Neuroprotective and Free Radicals Scavenging Potentials of Some Common Leafy Vegetables Consumed in South - Eastern Nigeria

Antioxidant potential, lipid peroxidation inhibition ability in brain homogenate and total phenolic and flavonoid contents of ethanol extracts of some leafy vegetables (Vernonia amygdalina, Gongronema latifolium and Ocimum gratissimum) consumed in south-eastern Nigeria were determined. The antioxidant and neuroprotective potentials of the ethanol extracts were assessed by 2, 2-diphenyl-1-picrylhydrazil (DPPH) assay and through determination of thiobarbituric acid (TBA) reactive substances in brain homogenates. Total phenolic and flavonoid contents were quantitatively determined in the extracts spectrophotometrically. Results obtained from the present study showed that G. latifolium and V. amygdalina extracts were effective against hydrogen peroxide-induced lipid peroxidation with threshold inhibitory concentrations (IC50) values of 357.36±15.6µg/ml and 629.5±22.72µg/ml respectively while O. gratissimum achieved only 20% inhibition (IC20) at 785.73±40.23µg/ml. In the DPPH free radical scavenging assay, 50% of DPPH radicals were scavenged at181.5(µg/ml), 153.33(µg/ml), and 189.67(µg/ml) of V. amygdalina, G. latifolium and O. gratissimum extracts concentrations respectively. Free radical scavenging ability of the extracts was in the order G. Latifolium >V. Amygdalina > O. gratissimum. Total phenolic content was 432.79±42.2mg/100g,274.1±37.3mg/100g, and 490.49±58.1mg/100g catechin equivalent, while flavonoid content was 843.09±21.6 mg/100g, 746.34±13.7mg/100g and 1160.98±24.5mg/100g catechin equivalent in V. amygdalina, G. latifoliumand O. gratissimum respectively. The inhibition of lipid peroxidation and DPPH radical scavenging followed a logistic dose response pattern.These results indicatethat these vegetables possess neuro-protective potentials and free radical scavenging ability. The present data scientifically corroborate with the consumption of these plants as an exogenous sources of antioxidants that could improve nutrition and boost antioxidant defense.