Highly brominated metabolites from marine red alga Laurencia similis inhibit protein tyrosine phosphatase 1B.

Five new highly brominated metabolites, 3′,5′,6′,6-tetrabromo-2,4-dimethyldiphenyl ether (1), 1,2,5-tribromo-3-bromoamino-7-bromomethylnaphthalene (2), 2,5,8-tribromo-3-bromoamino-7-bromomethylnaphthalene (3), 2,5,6-tribromo-3-bromoamino-7-bromomethylnaphthalene (4) and 2′,5′,6′,5,6-pentabromo-3′,4′,3,4-tetramethoxybenzo-phenone (5) were isolated from the red alga Laurencia similis. Their structures were elucidated by spectroscopic methods including one- and two- dimensional NMR as well as HREIMS analysis. Compounds 1 and 5 showed strong inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) with IC50 of 2.97 and 2.66μM, respectively.