Relation of amino acid composition, hydrophobicity, and molecular weight with antidiabetic, antihypertensive, and antioxidant properties of mixtures of corn gluten and soy protein hydrolysates

**Background:** Plant protein hydrolysates are sustainable sources of bioactive peptides with antidiabetic, antihypertensive, and antioxidant activities. Corn gluten meal (CGM) is rich in hydrophobic amino acids but deficient in lysine and tryptophan, while soy protein (SP) has high lysine but limited sulfur-containing and hydrophobic amino acids. Combining hydrolysates from both sources may compensate for individual deficiencies and enhance biological and functional properties. This study aimed to investigate the influence of combining CGM and SP hydrolysates on bioactivities and functional properties.

**Methods:** Soy protein isolate (~90% protein) and CGM (~62% protein) were hydrolyzed using Alcalase 2.4 L at 60°C, pH 8.0, enzyme/substrate ratio 2.5% w/w, to a degree of hydrolysis (DH) of 15%. Hydrolysis times were 90 min for SPI and 210 min for CGM. CPH and SPH were mixed at ratios of 30:70, 50:50, and 70:30 (% w/w), designated SPH30:CPH70, SPH70:CPH30, and SPH50:CPH50. Amino acid profiles were determined by RP-HPLC. Surface hydrophobicity (H0) was measured using ANS fluorescence. Molecular weight distribution was assessed by SDS-PAGE and gel permeation chromatography (GPC). Antioxidant activities were evaluated via DPPH, ABTS, and hydroxyl radical scavenging assays. ACE inhibitory activity, α-glucosidase inhibition, and α-amylase inhibition were measured spectrophotometrically. Functional properties including solubility at pH 4, 7, and 9, emulsifying activity index (EAI), emulsifying stability index (ESI), foaming capacity (FC), and foaming stability (FS) were determined.

**Key Results:** CP had higher hydrophobic amino acid content (43.35 g/100 g) while SP had higher hydrophilic content (72.06 g/100 g). Hydrolysis increased H0 values, especially for CPH. CPH, SPH30:CPH70, and SPH50:CPH50 showed the highest DPPH radical scavenging activity (46.25%, 46.70%, and 47.30%, respectively). SPH showed the highest ABTS (95.01%) and hydroxyl (82.30%) radical scavenging. SPH and SPH70:CPH30 exhibited the highest ACE inhibitory activity (95.45% and 94.76%, respectively) with IC50 values of 0.15 and 0.18 mg/mL. For α-glucosidase inhibition, SPH showed the highest activity (32.26%) with IC50 5.65 mg/mL, followed by SPH70:CPH30 (30.58%, IC50 7.15 mg/mL). For α-amylase inhibition, SPH showed 58.21% (IC50 0.23 mg/mL) and SPH70:CPH30 showed 55.88% (IC50 0.33 mg/mL). GPC revealed SPH had the lowest MW peptides (439 Da), while SPH70:CPH30 had a peak at 486 Da. SPH70:CPH30 showed the highest EAI (53.54 m²/g) and ESI (46.80 min) among all samples. Solubility at pH 4, 7, and 9 exceeded 92% for all hydrolysates.

**Clinical Implications:** The SPH70:CPH30 mixture demonstrated strong multifunctional bioactivity combining antioxidant, antihypertensive (ACE inhibition), and antidiabetic (α-glucosidase and α-amylase inhibition) properties with excellent techno-functional characteristics. This hydrolysate mixture could serve as a natural alternative to synthetic agents like acarbose, which has side effects. The balanced amino acid profile and enhanced functional properties make SPH70:CPH30 a promising ingredient for developing functional foods aimed at managing hypertension, diabetes, and oxidative stress. Further in vivo studies are needed to confirm these in vitro findings.