New laurane-type sesquiterpenoids from the Chinese red alga Laurencia okamurai Yamada

Two new laurane-type sesquiterpenoids, debromo-3α-hydroperoxy-3-epiaplysin (1) and debromo-3β-hydroperoxyaplysin (2), together with seven known related compounds (3-9), were isolated from the Chinese red alga Laurencia okamurai. Their structures were elucidated by detailed analysis of spectroscopic data and by comparison with the literature. In bioassay, compounds 2, 4, 8, and 9 exhibited significant PTP1B inhibitory activity with IC50 values ranging from 4.9 to 14.9 μg/ml.