Antioxidant properties of polar and non-polar extracts of some tropical 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 (224-642 mg kg⁻¹)) were higher than the non-polar antioxidant constituents (total phenol (703-3115 mg kg⁻¹), total flavonoid (130-1303 mg 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.