Raw and cooked African green leafy vegetables have greater antioxidant and cellular protective properties than spinach

Abstract

Leaves of amaranth, jute mallow, pumpkin and cowpea are widely consumed in sub‐Saharan Africa as green leafy vegetables (GLVs). These vegetables are generally underutilized because of the assumption that their nutritional value is less than that of exotic GLVs such as spinach. In this study we determined the total phenolic content, flavonoid content and antioxidant activity of these African GLVs, and their ability to protect against oxidative damage in erythrocytes, plasmid DNA and cell cultures, in comparison to spinach. The effect of boiling on these parameters was also determined. Total polyphenolic and flavonoid contents and antioxidant activity were determined. The ability of GLV extracts to protect against AAPH‐induced oxidative damage in erythrocytes, plasmid DNA and cell cultures was also determined. African GLVs had phenolic content, antioxidant activity and cellular protective properties greater than spinach. Boiling reduced the antioxidant content and activity, and increased the cellular protective properties of GLVs. Significant levels of cytotoxicity were observed in all extracts of raw GLVs, with highest levels in spinach than in African GLVs. The protection of erythrocytes and plasmid DNA against oxidative damage was dependent on individual GLV extracts. The current results can be used to promote the consumption and commercialization of African GLVs. Supported by the Water Research Commission of South Africa; The Faculty for the Future Program of the Schlumberger Foundation and the Organization for Women in Science for the Developing World.