Qualitative phytochemical screening and in vitro antioxidant activities of aqueous extracts of Rhaphiolepis bibas (Lour.) Galasso & Banfi

Abstract

Reactive oxygen species causes harm to cell membranes and biomolecules, wherefore chronic diseases develop. Antioxidants scavenge such free radicals combating oxidative stress. This research aimed to determine the antioxidant potential of the aqueous stem bark, root and leaf extracts of Rhaphiolepis bibas against standards. DPPH radical scavenging activity was high from th stem bark extract at 72.33% with root extract at 65.85% and leaf extract at 55.91%, while ascorbic acid scavenged 89.53% of DPPH radicals. The leaf extract had the highest H2O2 scavenging activity of 91.92% with stem bark at 91.17% and the root extracts at 89.12%. The aqueous root extract of R. bibas had a significantly higher FRAP capacity in comparison to the leaf extracts and the stem bark. The abilities to chelate iron by the leaf extract were statistically higher compared to the root and stem bark extracts. Stem bark extracts had the highest phenol content of about 149.44 followed by the root extract at 141.14 and the least amount of phenol was found in the aqueous leaf extract having 73.012 Gallic acid equivalent/g. The root extracts had the highest total flavonoid 377.66-milligram quercetin equivalent/gram dry weight followed by stem bark extract at 255.72 and the least amount was found in aqueous leaf extract having 164.52 mgQE/g of sample dry weight. The existence of secondary metabolites linked to antioxidant action was shown by the qualitative phytochemical screening.