Abstract: In this study, we aimed to evaluate the immunoregulatory activity of mung bean peptides. Three peptides were separated from mung bean protein hydrolyzed with alkaline protease by Sephadex G-15 column chromatography, and they were screened for their immunoregulatory activity in terms of macrophage proliferation rate, glycogen content, nucleic acid content, and cytokine secretion. Among these peptides, peptide MBPH-3 had the highest immunoregulatory activity, which increased macrophage proliferation rate by 9.05% compared with the blank control group. At the same time, all three mung bean peptides could promote glucose metabolism, increase the content of nucleic acid, and enhance the expression of cytokines such as interleukin (IL), IL-1β and tumor necrosis factor-α (TNF-α). The expression levels of cytokines in the MBPH-3 treated group were 1 566.47, 593.32, 828.13 pg/mL respectively. These values were significantly higher than those in the blank control group (136.55, 139.61 and 436.18 pg/mL) (P < 0.05). Moreover, MBPH-3 could inhibit cytokine secretion induced by lipopolysaccharide (LPS) in macrophages, and the amounts of TNF-α, IL-1β and IL-6 secreted by MBPH-3 treated macrophages were 2 152.94, 1 058.81 and 859.96 pg/mL (compared to 2 923.19, 3 707.09 and 2 880.74 pg/mL for LPS stimulated macrophages), respectively. In summary, the immunoregulatory effect of MBPH-3 is the best among the three mung bean peptides. The average molecular mass of MBPH-3 is approximately 903 Da and its amino acid sequence is Asn-Asn-Tyr-Gly-Pro-Thr-Met.

Key words: mung bean peptide, macrophage, cytokine, immune regulation