Nodulisporic acids C, C1, and C2: a series of D-ring-opened nodulisporic acids from the fungus Nodulisporium sp.

Nodulisporic acids C (4a), C1 (5a), and C2 (6a), a series of D-ring-opened nodulisporic acids, were isolated from fermentations of a mutant culture of Nodulisporium sp. MF5954. Nodulisporic acid C, the most potent of the three, showed good activity against fleas with an LD90 of 10 micro g/mL. These compounds tend to be unstable in the free acid form and were isolated as stable sodium salts.