Penicilazaphilones D and E: two new azaphilones from a sponge-derived strain of the fungus Penicillium sclerotiorum

Two new azaphilones, penicilazaphilones D ( 1 ) and E ( 2 ), along with four known analogs ( 3–6 ), were obtained from the sponge-derived fungus Penicillium sclerotiorum . Their structures were elucidated on the basis of comprehensive spectroscopic analyses, ECD calculation, single-crystal X-ray diffraction and comparison to the biosynthetically related compound 5 . Compound 1 represents the second reported azaphilone with a C-4 aliphatic side chain, and 2 is the first azaphilone with a tetrahydrofuran ring at C-3. Compound 3 displayed strong antiviral activity against HSV (IC 50 = 19.5 μM) and EV71 (IC 50 = 132 μM), 16 and 3 fold more potent than the positive control ribavirin, respectively.