New triterpenoid sulfates from the red alga Tricleocarpa fragilis.

Ten new sulfated terpenoids, including six cycloartenol sulfates (1-6), two 29-nor-cycloartenol sulfates (7,8), and two 29-nor-lanosterol sulfates (9,10), were isolated from brine shrimp-toxic fractions of the methanolic extract of the red alga Tricleocarpa fragilis collected in Hawaiian waters. Structures 1-10 were elucidated by spectral methods, and the absolute stereochemistry for compound 1 at C23 was determined by Mosher analysis. Compounds 7 and 10 showed brine shrimp toxicity at 50 microg/mL, while 1 and 3 showed substantial activity at 17 microg/mL. Compounds 2, 4, 5, and 9 were inactive. In cytotoxicity assays, compounds 1-10 were inactive at concentrations tested.