Alpha-amylase Inhibitory and Antioxidant Properties of Protein Hydrolysates Derived from Cucumeropsis mannii Seed

Abstract

<title>Abstract</title> Diabetes mellitus is a leading cause of death. Managing postprandial hyperglycemia, a key aspect of the disease, can be achieved through α-amylase inhibition and free radical scavenging. Recent studies highlight the potential of plant-derived peptides to inhibit α-amylase and scavenge free radicals. This study investigated the α-amylase inhibitory and antioxidant properties of protein hydrolysates from <italic>Cucumeropsis mannii</italic> (<italic>C. mannii</italic>) seed, a protein-rich antidiabetic used in traditional medicine. The amino acid composition of the hydrolysates was determined using amino acid analyzer. The results showed that <italic>C. mannii</italic> seed yielded 22.8% protein. The pancreatin- and pepsin-derived hydrolysate contained predominantly glutamate (10.61, 7.20 g/100g), leucine (9.32, 5.23 g/100g) and aspartate (7.11, 6.11 g/100g), respectively. The pancreatin- and pepsin-derived hydrolysates yielded alpha-amylase inhibitory activity with IC₅₀ values of 8.77 ± 0.35 mg/mL and &gt; 9.00 ± 0.00 mg/mL, respectively. Kinetics analyses revealed that pancreatin- and pepsin-derived hydrolysates exhibited uncompetitive and mixed uncompetitive inhibitions, respectively at 9 mg/mL. The pancreatin- and pepsin-derived hydrolysates exhibited 2,20-azinobis-3-ethylbenzothiazoline-6-sulphonate cation radical (ABTS⁺) scavenging activity with IC₅₀ values of 2.58 ± 0.01 mg/mL and &gt; 5.00 ± 0.00 mg/mL; 1,1-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activity with IC₅₀ values of &gt; 5.00 ± 0.00 mg/mL and &gt; 5.00 ± 0.00 mg/mL, respectively; and reducing power with 20.01 ± 1.20 mM Fe²⁺ equivalent and 22.80 ± 1.45 mM Fe²⁺ equivalent, respectively at 5 mg/mL. In conclusion, these findings suggest that the hydrolysates can manage postprandial hyperglycemia in diabetes mellitus by inhibiting α-amylase activity and reducing free radical production.