Malabaricane

Triterpenoids are a minor group of sponge metabolites of these malabaricane/isomalabaricane triterpenoids, Fig. (21) are known from Jaspis and Stelletla sponge species. All of this group shows cytotoxicity and anti-HIV activity [136-139]. 

These observations encouraged us to treat 2,3-oxidosqualene (37) with a catalytic quantity of titanocene. In this case, the cascade cyclization proceeded in a 6-endo/6-endo/5-exo manner, giving a mixture of malabaricane 38 and its C-13 epimer 39 (39% combined yield), together with minor amounts of achilleol A (9) and the acyclic alcohol 40 (Scheme 29) [53]. 

P-Sitosterol and stigmasterol are the common steroids in the genus. So far only few common triterpenes such as friedelin (207), e/ /-fnedelinol (208), a-amyrin (204), P-amyrin (205), a-amyrin acetate (206), taraxasterol (213), lupeyl acetate (209), magnificol (210) were isolated from Tanacetum species. However, T. sinaicum afforded unusual new malabaricane type triterpenoids 3p-acetoxymalabarican-14(26),17E,21-triene (211) and 3-oxo-malabarica-14(26),17E,21-triene (212) (Table 1). 

Sodagnitins. Chromogenic (color change with aq. KOH colorless reddish violet) triterpenoids (with modified malabaricane skeleton) from die cap skins of the toadstools Cortinarius sodagnitus. C. fulvoincar-natus and C. arcuatorum, e.g., S. C Cj HjoOio, Mr 642.78, colorless powder, mp. 116-119 C (dec.), la) -15 (CHjOH). 

Seven new triterpenes belonging to the rare malabaricane class from the sponge Jaspis stellifera were identified by Ravi et al. (139) by a combination of spectral evidence and chemical degradation as (13Z, 15 , 17E,22E,24Z)-3, 2-dioxomalabarica-l 3,15,17,22,24-pentaen-26-oic acid (215), (13Z,15E,17E,22Z,24Z)-3,12-dioxomalabarica-... 

Ravi, B.N., R.J. Wells, and K.D. Croft Malabaricane Triterpenes from a Fijian Collection of the Sponge Jaspis stellifera. J. Org. Chem. 46, 1998 (1981). 

Jaspis Triterpenes (malabaricane), macrolactones, halogenated cyclic depsipeptides, sulfated aromatic derivatives, original amino acids and nucleosides... 

Stelletta Acetylenic fatty acids, triterpenes (malabaricane), bipyridyl derivatives, S/N heterocycles, nitrogen-containing terpenes and meroterpenes. 

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-... 

Aurorals 1-4 are cytotoxic sesterterpenes derived from iso-malabaricane and similar to jaspiferals. They were all isolated from Rhabdastrella bosteUata, harvested in New Caledonia (Bourguet-Kondradd et al., 2000). Most of the stellettins A-M were isolated from species of the genus Stdletta, especially Stdletta tenuis (Su et al., 1994 lin et al., 2007), but some were also isolated also from Rhabdastrella bostdlata. 

Ravi, B.N. and Wells, R.J. (1982) Malabaricane triterpenes from a Great Barrier reef collection of the sponge Jaspis stellifera. Aust. J. Chem., 35, 39-50. 

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