Briarane-Related Diterpenoids from Octocoral Briareum stechei

Abstract

A known polyoxygenated briarane, briaexcavatolide P (1), was isolated from a Formosan octocoral Briareum stechei. Moreover, the same species B. stechei, collected from Okinawan waters, yielded three chlorine-containing briaranes, including two new compounds, briastecholides B (2) and C (3) as well as a known analogue, briarenol R (4). The structures of 1–4 were established using spectroscopic methods. In addition, briarane 1 demonstrated anti-inflammatory activity in lipo-polysaccharide-induced RAW 264.7 mouse macrophage cells by suppressing the expression of inducible nitric oxide synthase (iNOS) protein.

Marine natural products

“…577 Collections of B. stechei (synonymous with B. excavatum) afforded a range of structurally-related diterpenes including briarenols L 1340 (Ie Island), 578 O 1341, P 1342 (aquaculture), 579 U 1343, V 1344 (Ie island), 580 W 1345, X 1346, Y 1347 and Z 1348 (aquaculture) 581 and briastecholides A-C 1349-1351 (Ie Island). 582,583 A large number of known briaranes were also isolated during these studiesof note were the assignment of absolute conguration to briarenol G 1352 and solenolide C 1353 using XRD 578,582 and the reassignment of the structure of solenolide B 1354 to now incorporate a b-oriented 12-acetoxy group. 580 Biological screening for inhibitors of receptor activator of NF-kB ligand (RANKL)-induced osteoclast differentiation, in combination with GNPS molecular networking, led to the characterisation of 28 new examples of briaranes, gemmolides A-Z 2 1355-1382, some of which were weakly active in the bioassay or exhibited cytotoxicity to bone marrow macrophages.…”

A Survey of Recently Discovered Naturally Occurring Organohalogen Compounds

“…42 None of these metabolites are particularly active in various antiinflammatory assays. Similarly, several collections of the octocoral Briareum stechei from Formosa, 43 Okinawa, 44,45 and laboratory cultures 46 resulted in the discovery of the new briastecholides B (110) and C (111), 43 briarenols U (112) and V (113), 44 briastecholide J (114), 45 and briastecholides E (115) and F (116). 46 Briarenol U (112) significantly induces in vitro inflammatory activity in RAW264.7 cells by enhancing expression of iNOS and COX-2 proteins.…”