Structures of Two New 18,22-Cyclosterols, Emesterones A and B, f rom Emericella heterothallica.

Abstract

Two new 18, 22-cyclosterols, emesterones A (2) and B (3), were isolated along with Mer-NF8054X (1) from the culture filtrate of Emericella heterothallica. The structures of 2 and 3 were established as 3, 11-dioxo-18, 22-cycloergosta-6, 8(14)-diene-5β, 9β, 23S-triol and 3, 11-dioxo-18, 22-cycloergosta-4, 6, 8(14)-triene-9β, 23S-diol, respectively, on the basis of spectroscopic and chemical investigations. The antifungal activity of emesterone B (3) towards Aspergillus fumigatus was slightly weaker than that of Mer-NF8054X (1).