Briarane-type diterpenes from a closed-system cultured soft coral Briareum stechei

In this study, by using untargeted LC-MS/MS-based multi-informative molecular networking, 12 briarane diterpenoids were isolated from a closed-system cultured soft coral Briareum stechei . Among them, six unreported compounds were identified and named briastechols A–F ( 1 – 6 ). Notably, briastechols A ( 1 ) and B ( 2 ) possess a rare 11,14-ether bridge, while briastechols C ( 3 ) and D ( 4 ) feature a tetrahydrofuran moiety with an ether linkage between C-5 and C-8. Additionally, the absolute configurations of briastechol F ( 6 ) and briarenol H ( 10 ) were determined for the first time via X-ray crystallographic analysis. Evaluation of bioactivity indicated that the crude extract exerted pronounced anti-inflammatory effects, as reflected in the inhibition of superoxide anion formation and elastase secretion in human neutrophils triggered by N -formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLF/CB). Among the isolated compounds, briastechol E ( 5 ) showed significant anti-inflammatory potential, with IC₅₀ values of 7.89 ± 0.38 μM and 4.53 ± 0.68 μM against superoxide anion generation and elastase release, respectively. These findings underscore the structural novelty and chemical diversity of metabolites from cultured B. stechei using a closed system, highlighting its potential as a sustainable source of anti-inflammatory agents and further supporting the viability of closed aquaculture systems for marine natural product research.