Novel antimycobacterial benzoxazole alkaloids, from the West Indian sea whip Pseudopterogorgia elisabethae

Our screening for marine natural products with anti-tuberculosis activity f rom the West Indian gorgonian coral Pseudopterogorgia elisabethae resulted in the isolation of two active diterpenoid alkaloids, pseudopteroxazole (1) and seco-pseudopteroxazole (2), Their structures were elucidated by NMR sp ectral analysis, including a variety of two-dimensional techniques. Compoun ds 1 and 2 are previously undescribed diterpenoids containing the uncommon benzoxazole moiety, Biological screening studies indicated that pseudoptero xazole (1) is a potent growth inhibitor of Mycobacterium tuberculosis H37Rv , while seco-pseudopteroxazole (2) shows moderate to strong inhibitorial ac tivity.