Alpha-Pyronoids with Quorum Sensing Inhibitory Activity from the Mangrove Fungus Penicillium Camemberti OUCMDZ-1492

The mangrove fungus Penicillium camemberti OUCMDZ-1492 produced a new class of compounds under the oligotrophic condition, which were different from those under the eutrophic condition. Bioassay-guided isolation and chiral resolution for the racemic mixture resulted in the harvest of five alpha-pyronoids. Their structures were ideinfied as (R,E)-5-(3hydroxybut-1-en-1-yl)-4-methoxy-6-methyl-2H-pyran-2-one (1), pyrenocine A (2), (R)-pyrenocine B(3), (R)-(-)- pyrenocine E (4) and (S)-(+)- pyrenocine E (5). Their structures, including absolute configurations, were elucidated on the basis of spectral analysis, electronic circular dichroism (ECD) spectra, quantum chemical calculation, and chiral separation. New compound 1 was named as pyrenocine P, and the absolute configurations of compounds 3 similar to 5 were determined for the first time. Compounds 2 and 3 showed potent quorum sensing inhibitory activity in Chromobacterium violaceum CV026 with the minimal inhibitory concentrations of 0.16 and 1.0 mg.mL(-1), respectively. The minimum inhibitory concentration (MIC) value of (Z)-4-bromo-5-(bromomethylene)-furan-2(5H)-one (C-30), a positive control, was 0.08 mg.mL(-1).