Angiotensin converting enzyme inhibitory activity of proteolytic digests of peanut (Arachis hypogaea L.) flour

Defatted raw and roasted peanut flour were hydrolyzed with alcalase or sequentially with pepsin and pancreatin, and then the hydrolyzates were fractionated by RP-HPLC and tested for hypotensive potential. This research revealed that proteolytic peanut digests have an inhibitory effect on the activity of angiotensin converting enzyme (ACE). Three fractions from the hydrophobic end of the chromatogram of each hydrolyzate were the most potent for inhibiting ACE activity in comparison to seven other fractions. These potentially potent fractions were then assayed for IC50. Fractions from the alcalase digestion of raw peanut exhibited IC50 values of 8.7–122 μg/ml, and those from roasted flour exhibited values of 12–235 μg/ml. IC50 values of 7.9–65.9 μg/ml, and 11–36 μg/ml for raw and roasted peanut, respectively, from the pepsin–pancreatin system were observed. These values compare to the IC50 value of 0.36 μg/ml of a known commercial ACE inhibitor (pGlu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro).