Effects of tannin extract from gongronema latifolium leaves on lipoxygenase cucumeropsis manii seeds

Lipoxygenase (ec 1.13.11.12) was partially purified from germinated seeds of cucumeropsis manii to a purification fold of 47.14,enzyme activity recovery of 72.18,and specific activity of 326.25 units/mg protein,using a three-step process of centrifugation,ammonium sulphate precipitation and gel filtration. kinetic properties show maximum activity at ph 6.0 and at optimum temperature of 40°c. inhibitory effects of the extract from gongronema latifolium and two other known antioxidants: ascorbic acid and propyl gallate on lipoxygenase from cucumeropsis manii were studied. result shows presence of inhibition with ic50 of 4.2 × 10 - 3 ± 0.09 × 10 - 3 g/l,4.3 × 10 - 2 ± 0.11 × 10 - 2 g/l and 7.9 × 10 - 2 ± 0.11 × 10 - 2 g/l for the extract from ascorbic acid and propyl gallate,respectively. the extract when compared to the other antioxidants exhibits a competitive mechanism of inhibition. this tannin extract could be included during food processing as preservative against food deterioration that might be caused by oxidative enzymes such as lipoxygenase. © 2013 sabinus o. o. eze and bennett c. nwanguma.