Cytotoxic cuparene sesquiterpenes from Laurencia microcladia

Three new cuparene sesquiterpenes 1–3 were isolated from the organic extract of the red alga Laurencia microcladia, collected at Chios island in the North Aegean Sea, Greece. The structures and the relative stereochemistry of the compounds are proposed on the basis of their spectral data. Metabolite 2 shows an unprecedented (for the cuparene class of sesquiterpenes) migration of the C-1 methyl group. All metabolites 1–3 were found to exhibit significant cytotoxic activity against two lung cancer cell lines.