Gooseberry extract Dose/Route/Duration	Observations	Reference
1.	Nude mice	OVCAR3 cells (5 × 104 with Matrigel, s.c. into the right rear flank)	P. emblica (100 mg/kg BW/day, oral, 18 day)	Inhibits growth and angiogenesis, and induces autophagy (beclin and LC3B-II)	(21)
2.	Swiss albino mice	EAC or DLA cells (106, i.p. into the hind limb)	P. emblica extract (250, 500 mg and 1.25 g/Kg BW, oral, 5 day)	Increases the life span and survival	(22)
3	Nude mice	OV4485 cells [5 × 106 with Matrigel (1:1), s.c. into the right rear flanks]	P. emblica extract (100 mg/kg BW/day in 10% sucrose during night time for 4 weeks or until termination)	Inhibited tumor growth, HIF-1α, IGF1R, and SNAIL1 expression, but stimulated E-cadherin expression in OV4485 cell xenograft tumors	(23)

Treatment with P. emblica demonstrated significant suppression of tumor growth and progression with survival benefit in various cancer xenograft mouse models.

Mechanism(s) of Chemopreventive Actions

P. emblica appears to interrupt carcinogenesis at the initiation, post-initiation, and promotion stages, thereby acting as both “blocker” and “suppressor” of carcinogenesis (Figure 3). Based on preclinical studies, various mechanisms have been proposed for these effects, including preventing formation of pro-mutagenic and procarcinogen molecules via inhibition of cytochrome P450 (CYP450) isozymes or enhancement/modulation of phase II detoxifying enzymes; these mechanisms are discussed in detail below.

Figure 3.

Summary of modulatory effects of P. emblica and its extracts on cancer relevant mechanisms (yellow arrow pointing upwards indicate increase, red arrow pointing downwards indicate decrease).

Effects on Free Radical Scavengers and Lipid Peroxidation

Free radicals are reactive/unstable metabolic byproducts that are naturally produced in the body. These molecules trigger a chain reaction that damages multiple cell constituents. Antioxidants can prevent the oxidation process by reacting with free radicals, chelating catalytic metals, and acting as free radical scavengers. P. emblica, or its phytochemicals, have been shown to inhibit free radical terminators through both direct and indirect mechanisms.

An aqueous extract of P. emblica (20 μg/ml) inhibited γ-radiation-induced strand break formation by 30–83% in plasmid DNA (pBR322), as well as stopping lipid peroxide formation in rat liver microsomes. P. emblica has exhibited free radical scavenging activities against superoxide, DPPH, hydroxyl, nitric oxide (NO), hydrogen peroxide, peroxynitrite, singlet oxygen, and hypochlorous acid (24–26). When various organic and aqueous extracts of P. emblica were compared, the ethyl acetate fraction, containing gallic acid, methyl gallate, corilagin, furosin, and geraniin, showed the greatest NO scavenging activity In Vitro (25). Pozharitskaya et al. (2007) separated a P. emblica extract into free gallic and ellagic acids, and emblicanins A and B using thin layer chromatography, and showed that all of the compounds scavenged DPPH radicals; emblicanin B was the best scavenger and efficiency decreased in the order of emblicanin B > emblicanin A > gallic acid > ellagic acid A > ascorbic acid (27). An aqueous extract of P. emblica (100 μg/ml) significantly modulated the basal levels of oxidative markers and enhanced antioxidant defenses in HepG2 liver cells, and another P. emblica extract scavenged superoxide and hydroxyl radicals and decreased the level of lipid hydroperoxide and reactive oxygen species in HepG2, Dalton’s Lymphoma Ascites (DLA), and CeHa cells (15, 28). In mice irradiated with γ-radiation, treatment with P. emblica extract protected against radiation-induced damage to the cell membrane by lowering the elevated levels of lipid peroxides (29). P. emblica extract also showed a hepato- and renal-protective effect in rodents by decreasing the formation of lipid peroxides in response to toxic chemicals, such as hexachlorocyclohexane (30), CCl₄ (11), CdCl₂, and ochratoxin (18, 31).

Taken together, the literature indicates that P. emblica extracts scavenge free radicals, protect against lipid peroxidation, and thus may play a role in preventing diseases associated with oxidative stress, including cancer.

Effects on Antioxidant, Phase I & II Enzymes

During initiation of carcinogenesis, xenobiotics undergo cellular metabolism by phase I (CYP450) and phase II (GST) enzymes. The CYP450 enzymes process the xenobiotics to more electrophilic moieties, which in turn react with biomolecules to form DNA-adducts and protein-adducts, and mark the process of initiation. Phase II enzymes, also known as detoxifying enzymes [e.g., glutathione S-transferases (GSTs), UDP-glucuronosyltransferases (UGT), NADPH Quinone Dehydrogenase 1 (NQO1), and anti-oxidant enzymes, such as superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase], decrease the bio-molecular adduct load by detoxifying the reactive-intermediates in the cell. Phase II enzymes block the initiation process by increasing the conjugation reaction of reactive intermediates and endogenous bio-molecules, such as glutathione (GSH) and glucuronic acid, which makes them less toxic and more water-soluble. Thus, inhibiting activity of phase I (CYP450) enzymes and/or enhancing the activity of detoxifying phase II enzymes are potentially important for blocking cancer initiation; metabolizing enzymes are a plausible target for cancer chemoprevention (32–34).

Studies suggest that P. emblica modulates hepatic activation and detoxifying enzymes (16); oral pretreatment of Swiss albino mice a with P. emblica ethanolic extract (100, 250, or 500 mg/kg) for 7 day decreased the frequency of bone marrow micronuclei and CYP450 or CytB5 enzymes in the liver, and increased levels of GSH, GST, glutathione peroxidase (GPx), and glutathione reductase (GR) when the mice were injected intraperitoneally with the 7,12-dimethylbenz(a) anthracene (DMBA) carcinogen. An aqueous extract of P. emblica significantly reduced the mutagenicity of aflatoxin B1 (AFB1) and benzo[a]pyrene [B(a)P] in the Ames test (35) by inhibiting CYP450 enzymes, suggesting that P. emblica extracts have potent anti-mutagenic and anti-carcinogenic activities against those mutagens that require metabolic activation. Treatment with P. emblica extracts significantly reduced levels of drug-metabolizing enzymes, such as GST, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), aniline hydroxylase (AH), γ-glutamyl transpeptidase (GGT), and glutathione in the serum and liver tissues of rats with N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in a dose-dependent manner (17). Similar results were observed in various tissues (testis, liver, and kidney) of rats challenged with thioacetamide, CCl₄ (1 ml/kg BW, gavage in corn oil), or Cd as CdCl₂ (3 mg/kg BW, i.p., single) (11, 18). In addition, P. emblica increased GSH and GPx activity and inhibited malandialdehyde formation, DNA synthesis rate, and ornithine decarboxylase (ODC), GST, GR, and G6PD activities (11, 36).

Similarly, oral administration for seven days of P. emblica extract (250 and 500 mg/kg BW) or vitamin C (9 mg/kg BW), a major constituent of P. emblica, decreased CYP450 levels while increasing levels of GSH and other detoxification enzymes, such as superoxide dismutase (SOD), GPx, catalase (CAT), GR, and GST in mice challenged with single dose of oral B(a) P (125 mg/kg) or intraperitoneal cyclophosphamide (40 mg/kg) (28, 37). Similar results are reported in multiple carcinogen-induced cancer models with P. emblica extract treatments. P. emblica extracts have been shown to reduce (a) the effects of ionizing radiation [700 rads (7Gy), single dose] in mice (29); (b) hexachlorocyclohexane-induced oxidative stress and cytotoxicity in rat liver (30); (c) carbonyl content, lipid peroxidation, activities of antioxidant enzymes SDH, NADH dehydrogenase, and cytochrome c oxidase, as well as the cytochrome content of hepatic mitochondria in ethanol-treated rats (38); and (d) levels of antioxidant enzymes in NDEA-treated rats (15).

O⁶-alkylguanines are important DNA adducts formed by alkylating agents that can lead to mutation. These lesions can be eliminated by increasing the activity of O⁶-methylguanine-DNA methyltransferase (MGMT). Niture et al. showed that a P. emblica extract increases MGMT levels, accounting for the increased DNA repair in HT29 colon cancer cells (39). In total, these reports demonstrate that P. emblica extracts decrease the carcinogen-induced transactivation of CYP450 isozymes, resulting in decreased activity. Further, P. emblica treatment increases the transcription of phase II enzymes, resulting in increased enzyme activity, leading to carcinogen detoxification. Collectively, modulation of the phase I and phase II enzymes decreases the level of carcinogen-induced DNA adducts thus preventing cancer initiation.

Mechanisms of Anti-Promotion Activity

Effects on Cell Cycle, Cell Proliferation, and Apoptosis Markers

Phytochemicals in P. emblica extracts impact important cellular events that affect the cell cycle and cellular response markers, including inflammation, cellular proliferation, and apoptosis (Figure 2).

An aqueous extract of P. emblica was cytotoxic (IC50 = 16.5 µg/ml) and inhibited cell cycle-regulating cdc25 phosphatase (IC₅₀ = 5 µg/ml) in L929 mouse fibroblasts at a low concentration in a dose-dependent manner (5–25 µg/ml). However, inhibition of cdc2 kinase occurred only above 100 µg/ml in DLA and EAC cells (22). P. emblica extract (1.25 g/kg BW) reduced both ascites and solid tumors while also increasing the life span of Swiss albino mice with DLA cell-induced tumors (22). Additionally, P. emblica polyphenols reduce the activities of DNA topoisomerase I and cdc25 tyrosine phosphatase in Saccharomyces cervisiae mutant cell cultures (15). These reports, along with its cytotoxic effects, suggest that the anti-tumor activity of P. emblica extract is partly due to its effect on cell cycle regulation. P. emblica inhibits the proliferation of drug resistant cell lines of high-grade serous epithelial ovarian cancer (HGSOC) such as OV866(2) [TP53 mutant], OV4453 [TP53, BRCA2, CSMD3, and RB1 mutations], OV4485 [TP53 and BRCA1 mutations] and TOV3041G [non-mutated],) in a dose- and time-dependent manner (23).

P. emblica extract (50–100 μg/ml) significantly inhibits the cell growth of human colorectal (SW620), lung (A549), breast (MDA-MB-231), cervical (HeLa), ovarian (SK-OV3), and liver (HepG2) cancer cell lines (14). This inhibition was attributed to the death receptor-mediated apoptosis mechanism; apoptosis was induced by triggering of DNA fragmentation, caspase-3, −7, and −8 activity, and Fas protein expression (14). Similarly, both a polyphenol extract of P. emblica (PEEP) and one of its components, specifically pyrogallol, inhibit cell proliferation of chronic myelogenous leukemia cells (40) and cervical cancer (HeLa) cells by inducing G2/M phase cell cycle arrest and promoting apoptosis via increasing expression of Fas, FasL, and cleaved caspase-8 (41). De et al. demonstrated the anti-proliferative effects of a P. emblica extract (200–400 μg/mL) on ovarian cancer (OVCAR3 and SW626) cells In Vitro and In Vivo, independent of apoptotic cell death. They also showed that P. emblica (300 μg/mL) and quercetin, a phytochemical present in P. emblica, increased the expression of autophagic proteins (beclin1 and LC3B-II) In Vitro and in mouse xenograft tumors, and reported synergistic effects of P. emblica with cisplatin In Vitro with respect to inhibition of cell proliferation and increased expression of the autophagic proteins (21). A P. emblica extract (300 mg/kg), at either the therapeutic dose or a dose 50% lower, prevented necrosis in the rat model of hepatic damage induced by anti-tubercular drugs (isoniazid, rifampicin, and pyrazinamide) (42). Furthermore, the polyphenol fraction of P. emblica (200 µl/ml) induced apoptosis by initiating membrane blebbing, chromatin condensation, and internucleosomal breaks in CeHa cell lines (15), thus decreasing liver tumor development in the NDEA-induced rat model.

Effects on Transcription Factors and Oncogenes

All of the activated signaling pathways in cancer work by limiting transcription factors that signal the nucleus to change the transcription pattern of the cell. Activation of transcription factors is required for the survival, unrestrained growth, and metastatic development of all cancers (43). Mahata et al. elucidated the mechanism of action of P. emblica fruit extract by examining its impact on activator protein-1 (AP-1) activity and human papillomavirus (HPV) transcription, which are fundamental for tumorigenicity of cervical malignancy cells. They showed that P. emblica inhibits the DNA binding activity of constitutively active AP-1 in HPV16-positive (SiHa) and HPV18-positive (HeLa) cervical cancer cells in a dose-and time-dependent manner through downregulation of constituent AP-1 proteins, c-Jun, JunB, JunD, and c-Fos (44). In these cells, P. emblica extract inhibited the mRNA and protein levels of proinflammatory mediators, such as COX-2, and iNOS inflammatory markers, via downregulating NF-κB in LPS-Induced RAW 264.7 cells (45).

Effects on Inflammation

Inflammation is a major component of many disease processes and plays an integral part in healing or repair of the body. The anti-inflammatory activity of P. emblica has been shown through the synthesis of mediators of inflammation to fight the disease process. Asmawi et al. demonstrated that relatively low concentrations of P. emblica leaf extract inhibited migration of human polymorphonuclear leucocytes (PMNs) In Vitro. However, the extract did not inhibit leukotriene B4 (LTB₄) and platelet-activating factor (PAF) synthesis in the rat paw model, suggesting that lipid mediators were not involved in the anti-inflammatory mechanism (46). Similarly, P. emblica reduced edema and the protein content of the peritoneal exudates in two different acute models (carrageenan-induced rat paw edema and acetic acid-induced peritonitis in mice) of inflammation (47). P. emblica nanoparticles have been used in cancer chemoprevention to improve drug delivery, and multiple studies aim to refine nanotechnology-based treatments so as to reduce the side effects. Singh et al. administered biosynthesized silver nanoparticles of P. emblica to Wistar rats for 16 weeks and saw significant improvement in recovery from hepatic cancer. The nanoparticles decreased serum biochemical parameters (ALT, AST, ALP, AFP) and altered the level of proinflammatory cytokines (TNF-α, NF-κB, IL-6, and IL-1β) in diethyl nitrosamine (DEN)-induced hepatic cancer, suggesting the chemoprotective potential of phytofabricated silver nanoparticles (48). P. emblica extracts have also reportedly decreased the number of nodes on the lung surface and decreased the B(a)P-induced levels of COX-2, HIF-α, and proinflammatory cytokines MIP-2, TNF-α, IL-6, and IL-1β in lung tissue; the P. emblica extract also increased the expression of miR-101 while down-regulating IL-1β and Lin28B levels, suggesting that P. emblica extracts can shield the lung from provocative injury and prevent precancerous lung lesions via the IL-1β/miR-i101/Lin28B flagging pathway (49).

Effects on Tumor Progression

Cell invasion is a fundamental process during tumor progression and metastasis. The inhibition of human breast cancer MDA-MB-231 cells in a Matrigel invasion assay suggests the anticancer activity of P. emblica extract (25 and 50 μg/ml) (14). P. emblica (100 mg/kg BW/day in 10% sucrose for 18 day) also reduced endothelial cell antigen CD31-positive blood vessels and HIF-1α expression in mouse xenograft tumors, showing that P. emblica treatment suppressed tumor progression in ovarian cancer xenografts, via inhibition of angiogenesis and activation of autophagy (21). Yahayo et al. have shown that P. emblica extract (1–3 µg/ml) decreases the expression of both MMP2 and MMP9 in human fibrosarcoma (HT1080) cells, which seems to be plays a role in an antimetastatic cellular mechanism. This antimetastatic function further reduced the cell proliferation, migration, invasion, and adhesion in a dose and time-dependent manner (50). P. emblica significantly reduced the expression of HIF-1α, IGF1R, and SNAIL1 and increased the expression of E-cadherin by attenuating the migration and invasiveness properties of carboplatinum- and taxol-resistant HGSOC cell lines (TOV3041G, OV866(2), OV4453 and, OV4485). HIF-1α and IGF1R are related to angiogenesis, whereas SNAIL1 and E-cadherin are related to epithelial-mesenchymal transition (EMT). Furthermore, P. emblica significantly reduced the mouse xenograft tumors (>60%, derived from OV4855 cells) and expression of endothelial cell antigen-CD31, HIF-1α, IGF1R, and SNAIL1. However, it increased the expression of E-cadherin in tumor tissues (23). Altogether, these findings show that P. emblica sensitizes platinum- and taxol-resistant heterogenous HGSOC cells carrying mutations in p53, BRCA1/2 genes, and diminishes their malignant characteristics by targeting angiogenesis and metastasis signaling mechanisms.

Clinical Trials

Three clinical trials (Table 3) are currently listed at www.clinicaltrials.gov, they respectively study the effectiveness of Indian gooseberry in hypercholesterolemia, metabolic syndrome, and periodontitis. Many other clinical trials assessing its effectiveness in multiple diseases, either alone or in combination with standard treatments, are listed on the clinical trials registry of India. Clinical trials using gooseberry extract, based on searches of www.clinicaltrials.gov, the clinical trials registry of India, and PubMed, are listed in Table 4. Although human evidence of efficacy of P. emblica alone is limited, its use in combination with standard treatments has been demonstrated effective in various clinical trial phases. While there are no active trials listed that focus on clinical intervention using P. emblica in cancer patients, data from other trials suggest it may prevent tumors by reducing cancer promoting risk factors. In humans, P. emblica has been shown to reduce levels of various fat components, such as cholesterol, lipids, LDL, and triglycerides. Clinical data suggest that fresh fruit extract of Indian gooseberry: (a) significantly decreased the total cholesterol, triglycerides, lipids, and low-density lipoprotein-cholesterol levels and improved the high-density lipoprotein-cholesterol in both normal and diabetic volunteers (52); (b) significantly improved endothelial function and reduced biomarkers of oxidative stress and systemic inflammation in patients with type 2 diabetes mellitus, without any significant changes in laboratory safety parameters (55); (c) reduced oxidative stress in uremic patients (54); and (d) lowered multiple risk factors associated with cardiovascular disease in overweight adults (57). Notably, clinical trials of different gooseberry phytochemicals, such as ellagic acid, quercetin, vitamin C, chlorogenic acid, and coumaric acid, individually and combined with other phytochemicals, have been explored and demonstrated to be effective in many diseases, such as hypertension, cardiovascular disease, and cancer.

Table 4.

List of clinical trials evaluating the health benefits of P. emblica and its extracts in patients with various diseases.

S. No.	Study title (Clinical Trials Identifier)	Gooseberry extract Dose/Route/Duration	Objective	Observations summary	Reference
1	Effect of Indian Gooseberry Extract (AMX160) in Hypercholesterolemia (NCT03479983)	AMX160 (500 mg (one capsule) × two times daily for 90 day)	To see the effect on attenuation of increased blood cholesterol, LDL cholesterol, and triglycerides in patients with hypercholesterolemia	Significant decrease the hypolipidemic effect along with a reduction in blood pressure.	(51)
2	P. emblica on Metabolic Syndrome, Insulin Sensitivity and Insulin Secretion (NCT03633630)	P. emblica (Emblica officinalis) (500 mg (one capsule) × two times daily before breakfast and dinner for 90 day	To see the effect on treatment of obesity, dyslipidemia, hypertension, and insulin secretion, among others	Significantly decreases the total cholesterol, triglycerides, lipids, and low-density lipoprotein-cholesterol levels, and improved the high-density lipoprotein-cholesterol in both normal and diabetic volunteers.	(52, 53)
3	P. emblica Irrigation in Periodontitis (NCT03295461)	10% P. emblica irrigation for 3 mo,	To see the effectiveness of Emblica officinalis extract formulations as a potential adjunctive therapeutic strategy in the management of chronic periodontitis	P. emblica 10% irrigant adjunctive to SRP improved periodontal healing without side effects and may be an alternative to chlorhexidine for chronic periodontitis treatment.	(54)
4	A clinical trial to study the BP reduction and other protective effects of P. emblica extract as an add-on to standard treatment in patients with hypertension of unknown cause (CTRI/2018/05/013669)	P. emblica extract 500 mg twice daily plus (tablet amlodipine 5 mg once daily or enalapril 5 mg once daily) for 3 mo,	A clinical trial to study the BP reduction and other protective effects of P. emblica extract as an add-on to standard treatment in patients with hypertension of unknown cause	Mean reduction in systolic blood pressure from baseline at end of 3 mo,; Mean change from baseline in diastolic blood pressure, serum uric acid, HbA1c, liver function, lipid levels, hs-CRP, oxidant and anti-oxidant levels, pulse wave velocity at end of 3 mo,.	–
5	Study the efficacy of P. emblica (Emblica officinalis) on the process of aging in healthy volunteers –Randomized Controlled Clinical Trial (CTRI/2019/04/018396)	P. emblica fruit powder (3 grams per day early morning on empty stomach)	Research study on the effect of P. emblica fruit powder in age-related changes among healthy volunteers of the 50-to-59-years age group	NA (open to recruitment)	–
6	Prevalence of type 2 diabetes mellitus and the effectiveness of gooseberry juice vs. mucilage of okra (lady’s finger) in controlling blood sugar level among adults with type 2 diabetes mellitus in selected rural settings of Puducherry (CTRI/2020/07/026268)	P. emblica juices (100 ml) okra juices (20 0 ml) Daily for 90 day	Effect of P. emblica juice and mucilage of okra in controlling blood sugar level among adults with type 2 diabetes mellitus in selected rural settings of Puducherry	NA (open to recruitment)	–
7	Pharmacodynamic interaction study of Emblica officinalis (CAPROS) with clopidogrel and ecosprin in patients with type II diabetes mellitus (CTRI/2013/07/003810)	CAPROS® (standardized aqueous extract of Phyllanthus embilica oR Emblica officinalis, containing not less than 60% of low molecular weight hydrolyzable tannins, comprising of Emblicanin A, Emblicanin B, Pedunculagin and Punigluconin as bioactives, and not more than 4% of gallic acid)	Effect of P. emblica, clopidogrel, and ecosprin on platelet aggregation in patients with type II diabetes mellitus	Significant decrease in platelet aggregation with both single and multiple dose administration.	(10)
8	Effect of P. emblica (capros) on endothelial dysfunction and oxidative stress in Type II diabetes mellitus patients on glimiperide therapy (CTRI/2019/12/022350)	Emblica officinalis (one capsule twice daily for 12 weeks)	Effect of P. emblica in patients with type II diabetes on glimiperide	Significant reduction of endothelial dysfunction, systemic inflammation and oxidative stress, which are known to be precursors of cardiovascular disease in type 2 diabetes mellitus patients.	(55)
9	Evaluation of P. emblica –CAPROS on cold pressor induced cardiovascular changes in healthy human subjects (CTRI/2013/05/003656)	P. emblica Capsules (two 250 mg capsule oral for 14 day with 240 ml of water)	Evaluation of effect of P. emblica on stress-induced cardiovascular changes in healthy human subjects	Significant decrease of mean percent change in the indices of arterial stiffness (augmentation index, radial and aortic blood pressure) and increase in sub-endocardial viability ratio, an index of myocardial perfusion with cold pressor test.	(56)

Conclusion

Notwithstanding the enormous increase in our understanding of the basic biology, malignant growth, and treatment modalities, the overall mortality rates of cancer have not declined proportionally in the last few decades. Indian gooseberry (Phyllanthus emblica, Emblica officinalis, or Amla) has been used and studied extensively, and shown to possess anti-inflammatory, anti-mutagenic, anti-tumor/anticancer, antioxidant, hepatoprotective, and cardioprotective activities. In this review, we compiled the In Vitro and In Vivo preclinical studies and clinical trials showing the anti-initiating, anti-promoting, and anti-progression mechanisms of gooseberry, with emphasis on its anti-tumor effects. Although the human evidence for its anticancer properties is limited, P. emblica has been safely consumed by humans in various foods and traditional medicines for centuries. Importantly, In Vitro and In Vivo studies provide evidence suggesting P. emblica contains potential cancer preventing components that have demonstrated strong suppressive properties against tumor promoting mechanisms. Therefore P. emblica and its bioactive components should be further studied clinically to prevent cancers.

Abbreviations:

B[a]P

benzo(a)pyrene

CYP

Cytochrome

DAL

Dalton’s Lymphoma Ascites

DMBA

7,12-dimethylbenz(a)anthracene

GPx

glutathione peroxidase

GR

Glutathione reductase

GSH

glutathione

GST

glutathione S-transferases

HPV

human papillomavirus

NDEA

N-nitrosodiethylamine

NO

nitric oxide

NQO1

NADPH Quinone dehydrogenase

P. emblica

Phyllanthus emblica

UGT

UDP-glucuronosyltransferases