Antioxidant Effects of E. alba: A Narrative Review

ABSTRACT

Eclipta alba Linn, commonly known as Bhringaraja, exhibits significant antioxidant activity as demonstrated in various studies. Research has shown that E. alba contains bioactive components such as wedelolactone, dimethyl wedelolactone, flavonoids, and sterols, contributing to its antioxidant properties. Studies have evaluated the antioxidant activity of E. alba through assays like DPPH scavenging and reducing power assays, highlighting its effectiveness in scavenging free radicals and reducing oxidative stress. Additionally, the total phenolic and flavonoid contents in E. alba extracts have been linked to its potent antioxidant capabilities, further supporting its role as a natural antioxidant source. Overall, E. alba antioxidant potential makes it a promising candidate for further exploration in the development of pharmacologically active natural products with antioxidant properties.

INTRODUCTION

Background

The pathophysiology of several chronic diseases, including cancer, cardiovascular disease, diabetes, and neurodegenerative disorders, has been linked to oxidative stress, which is caused by an imbalance between the body’s ability to detoxify reactive oxygen species (ROS) with antioxidants and the production of ROS.[1] Due to their potential therapeutic benefits and reduced side effects when compared to synthetic antioxidants, the search for natural antioxidants derived from plant sources has attracted a great deal of attention recently.

E. alba overview

E. alba, commonly known as False Daisy or Bhringraj, is a medicinal plant from the Asteraceae family, widely distributed in warm temperate to tropical regions like India, China, Thailand, and Brazil.[2] Morphologically, E. alba exhibits three distinct morphotypes: prostrate, semierect, and erect, all sharing a constant chromosome number of 2n = 22.[3] The plant features soft, sessile stems and well-developed greyish cylindrical roots, with the roots being particularly significant for their allelopathic activity and antimicrobial properties.[4] Under the influence of elevated ultraviolet-B (eUV-B) radiation, E. alba shows adaptive resilience by increasing stomatal and trichome densities, while also stimulating the biosynthesis of medicinally important compounds like wedelolactone, essential for its therapeutic applications.[5] Additionally, taxonomic characterization of healthy and geminivirus-infected E. alba plants reveals qualitative similarities but quantitative differences in features like stomata types, trichome sizes, and pollen characteristics, emphasizing the importance of distinguishing between healthy and infected specimens for medicinal purposes.[6]

Traditionally used in Ayurvedic medicine, E. alba has been recognized for its various pharmacological properties, including hepatoprotective, anti-inflammatory, antimicrobial, and antioxidant activities.[7] The plant is rich in bioactive compounds such as wedelolactone (WL), dimethyl wedelolactone (DWL), and various flavonoids, which are believed to contribute to its medicinal properties.[8]

Importance of antioxidant research

Given the growing interest in plant-based antioxidants, E. alba has emerged as a promising candidate due to its wide range of bioactive constituents.[9] The antioxidant properties of E. alba have been studied in various in vitro models, highlighting its potential to mitigate oxidative stress and related diseases.[10] However, a comprehensive synthesis of the existing evidence is necessary to better understand the scope and effectiveness of E. alba as an antioxidant.

Objectives of the review

The primary objective of this systematic review is to critically evaluate the antioxidant effects of E. alba based on available scientific literature. This review aims to:

1. Summarize the phytochemical constituents of E. alba that contribute to its antioxidant activity.

2. Assess the in vitro studies investigating the antioxidant properties of E. alba.

3. Identify potential mechanisms through which E. alba exerts its antioxidant effects.

MATERIAL AND METHOD

Methods

The PRISMA guideline’s quality standards were followed to in the systematic review, and the protocol was not entered into the PROSPERO database.

Ethics

All research studies included in this analysis complied with the guidelines set forth by the relevant ethics committees regarding the use and welfare of laboratory animals.

Consent

There was no research with human subjects included.

Search strategy

We thoroughly searched PubMed, SpringerLink, Google Scholar, and other databases for pertinent studies that were published in English since the databases’ creation. The period is January 2020 to July 2024. In order to find more articles, we also looked through the key reviews’ reference lists. Combinations of “Antioxidant activity of E. alba” and “E. alba Antioxidant” were among our search terms. Fifty-three articles matched the original search query. This article’s selection of original research publications was narrowed down to 24 after duplicates; studies written in languages other than English and studies deemed irrelevant to our topic based solely on their abstracts were eliminated [Table 1].

Table 1.

Experimental study involving the antioxidant activity of E. alba by different methods

Author Name/Year	Part Use	Finding	Result
Aruna Barua, et al. 2023.[21]	Whole Plant	The aqueous fraction of E. alba exhibited significant antioxidant activity by scavenging DPPH radicals, with 87.5% inhibition at 100 μg/ml and an IC50 value of 7.86 μg/ml.	E. alba showed antioxidant, anti-inflammatory, antimicrobial, and thrombolytic activities. Phytochemical screening revealed presence of alkaloids, steroids, glycosides, and flavonoids.
Priyanshi Singh et al. 2022.[22]	Leaf extract of E. alba.	The extract reduced oxidative biomarkers in rats at doses of 50 mg/kg and 100 mg/kg. In vitro experiments showed the extract had an IC50 value of 45.68 μg/mL in the DPPH free-radical assay, compared to 3.26 μg/mL for standard ascorbic acid.	The leaf extract of E. alba exhibits antioxidant activity due to bioactive components like coumestans, flavonoids, and sterols, as demonstrated by DPPH and reducing power assays.
Pooja Mishra et al. 2022.[23]	Methanol and aqueous extracts of whole plant.	The study on E. alba demonstrates its potent antimicrobial and antioxidant properties, especially against ESBL-producing pathogens in urinary tract infections. The aqueous extract exhibited the strongest antibacterial activity, while all extracts showed significant, concentration-dependent antioxidant effects.	The study specifically compared the antioxidant activity of E. alba extracts to that of gallic acid, a well-known antioxidant, and found that the extracts exhibited significant antioxidant properties. The presence of various phytochemicals, such as polyphenols and flavonoids, in the extracts is believed to contribute to their antioxidant effects.
Sharma Shweta et al. 2022.[24]	NA	E. alba antioxidant potential was significantly enhanced by elicitors like proline, salicylic acid, and PGPR-Azospirillum, showing increased DPPH scavenging activity and FRAP values, along with elevated total phenolic content.	Elicitors increased antioxidant potential of E. alba significantly. Salicylic acid treatment showed the highest antioxidant activity in the plant. Salicylic acid treatment resulted in a significant increase in DPPH free-radical scavenging activity, showing a 17.05% improvement compared to the control group.
Purushothaman Ayyakkannu et al. 2020.[25]	Ethanolic extract of the leaves of E. alba.	The extract exhibited excellent DPPH, hydrogen peroxide, and superoxide radical scavenging activities, with IC50 values of 46.19±3.5 mg/mL for DPPH, 58.9±4.98 for hydrogen peroxide, and 64.2±4.9 for superoxide radicals at a concentration of 80 mg/mL.	The total phenolic content of E. alba was found to be 26.38±2.45 mg gallic acid equivalent per gram of extract, indicating a high concentration of phenolic compounds that contribute to its antioxidant activities. The ability of E. alba to inhibit DNA damage induced by ROS further supports its antioxidant properties, highlighting its potential in protecting against oxidative damage associated with aging, cancer, and degenerative diseases.

Study selection and data gather

The evaluation of research articles and academic works was based on their impact, importance, and relevance. In the situation of investigations related to the antioxidant effects of E. alba, a comprehensive scrutiny of appropriate publications was carried out without any text restrictions on keywords used in the search methodology. Research that investigated the antioxidant effects of E. alba extracts or constituents in in vitro study was incorporated in the review. The following are the exclusion criteria: literature that contained technical errors, literature that was not written in English, and literature that had no impact on our search.

Chemical constituents of E. alba

The diverse chemical composition of E. alba highlights its potential in both traditional and modern medicine, with various compounds working together to provide therapeutic benefits.

E. alba plant contains a variety of phytochemical compounds with diverse medicinal properties. Studies have identified various compounds in E. alba, including coumestans, terpenoids, alkaloids, volatile oils, flavonoids, and thiopenes.[11] Among these, coumestans, such as DWL and wedelolactone (WL), are prominent and have demonstrated anti-inflammatory, antioxidant, and antiaging activities.[12] Additionally, compounds like ecliptalbine, WL, ursolic acid, and beta amyrin have shown strong binding affinity against breast cancer target proteins, indicating potential therapeutic benefits in cancer treatment.[13] The plant’s bioactive compounds have also been explored for their pharmacological effects in wound healing, diabetes, obesity, antioxidants, cancer, hair growth, and neuroprotection, highlighting its broad spectrum of potential health benefits.[14,15,16]

Phytochemical analysis of E. alba leaves revealed the presence of bioactive metabolites like phthalic acid, isobutyl octadecyl ester, and hexadecanoic acid, which demonstrated antimicrobial properties against various pathogens.[17] It has been reported that the methanol extract of E. alba leaves exhibits a cytotoxic effect against oral squamous cell carcinoma; compound structures like palmitic acid and Stigmasta-3, 5-dien-7-one showed strong binding energies with target proteins, hence offering a potential herbal drug against cancer.[18]

Roots and Leaves

Hentriacontanol and heptacosanol are found in roots; stigmasterol and β-terthienylmethanol are found in leaves.[19,20]

Aerial parts

Phytosterols, triterpenic acid glucoside, and β-amirin have been isolated from the aerial parts. Polypeptides: On hydrolysis, they yield essential amino acids such as phenylalanine and methionine.

Nicotinic acid and nicotine

Present and contributing to the pharmacological profile.[20]

DISCUSSION

The findings presented in the various studies underscore the plant’s multifaceted biological activities, notably its significant antioxidant effects. Barua et al.[21] (2023) provide compelling evidence of E. alba ability to scavenge DPPH radicals, which emphasizes its potential role as a natural antioxidant in health-related applications. The reported IC50 values indicate a promising effectiveness compared to standard antioxidants, which is further corroborated by the work of Singh et al.[22] (2022), where the leaf extract demonstrated a notable reduction in oxidative biomarkers in an animal model. Such findings suggest that E. alba could be beneficial in mitigating oxidative stress in vivo. Moreover, the studies collectively highlight the importance of phytochemical constituents such as flavonoids and polyphenols in mediating these antioxidant properties.

Thenmozhi et al.[26] (2019) demonstrated the exceptional efficacy of petroleum ether extracts, achieving the lowest IC50 values in multiple assays, which suggests superior antioxidant activity in comparison to other solvents. This finding is corroborated by Mittal et al.[27] (2018), whose methanolic extracts displayed robust DPPH radical scavenging capabilities, indicating the plant’s ability to neutralize free radicals effectively. Furthermore, Sharma et al. (2018) and Singh et al. (2017) corroborated these findings, revealing considerable antioxidant activities across different extraction methods and radical scavenging assays.[28,29]

CONCLUSION

This review highlights the potent antioxidant activity of E. alba due to bioactive components like WL, DWL, flavonoids, and sterols. Several research papers have stated the efficacy of E. alba in free-radical scavenging and reducing oxidative stress through bioassays such as DPPH-scavenging and reducing power assays. Moreover, the high phenolic and flavonoid contents of the E. alba extracts support the potent antioxidant capabilities for the former, thus making this compound a potential candidate for developing pharmacologically active natural products with antioxidant properties. In this respect, the diversity of the E. alba chemical composition in coumestans, terpenoids, alkaloids, and flavonoids opens up perspectives for its application in traditional and modern medicine as a remedy with several therapeutic benefits. More specifically, E. alba is reportedly significantly effective against wound healing, diabetes, cancer, and neuroprotection owing to its very wide spectrum of probable health benefits.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.