Phytochemical Profiling and Free-Radical Scavenging Potential of Phyllanthus niruri Whole-Plant Extract: A Laboratory Study

Abstract

Background: Oxidative stress arising from an imbalance between reactive oxygen species and endogenous antioxidant defenses contributes to the pathogenesis of a wide spectrum of chronic non-communicable diseases. Medicinal plants used in the Ayurvedic and Siddha systems of South India represent an abundant and inexpensive reservoir of natural antioxidants. Phyllanthus niruri L. (locally "keezhanelli" or bhumyamalaki) is a widely used ethnomedicinal herb whose whole-plant preparations enjoy a long-standing reputation for hepatoprotective and antioxidant activity.

Objective: To characterise the phytochemical composition of a P. niruri whole-plant hydroalcoholic extract and to quantify it’s in vitro free-radical scavenging and ferric-reducing potential relative to ascorbic acid.

Methods: A laboratory-based phytochemical and in vitro antioxidant study was performed. The whole plant was subjected to hydro alcoholic extraction, and percentage yield was recorded across six batches. Qualitative phytochemical screening was undertaken using standard generic tests. Total phenolic content (TPC) was measured by the Folin–Ciocalteu method (mg Gallic acid equivalents [GAE]/g) and total flavonoid content (TFC) by the aluminum chloride method (mg quercetin equivalents [QE]/g). Antioxidant activity was evaluated by DPPH, ABTS and FRAP assays across 10–100 µg/mL in triplicate, with ascorbic acid as reference standard. Half-maximal inhibitory concentrations (IC50) were derived by four-parameter logistic regression. Data are expressed as mean ± standard deviation, with p<0.05 considered significant.

Results: The mean extraction yield was 12.30 ± 1.12% (dark green-brown, semi-solid extract). Screening revealed abundant flavonoids, phenolics, tannins, terpenoids, glycosides and carbohydrates; steroids were absent. TPC was 119.38 ± 2.00 mg GAE/g and TFC 62.88 ± 5.96 mg QE/g. Radical scavenging was concentration-dependent, reaching 55.33% (DPPH) and 60.75% (ABTS) at 100 µg/mL. Extract IC50 values were 52 µg/mL (DPPH) and 46 µg/mL (ABTS) versus 28 µg/mL for ascorbic acid, and ferric-reducing power rose to 217.13 µmol Fe(II)/g. The extract was consistently less potent than ascorbic acid but showed substantial, reproducible activity.

Conclusion: The P. niruri whole-plant extract is rich in phenolic and flavonoids and exhibits moderate-to-high, concentration-dependent free-radical scavenging and ferric-reducing capacity. These findings provide a plausible mechanistic basis for, and low-cost laboratory support of, its traditional South Indian medicinal use.