In vitro inhibition of lipase, α‐amylase, α‐glucosidase, and angiotensin‐converting enzyme by defatted rice bran extracts of red‐pericarp rice mutant

Abstract

AbstractBackground and objectivesFreeze‐dried aqueous and various ethanolic (25%, 50%, 75%, and 95%) extracts of defatted red rice (mutant AM‐425) bran were prepared and designated as E0, E25, E50, E75, and E95, respectively. Phenolic constituents of extracts and the in vitro inhibitory effects of extracts against lipase, α‐amylase, α‐glucosidase, and angiotensin‐converting enzyme (ACE) were examined.FindingsYields of extracts ranged from 16.45% (E0) to 11.57% (E95). The E50 and E75 had higher total phenols (79.2–80.9 mg ferulic acid equivalent (FAE)/g extract) than other extracts. The E75 and E95 had higher total flavonoids (20.46–21.35 mg catechin equivalent/g extract). The most abundant phenolic acid and flavonoid were ferulic acid and catechin, respectively. Both E50 and E75 had higher inhibitory activity against lipase (IC50, 35.95–35.97 mg/ml), α‐amylase (IC50, 21.99–22.02 mg/ml), α‐glucosidase (IC50, 1.67 mg/ml), and ACE (IC50, 2.93–2.97 mg/ml).ConclusionsBoth E50 and E75 can be used to produce high‐value functional supplements. However, further studies with in vivo models reflecting potential human benefits are needed in the future.Significance and noveltyThe tested E50 and E75 had higher contents of total phenols. Moreover, both E50 and E75 were able to inhibit key enzymes relevant to obesity (lipase), type‐2 diabetes mellitus (α‐amylase and α‐glucosidase), and hypertension (angiotensin‐converting enzyme) in an in vitro model. The results suggest that defatted rice bran extracts could be considered as potential candidates for developing functional foods or supplements.