Antibiotic. Shows antiviral, antifungal and antitumor properties. Immunosuppressive drug used to prevent rejection in organ transplantation, rheumatoid arthritis, and psoriasis. Potent reversible inhibitor of inosine-5′-monophosphate dehydrogenase (IMPDH), leading to depletion of GMP and interruption of the de novo synthesis of purine nucleotides necessary for B and T lymphocyte proliferation. Inhibits the type II IMPDH isoform (IMPDH-2) 5-fold more potently compared to type I isoform. Inhibits RNA and DNA synthesis. Inducible nitric oxide synthase (iNOS/NOS II) inhibitor. Apoptosis and necrosis inducer. Novel type of inhibitor against RNA guanylyltransferases. Inhibits TNF-alpha-stimulated MAPK/NF-kappaB and ROS generation.