MICROSCLERODERMIN-A AND MICROSCLERODERMIN-B - ANTIFUNGAL CYCLIC-PEPTIDES FROM THE LITHISTID SPONGE MICROSCLERODERMA SP

The microsclerodermins are cyclic hexapeptides from a deep water spong e of the genus Microscleroderma. The structures of microsclerodermins A (1) and B (2) were determined by interpretation of spectral data. Th e absolute stereochemistry at each of the 10 asymmetric centers was de termined by interpretation of NMR data, particularly the nOe data, and by chemical degradation followed by analysis of the resulting amino-a cids by GC-MS using a chiral column. Microsclerodermins A and B inhibi t the growth of C. albicans at 2.5 mu g/disk. Examination of the symbi otic filamentous micro-organisms associated with the sponge revealed t hat they were eubacteria similar in appearance to members of the famil y Beggiatoaceae.