Antioxidant and angiotensin-I-converting enzyme (ACE-I) inhibitory activities of protein hydrolysates derived from water buffalo (Bubalus bubalis) liver

In the current study, we attempted to use ginger as a novel and natural source of protease in comparison with other commercially available enzymes to extract and characterize antioxidant and antihypertensive hydrolysates from water buffalo liver, a protein rich offal. Hydrolysis of protein extracts from buffalo liver using proteinase-K, pronase-E and ginger protease significantly increased the %degree of hydrolysis (18.5-55%) and generated low-molecular weight peptides evident from SDS-PAGE. Enzyme treated hydrolysates exhibited higher (p < 0.05) DPPH radical scavenging activity (43.7-82.4%) and angiotensin-I-converting enzyme (ACE-I) inhibitory activity (46.9-50.1%) relative to control. Mass spectrometric analysis (MALDI-TOF MS) of selected gel-filtered fractions identified few important peptides derived from nuclear ribonucleoprotein, pyruvate kinase and phosphoglycerate kinase that possess strong antioxidant activity. Present findings indicate the efficacy of partially purified ginger as a novel source of protease in generating protein hydrolysates from water buffalo liver with significant antioxidant and antihypertensive activity in vitro. We successfully demonstrated the recovery of functional bioactive peptides from water buffalo liver which presents a potential opportunity for the meat industries to economically use this important byproduct.