UCH9, A NEW ANTITUMOR ANTIBIOTIC PRODUCED BY STREPTOMYCES - II - STRUCTURE ELUCIDATION OF UCH9 BY MASS AND NMR-SPECTROSCOPY

The structure of UCH9, which is a novel antitumor agent, was determine d by spectroscopic methods. UCH9 consists of an aglycone and five 2,6- dideoxy sugars (three D-olivoses, one CO-methyl-D-olivose and one D-ol iose). Four of the five sugars are sequentially connected through a be ta 1-->3 linkage >3-4-O-methyl-olivose-1-->3-oliose-1-->3-olivose). On the basis of the results of spectroscopic analysis, it was found that UCH9 belongs to the aureolic acid family of antibiotics. The structur e of UCH9 is unique in that mono-and tetrasaccharide moieties, and a l ong hydrophobic side chain (sec-butyl group) are attached to the aglyc one, while di-and trisaccharide moieties and a methyl or a hydrogen ar e attached in the case of the known aureolic acid analogs. It is known that aureolic acid analogs form a dimer in the presence of Mg2+. NMR, FAB-MS and atomic absorption analysis revealed that UCH9 isolated fro m Streptomyces also forms a dimer, containing one equivalent molar Mg2 +.