Alpha-amylase, α-glucosidase and lipase inhibiting activities of polyphenol-rich extracts from six common bean cultivars of Southern Italy, before and after cooking.

Common beans (Phaseolus vulgaris) are a good source of nutrients and phenolic compounds with versatile health benefits. Polyphenol-rich extracts of six ecotypes of P. vulgaris were analysed to determine their phenolic profiles and assayed in vitro for inhibitory effects on digestive enzymes relevant to carbohydrates and lipids metabolism. The extracts inhibited enzyme activities in a dose-dependent manner. IC 50 values ranged from 69 ± 1.9 to 126 ± 3.2 μg/mL and from 107.01 ± 4.5 to 184.20 ± 5.7 μg/mL, before and after cooking, for α-amylase, from 39.3 ± 4.4 to 74.13 ± 6.9 μg/mL and from 51 ± 7.7 to 122.1 ± 5.2 μg/mL for α-glucosidase and from 63.11 ± 7.5 to 103.2 ± 5.9 μg/mL and from 92.0 ± 6.3 to 128.5 ± 7.4 μg/mL for lipase. Results suggest encouraging their consumption, being natural sources of enzyme inhibitors important for type-2 diabetes and obesity prevention/control. Well-monitored in vivo studies would help to establish their beneficial effects, making them worthwhile of further consideration as functional foods.