Fig. 4From: Small molecule inhibitors against PD-1/PD-L1 immune checkpoints and current methodologies for their development: a reviewChemical structures of natural products based PD-1/PD-L1 inhibitors including cyclo(-Leu-DTrp-Pro-Thr-Asp-Leu-DPhe-Lys(Dde)-Val-Arg-), rifabutin, kaempferol, kaempferol-7-O-rhamnoside, eriodictyol, fisetin, glyasperin C, cosmosiin, ellagic acid, and caffeoylquinic acidsBack to article page