Antioxidant and type II diabetes related enzyme inhibition properties of methanolic extract of an underutilized food legume, Canavalia ensiformis (L.) DC: Effect of traditional processing methods

The methanolic extract of Canavalia ensiformis (L) DC (Jack bean) seed, an underutilized food legume collected from India was analyzed for antioxidant and health relevant functional properties. The raw seeds contained total free phenolic content of 12.98 +/- 1.63 g catechin equivalent/100 g extract DM. The raw seed extract exhibited ferric reducing/antioxidant power (FRAP, 1218 mmol Fe[II]/mg extract), inhibition of beta-carotene degradation (49.81%), radical scavenging activity against DPPH (56.78%) and superoxide (35.89%). In addition, 77.56% of alpha-amylase and 75.45% of alpha-glucosidase enzyme inhibition characteristics were found under in vitro starch digestion bioassay. Sprouting + oil-frying caused an apparent increase on the total free phenolic content with significant improvement on antioxidant and free-radical scavenging capacity, while soaking + cooking as well as open-pan roasting treatments showed diminishing effects. Inhibition of alpha-amylase and alpha-glucosidase enzyme activities were declined to 22.69 and 42.69%, respectively during sprouting + oil-frying treatment is more desirable for the dietary management of type II diabetic patients. (C) 2012 Elsevier Ltd. All rights reserved.