Chemical constituents of the soft corals Sinularia vanderlandi and Sinularia gravis from the coast of Madagascar

Abstract

The crude extracts of the Madagascan soft corals Sinularia vanderlandi and Sinularia gravis (Alcyoniidae) showed activity against Plasmodium falciparum which led us to study their chemical constituents. The new cadinane-type sesquiterpenoid vanderlandin (1) has been obtained from S. vanderlandi along with 24-methylenecholesterol (2). Four new compounds, the spatane-type diterpenoid gravilin (3), the monoalkylmonoacylglycerol 4, the dihomoditerpenoid ketone 5, and isodecaryiol (9), along with the three known compounds (+)-(S)-geranyllinalool (6), (-)-(R)-nephthenol (7), and 11,12-epoxysarcophytol A (8) have been isolated from the methanol extract of S. gravis. The structures were elucidated based on extensive spectroscopic methods, in particular various 2D NMR techniques. The structure of isodecaryiol (9) including its absolute configuration could be confirmed by X-ray diffraction.

Isolation and structure elucidation of natural products of three soft corals and a sponge from the coast of Madagascar

“…Compound 10 was obtained as a colorless solid and, based on MS, IR, 1D, and 2D NMR data, identified as 24-methylenecholesterol (10). 1,3,[49][50][51][52] Comparison of the 1 H NMR data of 10 with those reported by Su et al 52 for a synthetic sample (Table S11 †) and of the 13 C NMR shift values with those reported for a sample isolated from Litophyton viridis 51 (Table S12 †) confirmed the assignment. 24-Methylenecholesterol (10) has been found in various soft corals, for example, Capnella imbricata, 53 Litophyton viridis, 51 Sinularia flexibilis, 54 Sinularia maxima, 55 and Sinularia vander-landi.…”

“…1). The fourth compound, (+)-(7R,8R,14S,1Z,3E,11E)-14-acetoxy-7,8epoxycembra-1,3,11-triene [(+)- 3], was found only in the diethyl ether extract. In addition, the diethyl ether extract of S. stellatum contained a small amount of (S)-3-O-octadecylglycerol (batyl alcohol) (5), the scaffold structure for a variety of ether lipids of the 1-O-alkyl-2,3-O-diacyl-sn-glycerol type (Fig.…”

“…[18][19][20] In our previous study on Madagascan soft corals, we have isolated five new compounds including the cadinane-type sesquiterpene vanderlandin, the spatane-type diterpene gravilin and the cembranoid diterpene isodecaryiol. 3 These results encouraged us to extend our search for new and potentially bioactive compounds by investigating further soft coral species and a sponge from this region.…”

“…In continuation of our studies on the chemical constituents of marine organisms from the coast of Madagascar including red algae, 1 brown algae, 2 and soft corals, 3 we herein turned our attention to soft corals of the species Sarcophyton stellatum, Capnella fungiformis, and Lobophytum crassum. A sponge of the species Pseudoceratina arabica has also been included in the present investigation.…”

“…[4][5][6][7][8][9][10][11][12][13][14] However, only a few reports are available on soft corals and sponges from the coast of Madagascar. 3,[15][16][17] This region is of particular interest since it is known that the marine environment of the Southern Africa and Western Indian Ocean region contains a wealth of endemic species, which increases the chance to find new natural products with useful biological activities. [18][19][20] In our previous study on Madagascan soft corals, we have isolated five new compounds including the cadinane-type sesquiterpene vanderlandin, the spatane-type diterpene gravilin and the cembranoid diterpene isodecaryiol.…”