Antioxidant activities and total phenolic and flavonoid contents in three indigenous medicinal vegetables of north-east India.

Antioxidant activities of the n-hexane, ethyl acetate and methanol extracts of three indigenous leafy vegetables of north east India viz., Polygonum microcephallum, Oxalis corniculata and Portulaca oleraceae were measured by spectroscopic methods using the 1, 1-diphenyl-2-picrylhydrazyl (DPPH*) radical assay and xanthine/xanthine oxidase assay. The total phenolic and total flavonoid contents of each extract were also measured to assess their effect on the antioxidant activity. It was observed that the methanol extracts of all the species showed the highest antioxidant activities and high values for total phenolic and flavonoid contents. A strong correlation between the antioxidant activities and the total phenolic content was observed for the three vegetables. It indicates that phenolics are one of the main components responsible for the antioxidant behavior of vegetables. HPLC analysis showed the presence of a number of identified phenolic compounds.