Amino acid composition and antioxidant properties of protein hydrolysates from Cucumeropsis mannii Naudin seed

Oxidative stress results from an imbalance between reactive oxygen species (ROS) production and antioxidant defenses, driving various pathological conditions. Amino acid deficiency weakens these defenses, worsening cellular damage in a vicious cycle. Therefore, supplementing with amino acid-derived antioxidants can help restore the body’s protective mechanisms. In this study, proteins were isolated via alkaline solubilization-acid precipitation and enzymatically cleaved using pancreatin and pepsin to yield Cucumeropsis mannii Naudin (C. mannii) seed protein hydrolysates. The amino acid composition of the hydrolysates was determined using spectrophotometric method. The hydrolysates were investigated for their antioxidant properties were evaluated using 2, 20-azinobis-3-ethylbenzothiazoline-6-sulphonate cation radical (ABTS+) scavenging, 1,1 diphenyl-1-picrylhydrazyl radical (DPPH) scavenging and ferric ion reducing antioxidant power (FRAP) assays. Following the experiments, 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 exhibited ABTS+ scavenging activity with IC₅₀ values of 2.58 ± 0.01 mg/mL and 5.24 ± 0.03 mg/mL; DPPH scavenging activity with IC₅₀ values of 9.44 ± 0.69 mg/mL and 7.88 ± 0.24 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, the hydrolysates have the potential to function as an amino acid supplement for illness-related malnutrition and as antioxidant adjuvants in mitigating oxidative stress linked to various health conditions.