Tremaster novaecaledoniae

In contrast with the common 25S configuration of the many 26-hydroxysteroids isolated from starfishes, polyhydroxysteroids with the 25R configuration have been isolated from Tremaster novaecaledoniae (129) a polyhydroxylated sterol analog but with the 5p skeleton (cis AB ring fusion) has been isolated from the same starfish. Their structures include (25R) 5a-cholestane-3p,5,6p,15a,16p,26-hexaol (173), its 15-sulphate derivative and (25R) 5p-cholestane-3a,6P,15a,16P,26-pentaol (174). More interestingly Tremaster novaecaledoniae has also given a... 

The species Myxoderma platyacanthum and Tremaster novaecaledoniae contain unusual polyhydroxy-sterols for which there are no known equivalents in other species. In the first species (M. platyacanthum), the side chain is an amide whose carbonyl derives from the oxidation of carbon 26 and the nitrogenous part of taurine. The second species (T. novaecaledoniae) contains the first knovm example of a phosphoric ester in position 6a with a classical side chain. This phosphoric ester is in addition associated with asterosaponins, also phosphorylated (see below). The role of these exceptional derivatives in these two sea stars seems not yet be known. Minutoside B is a glycoside isolated from the starfish Anasterias minuta harvested in Patagonia whose aglycone has the same atypical side chain of steroids as that found in Myxoderma platyacanthum (Chludil and Maier, 2005). 

Also isolated from Tremaster novaecaledoniae, tremaster-ols A-C are characterized by the presence of a Sp-sulfate group and a 6a-phosphoric ester of glucose, more or less acetylated. 

De Riccardis, F., Minale, L., Ricdo, R., Giovannitti, B., lorizzi, M., and Debitus, C. (1993a) Phosphated and sulphated marine polyhydroxylated steroids from the starfish Tremaster novaecaledoniae. Gazz. Chim. Ital., 123, 79-85. 

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