Antibiotic [1]. Shows antiviral, antifungal and antitumor properties [1, 2]. Immunosuppressive drug used to prevent rejection in organ transplantation, rheumatoid arthritis, and psoriasis [3-6, 13]. 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 [7, 8]. Inhibits the type II IMPDH isoform (IMPDH-2) 5-fold more potently compared to type I isoform [11]. Inhibits RNA and DNA synthesis [13]. Inducible nitric oxide synthase (iNOS/NOS II) inhibitor [8, 10]. Apoptosis and necrosis inducer [9, 12]. Novel type of inhibitor against RNA guanylyltransferases [14]. Inhibits TNF-α-stimulated MAPK/NF-κB and ROS generation [15]. Autophagy suppressor. Broad-spectrum antiviral compound with inhibitory activity against different coronavirus, including SARS-CoV, MERS-CoV and SARS-CoV-2, cause of COVID-19. It binds to the active site of SARS-CoV-2 papain-like protease (PLpro) possibly inhibiting viral replication.