Eleven sesquiterpenes (1−11) and one long chain aldehyde (12) have been isolated from the dichloromethane extract of the red alga Laurencia scoparia. Four of them are new natural products. Scopariol(1) is a new natural product with an unusual rearranged chamigrane-type structure. The other three areβ-chamigrenes: isorigidol (2), (+)-3-(Z)-bromomethylidene-10β-bromo-β-chamigrene (3), and (−)-3-(E)-bromomethylidene-10β-bromo-β-chamigrene (4). The in vitro activity of compounds 1−12 against theparasitant stage of Nippostrongylus brasiliensis (L4) has been studied.
