New antibacterial diterpenes from Pseudopterogorgia elisabethae

From the MeOH extract of Pseudopterogorgia elisabethae, collected from the Bahamas, four new diterpenes, elisabethin E (1), elisabethin F (2), pseudopterosin P (3), and pseudopterosin Q (4), were isolated and their structures established with the aid of extensive spectroscopic studies. Compounds 3 and 4 showed antibacterial activity selectively against the Gram-positive bacteria Streptococcus pyogenes, Staphylococcus aureus, and Enterococcus faecalis.