Identification and functional characterisation of bioactive peptides in rice bran albumin hydrolysates

The potential heath-benefitting bioactivities of rice bran albumin hydrolysates were investigated. The antioxidant and alpha-glucosidase-and angiotensin-converting enzyme (ACE)-inhibitory activities of the crude hydrolysates and their fractions were determined. The fractions with the highest bioactivities were analysed by liquid chromatography-tandem mass spectrometry/mass spectrometry to identify the active peptide sequences. Hydrolysates produced by commercial proteases Alcalase and Protamax exhibited the highest alpha-glucosidase-and ACE-inhibitory activities, resulting in 43.1 +/- 2.1% and 54.4 +/- 5.1% inhibition of the enzymes, respectively. Inhibitory activities against both enzymes were highest in the MW<3-kDa fractions that were eluted under alkaline conditions. A number of peptide sequences were identified in the fractions, which contained several sequences with reported alpha-glucosidase-or ACE-inhibitory activities. This is the first time that such activities are reported for rice bran albumin hydrolysate, and it demonstrated that the hydrolysates may be developed into nutraceuticals useful in managing diabetics and hypertension.