New sesquiterpene derivatives from the red alga Laurencia scoparia.: Isolation, structure determination, and anthelmintic activity

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 are beta-chamigrenes: isorigidol (2), (+)-3-(Z)-bromomethylidene-10beta-bromo-beta-chamigrene (3), and (-)-3-(E)-bromomethylidene-10beta-bromo-beta-chamigrene (4), The in vitro activity of compounds 1-12 against the parasitant stage of Nippostrongylus brasiliensis (L4) has been studied.