Cytotoxic Squalene-Derived Polyethers from the Marine Red Alga Laurencia obtusa (Hudson) Lamouroux

Abstract
Five new cytotoxic triterpenoids with squalene carbon skeleton have been isolated from the title alga. The structures of 15(28)-anhydrothyrsiferyl diacetate, 15-anhydrothyrsiferyl diacetate, and magireol-A were confirmed by the spectral and chemical methods. The structures of magireol-B and -C were deduced from the spectral data.