Actaplanin (A4696), a new complex of broad spectrum Gram-positive antibiotics is produced by Actinoplanes inissouriensis. High performance liquid chromatography was used to show that this complex is composed of several actaplanins. Hydrolytic experiments with actaplanins A, B1, B2, B3, C1 and G showed that these actaplanins were composed of the same peptide core, an amino sugar and varying amounts of glucose, mannose and rhamnose. The neutral sugar content was determined for each actaplanin. A bioautographic study of aglycone formation during hydrolysis of the actaplanin complex showed that within a short time a simple mixture of two antimicrobially active hydrolysis products was obtained. These substances retained the antimicrobial spectrum and a high percentage of the antibiotic activity of the parent actaplanin complex. Methanolysis of the actaplanin complex as well as the individual actaplanins resulted in the selective loss of the neutral sugar moieties and the isolation of actaplanin Ψ(pseudo)-aglycone-the core peptide which still retained an amino sugar group. The 1H NMR spectrum of this substance indicated a similarity to many features of ristocetin Ψ-aglycone. Hydrolytic studies showed that the amino sugar present in actaplanin was identical with L-ristosamine. It is concluded that the aglycone of actaplanin is a complex peptide composed of aromatic amino acids, and that the actaplanins each possess this aglycone and L-ristosamine but are differentiated by their neutral sugar composition.
Japan Antibiotics Research Association