PHYTOCHEMICAL COMPOSITION AND ANTIOXIDANT ACTIVITY OF SELECTED MEDICINAL PLANTS

Abstract

For centuries, medicinal plants have been the backbone of traditional medicine . Their therapeutic value is mainly due to bioactive secondary metabolites especially phenolics and flavonoids which scavenge free radicals and prevent oxidative stress. The development of natural antioxidants is a priority for drug and nutraceutical development since oxidative stress plays a role in the pathogenesis of cardiovascular disease, diabetes, neurodegeneration, and cancer. The aim of the present study was to assess the qualitative phytochemical constituents, total phenolic content, total flavonoid content and in vitro antioxidant activity of four selected medicinal plants Azadirachta indica, Moringa oleifera, Ocimum sanctum and Punica granatum by cold maceration method, standard qualitative screening methods, Folin–Ciocalteu and aluminum chloride colorimetric method and DPPH radical scavenging assay.Qualitative screening revealed the presence of alkaloids, flavonoids, phenolics, tannins, saponins, terpenoids and glycosides in all the extracts, with A. indica having the widest range. The TPC was found to be 6.64 mg GAE/g for A. indica and 85.60 ± 4.87 mg GAE/g for P. granatum peel. The TFC was found to be up to 118.57 ± 0.08 mg QE/g in A. indica leaf extract. All the extracts scavenged DPPH radicals in a concentration dependent manner. The most effective material was Punica granatum peel, which showed the highest activity (EC50 3.88 ± 0.33 µg/mL; 96.76% inhibition at 40 µg/mL, approaching the synthetic standard BHA). Among the leaf materials, O. sanctum was the most active (IC50 47.73 µg/mL versus 41.34 µg/mL for ascorbic acid). The order of antioxidant activity was in accordance with phenolic content with high positive correlation (r=0.981 and 0.958) confirming that polyphenolics are the main determinants of activity.

The results confirm the traditional medicinal use of the chosen species and highlight pomegranate peel, a discarded agro-industrial waste, as a promising low-cost source of natural antioxidants for nutraceutical and food preservation applications.