Antioxidant versus anti-diabetic properties of leaves from Vernonia amygdalina Del. growing in Malaysia.

The antioxidant and anti-diabetic properties of the sequential extracts of Vernonia amygdalina based on the chemical composition of the most effective anti-diabetic extract were studied. Using DPPH and ABTS radical scavenging as well as FRAP assays, the extracts showed a consistent dose-dependent trend of potent antioxidant activity in the following solvents: water extract>methanol extract>chloroform extract>and petroleum ether extracts. In the oral glucose tolerance test, the chloroform extract exerted the highest response (33.3%), similar to metformin (27.2%), after 2h compared to the control (50.8%, P<0.05). After a 14-day administration in diabetic rats, the chloroform extract recorded the highest blood (23.5%) and serum (21.4%) glucose-lowering effects (P<0.05). GC-MS analysis of the chloroform extract revealed high levels of linoleic acid (4.72%), α-linolenic acid (10.8%) and phytols (12.0%), as well as other compounds.