Clethramycin, a new inhibitor of pollen tube growth with antifungal activity from Streptomyces hygroscopicus TP-A0623 II.: Physico-chemical properties and structure determination

Clethramycin is a novel linear polyene polyketide produced by a plant-associated actinomycete Streptomyces hygroscopicus TP-A0623. It possesses a guanidino and carboxyl residue at each end and an O-sulfate group and a hexaene moiety in the molecule, and its molecular formula is C63H99N3O18S. The structure was determined by analyzing 2D-NMR and FAB-MS data, using C-13-enriched compounds. Clethramycin is structurally similar to linearmycin, an inhibitor of spheroplast regeneration in Candida albicans. Clethramycin shows potent antifungal and pollen tube growth inhibitory activity.