Phenytoin stimulation of testosterone metabolism in inflamed human gingival fibroblasts.

17B-ol-3-one, 5( 10)-estren17/3-ol-3-one, an isomer each of 5-estrane-3,17-diol and estradiene-3,17-diol and two isomers each of S( 10)-estren-3-ol-17-one and S( l0)-estrene3,17-diol were identified. None of these steroids was detected in the blank incubated samples. In the blank phenolic fractions traces of oestrone and oestradiol-17P were present. In the post-incubation extracts a definite increase in these oestrogens was observed in all cases showing enzymic conversion of C, , neutral to phenolic steroids. The derivatized molecular masses and the electron impact mass spectral data of the steroids identified are summarized in Table 1. The results demonstrate that unconjugated S( lO)-estrene3,17-diols can be metabolized in stallion testis by a number of enzyme systems. The 17B-hydroxysteroid oxidoreductase (EC 1 . l . 1.64) forms the S( lO)-estren-3-ol-17-one metabolites and the 3-hydroxysteroid oxidoreductase (EC 1.1.1.5 1 ) forms the 5( lO)-estren17-ol-3-one or S( 10)-estrene-3,17dione metabolites. The 5( lO)-estren-3-one steroids are isomerized to form 4-estren17P-ol-3-one ( 19-nortestosterone) and 4-estrene-3,17-dione found in stallion testes and urine. A similar conversion of the synthetic contraceptive steroid norethynodrel ( 17a-ethynyl-5( 10)-estren17P-ol-3-one) to norethisterone ( 17 a-ethynyl-4-estren1 7B-ol-3-one) in vitro by human endometrium has also been reported [9]. This enzymic conversion is analogous to the 3-hydroxysteroid dehydrogenase isomerase (EC 1.1.1.51 and EC 5.3.3.1) enzyme which converts 3B-hydroxy-5-ene steroids to 4-en3-one configuration. Further reduction of 19-nortestosterone to 5-estrane-3,17-diol demonstrates the presence of 4-en-3-one reductases in stallion testes. The mass spectrum of estradiene-3,17-diol identified in the present study suggests that the double bond is introduced in either the A or the B-ring. It can arise by mixed function oxygenase hydroxylation and subsequent dehydration. If as previously reported for other 19-nor steroids, this metabolite arises from ID-hydroxylation and dehydration, i t can then serve as a precursor in oestrogen biosynthesis by oxidation of the 3-hydroxy group. The l-hydroxy-estr-4-en-3-one steroids are unstable and dehydrate on acid or alkaline treatment to form oestrogens as artefacts [ 10-121. In the present study, since neither acid nor base was used during the experimental procedures, the increased levels of oestrogens found in the phenolic fractions demonstrates the aromatization of neutral C , , steroids in vitro to phenolic compounds.