Antioxidant content and in vitro 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity of selected medicinal plants

Background/Aim: The medicinal plants and their derivatives have long been recognized as important sources of antioxidants in the prevention and treatment of various diseases. This study investigated phytochemicals, antioxidant content, and in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activities of methanolic and aqueous leaves extracts of Anogeissus leiocarpus, Ipomoea asarifolia, Bauhinia rufescens, Guiera. Senegalensis, and Moringa oleifera. Materials and Methods: The extracts were subjected to qualitative phytochemical analysis to identify the bioactive constituents in each plant. Total phenolics and proanthocyanidin contents were determined using Folin-Ciocalteu and vanillin-methanol assays while antioxidant free scavenging activity was estimated using DPPH assay. Results: The phytochemical screening revealed the presence of alkaloids, flavonoids, and tannins in all the five plants investigated. The total phenolic and proanthocyanidin contents of methanolic extracts were significantly higher (p < 0.05) as compared with aqueous extracts. DPPH-free radical scavenging activity of methanolic extracts of A. leiocarpus and M. oleifera was similar to vitamin C. In vitro DPPH radical scavenging activity of methanolic extracts of A. leiocarpus and M. oleifera were better as compared with B. refescens, I. asarifolia, G. senegalensis, and aqueous extracts. The antioxidant activities of both extracts were in a dose-dependent manner. Furthermore, the lower IC50 of methanolic extracts of A. leiocarpus, B. refescens, and M. oleifera correlated with strong scavenging activities of these plants. Conclusion: This study demonstrated the antioxidant content and DPPH-free radical scavenging activities of five medicinal plants. Thus, the study underscored these plants as potential sources of natural antioxidants that can be explored for the treatment of oxidant-related diseases.