Polyhydroxy steroids

Partially protected carbohydrates can be selectively oxidized at the primary hydroxy group to uronic acids at the nickel hydroxide electrode. At the same electrode, in polyhydroxy steroids, a preferential oxidation of the sterically better accessible hydroxyl groups is achieved [142]. By way of the mediator, TEMPO, carbohydrates that are only protected at the anomeric hydroxyl group are selectively oxidized at the primary hydroxyl group (Fig. 27) [143-145]. 

Steroids Polyhydroxy steroids (e.g., the te-trol for which spectra are shown in Fig. 2.18) give El spectra that often show weak or nonexistent molecular ion peaks. For this tetrol facile dehydration is only partly caused by heating. 

The last additions are the carolisterols A - C (179 -181) isolated from the starfish Styracaster caroli collected at a depth of2000 m off New Caledonia. These are a striking new addition to the large number of polyhydroxysteroids isolated from marine sources, being the first bile acid-type polyhydroxy steroids isolated from marine organisms. Asa further singolar characteristic the 24-oic function is found in all compounds as an amide derivative of D-cysteinolic acid (131). 

A comprehensive study of Pseudopterogorgia elisabethae from different regions of the Caribbean Sea and tropical Atlantic areas unveiled a novel class of compounds, known collectively as the pseudopterosins. Pseudopterosins are metabolites which contain diterpene glycoside moieties. Polyhydroxy steroids are another class of compounds commonly isolated from solvent extracts of this specie. 

As described by D Auria et al. 20] it is well known that many marine invertebrates are a rich source of polyhydroxylated steroids. One such metabolite, 5a-cholestane-3P,5,6p,9-tetrol, 12, initially isolated by Sjostrand et al. [21] and then later by Schmitz et al. [22], was the first polyhydroxy steroid to be isolated from the marine specie, P. elisabethae. 

Extracts of Pseudopterogorgia acerosa produced a family of diterpenoids derived from the pseudopterane skeleton 62 [5]. Other complex secondary metabolites produced by P. acerosa include cembranes, polyhydroxy steroids and carotenoids. 

Most of these polyhydroxy steroids have cytotoxic and/or antihistaminic activities (Dopeso et al, 1994). 

Anjaneyulu, V, Rao, K.N., and Radhika, P. (1999) A new sphingosine derivative and a new polyhydroxy steroidal glycoside from Sinularia gravis Tixier-Durivault of the Andaman and Nicobar Islands. Indian J. Chem. Sect. B, 38, 357-360. 

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