Proximate and antioxidant activity analyses of six indigenous Nigerian vegetables

Abstract

Six commonly consumed indigenous vegetables in Nigeria, Ocimum gratissimum, Talinum triangulare, Telfairia occidentalis,
Amaranthus hybridus, Vernonia amygdalina, and Basella alba were analysed for their proximate composition and antioxidant
properties. The antioxidant properties were measured qualitatively and quantitatively by DPPH. The ash contents of the
vegetables ranged from 3.99±0.01 to 11.5±1.40%, while the crude fibre content was between 5.35±0.04 and 10.20±0.1% based
on dry weight. B. alba had the highest moisture content (92.55±0.07%), but the lowest ash and crude fibre contents.All the
vegetable extracts exhibited antioxidant activities in terms of free radical scavenging abilities and the activities were concentration
dependent. O. gratissimum and V. amygdalina exhibited antioxidant activities that were comparable to the reference antioxidant
compound, ascorbic acid. The vegetables contained different quantities of phenolic compounds, which seemed significantly
contributing to differences in their antioxidant activities. The IC50 value of A. hybridus, O. gratissimum, V. amygdalina, B. alba
and T. occidentalis were 0.20, 1.23, 10.52, 44.65 and 76.90 µg/mL respectively. All the vegetables displayed high antioxidant
ability except T. trianguleae with IC50 502.81 µg/mL. Our results showed that all the vegetables are suitable sources of antioxidant
compounds and could be health promoting.