Clavularia inflata

The structure and relative configuration of six new dolabellanes (30-35) isolated from the soft coral Clavularia inflata collected at Orchid Island located 44 nautical miles off Taiwan s southeast coast is depicted in Fig. 4 [16]. The relative configuration was assigned based on ID and 2D NMR spectroscopy and supports the cis arrangement between the isopropyl group at... 

Fig. 4 Six dolabellanes (30-35) isolated from the soft coral Clavularia inflata (2001)...

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). 

Shen Y-C, Pan Y-L, Ko C-L, Kuo Y-H, Chen C-Y (2003) New Dolabellanes from the Taiwanese Soft Coral Clavularia inflata. J Chin Chem Soc 50 471... 

C12 hydrocarbon (271)135 by a similar route but this compound is not identical to a tricyclic hydrocarbon isolated from East Indian sandalwood oil and reported to have this structure. (+)-Copacamphor (272) and (+)-copaborneol (273) have been isolated from Espeltiopsis guacharaca.136 The interesting sinularene derivative (274) and the acetoxycyclosinularane (275) have been isolated from the marine source, Clavularia inflata.137 These compounds, together with an aromadendrane derivative (see p. 181) are the first sesquiterpenoids from Octocorallia of the order Stolonifera. 

In addition to the two sinularane derivatives isolated from the marine source Clavularia inflata (see p. 114), the aromadendrane derivative (802) has also been identified in the related species Clavularia koellikeri.137 Another aromadendrane compound is the diol (803) obtained from the plant Senecio nemorensis.314 An X-ray analysis of nardosinone has confirmed its structure as (804).366 The soft coral Lemnalia africana is a rich source of sesquiterpenoids and recent investigations 383 e Trifilieff, Phytochemistry, 1980, 19, 2467. 

As expected due to chemical instability the number of acyclic peroxides is lower. Most of them occur as plant derived products, but also in soft corals hke Clavularia inflata, hydroperoxides with potent cytotoxicity exist. Interestingly the bioactivity disappeared when the hydroperoxide function was deleted. It must be noted that most of natural hydroperoxides in plants are foimd in the group of saponins from Panax ginseng or Ficus microcarpa, which are used in ethnomedicine in South East Asia. 

A group of tricyclic diterpenoids related to dolatriol has been isolated from the marine invertebrate Clavularia inflata. The structure of the diol (122) was obtained by X-ray analysis and those of (123) and (124) by chemical correlation. 

Metabolites of various algae and eorals also inelude dolastadienes and -trienes, exemplified by l(15),8-dolastadiene-4p,14p-diol (amijiol), its isomer isoamijiol, and l(15),7,9-dolastatrien-14p-ol from brown algae Dictyota linearis and D. cervi-cornis, as well as l(15),17-dolastadiene-3a,4p-diol from the soft coral Clavularia inflata. 

Tris 6>rsesquiterpenes have been isolated from a Cespitularia and two Clavularia species. 1,4-Dimethyl-2,3,3a,4,5,6-hexahydroazulene (470) was a metabolite of the former 394). The soft coral Clavularia koellikeri furnished clavukerin A (471) (395), B (472), and C (473) (396). The structure reported for clavukerin B (472) was identical with that of inflatene from Clavularia inflata (397). Inflatene (472) has shown ichthyotoxicity toward the Pacific damselfish Pomacentrus coeruleus at 10 pg/mL. A -Africanene (474), a tricyclic sesquiterpene, has been isolated from Sinularia erecta (39S) and S. polydactyla (399). 

I-)-Cubetol (535) was a tricyclic monohydric alcohol from a Ce-spitularia species 394). A sample of Clavularia inflata yielded two sesquiterpenes closely related to sinularene, 12-acetoxycyclosinularane (536) and 12-acetoxysinularene (537) (422). Compound 537 could be derived from 536 by opening of the cyclopropane ring. Another species of the order Stolonifera, C. koellikeri yielded the methyl ester (538) 422). 

IzAC, R.R., W. Fenical, and J.M. Wright Inflatene, an Ichthyotoxic C12 Hydrocarbon from the Stoloniferan Soft Coral Clavularia inflata var. luzoniana. Tetrahedron Lett. 25, 1325 (1984). 

Bowden, B.F., J.C. Braekman, J.C. Coll, and S.J. Mitchell Studies of Australian Soft Corals. XX. A New Sesquiterpene Furan from Soft Corals of the Family Xenii-dae and an Examination of Clavularia inflata from North Queensland Waters. Aust. J. Chem. 33, 927 (1980). 

Braekman, J.C., D. Daloze, A. Dupont, B. Tursch, J.P. Declercq, G. Germain, and M. van Meerssche Chemical Studies of Marine Invertebrates-XLIII. Novel Sesquiterpenes from Clavularia inflata and Clavularia koellikeri (Coelenterata, Octocorallia, Stolonifera). Tetrahedron 37,179 (1981). 

Wang, S.-K., Huang, M.-J., and Duh, C.-Y. (2006b) Cytotoxic constituents from the Formosan soft coral Clavularia inflata var. luzoniana.J. Nat. Prod., 69, 1411-1416. 

A very unusual tricyclic derivative with 15 carbon atoms and resembling a sesquiterpene was isolated from the stoloniferan Clavularia inflata var. luzoniana collected in Formosa (Taiwan). No proposal regarding the biosynthesis of this particularly atypical derivative was formulated (Wang, Huang, and Duh, 2006b). 

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