Phenolics Content and Antioxidant Capacity of Extracts and Fractions of Vernonia blumeoides (Asteraceae)

摘要

Leaf extract and fractions of Vernonia blumeoides were evaluated for total phenolics content (Folin-Ciocalteu method), free radical scavenging activity (1, l-diphenyl-2-picrylhydrazyl radical assay), total antioxidant capacity (Phosphomolybdate assay)and ferric reducing power. The results of the phenolics content expressed in mg/100 g of Gallic Acid Equivalent (GAE) showed thai the n-butanol fraction has significantly (p<0.05) higher phenolics content (410±0.8) than the chloroform fraction and ethanol extract. The radical scavenging activity of the extract and solvent fractions displayed strong concentration dependent activity. But it was also observed that the ethyl acetate fraction showed highest activity in all concentration tested ranging from70.56 to 99.0-1%. However, the total antioxidant capacity (mg g~(-1) ascorbic acid) showed that n-butanol fraction has the highest capacity (60.0 mg g~(-1)). The results also showed that the n-butanol extract has strongest reducing ability (2.105±0.109nm) at higher concentration which is comparable to that of Gallic acid at all the concentrations tested. Phytochemical screening on the extracts revealed the presence of flavonoids, saponins and tannins. The results suggest that the plant especially then-butanol and ethyl acetate fractions are very rich in antioxidant compounds worthy of further investigations.