Isomalabaricane triterpenes

Bioassay-guided fractionation of an aqueous extract from a Philippine Islands collection of the soft coral Lohophytum spp. yielded cembranoid diterpenes, Fig. (3), which exhibited moderate HIV-inhibitory activity in a cell-based in vitro anti-HIV assay [44], while new isomalabaricane triterpenes. Fig. (4), have been isolated from the sponge Stelletta spp. [45]. Other anti-HIV diterpenes also included the dolabellane diterpenes isolated from the Brazilian brown algae Dictyota pfaffi [46] and Dictyota menstrualis [47]. To investigate the effect of these diterpenes in the reverse transcription of the viral genomic RNA, the recombinant HIV-1 RT was assayed in vitro in the presence of each compound. All compounds inhibited the RNA-dependent DNA-polymerase activity of HIV-1 RT and consequently virus replication. 

Table 3. Bioactivities of the isomalabaricane triterpenes from Stelleta globoslellala...

Oku, N., Matsimaga, S Wada, S., Watabe, S and Fusetani, N. (2000) New isomalabaricane triterpenes from the marine sponge Stelletta globostellata that induce morphological changes in rat fibroblasts, f Nat. Prod., 63, 205—209. 

Tsuda, M., Ishibashi, M., Agemi, K., Sasaki, T, and Kobayashi, J. (1991) Stelliferins A-F, new antineoplastic isomalabaricane triterpenes from the Okinawan marine sponge Jaspis steUifera. Tetrahedron, 47, 2181-2194. 

The two previous compoimds correspond respectively to the skeletons of malabaricane (81 , 9R) and isomalabaricane (8S,9S), most frequently encountered, faspiferals and geoditins represent a series of nor-triterpenes from C29 to 22-... 

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