Correlation of Flavonoid and Phenolic Content with Antioxidant and Cytotoxic Activities of Centella asiatica L. Leaves

Oxidative stress plays a central role in the pathogenesis of numerous chronic diseases, including cancer, neurodegenerative disorders, cardiovascular dysfunction, diabetes, and inflammation. This biological imbalance occurs when the generation of reactive oxygen species exceeds endogenous antioxidant defenses, ultimately leading to cellular injury and cytotoxicity. Medicinal plants are widely recognized as rich sources of antioxidant and cytotoxic agents, largely attributed to their bioactive phytochemicals such as phenolics and flavonoids. Despite India's extensive plant biodiversity, many traditionally used species remain insufficiently explored for their phytochemical composition and cytotoxic potential. Centella asiatica L. (Gotu kola), an important medicinal herb in Ayurvedic, African, and Chinese systems of medicine, has been historically valued for its cognitive, dermatological, anti-inflammatory, and wound-healing properties. However, limited information exists regarding the relationship between its phenolic and flavonoid content, antioxidant activity, and cytotoxic effects. The present study aimed to quantify the total phenolic and flavonoid content of C. asiatica leaf extracts (chloroform, ethanol, and aqueous), evaluate their antioxidant capacity using DPPH and hydrogen peroxide scavenging assays, and assess cytotoxicity via the brine shrimp lethality bioassay. The ethanolic extract contained the highest levels of flavonoids (77.01mg HE/g) and phenolics (28.05mg GAE/g), followed by the aqueous and chloroform extracts. Consistent with its higher phytochemical content, the ethanolic extract exhibited the strongest antioxidant properties, demonstrating an IC₅₀ of 51.66μg/mL in the DPPH assay and 4.88 μg/mL for hydrogen peroxide scavenging, approaching the activity of the standard ascorbic acid. Cytotoxic evaluation revealed a dose-dependent response, with the ethanolic extract again showing the greatest potency (LC₅₀ = 62.50μg/mL), followed by aqueous and chloroform extracts. Overall, the study establishes a clear correlation between phenolic/flavonoid concentration and both antioxidant and cytotoxic activities in C. asiatica leaves. These findings support the plant's traditional medicinal applications and highlight its potential as a promising source of bioactive compounds for future fractionation, mechanistic investigations, and therapeutic development.