Cembranes

Review of oxygenated 2,11-cyclized marine cembranoids, tri- and tetracyclic bioactive 0-heterocycles with cembrane skeleton 98H(49)531. 

The GC-MS data of fraction 1 revealed a strong peak of verticilla-4(20),7,ll-triene (compound 1) accompanied by small amounts of cembrane A and cembrane C. To purify the violet spot and isolate compound 1, it was necessary to reduce the solvent strength. In the mobile phase dichloromethane-hexane (9 + 1 v/v), the development time decreases, which leads to minor diffusion of the zone. The zone of (compound 1) was marked by X = 254 nm UV light. To exclude the impurities, the separation process had to be repeated several times. The zone was removed from the glass plate and eluted from die adsorbent with dichloromethane. The concentrated solution achieved was applied onto a TLC plate as well as injected onto a GC column the... 

The separation and collection of the violet zone (Rj 0.98) of fraction 1 led to the isolation of m- and p-camphorene (compound 4 and compound 5) and cembrane A as well. Thongh m- and p-camphorene are taxonomic marker substances of the species B. serrata, it is pointless to use them in TLC, because the corresponding violet spot on the chromatogram of B. carterii stands for verticilla-4(20),7,l 1-triene, the taxonomic marker substance of B. carterii and cembrene A, too. These violet snbstances shonld be reserved for GC investigations. 

KIN-YIU WONG, LINGCHUN SONG, WANGSHEN XIE, DAN T. MAJOR, YEN-LIN LIN, ALESSANDRO CEMBRAN, AND JIALI GAO... 

Migani A, Sinicropi A, Ferr N, Cembran A, Garavelli M, Olivucci M (2004) Structure of the intersection space associated with Z/E photoisomerization of retinal in rhodopsin proteins. Faraday discuss 127 179... 

Frankincense, also called olibanum, is a natural oleo gum resin that exudes from incisions in the bark of Boswellia trees [46, 47]. Diterpenes like incensole or isoincensole and their oxide or acetate derivatives (see Figure 10.3) are characteristic biomarkers of olibanum [48]. Although diterpenoid hydrocarbons possessing the cembrane skeleton have been isolated from a variety of terrestrial and marine organisms, their occurrence and particularly that of cembrenes A and C (see Figure 10.3) is supplementary proof of the presence of olibanum in a sample. Optimisation of the SPME conditions was done with the aim of trapping these low volatile diterpenes. 

Fig. 25 Cembrane derivatives from New World Crematogaster ants...

Uegaki, R., T. Fujimori, N. Ueda, and A. Ohnishi. Cembrane-derived diterpenoid having a carbotricyclic skeleton. Phytochemistry 1987 26(11) 3029-3031. Wahlberg, I., C. Vogt, A. M. Eklund, and C. R. Enzell. Tobacco chemistry. Two new 20-norcembranoids from tobacco. Acta Chem Scand Ser B 1987 41(10) 749-753. 

Wahlberg. Tobacco chemistry. 4,6,8-Trihydroxy-11-capnosene-2,10-dione, a new cembrane-derived bicyclic diterpenoid from tobacco. Acta Chem... 

Tobacco chemistry. Seven new cembrane-derived compounds from tobacco. Acta Chem Scand 1994 48(10) 850-856. 

NT442 Shimazaki, M., and A. Ohta. Asymmetric synthesis of (-) (E)-5-hydroxy-5 isopropyl 3 hepten-2 One, a cembrane-derived compound from Greek tobacco. Synthesis 1992 1992(10) 957-958. 

A large number of cembrane diterpenoids have been obtained from marine organisms, particularly soft corals. 2-Hydroxynephthenol (116) was isolated from Litophyton viridis. A dehydro-derivative (117) of epoxynephthenol was... 

The oxidation of various cembrane diterpenoids by chromium trioxide has been noted. The full paper on the X-ray analysis of ovatodiolide and ovatodiolic acid has appeared. Detailed n.m.r. studies have led to the structures (124)—(127)... 

An intramolecular cycloaddition of the tetradecatrienyl nitroethyl ether 263 was used in the synthesis of the 14-membered bicyclic precursor 265 of crassin acetate 266, a cembrane lactone possessing antibiotic and antineoplastic activity (332). Nitro compound 263 was obtained from farnesyl acetate (262) in several steps and was then treated with phenyl isocyanate and triethylamine to give the tricyclic isoxazoline 264 (Scheme 6.98). Conversion to ketone 265 was accomplished by hydrogenation of the cycloadduct with Raney Ni and boric acid followed by acetylation (332). In this case, the isoxazoline derived from a 3-butenyl nitroethyl ether moiety served to produce a 3-methylenetetrahydropyran moiety (332). 

Isopr. DITERP. cvclized cembranes (pantrop., C 6.1.1.1) STEROIDS norcholestanes diosgenin Dioscorea spp. MI and other Liliales, Ang. AY). 

Isopr. DITERP. 3.7-cvclized cembrane coralloidolide C (Alcyonium [= Parerythmpodium] coralloides Pallas, 1766, Alcyonacea, Cnid. from East Pyrenean waters D Ambrosio 1990) TRITERP. soualene derived testudinariol Pleurobranchus testudinarius, Notaspidea, Moll, from the Thyrrenian Sea Spinella 1997) raspacionins Raspaciona aculeata, Axinel., Porif. from eastern Pyrenean waters Cimino 1993) STEROIDS AB-nor incisterol Dictyonella incisa, Halichon., Porif from the Ligurian Sea Ciminiello 1990). 

New diterpenoids of the dolabellane class have been reported, such as clavinflol B (592) from the Taiwanese soft coral Clavularia inflata (706). This metabolite has comparable cytotoxicity against the KB cell line to doxorubicin. A sea whip of the genus Eunicea has yielded the cembrane 593 (707). Both 592 and 593 are considered to be natural since no chlorinated solvents were used in the isolation process, and in both metabolites the chlorine is attached to the less substituted carbon, opposite to what is expected for acid-induced epoxide ring opening. A Kenyan soft coral, Sinu-laria erecta, contains the norcembrane sinularectin (594) (708). 

Fontana, A., Ciavatta, M. L., Amodeo, P., and Cimino, G., Single solution phase conformation of new antiproliferative cembranes, Tetrahedron, 55, 1143, 1999. 

The characteristic H(4)-H(5) H NMR coupling constants of the 3-oxabicyclo[3.2.0]heptane derivatives anti-% (V//,//=1.3 Hz) and ry -51 Jh,h = 5.6 Hz) have been used to establish the structural assignments for these isomers <20060L491>. The structure of the rearranged cembrane derivative ciereszkolide 52 has been elucidated by onedimensional (TD) and 2-D NMR spectra, high-resolution fast atom bombardment mass spectrometry (HRFAB-MS), infrared (IR), and ultraviolet (UV) as well as by single crystal X-ray analysis <2004EJ03909>. 

Sarcophyton, and Sinidaria are the most prolific. This review mainly pertains to the cembrane-type constituents of the soft corals of the Sarcophyton genus. 

CEMBRANE-TYPE CONSTITUENTS FROM THE SARCOPHYTON GENUS... 

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