Apicularens A and B, new cytostatic macrolides from Chondromyces species (Myxobacteria): Production, physico-chemical and biological properties

A never macrolide, apicularen A, was produced by several species of the gen us Chondromyces. Initially it was discovered by bioassay-guided RP-HPLC-fra ctionation of culture extracts of Chondromyces robustus, strain Cm a13. Api cularen A showed no antimicrobial activity, but was highly cytotoxic for cu ltivated human and animal cells, with IC50 values ranging between 0.1 and 3 ng/ml. A cometabolite of apicularen A, the N-acetylglucosamine glycoside a picularen B, was distinctly less cytotoxic with IC50 values between 0.2 and 1.2 mu g/ml, and showed weak activity against a few Gram-positive bacteria . Apicularen A is chemically closely related to the salicylihalamides A and B from the marine sponge Haliclona sp.