Pafuranones A and B, two dimeric polyketides from a rare marine algae-derived fungus Paraconiothyrium sp.

Pafuranones A (1) and B (2), a pair of new epimeric polyketide dimers, were isolated from the fungus Paraconiothyrium sp. OUCMDZ-3316 associated with the marine algae Enteromorpha prolifera. Their structures, including absolute configurations, were fully elucidated based on spectroscopic analysis, calculated ECD, and chemical methods. Pafuranones A (1) and B (2) possess a rare dimeric furanone skeleton, which might be formed through a conjugate addition of the monomeric units followed by an intramolecular cyclization.