Two new 4-methylidene containing steroids, craterol A and B, from the New Zealand two sponge association between Stelletta crater and Desmacella dendyi

NMR-directed investigation of the two sponge association between Stelletta crater and Desmacella dendyi has resulted in the isolation of two new members of the rare 4-methylidene class of sterols. Craterol A (1) and B (2) represent the first examples of natural products reported from the species S. crater. The isolation of these compounds challenges the role of 4-methylidene sterols as chemotaxonomic markers for the sponge genus Theonella.