Abstract
Four new briarane diterpenoids, briaviolides K–N (1–4), have been obtained from the cultured-type octocoral Briareum violaceum. Using a spectroscopic approach, the structures of briaranes 1–4 were identified. This study employed an in vitro model of lipopolysaccharide (LPS)-induced inflammation in the murine macrophage RAW 264.7 cell line, and found that among the four briaranes, briarane 2 possessed anti-inflammatory activity against inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions in cells. In addition, principal component analysis using the chemical global positioning system (ChemGPS) for natural products (ChemGPS-NP) was employed in order to analyze the structure-activity relationship (SAR), and the results indicated that the ring conformation of the compound has a leading role in suppressing the expressions of pro-inflammatory iNOS and COX-2 proteins in macrophages.
Highlights
The octocoral Briareum violaceum (Quoy & Gaimard, 1883) (Figure 1) [1] is a rich source of diterpenoids with a briarane carbon skeleton that often have complex structures and bioactivities [2,3,4,5,6]
Specimens of the octocoral B. violaceum were collected from the waters off Taiwan, and relocated to a 270-ton cultivation tank located in the National Museum of Marine Biology and Aquarium (NMMBA), Taiwan, in 2011; the material used for this study was of the cultured-type B. violaceum, collected from the tank in December 2016
Our continuous search for more potent anti-inflammatory briaranes resulted in an acquisition of four new metabolites, named briaviolides K–N (1–4)
Summary
The octocoral Briareum violaceum (Quoy & Gaimard, 1883) (family Briareidae) (Figure 1) [1] is a rich source of diterpenoids with a briarane carbon skeleton that often have complex structures and bioactivities [2,3,4,5,6]. In studies of the chemical constituents of cultured B. violaceum, four new briaranes, briaviolides K–N (1–4), were obtained (Figure 1). We isolated these compounds from cultured-type octocoral B. violaceum, determined their structures, and further studied their anti-inflammatory. Mar. Drugs 2018, 16, 75; doi:10.3390/md16030075 www.mdpi.com/journal/marinedrugs. Mar. Drugs 2018, 16, 75 activities in terms of their inhibition of inducible oxide synthase (iNOS) and cyclooxygenase-2 (COX-2).
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