An Acetophenone Derivative, Clavatol, and a Benzodiazepine Alkaloid, Circumdatin A, from the Marine-Derived Fungus Cladosporium

The crude extract of the mycelium of Cladosporium was found to exhibit antimicrobial activity against the Staphylococcus aureus, methicillin-resistant S. aureus, and multidrug-resistant S. aureus. Bioassay-guided fractionation of an organic extract led to the isolation of an acetophenone derivative, clavatol (2`,4`-dihydroxy-3`,5`-dimethylacetophenone) (1), and a benzodiazepine alkaloid, circumdatin A (2). Compound 1 showed moderate antibacterial activity against S. aureus, methicillin-resistant S. aureus, and multidrug-resistant S. aureus with minimum inhibitory concentration (MIC) values of 62.5, 62.5, 31.0 μg/mL, respectively, but compound 2 was inactive. Compounds 1 and 2 exhibited UV-A protection activity with ED50 values of 227.0 and 82.0 μM, respectively, indicating that they were more potent than the positive control, oxybenzone (ED50 350 μM), a common sunscreen agent.