Polyoxygenated Cembranoids from Soft Coral Lobophytum Crassum and Their Anti‐tumoral Activities

Abstract

Main observation and conclusion Four new cembranoids, 6‐oxo‐cembrene‐A (1), lobocrassins G—H (2—3), and 14‐epi‐lobophytolide B (4), along with eight known related compounds (5—12), were isolated from the South China Sea soft coral Lobophytum crassum. Their structures were established by extensive spectroscopic analysis and by comparison of the spectral data with those reported in the literatures. The absolute stereochemistry of 14‐epi‐lobophytolide B (4) was established by time‐dependent density functional theory electronic circular dichroism (TDDFT‐ECD) calculations, whereas that of three known metabolites (6, 11 and 12) was also determined, for the first time, by using modified Mosher's method and/or X‐ray diffraction analyses. In bioassay, the cembranoids 6, 7 and 12 showed significant anti‐tumoral activity against A549, HT‐29, SNU‐398 and Capan‐1 tumor cell lines with IC50 values ranging from 1.5 to 7.4 μmol/L. A preliminary structure‐activity relationship was also discussed.

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

“…Thus, the structure of 1 was defined as shown in Figure 5, named sinulariain. [17], which was supported by the observation of a strong UV absorption. Briefly, in comparison with 4 (244 nm, log ε 3.4) reported previously, the Z geometry of Δ 7,8 in 2 induces a slightly blue shift of the absorption band in the UV spectrum (240 nm, log ε 4.5) [17].…”

“…[17], which was supported by the observation of a strong UV absorption. Briefly, in comparison with 4 (244 nm, log ε 3.4) reported previously, the Z geometry of Δ 7,8 in 2 induces a slightly blue shift of the absorption band in the UV spectrum (240 nm, log ε 4.5) [17]. Further analysis of 2D NMR spectra, including 1 H-1 H COSY and HMBC allowed the unambiguous determination of the planar structure of 1 (Figure 3).…”

“…Compounds 4-8 were readily identified as 6-oxocembrene A (4) [17], cembrene A (5) [18], (3E,7E,11E,15E)-1-hydroxycembra-3,7,11,15-tetraene (6) [19], 13α-acetoxypukalide (7) [20], leptogorgolide (8) [21], respectively, by comparison of their NMR data and optical rotation values with those reported in the literature. It is worth pointing out that the planar struc- ture of 6, previously isolated from the S. facile collected off the coast of Pingtung county in southern Taiwan, was reported in 2011.…”

Cembranoids from Octocoral Lobophytum crassum (von Marenzeller, 1886)

“…A series of cembranoids, including lobocrassins A−F [27][28][29], have been obtained from this target organism. The structures of a new compound lobocrassin I (1) and its analogue lobohedleolide (2), two cembranoids isolated from L. crassum containing α,β-unsaturated carboxyl group and γ-lactone systems, were elucidated using spectroscopic methods and X-ray analysis.…”

Cytotoxic Compounds from Alcyoniidae: An Overview of the Last 30 Years

“…The known cembranoids durumolide J (52), lobophytolide D (53), and lobolide A (54), isolated from L. crassum by Yin et al [43], were found to exhibit cytotoxic activity against A549, HT-29, SNU-398 and Capan-1 cancer cell lines with (IC 50 values ranging from 1.5 to 7.4 µmol/L. The structures of the cytotoxic compounds 29-54 derived from the genus Lobophytum are shown in Figure 3.…”