Total polyphenolic content and antioxidant properties of Moringa oleifera leaf extracts
The study was carried out to evaluate the relative antioxidant properties and polyphenol contents of partially purified fractions of Moringa oleifera leaves extracts. The total phenolic, total flavonoid, anthocyanin, proanthocyanidine and tannin contents of the crude methanolic extract, aqueous fraction and ethyl acetate fraction were determined using established methods, while the antioxidant properties of the test fractions were evaluated using five in vitro radical scavenging assays: 2,2-diphenyl- 1-picrylhydrazyl (DPPH) radical scavenging assay, nitric oxide inhibitory assay, lipid peroxidation assay, reductive potential assay, and the ferric reducing ability of plasma (FRAP) assay. The highest radical scavenging effect and polyphenol contents were observed in the ethyl acetate fractions than the other fractions: the order of activity for all the assays was ethyl acetate reaction > crude extract > aqueous extract. The results obtained in the present study indicates that M. oleifera could be a potential source of natural antioxidant and could be applied as a functional food as regard its relatively low tannin content.
Keywords: 2, 2-Diphenyl-1-picryl hydrazyl, Antioxidant, Polyphenols, Moringa