Immunoregulatory peptides from <em>Ganoderma sinense</em>: Characterization, isolation, molecular docking and molecular mechanism

<em>Ganoderma sinense</em> is a traditional and protein-rich edible plant with outstanding immunoregulatory activity. However, the mechanism through which <em>G. sinense</em> protein hydrolysates and peptides exert their immunomodulatory effects is unclear. The objective of this study was to prepare and isolate immunologically active peptides from <em>G. sinense</em> protein hydrolysates (GSP) and to investigate their impact on the activation of macrophages. <em>G. sinense</em> peptides with low molecular weights ( &lt; 1 kDa, 87.78%) markedly promoted RAW264.7 cell proliferation; increased their phagocytic capacity, nitric oxide (NO), TNF-<em>α</em>, IL-10, and IL-6 secretion and ROS production; and upregulated <em>Tlr2</em> mRNA expression. In addition, GSP promoted NF-<em>κ</em>B activation and translocation through the upregulation of p65 and p-p65 protein expression. Virtual molecular screening technology revealed that compared with other peptides, the SFAGNIPVNR, YGDAFIR and TVSYLPAPQR peptides derived from GSP showed stronger binding affinities. Interaction site map analysis indicated that the SFAGNIPVNR and YGDAFIR peptides formed stable hydrogen bonds with TLR2. Together, these results suggested that <em>G. sinense</em> peptides can serve as important ingredients in nutraceuticals or functional foods.