Angiotensin I-converting enzyme inhibitor derived from cottonseed protein hydrolysate

Abstract

Six proteolytic enzymes, including alcalase, flavourzyme, trypsin, neutrase, papain and pepsin, were employed to hydrolyze cottonseed protein to produce the hydrolysates of Angiotensin I-converting enzyme (ACE) inhibitory activity. The result indicated that the cottonseed protein hydrolysate (CPH) produced by papain had the highest ACE inhibitory activity. Therefore, papain was selected for enzymatic production of ACE inhibitor from cottonseed protein isolates (CPI). CPI was hydrolyzed with papain for 1 - 8 h, and the 6 h hydrolysate had the strongest ACE inhibitory ability. The product was separated into four ranges of molecular weight (UF-I, > 30 kDa; UF-II, 30 – 10 kDa; UF - III, 10 - 5 kDa; UF - IV, 2.43 kDa, 2.43 - 0.82 kDa, 0.82 - 0.35 kDa and <0.35 kDa, respectively. Fra II exhibited the strongest ACE inhibitory ability (IC 50 = 0.159 mg/ml) with the yield of 41.63%. It was suggested that Fra II with good ACE inhibitory activity can be a potential source of natural ACE inhibitor. Keywords: Cottonseed protein hydrolysate, peptide fractions, angiotensin I-converting enzyme inhibitory ability, ultrafiltration