Peunipyrone A, an Unexpected Highly Oxygenated γ-Pyrone with a 6/6/6/6/6 Pentacyclic Ring System from a Sponge-Derived Fungus Aspergillus peuniceus

A highly oxygenated γ-pyrone with an unprecedented carbon skeleton, peunipyrone A (1), was isolated from the sponge-derived fungus Aspergillus peuniceus. Compound 1 features a unique fused 6/6/6/6/6 pentacyclic ring system. The chemical structure of compound 1 was elucidated by comprehensive spectroscopic techniques and single-crystal X-ray diffraction. The plausible biosynthetic pathway of compound 1 was proposed. Compound 1 promoted leukemic cell apoptosis by increasing p53 expression.