Isolated from Streptomyces hygroscopicus. Antibiotic. Antibacterial and antifungal properties. Forms a complex with FKBP12 and inhibits the molecular target of rapamycin (mTOR). Inhibits the response to interleukin-2 (IL-2), and thereby blocks activation of T and B cells. Potent immunosuppressant used as an alternative to calcineurin inhibitors. Restricts the proliferation of smooth-muscle cells by blocking cell cycle progression at the G1/S transition. Anti-proliferative. Antitumor compound. Apoptosis enhancer. Activator of autophagy both in vitro and in vivo. Anti-HIV and anti-aging compound. Neuroprotective.