Brominated diterpenes with antibacterial activity from the red alga Sphaerococcus coronopifolius.

Four new brominated diterpenes (1, 2, 4, 5), along with two previously reported metabolites (3, 6), were isolated from the organic extract of Sphaerococcus coronopifolius, collected in Palaiokastritsa Bay at the west coast of Corfu Island. The structures of the new products, as well as their relative configuration, were established by means of spectroscopic data analyses, including 2D NMR experiments. The isolated metabolites were evaluated for their antibacterial activity against a panel of multidrug-resistant (MDR) and methicillin-resistant Staphylococcus aureus (MRSA) with MICs in the range 0.5-128 microg/mL.