Antioxidant properties of polar and non-polar extracts of some green leafy vegetables

BACKGROUND: The higher consumption of vegetables and fruits could be a practical approach to the management of oxidative stress. The present study sought to compare the antioxidant properties of polar and non-polar constituents of some tropical green leafy vegetables (Struchium sparganophora, Amaranthus cruentus, Telfairia occidentalis, Ocimum gratissimum, Talinium triangulare, Cnidoscolous aconitifolius and Vernonia amygdalina). RESULTS: The polar antioxidant constituents (total phenol (3330-17 572 mg kg(-1)), total flavonoid (1668-4306 mg kg(-1)) and vitamin C (224-642mg kg(-1))) were higher than the non-polar antioxidant constituents (total phenol (703-3115 mg kg(-1)), total flavonoid (130-1303mg kg(-1)) and carotenoids (132-1303 mg kg(-1))). Furthermore, the polar extracts had a significantly higher (P < 0.05) 1,1-diphenyl-2-picrylhydrazyl radical scavenging ability (except T. triangulare), total antioxidant capacity, reducing power (except T. triangulare and A. cruentus) and Fe(II) chelating ability (except C aconitifolius and S. sparganophora). However, the polar and non-polar extract of O. gratissimum had the highest antioxidant properties while that of T. triangulare had the least antioxidant properties. CONCLUSION: The polar extract of most of the vegetables had higher antioxidant properties than the non-polar extract, with O. gratissimum extracts having the highest antioxidant properties. (c) 2008 Society of Chemical Industry