title: Polyene antibiotics. VII. Carbon-13 nuclear magnetic resonance evidence for cyclic hemiketals in the polyene antibiotics amphotericin B, nystatin A1, tetrin A, tetrin B, lucensomycin, and pimaricin1,2.
abstract: Carbon magnetic resonance establishes conclusively that six polyene macrolide antibiotics containing keto groups (the heptaene amphotericin B, the tetraene-diene nystatin A1, and the tetraenes tetrin A, tetrin B, pimaricin, and lucensomycin) exist in the hemiketal form in solution. Their spectra all contain a hemiketal carbon's absorption near 97 ppm but lack a keto carbon's absorption near 210 ppm. The non-polyenic macrolide erythromycin, on the other hand, exists in the keto form.
mesh_terms: D000666:Amphotericin B / Q000032:analysis*; D000935:Antifungal Agents / Q000032:analysis*; D002247:Carbon Isotopes; D004917:Erythromycin / Q000032:analysis; D007783:Lactones / Q000032:analysis; D008155:Lucensomycin / Q000032:analysis*; D018942:Macrolides; D009682:Magnetic Resonance Spectroscopy; D010866:Natamycin / Q000032:analysis*; D009761:Nystatin / Q000032:analysis*
chemical_list: D000935:Antifungal Agents; D002247:Carbon Isotopes; D007783:Lactones; D018942:Macrolides; D009761:Nystatin; C003421:tetrin B; C003420:tetrin A; D008155:Lucensomycin; D004917:Erythromycin; D000666:Amphotericin B; D010866:Natamycin