Abstract:The effects of pre-hydrolysis using different proteases on the degree of gastrointestinal digestion of maca proteins and the immunomodulatory activity of their digestion products were explored. Dispase, alcalase, papain, bromelaine, and protamex were selected to pre-hydrolyze maca proteins, and the final five digestion products after subsequent in vitro simulated gastrointestinal digestion were obtained. The yield, degree of hydrolysis, soluble peptide content, and free amino acid content of the digested products were determined using the TNBS method and Folin-Ciocâlteu assay. Mouse macrophages RAW 264.7 were used as the model to explore the immunomodulatory activity of the digestion products. Following pre-hydrolysis with the five proteases, the degree of hydrolysis, soluble peptide content, and free amino acids content of the maca protein digestion products were augmented by respectively 35%, 5%~16% and 37%~92%, while no significant inhibitory effect of their promotion on the secretion of TNF-α by macrophages was observed. The digestion products obtained via bromelain pre-hydrolysis showed the highest immunomodulatory activity and comprised 15 154 peptides, with a molecular weight of <3 000 u. Among the top 10 peptides with the strongest interactions with TLR2 and TLR4 predicted based on activity scores and molecular docking, NPYPFFGFSI exhibited the highest immunomodulatory activity. HOMO analysis revealed that the active site of this peptide is located at tyrosine. Therefore, the digestibility of maca proteins can be improved via pre-hydrolysis without compromising their immunomodulatory activity.
