Comparison of 16-androstene steroid concentrations in sterile apocrine sweat and axillary secretions: interconversions of 16-androstenes by the axillary microflora--a mechanism for axillary odour production in man?

The concentrations of five 16-androstene steroids were determined, by a GC-MS method, in freshly-produced apocrine sweat (adrenaline-induced), in 8 men and 2 women. The ranges of concentrations (nmol/microliter) in apocrine sweat were: 5 alpha-androst-16-en-3-one (5 alpha-A), 0.1-2.0 and 4,16-androstadien-3-one (androstadienone), 0-1.9, 5,16-Androstadien-3 beta-ol (androstadienol) was also found in 5 of the subjects (range 0.05-1.05). 5 alpha-Androst-16-en-3 alpha- or 3 beta-ols [3 alpha (beta)-androstenols] were only found in small amounts (< 0.1 nmol/microliters) in a few subjects. In the second study, prior to apocrine sweat collection (adrenaline injection), the axillary skin of 6 of the male subjects was washed with diethyl ether on an adjacent site of the axillary vault. The concentrations of 16-androstenes were compared in the ethereal extracts and apocrine sweat. The former contained detectable levels (pmol/cm2) of androstadienone (17.9 +/- 2.4), 3 alpha-androstenol (6.9 +/- 3.7), 3 beta-androstenol (1.8 +/- 1.0) and androstadienol (1.9 +/- 0.5) (means +/- SEM) in all 6 subjects. All but 1 subject also had 5 alpha-androstenone, the mean value for the others being 2.5 +/- 0.6. The axillary skin levels of 3 alpha- and 3 beta-androstenols, androstadienol and, in 3 subjects, androstadienone exceeded those in the apocrine sweat obtained from the same subjects, whereas levels of 5 alpha-androstenone in the skin extracts were all lower than in apocrine sweat samples, when related to the corresponding areas of skin sampled. The metabolism of 16-androstenes was studied in vitro in the presence of two aerobic coryneform bacteria, previously shown to metabolize testosterone as well as being capable of producing odour from extracts of axillary sweat in an odour-generation test. Although both coryneforms caused complex metabolic reactions and were capable of oxidation or reduction at C-3 and C-4, the overall direction favoured reduction. For example, large quantities of the more odorous 5 alpha-androstenone and 3 alpha-androstenol were formed from androstadienol and androstadienone. In contrast, strains of corynebacteria, unable to produce odour and incapable of metabolizing testosterone, were also unable to metabolize 16-androstenes.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytochrome P450c17 from porcine and bovine adrenal catalyses the formation of 5,16-androstadien-3 beta-ol from pregnenolone in the presence of cytochrome b5

The synthesis of 5,16-androstadien-3 beta-ol from pregnenolone occurs via a cytochrome P450-dependent reaction (andien-beta synthase) that is analogous to the C17-hydroxylase/lyase reaction. It is not known whether the andien-beta synthase activity in adult porcine testis involves cytochrome P450c17 or is unique to porcine testis. Andien-beta synthase activity in testis microsomes was inhibited by high pH and concentration of salt, while C17-hydroxylase/lyase activity was stimulated under these conditions. Cytochrome P450c17 purified from adult porcine testis and adrenal glands and bovine adrenal glands had only C17-hydroxylase/lyase activity in the absence of cytochrome b5. However, when cytochrome b5 isolated from porcine testis was added, andien-beta synthase activity was detected in all three preparations of cytochrome P450c17, with the highest activity found in the porcine preparations. The andien-beta synthase activity was further increased from 2.5 to 6 times when NADH cytochrome b5 reductase was added along with cytochrome b5. Levels of mRNA for cytochrome b5 relative to cytochrome P450c17 mRNA were five times higher in porcine testis than in porcine adrenal. It appears that the andien-beta synthase activity is catalysed by cytochrome P450c17, which is not unique to the porcine testis and is dependent upon adequate levels of cytochrome b5.

Studies on anabolic steroids--11. 18-hydroxylated metabolites of mesterolone, methenolone and stenbolone: new steroids isolated from human urine

New metabolites of mesterolone, methenolone and stenbolone bearing a C18 hydroxyl group were isolated from the steroid glucuronide fraction of urine specimens collected after administration of single 50 mg doses of these steroids to human subjects. Mesterolone gave rise to four metabolites which were identified by gas chromatography/mass spectrometry as 18-hydroxy-1 alpha-methyl-5 alpha-androstan-3,17-dione 1, 3 alpha,18-dihydroxy-1 alpha-methyl-5 alpha-androstan-17-one 2, 3 beta,18-dihydroxy-1-alpha-methyl-5 alpha-androstan-17-one 3 and 3 alpha,6 xi,18-trihydroxy-1 alpha-methyl-5 alpha-androstan-17-one 4. These data suggest that mesterolone itself was not hydroxylated at C18, but rather 1 alpha-methyl-5 alpha-androstan-3,17-dione, an intermediate metabolite which results from oxidation of mesterolone 17-hydroxyl group. In addition to hydroxylation at C18, reduction of the 3-keto group and further hydroxylation at C6 were other reactions that led to the formation of these metabolites. It is of interest to note that in the case of both methenolone and stenbolone, only one 18-hydroxylated urinary metabolite namely 18-hydroxy-1-methyl-5 alpha-androst-1-ene-3,17-dione 5 and 18-hydroxy-1-methyl-5 alpha-androst-1-ene-3,17-dione 6 were both detected in post-administration urine specimens. These data indicate that the presence of a methyl group at the C1 or C2 positions in the steroids studied is a structural feature that seems to favor interaction of hepatic 18-hydroxylases with these steroids. These data provide further evidence that 18-hydroxylation of endogenous steroids can also occur in extra-adrenal sites in man.

Cholesterol oxidase susceptibility of cholesterol and 5-androsten-3 beta-ol in pure sterol monolayers and in mixed monolayers containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine

This study has examined the importance of the isocaproic side chain at C-17 of cholesterol to sterol/phospholipid interactions in monolayer membranes and to the cholesterol oxidase-susceptibility of cholesterol in pure and mixed monolayers at the air/water interface. The interactions between cholesterol or 5-androsten-3 beta-ol (which lacks the C-17 side chain) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) in monolayers indicated that 5-androsten-3 beta-ol was not very efficient in causing condensation of the monolayer packing of POPC. Whereas cholesterol condensed the packing of POPC at all molar fractions examined (i.e., 0.25, 0.50 and 0.75 with regard to POPC), 5-androsten-3 beta-ol caused a slight condensing effect on POPC packing only in the equimolar mixture. The mean molecular area requirement of 5-androsten-3 beta-ol (in pure sterol monolayers at different lateral surface pressures) was 2.2-6.7% less than that observed for cholesterol. The pure 5-androsten-3 beta-ol monolayer also collapsed at lower lateral surface pressures compared with the pure cholesterol monolayer (34 mN/m and 45 mN/m, respectively). The cholesterol oxidase (Streptomyces sp.) catalyzed oxidation of cholesterol or 5-androsten-3 beta-ol in pure monolayers in the air/water interface (10 mN/m) proceeded with very similar rates, indicating that the enzyme did not recognize that the C-17 side chain of 5-androsten-3 beta-ol was missing. The oxidation of cholesterol or 5-androsten-3 beta-ol in mixed POPC-containing monolayers (equimolar mixture) also revealed similar reaction rates, although the reaction was slower in the mixed monolayer compared with the pure sterol monolayer. When the oxidation of cholesterol and 5-androsten-3 beta-ol was examined by monitoring the production of H2O2 (the sterol was solubilized in 2-propanol and the assay conducted in phosphate buffer), the maximal reaction rate observed with 5-androsten-3 beta-ol was only about 41% of that measured with cholesterol. From the cholesterol oxidase point-of-view, it can be concluded that the enzyme did not recognize the C-17 side chain of cholesterol (or lack of it in 5-androsten-3 beta-ol), when the sterol was properly oriented as a monolayer at the air/water interface. However, when the substrate was presented to the enzyme in a less controlled orientation (organic solvent in water), 5-androsten-3 beta-ol may have oriented itself unfavorably compared with the orientation of cholesterol, thereby leading to slower oxidation rates.

Synthesis and biochemical studies of 16- or 19-substituted androst-4-enes as aromatase inhibitors

Androst-4-en-17-one derivatives [19-acetoxide 4, 16-bromides 14 and 15, 19,19-difluoride 18, and (19R,S)-19-acetylenic alcohol 25] and androst-4-en-17 beta-ol derivatives 3, 5, 10, 12, and 19 were synthesized and tested for their ability to inhibit aromatase in human placental microsomes. All the 17-oxo steroids, except compound 25 and 17,19-diol 3 of this series, were effective competitive inhibitors with apparent Ki's ranging from 170 to 455 nM. 19,19-Difluoro steroid 18 and 19-acetylenic alcohol 25, a weak competitive inhibitor (Ki = 7.75 microM), caused a time-dependent, pseudo-first-order inactivation of aromatase activity with kinact's of 0.0213 and 0.1053 min-1 for compounds 18 and 25, respectively. NADPH and oxygen were required for the time-dependent inactivation, and the substrate, androst-4-ene-3,17-dione, prevented it, but a nucleophile, L-cysteine, did not in each case. The results strongly suggest that aromatase would attack the 19-carbon of steroids 18 and 25.

Theoretical studies on the mechanism of conversion of androgens to estrogens by aromatase

Semiempirical molecular orbital calculations (AM1) were used to model several possible reaction mechanisms for the third oxidation of the aromatase-catalyzed conversion of androgens to estrogens. The reaction mechanisms considered are based on the assumption that the third oxidation is initiated by 1 beta-hydrogen atom abstraction. Homolytic cleavage of the C10-C19 bond was modeled for both the 3-keto and 2-en-3-ol forms of the androgen 1-radicals. The addition of a protein nucleophile to the 19-oxo intermediate was also considered, and -OCH3, -SCH3, and -NHCH3 were used to represent the Ser, Cys, and Lys adducts. The transition states were estimated and optimized from the reaction coordinates obtained by constraining and increasing the C10-C19 bond lengths. The enthalpies of activation range from 14 to 21 kcal and are approximately 2 kcal lower for cleavage of the enol form. Given the tendency for AM1 to overestimate activation energies, all reactions may be energetically accessible. Other reactions modeled include a homolytic cleavage reaction from a thioether radical cation and the direct additions of oxygen radical compounds to the carbonyl of the 1-radical-2-en-3-ol-19-oxo androgen. A mechanism is proposed in which the 19-oxo intermediate is subject to initial nucleophilic attack by the protein. Since rotation of the 19-carbonyl can bring the oxygen within 2.1 A of the 2 beta-hydrogen, the formation of a tetrahedral intermediate can occur with concomitant removal of the 2 beta-proton. Enolization activates the C1-position for hydrogen atom abstraction, since the resulting radical is resonance stabilized.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on anabolic steroids--6. Identification of urinary metabolites of stenbolone acetate (17 beta-acetoxy-2-methyl-5 alpha-androst-1-en-3-one) in human by gas chromatography/mass spectrometry

The metabolism of stenbolone acetate (17 beta-acetoxy-2-methyl-5 alpha-androst-1-en-3-one), a synthetic anabolic steroid, has been investigated in man. Nine metabolites were detected in urine either as glucuronic or sulfuric acid aglycones after oral administration of a single 50 mg dose to a male volunteer. Stenbolone, the parent compound, was detected for more than 120 h after administration and its cumulative excretion accounted for 6.6% of the ingested dose. Most of the stenbolone acetate metabolites were isolated from the glucuronic acid fraction, namely: stenbolone, 3 alpha-hydroxy-2-methyl-5 alpha-androst-1-en- 17-one, 3 alpha-hydroxy-2 xi-methyl-5 alpha-androst-17-one; 3 isomers of 3 xi, 16 xi-dihydroxy-2-methyl-5 alpha-androst-1-en-17-one; 16 alpha and 16 beta-hydroxy-2-methyl-5 alpha-androst-1-ene-3, 17-dione; and 16 xi, 17 beta-dihydroxy-2-methyl-5 alpha-androst-1-en-3-one. Only isomeric metabolites bearing a 16 alpha or a 16 beta-hydroxyl group were detected in the sulfate fraction. Interestingly, no metabolite was detected in the unconjugated steroid fraction. The steroids identities were assigned on the basis of their TMS ether, TMS enol-TMS ether, MO-TMS and d9-TMS ether derivatives and by comparison with reference and structurally related steroids. Data indicated that stenbolone acetate was metabolized into several compounds resulting from oxidation of the 17 beta-hydroxyl group and/or reduction of A-ring delta-1 and/or 3-keto functions with or without hydroxylation at the C16 position. Finally, comparison of stenbolone acetate urinary metabolites with that of methenolone acetate shows similar biotransformation pathways for both delta-1-3-keto anabolic steroids. This indicates that the position of the methyl group at the C1 or C2 position in these steroids has little effect on their major biotransformation routes in human, to the exception that stenbolone cannot give rise to metabolites bearing a 2-methylene group since its 2-methyl group cannot isomerize into a 2-methylene function through enolization of the 3-keto group as previously observed for methenolone.

Inhibitory effect of some imidazole antifungal compounds on the synthesis of 16-ene-C19-steroid catalyzed by pig testicular microsomes

The activity of the enzyme (16-ene-C19-steroid synthesizing enzyme) responsible for the conversion of C21-steroids to 16-ene-C19-steroids, which was localized on pig testicular microsomes, was inhibited by some typical imidazole antifungal compounds such as clotrimazole, econazole, miconazole and ketoconazole which are known to be universal inhibitors of cytochrome P-450-dependent enzymes. The 50% inhibitory concentrations of clotrimazole, econazole and miconazole were 0.29, 0.36 and 1.25 microM, respectively for 16-ene-C19-steroid synthesizing enzyme activity. Clotrimazole was the most powerful inhibitor of all the compounds examined, which shows the competitive inhibition for 16-ene-C19-steroid synthesizing enzyme activity. The Ki-value was 0.26 microM for its activity. The degree of the inhibition by these imidazole compounds was very similar to the inhibition of 17 alpha-hydroxylase and C17,20-lyase activities on pig testicular microsomes.

16-Ene-steroids in the human testis

Incubation of human testicular homogenates with [4-14C]pregnenolone gave substantial amounts of an unknown metabolite within 1 min, reaching plateau values of 17-23% of total radioactivity added within 5 min. Mass spectrometry of the metabolite showed it to be identical to the boar sex pheromone precursor androsta-5, 16-diene-3 beta-ol (ADL). In cell cultures the major source of ADL and its dehydrogenated metabolite androsta-4, 16-diene-3-one (ADN) was the Leydig cell. In rat and monkey testicular homogenates 16-ene-synthetase activity, a prerequisite for the synthesis of ADL and ADN, was completely lacking, limiting the presence of 16-androstenes to boars and men. In contrast to boars, however, in the human testis no 5 alpha-reductase activity was found and consequently no 5 alpha-reduced-16-androstenes, e.g. androstenol (AL, musk like) and androstenone (AN, urine like), known sex pheromones in pigs. As both sex pheromones have been identified in urine, plasma, sweat and saliva of men and (especially hirsute) women we hypothesize that AL and AN are synthesized from ADL via ADN peripherically in tissues rich in 5 alpha-reductase, i.e. skin, axillary sweat glands and probably also the salivary glands. So far, there is some evidence that both sex pheromones may have similar functions in humans as in boars.

Differential metabolism of pregnenolone by testicular homogenates of humans and two species of macaques. Lack of synthesis of the human sex pheromone precursor 5,16-androstadien-3 beta-ol in nonhuman primates

In previous reports we described the early time sequence in in vitro [4-14C] pregnenolone metabolism in human and rat testicular homogenates and, apart from a difference in the preferred route of the conversion of pregnenolone to testosterone, we demonstrated the presence of delta 16-synthetase activity in human but not in rat testes. In the study of testicular function higher monkeys are increasingly used as a model for human reproduction. The availability of testes from 2 different species of macaques (rhesus and crab eating monkeys) enabled us to compare the in vitro metabolism of pregnenolone in these testes with human testes. The pattern obtained in both monkey species were very similar, but completely different from those found in man. The delta 4 pathway was the preferred route for the conversion of pregnenolone to testosterone in the monkeys tested, the delta 5 pathway in the humans. delta 16-Synthetase activity, a prerequisite for the synthesis of the sex pheromone precursors 5,16-androstadien-3 beta-ol and 4,16-androstadien-3-one, was clearly measurable in the human but not in the monkey testicular homogenates. So far, man and boar are the only species harbouring delta 16-synthetase activity in their testes. These in vitro data indicate that the nonhuman primates studied are not suitable models for the study of human testicular function.

Interaction of cholesterol with saturated phospholipids: role of the C(17) side chain

Cholesterol and 5-androsten-3 beta-ol differ structurally only in the presence of an eight carbon side chain at the C(17) position in the former sterol. Both molecules decrease the main transition enthalpy change (delta H) in a series of phosphatidylcholines and phosphatidylethanolamines, of acyl chain length n, with the reduction being a linear function of sterol concentration (c). The sterol concentrations at which delta H = 0 bear a straight line relationship to n and are equivalent for both cholesterol and 5-androsten-3 beta-ol. In addition, both sterols give identical delta H versus c slopes. These results underscore the importance of acyl chain length in the cholesterol/phospholipid interaction and also indicate that the cholesterol C(17) side group is not an essential requirement for the capacity of the sterol to decrease the enthalpy change of the main transition.

Involvement of cytochrome P-450 in the synthesis of 5,16,androstadien-3 beta-ol from pregnenolone in pig testes microsomes

The conversion of pregnenolone to 5,16,androstadien-3 beta-ol, the first intermediate in the biosynthetic pathway of the androst-16-ene steroids, is catalysed by a microsomal enzyme system in the testes of the pig. This reaction is analogous to the conversion of pregnenolone to dehydroepiandrosterone in the biosynthesis of the androgens, since both systems involve the conversion of C21 steroids to C19 steroids by removal of the 2-carbon side chain. Cytochrome P-450SCCII catalyses the formation of the first C19 androgen intermediates, while the enzyme system that catalyzes the formation of the first androst-16-ene intermediates, so called andien-beta synthase, has not previously been well characterized. Andien-beta synthase and cytochrome P-450SCCII activities have been measured in an in vitro assay system with boar testes microsomes using [14C]pregnenolone as substrate. Both enzyme systems require NADPH and oxygen for maximal activity and are inhibited by carbon monoxide when oxygen levels are low. Classical inhibitors of cytochrome P-450 including SKF-525A, metyrapone and alpha-naphthoflavone inhibited both enzyme systems to a similar extent. In addition, inhibitory antibodies against NADPH cytochrome P-450 reductase also inhibited both enzyme activities in testes microsomes. It is concluded that the formation of 5,16,androstadien-3 beta-ol from pregnenolone in pig testes microsomes is catalyzed by cytochrome P-450.

The concentration of 16x-hydroxy androgens in serum and cyst fluid of women with gross cystic disease of the breast

The concentrations of 16 alpha-hydroxydehydroepi-androsterone sulfate (16 alpha-OHDHAS) and androst-5-ene-3 beta, 16 alpha-, 17 beta-triol-3-sulfate (A-TriolS) were measured in the plasma and breast cyst fluid (BCF) of women with gross cystic disease of the breast. In the 19 BCF samples analyzed, the 16 alpha-OHDHAS and A-TriolS concentrations ranged from 15 to 1130 ng/mL, and 12 to 871 ng/mL, respectively. However the concentrations of these steroids in the sera of these women were lower (15-179 ng/mL, 8-80 ng/mL, respectively). Estriol-3-sulfate (E3-3S) concentrations in the BCF samples ranged from barely detectable (0.2 ng/mL) to 3 micrograms/mL. In BCF or serum a positive linear correlation was observed in the concentration of 16 alpha-OHDHAS and A-TriolS (p less than 0.001 and 0.05, respectively). However, in the same patients no statistical significance was observed in the BCF vs serum concentrations of these two steroids. When the specimens from this and previous studies were combined, positive correlation was found between potassium ion concentration and E3-3S or 16 alpha-OHDHAS. The origin of the high concentration of E3-3S is still obscure. Although no linear correlation between 16 alpha-OHDHAS and E3-3S was observed, the possibility of a precursor-product relationship between the two is not elimnated.

Factors affecting the pheromone composition of voided boar saliva

The pheromone binding protein 'pheromaxein' which binds the pheromonal 16-androstene steroids in the saliva of the male pig (boar), was degraded and lost its binding activity in saliva incubated in air for 72 h at 21 degrees C and 37 degrees C. However, pheromaxein and its binding activity were retained in saliva incubated for 168 h at 4 degrees C. When the 3H-labelled pheromones 5 alpha-androst-16-en-3 alpha-ol (3 alpha-androstenol), 5 alpha-androst-16-en-3-one (5 alpha-androstenone) and 5 alpha-androst-16-en-3 beta-ol (3 beta-androstenol) were incubated with boar saliva for 168 h at 21 degrees C, 3 alpha-androstenol was primarily converted to 5 alpha-androstenone and 5 alpha-androstenone to 3 beta-androstenol; 3 beta-androstenol was unchanged. Evidence was obtained for microorganisms being responsible for these steroid transformations.

The sex pheromone precursor androsta-5,16-dien-3 beta-ol is a major early metabolite in in vitro pregnenolone metabolism in human testicular homogenates

In an earlier report we described the early time sequence of the in vitro metabolism of [4-14C]pregnenolone ([4-14C]P5) to testosterone in homogenates of human and rat testes and demonstrated the appearance of mainly delta 5 (humans)- and delta 4 (rats)-steroids within minutes after starting the incubation. In this study strong evidence is presented for the substantial synthesis from P5 of the sex pheromone precursor androsta-5,16-dien-3 beta-ol (ADL) in human, but not rat, testicular homogenates. The 16-unsaturated C19 steroid ADL appeared after 1 min of incubation, and within 5 min reached values (17-23% of total radioactivity added as [4-14C]P5) comparable to those of the major delta 5-steroids 17 alpha-hydroxypregnenolone and dehydroepiandrosterone. Thus, in humans, as in boars, the sex attractant precursor ADL is a major early testicular metabolite of P5.

Conversion of androstenedione to 3 beta-hydroxy-5-androsten-17-one and 3 beta-hydroxy-4-androsten-17-one by the testicular microsomal fraction of Sprague-Dawley rats

When androstenedione was incubated with testicular microsomes of Sprague-Dawley rats in the presence of reduced nicotinamide-adenine dinucleotide (NADH), unknown metabolites were produced, in addition to testosterone and 7 alpha-hydroxyandrostenedione. The metabolites were identified as 3 beta-hydroxy-4-androsten-17-one and 3 beta-hydroxy-5-androsten-17-one (3:1) by biochemical and radiochemical methods. These results confirmed the occurrence of the reverse reactions from androstenedione to 3 beta-hydroxy-4-androsten-17-one and 3 beta-hydroxy-5-androsten-17-one catalyzed by the 3 beta-hydroxysteroid dehydrogenase and 5-ene-4-ene isomerase in the microsomal fraction of Sprague-Dawley rat testes.

Epoxidation of androsta-5,16-dien-3 beta-ol by hepatic microsomal lipid peroxidation

Male rat liver microsomes oxidized androsta-5,16-dien-3 beta-ol (delta 16-ANDO) to delta 16-ANDO-5,6 alpha-, -5,6 beta-, -16,17 alpha-, and -16,17 beta-epoxides and delta 16-ANDO-5 alpha,6 beta-, -16 alpha,17 beta-, and -16 beta,17 alpha-glycols in the presence of an NADPH-generating system and the microsomal lipid peroxidation accelerator, Fe2+-ADP. The hepatic microsomes hydrolyzed all the delta 16-ANDO epoxides to the glycols. delta 16-ANDO-5 alpha,6 beta-glycol was the sole metabolite from both 5,6 alpha- and 5,6 beta-epoxides. Microsomal epoxide hydrolase also hydrolyzed delta 16-ANDO-16,17 alpha-epoxide specifically to the 16 beta,17 alpha-glycol and the isomeric 16,17 beta-epoxide to the 16 alpha,17 beta- and 16 beta,17 alpha-glycols approximately in the equal ratio. The delta 5-epoxidation of delta 16-ANDO by microsomes occurred only under the conditions that lipid peroxidation took place. Direct evidence was obtained for the participation of microsomal lipid hydroperoxides in the epoxidation of delta 16-ANDO by using photochemically prepared hydroperoxides of phospholipids separated from the hepatic microsomes. The hydroperoxides generated active oxygens, tentatively assigned as alk(ylper)oxy radicals, by the action of ferrous ion and epoxidized delta 16-ANDO to afford the 5,6- and 16,17-epoxides. The Fe2+-ADP-mediated epoxidation of delta 16-ANDO by the phospholipid hydroperoxides occurred preferentially at delta 5 to delta 16 and afforded the 5,6 beta-epoxide in a higher ratio than the 5,6 alpha-epoxide, similar to the Fe2+-ADP-mediated microsomal epoxidation, while the alpha-epoxide was preferentially formed to the beta-epoxide for delta 16 in the epoxidation by both systems.

The obligatory intermediacy of 16,17 alpha- and 16,17 beta-epoxides in the biotransformation of androsta-5,16-dien-3 beta-ol to androst-5-ene-3 beta, 16 alpha, 17 beta- and -3 beta, 16 beta, 17 alpha-triols by male rat liver microsomes

The C16-double bond of the biolefinic steroid, androsta-5,16-dien-3 beta-ol (delta 16-ANDO), was regioselectively oxidized by male rat liver microsomes in the presence of NADPH and EDTA to 16 alpha, 17 alpha-epoxyandrost-5-en-3 beta-ol (delta 16-ANDO 16,17 alpha-epoxide), 16 beta,-17 beta-epoxyandrost-5-en-3 beta-ol (delta 16-ANDO 16,17 beta-epoxide), androst-5-ene-3 beta, 16 alpha, 17 beta-triol (delta 16-ANDO 16 alpha, 17 beta-glycol), and androst-5-ene-3 beta, 16 beta, 17 alpha-triol (delta 16-ANDO 16 beta, 17 alpha-glycol). The microsomes hydrolyzed delta 16-ANDO 16,17 alpha-epoxide specifically to the 16 beta, 17 alpha-glycol and delta 16-ANDO 16,17 beta-epoxide to the 16 beta, 17 alpha-glycol and the 16 alpha, 17 beta-glycol in an equal ratio. delta 16-ANDO 16,17 alpha-epoxide was much more susceptible to microsomal hydrolysis than the 16,17 beta-epoxide. The xenobiotic epoxide hydrolase inhibitor, 3,3,3-trichloropropene 1,2-oxide, potently inhibited microsomal hydrolysis of delta 16-ANDO 16,17-epoxides as well as of benzo[a]pyrene 4,5-epoxide and styrene 7,8-epoxide. Addition of 3,3,3-trichloropropene 1,2-oxide accumulated the 16,17-epoxides formed from delta 16-ANDO in the reaction medium with concomitant decrease in the amounts of the 16,17-glycols formed, leading to a conclusion that the 16,17-epoxides played a role as obligatory intermediates in the microsomal delta 16-oxidation of delta 16-ANDO to the 16,17-glycols. Epoxidation of delta 16-ANDO was stereoselectively mediated by a cytochrome P-450 with quite unique properties to form the 16,17 alpha-epoxide as the major oxidation product and the 16,17 beta-epoxide as the minor. The epoxidation was strongly inhibited with CO, activated with 2-diethylaminoethyl 2,2-diphenylvalerate hydrochloride more than twice as much, and little affected with metyrapone and 7,8-benzoflavone. A pretreatment of the animals with 3-methylcholanthrene induced the delta 16-ANDO-epoxidizing activity of their microsomes 1.5 times higher than those from the control animals. However, a pretreatment with phenobarbital reduced the enzyme activity to one-half of the control microsomes. Under the same conditions, microsomal activities of hydroxylation of benzo[a]pyrene and N-demethylation of benzphetamine were significantly induced by the pretreatments with 3-methylcholanthrene and phenobarbital, respectively.

Gas chromatographic-mass spectrometric study of metabolites of C21 and C19 steroids in neonatal porcine testicular microsomes

Microsomal fractions obtained from testes of 3-week-old piglets have been incubated, separately, with progesterone, 17-hydroxyprogesterone, 5-pregnene-3 beta,20 beta-diol, 16 alpha-hydroxypregnenolone, 5-androstene-3 beta,17 alpha-diol and dehydro-epiandrosterone. The metabolites, after derivatization, have been separated by capillary gas chromatography and identified by mass spectrometry. Quantification was by selected ion monitoring. Progesterone was shown to be 17-hydroxylated and also converted into 4,16-androstadien-3-one (androstadienone). The major metabolite of 17-hydroxyprogesterone was 4-androstene-3,17-dione (4-androstenedione), but little, if any, androstadienone was formed, indicating that this particular biosynthesis did not require 17-hydroxylation. The metabolites of 5-pregnene-3 beta, 20 beta-diol were found to be 17-hydroxypregnenolone, 3 beta-hydroxy-5,16-pregnadien-20-one (16-dehydropregnenolone) and 5,16-androstadien-3 beta-ol. Dehydroepiandrosterone and 5-androstene-3 beta,17 alpha-diol were interconvertible but neither steroid acted as a substrate for 16-androstene formation. However, dehydroepiandrosterone was metabolized to a small quantity of 4-androstenedione. Under the conditions used, no metabolites of 16 alpha-hydroxypregnenolone could be detected. The present results, together with those obtained earlier, indicate that the neonatal porcine testis has the capacity to synthesize weak androgens, mainly by the 4-en-3-oxo steroid pathway. Although 16-androstenes cannot be formed from C19 steroids, progesterone served as a substrate and may be converted directly to androstadienone, without being 17-hydroxylated first. The pathway to 5,16-androstadien-3 beta-ol, however, involves 17-hydroxypregnenolone and 16-dehydropregnenolone as intermediates.

Cyanoketone competition with estradiol for binding to the cytosolic estrogen receptor

Cyanoketone, an inhibitor of many steroidogenic processes, has been found to inhibit binding of estradiol to its receptor in a competitive manner. The Ki observed was 1.2 X 10(-6)M. This action may explain some of cyanoketone's effects in vivo.

Properties of porcine liver and testicular steroid sulphotransferases: reaction conditions and influence of naturally occurring steroids and steroid sulphates

Sulphotransferase activity has been assayed in porcine liver and testis cytosol using either 3'-phosphoadenosine-5'-phospho [35S]sulphate (PAPS) or unlabelled PAPS as sulphate donors. In porcine liver the sulphotransferase for DHA was linear for up to 10 min, the optimum pH was 7.7 and optimum temperature, 37 degrees C. The apparent Km value was found to be 91 mumol/l and the activity was inhibited non-competitively by 5 alpha-androst-16-en-3 beta-yl sulphate, with all concentrations used (0.02-25 mumol/l) inhibiting the enzyme to the same extent. Time courses for sulphoconjugation of pregnenolone and 5 alpha-androst-16-en-3 beta-ol were linear for up to at least 10 min or up to only 5 min, respectively. The optimum pH values and temperatures were pH 8.0 and 37 degrees C in each case. The porcine testicular sulphotransferase activity for DHA as substrate was linear with time up to 10 min, the apparent Km for the reaction was 2 mumol/l and apparent Vmax 10 nmol/l/mg/min. 5 alpha-Androst-16-en-3 beta-yl sulphate (11.3-45.2 mumol/l) failed to inhibit the enzyme activity. The time-course for the reaction, when pregnenolone was used as substrate, was also linear up to 10 min at the optimum pH 8.0 but, in contrast to the reaction when DHA was the substrate, had an apparent Km of 20 mumol/l and was inhibited by pregnenolone sulphate, 5 alpha-androst-16-en-3 beta-yl sulphate, DHA and 5 alpha-androst-16-en-3 beta-ol, but not by DHA sulphate. 5 alpha-Androst-16-en-3 beta-yl sulphate inhibited the reaction non-competitively and to the same extent at concentrations over the range 11.3-45.2 mumol/l. These data suggest that DHA and pregnenolone may not be sulphoconjugated by the same sulphotransferase. With 5 alpha-androst-16-en-3 beta-ol as substrate, the time-course for its sulphate formation was linear up to 15 min, and this reaction could explain the quantities of 5 alpha-androst-16-en-3 beta-yl sulphate that are found endogenously in porcine testis. Our results further suggest that these quantities could well inhibit the sulphation of pregnenolone in porcine testis in vivo, and the possibility of control of sulphoconjugation in this tissue is discussed. Having regard to the smaller quantities of 5 alpha-androst-16-en-3 beta-yl sulphate present in porcine liver, our results suggest that the sulphation of DHA there may not be so much affected.

Adrenal of male dog secretes androgens and estrogens

In the absence of functioning gonads, the adrenal is an important source of androgens and estrogens. In order to precisely quantitate the adrenal secretion rates of the sex steroids, we cannulated the adrenal veins and measured venous blood flow and arterial venous steroid gradients in adult male beagle dogs under pentobarbital anesthesia. Celite chromatography and specific radioimmunoassays were utilized to measure steroid levels. During basal conditions, the adrenal produced larger amounts of the androgens (667 ng/min of androstenedione, 5.45 ng/min of testosterone, and 3.43 ng/ min of dihydrotestosterone) than of the estrogens (1.245 ng/min of estradiol and 0.239 ng/min of estrone. These secretion rates were 20- to 50,000-fold less than that of cortisol (12,360 ng/min). Studies were also carried out during adrenal suppression with hydrocortisone to block ACTH release and with the adrenal steroidogenesis inhibitor, aminoglutethimide, plus hydrocortisone. The secretion rates of each androgen measured fell during ACTH inhibition. Significant suppression of estrone and estradiol, however, required addition of aminoglutethimide. This study provides direct evidence that the adrenal in the male dog can secrete estrogens, a previously controversial issue.

The specificity of the human uterine receptor

The aim of the present study was to assess the contribution of different parts of natural and synthetic steroid molecules in their binding to high affinity oestradiol receptor preparations obtained from whole human uteri. Fifty-five compounds were used in the study of which 38 contained the steroid nucleus. The affinity (in terms of association constants) of the compounds for the receptor was determined from competitive studies with radioactive oestradiol. As a consequence the compounds could be grouped according to their association constants for the receptor. The contribution of the individual functional groups of the steroid molecule to the binding process was analysed. The preliminary quantitative evaluation of the contribution was derived from the equation: log K=logdeltaKs + sigmalogdeltaKF where K8 is the contribution of the basic 1,3,5-(10)-oestratriene skeleton, KF the associated functional groups and K the affinity constant for the entire molecule. The main positive contribution in the binding is provided by skeleton and the 3-hydroxyl group. It is concluded that functional groups present at either the 3 or 17 position act independently of each other in the binding process. The possible synergism between the functional groups and the steroid skeleton is discussed.