Antioxidant terpenoids from the red alga Laurencia tristicha.

One new laurane-type sesquiterpene, 10-hydroxyepiaplysinol (1), along with two known related sesquiterpenes, epiaplysinol (2) and ar-bisabol-9-en-7,11-diol (3), and one carotenoid metabolite, loliolide (4), were obtained from the red alga Laurencia tristicha. Their structures were elucidated based on comprehensive spectroscopic data analysis. Of the known compounds, 4 was isolated from the genus Laurencia for the first time. Additionally, the antioxidant activities of eleven laurane-type sesquiterpenes from L. tristicha were evaluated.