Ylangene-Type and Nardosinane-Type Sesquiterpenoids from the Soft Corals Lemnalia flava and Paralemnalia thyrsoides

Abstract

Chemical investigations of the Formosan soft coral Lemnalia flava have obtained a new ylangene-type sesquiterpenoid, (1S,2S,4R,6S,7R,8S)-4a a-formyloxy-b b-ylangene (1), along with two known sesquiterpenoids, lemnalol (2) and isolemnalol (3). Three new nardosinane-type sesquiterpenoids, designated as paralemnolins J-L (4-6), and five known sesquiterpenoids (7-11), were isolated from the other soft coral Paralemnalia thyrsoides. The structures of metabolites 1 and 4-6 were elucidated through extensive spectroscopic analysis and chemical methods. Moreover, the anti-inflammatory activity of metabolites 1-7 and 11 was evaluated in vitro.Key words Lemnalia flava; ylangene-type sesquiterpenoid; nardosinane-type sesquiterpenoid; Paralemnalia thyrsoides; antiinflammatory activity Chem. Pharm. Bull. 58(3) 381-385 (2010) © 2010 Pharmaceutical Society of Japan * To whom correspondence should be addressed. e-mail: yihduh@mail.nsysu.edu.tw . Moreover, the 1 H-1 H correlation spectroscopy (COSY) correlations (Fig. 2) between H-4 and H-16, and the heteronuclear multiple bond correlation (HMBC) correlations from H-16 to C-4 confirmed the location of the formyloxy functionality at C-4. Therefore, the planar structure of 1 was proposed decidedly.The computer modeled 3D structure of 1 was generated by using MM2 force field calculations for energy minimization with the molecular modeling program Chem3D Ultra 9.0. The relative stereochemistry of 1 assigned by the nuclear Overhauser effect spectroscopy (NOESY) spectrum was compatible with those of 1 offered by computer modeling, in which the close contacts of atoms calculated in space were consistent with the NOESY correlations (Fig. 3). A large long-range coupling constant ( 4 J 2,6 ϭ5.9 Hz) due to a W-type coupling between H-2 and H-6 further indicated the presence of a bridged cyclobutane system in 1. In addition, no coupling was observed between H-7 and the adjacent protons (H-2, H-6, and H-8), suggesting a dihedral angle of approximately 90°between these protons. The NOESY correlations between H 3 -11 with both H-4 and H-5b positioned the b-orientation of the aforementioned protons. Furthermore, H-7 382Vol. 58, No. 3

Terpenoids from Marine Soft Coral of the Genus Lemnalia: Chemistry and Biological Activities

“…It was reported that a new ylangene-type sesquiterpenoid ( 32 ) was isolated from the Formosan soft coral L. flava [ 27 ] along with two related known ones, lemnalol ( 33 ) [ 28 ] and cervicol ( 34 ) [ 29 ]. It is worth mentioning that the parent hydrocarbon of ylangane is a stereoisomer of α -copaane as regards the orientation of the isopropyl group at C-8 ( α -orientation for ylangane, β -orientation for copaane) [ 30 ].…”

Syntheses of bicyclo[3.3.0]octanes and bicyclo[4.3.0]nonanes by ring expansion of isopropylidenecyclobutanes

“…15 The reaction was found to be both stereo-and regioselective as seen from both spectroscopic data and X-ray crystallography. Previous attempts in our group to achieve ring expansion of compound 1 using protic acids like HCl, p-toluenesulfonic acid or CF 3 COOH, and Lewis acids like BF 3 , AlCl 3 , HgSO 4 , Hg(OAc) 2 or AgNO 3 were unsuccessful. 15 However, using 45 % HBr in acetic acid a near quantitative yield of a product corresponding to compound 5 was achieved.…”

Oxygenated Ylangene-Derived Sesquiterpenoids from the Soft Coral Lemnalia philippinensis

“…In recent years, soft corals have become one of the most prolific sources for the discovery of novel secondary metabolites [ 1 ]. Previous chemical investigations on soft corals of the genus Lemnalia have led to the isolation and identification of variety of ylangene-derived sesquiterpenoids [ 2 , 3 , 4 , 5 ]. Some of these have been found to possess various biological activities, such as cytotoxic [ 4 ] and anti-inflammatory properties [ 6 ].…”