Furan derivatives and antibacterial anthraquinone- isochroman hybrid identified from the marine- derived fungus Penicillium citrirum 8413.

Two new furan derivatives designated citrifuranin A (1) and citrifuranin B (2), a new anthraquinone-isochroman hybrid named penicillanthranin C (3) were isolated from the South China Sea-derived fungus Penicillium citrirum 8413, together with the known compounds emodin (4), 6,8-dihydroxy-3,4,5-trimethylisochroman (5), and penicitrinol A (6). The planar structures of these new compounds were elucidated by HR-MS and NMR spectroscopic data analyses. Citrifuranins A (1) and B (2) were determined to be a pair of E/Z isomers on the basis of the observed NOE correlations. Penicillanthranin C (3) was determined be a hybrid structure comprised of compounds 4 and 5. The absolute configurations of 3 were confirmed by comparing the experiment ECD spectrum with the calculated one. Penicillanthranin C (3) showed selective antibacterial activities against the Gram positive Staphylococcus aureus ATCC 29213 and methicillin-resistant S. aureus N315 with MIC values of 12.7 and 15.3 μg/mL, respectively.