Comparative In vitro Antioxidant Activities of Aqueous Extracts of Garcinia kola and Buchholzia coriacea Seeds

Comparative in vitro antioxidant activities of aqueous extracts of Garcinia kola and Buchholzia coriacea seeds were carried out using 2, 2-diphenyl 1-picrylhydrazyl (DPPH) free radical scavenging activities, ferric reducing antioxidant power (FRAP) and inhibition of lipid peroxidation assays. Total phenolics, alkaloids, tannins, saponins and flavonoids constituents of the samples were also determined. G. kola seeds contained higher concentrations of secondary metabolites compared to B. coriacea seeds except flavonoids. Both G. kola and B. coriacea exhibited minimum percentage inhibition when compared with the gallic acid. However, B. coriacea exhibited significantly (p < 0.05) higher percentage DPPH scarvenging activities (44.66%) when compared with G. kola (43.62%) at maximum concentration of 100 μg/mL. G. kola on the other hand, showed higher percentage inhibition of lipid peroxidation when compared with B. coriacea at all tested concentrations. Percentage FRAP by B. coriacea was significantly (p < 0.05) higher than G. kola at 100 μg/mL (46.65%, and 38.35%, respectively) and 50 μg/mL (38.75%, and 46.05%, respectively), while lower percentage FRAP of the G. kola than B. coriacea were recorded at 25 μg/mL (24.26% and 38.24%, respectively) and 12.5 μg/mL (34.41% and 37.41%, respectively). Therefore, Garcinia kola and B. coriacea showed appreciable antioxidant activities at varying concentrations and this may be due to the presence of various phenolic compounds in both samples. Keywords: Buchholzia coriacea; Garcinia kola; Antioxidant; DPPH free radicals; Secondary metabolites