Norisoprenoids from the Brown Alga Sargassum naozhouense Tseng et Lu.

A new C-norisoprenoid derivative, sargassumone (), has been isolated from together with six known norisoprenoids and a highly oxygenated cyclopentene: (2,6,8,9)-hexahydro-2,9-dihydroxy-4,4,8-trimethyl-6-acetyloxy-3(2)-benzofuranone (), (6,8,9)-hexahydro-6,9-dihydroxy-4,4,8-trimethyl-2(2)-benzofuranone (), (6,8,9)-hexahydro-6,9-dihydroxy-4,4,8-trimethyl-2(2)-benzofuranone (), loliolide (), (+)-epiloliolide (), spheciospongones A (), and (+)-kjellmanianone (). Compound was identified on the basis of nuclear magnetic resonance (NMR) and mass spectrometry (MS) analysis, and the absolute stereochemistry was defined by NOESY spectroscopy, minimizing energy calculation, and circular dichroism (CD) spectra. The known compounds -, isolated from for the first time, were identified by comparison of their physical and spectroscopic data with those reported in the literature. Compound was tested for its inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), antioxidant activity with 1,1-diphyl-2-picrylhydrazyl (DPPH) free radicals, and antimicrobial activity against resistant clinical isolates of , methicillin-resistant , and .