Laurane-, cyclolaurane-, and cuparane-type sesquiterpenes from the marine red alga Laurencia okamurai

Abstract

Chemical investigation of the secondary metabolites extracted from the marine red alga Laurencia okamurai has resulted in the isolation of one new (lauramurin, 1) and six known (2-7) sesquiterpenes. On the basis of the data obtained by our detailed spectroscopic analysis as well as by comparison with those reported, the structures of these compounds were elucidated as four laurane sesquiterpenes including lauramurin (1), laur-11-en-10-ol (2), aplysinol (3), and debromoaplysinol (4), two cyclolaurane sesquiterpenes laurequinone (5) and laurentristich-4-ol (6), and one cuparane ether sesquiterpene (7). The antibacterial activity against Staphylococcus aureus and brine shrimp (Artemia salina) lethality for the isolated compounds were evaluated. Compounds 2 and 5-7 displayed moderate lethality against brine shrimp.