Sinulariapeptide F, a new peptide from culture broth of marine-derived fungus Simplicillium sp. SCSIO 41222

One new compound named sinulariapeptide F (1) together with one known butyrolactone (2) and seven known peptides (3–9) were isolated from the fungus Simplicillium sp. SCSIO 41222. Their structures and absolute configurations were established using HRESIMS, NMR spectroscopy (¹H, ¹³C, HSQC, HMBC) and marfey’s method. All of these compounds were assessed their inhibitory activity of acetylcholinesterase (AChE) and pancreatic lipase (PL). Compounds 4 and 6 were selected to test for the inhibitory activity against programmed cell death-1 (PD-1)/ programmed cell death-ligand 1 (PD-L1). The results indicated that compound 4 displayed potent inhibition activity against PD-1/ PD-L1 with an IC₅₀ value of 0.656 μM. Furthermore, the docking analysis demonstrated the interactions between 4 and proteins, suggesting PD-L1 to be a probable target for compound 4.