Lochmolins A–G, New Sesquiterpenoids from the Soft Coral Sinularia lochmodes

Abstract

Seven new sesquiterpenoids, lochmolins A–G (1–7), were isolated from a Taiwanese soft coral Sinularia lochmodes. The structures of these metabolites were elucidated by extensive spectroscopic study. Compounds 1–4 were found to inhibit the accumulation of the LPS-induced pro-inflammatory COX-2 protein in RAW264.7 macrophage cells.

Asteriscane-Type Sesquiterpenoids from the Soft Coral Sinularia capillosa

“…Accordingly, the gross structure of 1 was determined as 7-hydroxyasterisca-8-en-6-one. [3][4][5][6][7][8][9][10][11][12][13][14][15]) assigned OH-7 the same face as H 3 -15 ( Figure 1). The absolute configuration of 1 was determined using the modified Mosher's method.…”

“…The APT spectrum displayed four olefinic carbons for two double bonds and two oxygenated methines. The HMBC correlations observed from H 3 -12 (δ H 1.00, s) and H 3 -13 (δ H 0.84, s) to C-10 (δ C 85.4), H 3 -14 (δ H 1.67, s) to C-6 (δ C 69.6), C-7 (δ C 140.0), and C-8 (δ C 120.9), and H [3][4][5][6][7][8][9][10][11][12][13][14][15]d,J = 6.9 Hz) to C-2 (δ C 141.5) established conjugated double bonds at Δ 2,9 and Δ 7,8 . The COSY correlations of the D 2 O exchangeable protons at δ H 4.63 and 5.42 with H-6 and H-10, respectively, showed C-6 and C-10 to be hydroxylated.…”

“…20 First, reduction of 1 by NaBH 4 yielded 1a ( Figure 2). The NOE interaction between H-6 (δ H 3.49,dd,J = 2.5,10.5 Hz) and H [3][4][5][6][7][8][9][10][11][12][13][14][15]d,J = 6.8 Hz) in association with the absence of NOE interaction between H 3 -14 (δ H 1.36, s) and H-6 indicated H-6 of 1a had the same orientation as that of H 3 -15 and was on the opposite face compared to H 3 -14. By a standard procedure, the (R)-and (S)-MPA (methoxyphenylacetic acid) esters of 1a were synthesized.…”

“…Thus, a bicyclic nucleus is required from the molecular unsaturation. The COSY crosspeaks established an alkyl spin system from C-1 to C-5 and extended to H [3][4][5][6][7][8][9][10][11][12][13][14][15]d,J = 6.9 Hz), whereas the HMBC correlations observed from H 3 -12 (δ H 1.03, s) and H 3 -13 (δ H 0.73, s) to C-1 (δ C 47.1), C-10 (δ C 53.1), and C- 11 (δ C 36.9) in addition to the correlations from the geminal protons H 2 -10 (δ H 2.12, 1.75) to C-1, C-2 (δ C 40.1), C-9 (δ C 142.5), and C-8 (δ C 128.8) revealed a dimethylcyclopentane ring. Further HMBC correlations from the olefinic proton H- 8 (δ H 5.42, s) to C-2, C-7 (δ C 76.5) and C-6 (δ C 216.6) and from H 2 -4 (δ H 1.89, m) and H 2 -5 (δ H 3.14, 1.96) to C-6 resulted in a cyclooctenone substructure, which was fused to the cyclopentane ring across C-2 and C-9.…”

“…The structural patterns of sesquiterpenoids derived from Sinularia species consist of cadinanetype, 6 oppositane-type, 7,8 africane-type, 9−12 and others. 13 −15 In order to examine the chemical diversity and the structural variation of soft coral species inhabiting different geographic locations, we collected the specimen Sinularia capillosa from the coral reef near Hainan Island. Chromatographic (HPLC) and 1 H NMR spectroscopic analyses revealed that the EtOAc extract of this specimen featured numerous terpenoids, differing from those reported in the literature.…”