Homopseudopteroxazole, a new antimycobacterial diterpene alkaloid from Pseudopterogorgia elisabethae

In the course of our study to find novel antimycobacterial secondary metabolites from Caribbean gorgonian octocorals, we have isolated a new diterpene alkaloid, namely, homopseudopteroxazole (1), as a minor constituent of the hexane extract from the sea plume Pseudopterogorgia elisabethae. Its structure was deduced by interpretation of combined spectroscopic data, including extensive 1D and 2D NMR measurements, and NMR spectral comparisons with known amphilectane models. Biological screening studies indicate that homopseudopteroxazole (1) is a strong growth inhibitor of Mycobacterium tuberculosis H37RV.