Novel immunomodulatory peptides from hydrolysates of the Rana spinosa (Quasipaa spinosa) meat and their immunomodulatory activity mechanism.

In this study, hydrolysates of Rana spinosa meat were purified and characterized, and combined with molecular docking to screen potential immunomodulatory peptides and explore their activities and mechanisms of action. The results showed that 582 peptides were identified from the hydrolysates, and three novel immunomodulatory peptides, GIHETTYNS (1020.4512 Da), IADRMQKE (989.4964 Da), and IVRDIKEK (999.6077 Da), were obtained by molecular docking. These peptides significantly increased the proliferative activity of RAW264.7 cells and accelerated its cell cycle proceeding, promoted the production of NO, IL-6, and TNF-α, and enhanced ROS levels. The molecular docking analysis revealed that immunomodulatory peptides bound to the key regions of TLR4/MD-2 by hydrogen bonds and hydrophobic interactions, and the common sites of action were LYS A:458, ARG A:434, and ARG D: 90. Furthermore, these immunomodulatory peptides had favorable safety and stability properties in silico analysis. These novel peptides are expected to be new natural materials for immunomodulators.