Briavioid D, a rare 7β,8β-epoxybriarane from Briareum violaceum

[Display omitted] •A rare 7β,8β-epoxybriarane, briavioid D (1), was isolated from Briareum violaceum.•The structure of briarane 1 was determined by a single-crystal X-ray diffraction analysis.•Briavioid D is the first example of briarane analog possessing a 7,8‑epoxy group in the γ-lactone moiety. A rare 7β,8β-epoxybriarane, briavioid D (1), has been isolated from a cultured octocoral Briareum violaceum. The structure of 1 was deduced by extensive 2D NMR studies. Single-crystal X-ray diffraction analysis was performed to identify the structure of 1 and this compound was found to reduce the release of iNOS to 85.77 %, at a concentration of 10 μM.