Cowpea seed extracts have been investigated for its antioxidant potentials, enzyme-inhibitory activities, antifungal and nematocidal properties among others. Also, protein hydrolysates of cowpea seeds have been evaluated for its antioxidant and antihypertensive potentials in vitro. However, there has been relative paucity of information on the α-amylase inhibitory activities of cowpea seed protein hydrolysates. Consequently, this study evaluated the α-amylase – inhibitory activities and antioxidant potentials of protein hydrolysates derived from cowpea seed proteins. Cowpea seeds were defatted using n-hexane and proteins were extracted from the resulting seed meal. The proteinases namely pepsin and trypsin were used for protein hydrolysis and the resulting hydrolysates were investigated for antioxidant properties (using hydrogen peroxide and ferric ions) and α-amylase inhibitory activity. Antioxidant assays indicated that hydrolysates derived from trypsin digestion showed better ferric reducing power even as both hydrolysates demonstrated similar hydrogen peroxide scavenging capacities. α-amylase inhibition studies showed that peptic hydrolysates had better inhibitory activity (IC50 = 0.127±0.012 mg/ml). Kinetic data indicated mixed mode of inhibition for both hydrolysates, with peptic hydrolysates showing higher binding affinity (ki = 0.089 mg/ml). It is suggested that proteins from cowpea might encode certain peptides with potent biofunctionalities beyond their nutritional benefits and as such could be further processed to develop novel anti-diabetic agents and food additives.
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