Gymnastatins F-H, cytostatic metabolites from the sponge-derived fungus Gymnascella dankaliensis

Gymnastatins F -H (2-4) and gymnamide (5) have been isolated from the mycelial MeOH extract of the Halichondria sponge-derived fungus Gymnascella dankaliensis. Their stereostructures have been established on the basis of spectroscopic analyses using 1D and 2D NMR techniques. The stereochemistry of gymnastatin H (4) was determined by its synthesis. Among these compounds, gymnastatins F (2) and G (3) possess a unique bicyclo[3.3.1]nonane ring as natural products, and they were found to exhibit potent growth inhibition against the P388 Cancer cell line.