New production of 5-bromotoluhydroquinone and 4-O-methyltoluhydroquinone from the marine-derived fungus Dothideomycete sp.

The addition of NaBr to the fermentation medium of a marine isolate of the fungus Dothideomycete sp. resulted in induced production of two toluhydroquinone derivatives, 5- bromotoluhydroquinone (1) and 4-O-methyltoluhydroquinone (2), and two known compounds, toluhydroquinone (3) and gentisyl alcohol (4). The structures of 1 and 2 were assigned through the spectroscopic data analyses. Compounds 1-4 showed a potent antibacterial activity against the methicillinresistant and multidrug-resistant Staphylococcus aureus (MRSA and MDRSA) with MIC (minimum inhibitory concentration) values of 6.2, 12.5, 6.2, and 12.5 microgram/ml, respectively. Compounds 1-4 also exhibited a moderate radical scavenging activity against 1,1-diphenyl-2- picrylhydrazyl (DPPH) with IC(50) values of 11.0, 17.0, 12.0, and 7.0 microM, respectively, which were more active than the positive control, L-ascorbic acid (IC(50), 20.0 μM).