Lankacidinol (T-2636 F) is an antibiotic. Lankacidinol and its related metabolites 2,18-seco-lankacidinol A (1) and 2,18-seco-lankacidinol B (2) have significant biological activities and potential medicinal value. In addition, 2,18-seco-lankacidinol A exhibits potent antitumor activity.