Briarenolides M-T, new briarane diterpenoids from a Formosan octocoral Briareum sp.

Eight new briarane diterpenoids, designated briarenolides M-T (1-8), were isolated from an octocoral identified as Briareum sp. The structures of briaranes 1-8 were established by spectroscopic methods and by comparison of the spectroscopic data with those of known analogues. The relationship between H-1 and C-13 NMR chemical shifts of 2-hydroxybriaranes possessing of (A) a Delta(3,5(16))-conjugated diene moiety or (B) a Delta(3,5)-conjugated diene moiety are described. Briarenolides M (1), P (4), S (7), and T (8) were found to inhibit the accumulation of the pro-inflammatory inducible nitric oxide synthase (iNOS) protein and briarenolides N (2), P (4), and T (8) were found to inhibit the accumulation of the pro inflammatory cyclooxygenase-2 (COX-2) protein in LPS (lipopolysaccharide)-stimulated RAW264.7 macrophage cells. (C) 2015 Elsevier Ltd. All rights reserved.