Chemometric evaluation of enzymatic hydrolysis in the production of fish protein hydrolysates with acetylcholinesterase inhibitory activity

Effects of walnut seed coat polyphenols on walnut protein hydrolysates: Structural alterations, hydrolysis efficiency, and acetylcholinesterase inhibitory capacity

The walnut meal is rich in nutrients such as protein from the kernel and polyphenolic compounds from the seed coat. However, the influences of seed coat polyphenols on walnut protein (WP) hydrolysis remained unclear. In this study, our findings indicated that polyphenols induced alterations in the secondary structure and amino acid composition of WP. These changes resulted in both a hindrance of hydrolysis and an enhancement of acetylcholinesterase (AChE) inhibition. Furthermore, four peptides of 119 identified peptides (LR, SF, FQ, and FR) were synthesized based on higher predicted bioactivity and Vinascores in silico. Among them, FQ showed interaction with amino acid residues in AChE through the formation of four π-π stacking bonds and two hydrogen bonds, resulting in the highest AChE inhibitory capacity. The combination index showed that chlorogenic acid derived from the seed coat and FQ at the molar ratio of 1:4 exhibited synergistic effects of AChE inhibition.

Comparison of amino acid release between enzymatic hydrolysis and acid autolysis of rainbow trout viscera

Fish protein hydrolysates were obtained from cultured rainbow trout (Oncorhynchus mykiss) viscera using commercial and endogenous enzymes. Two methods were employed for hydrolysis: acid autolysis (also known as silage) at room temperature for 10 days in acidic conditions, until total solubilisation, and enzymatic hydrolysis using Alcalase 2.4 LFG, Protana Prime, and the endogenous enzymes in the viscera. The effectiveness of both methods in releasing free amino acids (FAA) was assessed. After evaluating the results, the most effective enzymatic hydrolysis was optimized. The findings indicated that enzymatic hydrolysis with Alcalase, Protana Prime and endogenous enzymes combined for 7 h at a dose of 1% of protein, and a 7-day acid autolysis yielded the highest degree of hydrolysis (83.8% and 75.8%), a yield of FAA from viscera of 5.9% and 3.2%, and a yield of FAA from total protein of 71.3% and 52.5%, respectively. In conclusion, the use of commercial enzymes was more efficient in releasing amino acids, but endogenous enzymes showed a strong proteolytic capacity during acid autolysis, suggesting it also as a promising method to produce FAA-rich hydrolysates.

Anticholinesterase Inhibition, Drug-Likeness Assessment, and Molecular Docking Evaluation of Milk Protein-Derived Opioid Peptides for the Control of Alzheimer’s Disease

The drug-likeness and pharmacokinetic properties of 23 dairy-protein-derived opioid peptides were studied using SwissADME and ADMETlab in silico tools. All the opioid peptides had poor drug-like properties based on violations of Lipinski’s rule-of-five. Moreover, prediction of their pharmacokinetic properties showed that the peptides had poor intestinal absorption and bioavailability. Following this, two well-known opioid peptides (βb-casomorphin-5, βb-casomorphin-7) from A1 bovine milk and caffeine (positive control) were selected for in silico molecular docking and in vitro inhibition study with two cholinesterase enzyme receptors important for the pathogenesis of Alzheimer’s disease. Both peptides showed higher binding free energies and inhibitory activities to butyrylcholinesterase (BChE) than caffeine, but in vitro binding energy values were lower than those from the docking model. Moreover, the two casomorphins had lower inhibitory properties against acetylcholinesterase (AChE) than caffeine, although the docking model predicted the opposite. At 1 mg/mL concentrations, βb-casomorphin-5 and βb-casomorphin-7 showed promising results in inhibiting both cholinesterases (i.e., respectively 34% and 43% inhibition of AChE, and 67% and 81% inhibition of BChE). These dairy-derived opioid peptides have the potential to treat Alzheimer’s disease via cholinesterase inhibition. However, appropriate derivatization may be required to improve their poor predicted intestinal absorption and bioavailability.