17 alpha,20 beta-dihydroxy-4-pregnen-3-one 20-sulphate: a major new metabolite of the teleost oocyte maturation-inducing steroid.

This paper describes the discovery of 17 alpha,20 beta-dihydroxy-4-pregnen-3-one 20-sulphate (17,20 beta-P-sulphate) in urine of male and female plaice Pleuronectes platessa, in female Atlantic salmon Salmo salar and in female Dover sole Solea solea. 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P) induces oocyte final maturation in teleosts and, whereas levels of the free steroid in maturing/ovulating female plaice are generally less than 1 ng ml-1 and poorly associated with the stage of maturation, the levels of 17,20 beta-P-sulphate are around 1500 ng ml-1 urine, 11 ng ml-1 blood plasma and six-fold higher in maturing than in nonmaturing fish. There are also high levels in spermiating male plaice (ca. 2300 ng ml-1 urine and 20 ng ml-1 blood plasma). 17,20 beta-P-sulphate cannot be hydrolysed by snail (Helix pomatia) sulphatase, but can be completely solvolysed by treatment with trifluoroacetic acid (TFA)/ethyl acetate (1/100, v/v) at 45 degrees for 18 hr. A number of other sulphated steroids have been identified in plaice urine: cortisol, 11-deoxycortisol and 3 alpha,17 alpha,21-trihydroxy-5 beta-pregnan-20-one (which can all be hydrolysed by snail juice); 17 alpha,20 alpha-dihydroxy-4-pregnen-3-one and 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one (which can both be solvolysed by TFA/ethyl acetate).