Corals Clavularia

Clavulones I and II are members of an unusual family of marine prostanoids from the coral Clavularia viridis which are biosynthesiied by a cationic (i.e. non-radical, non-endoperoxide) pathway. The total synthesis of clavulones I and II was accomplished from cyclopentadiene as SM goal. 

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)...

Iwashima, M. Okamoto, K. Miyai, Y. Iguchi, K. (1999) 4-Epiclavulones, new marine prostanoids fixm the Okinawan soft coral, Clavularia viridis. Chem. Phaim. Bull., 47, 884-6. 

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). 

A practical racemic synthesis of the known chlorovulone II from the Okinawan soft coral Clavularia viridis has been accomplished (922). This coral has more recently afforded the new prostanoids 852-856 (923), 857-871 (924), and, from a Taiwanese collection, 872, 873 in addition to 857 and 858 (925). The absolute configuration of the previously known punaglandin 8 (852, X = Cl) was determined as shown (923). This soft coral also contains several non-halogenated possible biosynthetic precursors to these halogenated metabolites (926). 

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... 

Iwashima M, Nara K, Nakamichi Y, Iguchi K (2001) Three New Chlorinated Marine Steroids, Yonarasterols G, H and I, Isolated from the Okinawan Soft Coral, Clavularia viridis. Steroids 66 25... 

Watanabe K, Sekine M, Takahashi H, Iguchi K (2001) New Halogenated Marine Prostaglandins with Cytotoxic Activity from the Okinawan Soft Coral Clavularia viridis. J Nat Prod 64 1421... 

Iwashima, M., Watanabe, K., and Iguche, K., New marine prostanoids, preclavulone lactones, from the Okinawan soft coral Clavularia viridis, Tetrahedron Lett., 38, 8319, 1997. 

Bathydoris hodgsoni can be found in the deep waters of the Weddell Sea. This nudibranch elaborates the drimane sesquiterpene hodgsonal (Structure 7.78) and sequesters it in its mantle tissues.50 164The nudibranch Tritoniella belli collected from McMurdo Sound is the only documented example of an Antarctic mollusc sequestering defensive chemistry from its diet.44 Among the glyceride esters (Structures 7.79-7.81) isolated from this species, chimyl alcohol (Structure 7.79) can also be found in one of its prey items, the stoloniferan coral Clavularia frankliniana. Sequestration of these defensive chemicals is opportunistic, however, and other, still undescribed metabolites are more commonly associated with defense in this mollusc.49... 

Only one report of Antarctic soft coral secondary metabolite chemistry has appeared in the literature. As described above, the stoloniferan coral Clavularia frankliniana has been demonstrated to produce fatty glyceride esters, chimyl alcohol (Structure 7.79) in particular, that are also found in its predator, the nudibranch Tritoniella belli.44 Chimyl alcohol has been investigated in ecological bioassays and has been implicated in deterring predation by the omnivorous sea star Odontaster validus.44... 

Chimyl alcohol (Structure 7.79), isolated from the mantle tissues of the nudibranch Tritoniella belli,44 caused rejection by O. validus of shrimp-treated disks at natural tissue-level concentrations. T. belli sequesters this defensive chemistry from its diet, the stoloniferan coral Clavularia franklin-iana. Sequestration of chimyl alcohol from the diet, however, seems to be opportunistic, and T. belli also provisions its mucus with other yet undescribed deterrent natural products.49 Chimyl alcohol is reported from other non-Antarctic molluscs209 and has been demonstrated to function as an antibacterial and a fish antifeedant at levels found in the tissues of the dorid nudibranchs Archidoris montereyensis and Aldisa sanguinea cooperi.210... 

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). 

Kobayashi, M., B.W. Son, M. Kido, Y. Kyogoku, and I. Kitagawa Clavukerin A, a New Triwor-guaiane Sesquiterpene from the Okinawan Soft Coral Clavularia koellikeri. Chem. Pharm. Bull. (Japan) 31, 2160 (1983). 

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). 

Endo, M., M. Nakagawa, Y. Hamamoto, and T. Nakanishi Clavularins, a New Class of Cytotoxic Compounds Isolated from the Soft Coral, Clavularia koellikeri. J. Chem. Soc., Chem. Commun. 1983, 322. Erratum J. Chem. Soc., Chem. Commun. 1983, 980. 

Suzuki, M., Watanabe, K., Fujiwara, S Kuruzawa, T, Wakabayashi, T Tsuzuki, M., Igudii, K., and Yamori, T. (2003) Isolation of peridinin-related norcarotenoids with cell growth-inhibitory activity from the cultured dinoflagellate of Symbiodinium sp., a symbiont of the Okinawan soft coral Clavularia viridis, and analysis of fatty acids of the dinoflagellate. Chem. Pharm. Bull., 51, 724-727. 

Duh, C.-Y, Chia, M., Wang, S., Chen, H., El-Gamal, A.A.H., and Dai, C.-F. (2001b) Cytotoxic dolabeUane diterpenes from the Formosan soft coral Clavularia injlata.j. Nat. Prod., 64,1028-1031. 

Fujiwara, S., Yasui, K., Watanabe, K., Wakabayashi. T, Tsuzuki, M and Igudii, K. (2003) Molecular phylogenetic relationships between prostanoid-containing Okinawan soft coral Clavularia viridis) and nonprostanoid-contarning Clavularia spedes based on ribosomal ITS sequences. Mar. Biotechnol., 5,401—407. 

Iguchi, K., Fukaya, T., Takahashi, H., and Watanabe, K. (2004) Stolonilactone, a novel terpenoid-related compound, isolated from the Okinawan soft coral Clavularia Icoellilceri. J. Org. Chem., 69, 4351— 4355. 

---