Microsclerodermins C - E, antifungal cyclic peptides from the lithistid marine sponges Theonella sp. and Microscleroderma sp

Three new cyclic peptides, microsclerodermins C - E ( 3–5), were isolated from two species of lithistid sponges from the Visayan Islands, Philippines. The sponge Theonella sp. contained peptides 3 and 4, while Microscleroderma sp. contained peptides 4 and 5. Their structures, which feature three unprecedented amino acids, were elucidated using spectroscopic methods and chemical degradation. Three new peptides were isolated from two different genera of lithistid sponges from the Philippines. One of the peptides was found in both genera of sponges.