Chemical Composition and in vitro Antioxidant Activities of Some Nigerian Vegetables

This study was designed to investigate the chemical composition of fourteen vegetables popularly consumed in the South Western part of Nigeria and also to evaluate some in vitro antioxidant activities of the selected vegetables. Ethanolic extracts of the vegetables were injected into GC-MS to investigate the presence of some chemical compounds and were also screened for their lipid peroxidation inhibitory potentials and free radical scavenging activities by two complementary. GC-MS studies showed that caffeic acid was present in all the vegetable samples with the exception of Celocia argentia and Talinum triangulare in addition to other compounds identified in some of the vegetables (phenylacetic acid, vanillic acid, genticic acid, protocatechuic acid, syringic acid, p-coumaric acid, garlic acid, ferulic acid, epicatechin and catechin. Lipid peroxidation inhibition studies revealed that lipid peroxide inhibition ranges from 3.59-69.47 (%) while conjugated diene inhibition ranges from 84.33-97.31 (%). Scavenging ability of the vegetables towards hydrogen peroxide ranges from 4.89±0.55-60.26±1.23 (%) while superoxide scavenging activities ranges from 75.62±1.42-97.01±1.32 (%). Total flavonoid mg mL-1 and total antioxidant activity (mg mL-1) ranges from 0.12 to 3.08 and 0.13 to1.60, respectively. Results from conjugated diene formation and superoxide radical scavenging activity show that the evaluated vegetables exhibited a relatively high lipid peroxidation inhibitory potentials and free radical scavenging activity which could possibly be as a result of caffeic acid and other compounds present in the vegetables