1
|
Kwan TK, Kraevskaya MA, Makin HL, Trafford DJ, Gower DB. Use of gas chromatographic-mass spectrometric techniques in studies of androst-16-ene and androgen biosynthesis in human testis; cytosolic specific binding of 5alpha-androst-16-en-3-one. J Steroid Biochem Mol Biol 1997; 60:137-46. [PMID: 9182868 DOI: 10.1016/s0960-0760(96)00162-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Homogenates of histologically normal human testis from three men were incubated separately with pregnenolone, 16-dehydropregnenolone, 5alpha-pregnane-3,20-dione, 3beta-hydroxy-5alpha-pregnan-20-one and androsta-5,16-dien-3beta-ol (androstadienol) in the presence of NADPH in a study of androst-16-ene and androgen biosynthesis. After the addition of internal standards and initial extraction and purification, metabolites were identified using gas chromatography-mass spectrometry (GC-MS) and monitoring selectively for three principal ions in each case at the appropriate GC retention time. Quantification was achieved by comparison with calibration lines for authentic steroids, together with the appropriate internal standards, prepared by monitoring three ion fragments for each analyte. In all experiments, androstadienol was found to be the major androst-16-ene metabolite of pregnenolone (seven times the control, i.e. endogenous, quantity; 19.8 +/- 3 ng/100 mg homogenate protein, mean +/- SEM, n = 9). Pregnenolone was also converted to androsta-4,16-dien-3-one (androstadienone) with three times the endogenous quantity (44 +/- 10 ng/100 mg homogenate protein, mean +/- SEM, n = 9) being formed. The formation of testosterone occurred only in trace amounts in the incubations of testis taken from one man (a 69-yr-old) but appreciable yields (six times endogenous levels 90 +/- 7 ng/100 mg homogenate protein, mean +/- SEM, n = 9) were found with testes from two younger men. Only traces of 5alpha-dihydrotestosterone were detected. Using androstadienol as the substrate, androstadienone was shown to be the major metabolite (approximately 10 times greater than control incubations) together with 5alpha-androst-16-en-3alpha- and 3beta-ols at approximately twice the endogenous quantities (5 ng/100 mg homogenate protein). In some incubations with androstadienol, 5alpha-androst-16-en-3-one (5alpha-androstenone) was formed (32 +/- 1 ng/100 mg homogenate protein/h; mean +/- SEM, n = 3); surprisingly, no endogenous 5alpha-androstenone could be detected. No evidence was obtained for the production of testosterone or 5alpha-DHT from androstadienol. Using cytosolic fractions of human testis, specific (displaceable) binding of 5alpha-androstenone was determined, with binding sites of approximately 200 fmol/mg tissue and a Ka of approximately 8 nmol/l.
Collapse
Affiliation(s)
- T K Kwan
- Department of Clinical Biochemistry, St. Bartholomew's and the Royal London School of Medicine and Dentistry, U.K
| | | | | | | | | |
Collapse
|
2
|
Weusten JJ, Legemaat G, van der Wouw MP, Smals AG, Kloppenborg PW, Benraad T. The mechanism of the synthesis of 16-androstenes in human testicular homogenates. JOURNAL OF STEROID BIOCHEMISTRY 1989; 32:689-94. [PMID: 2739409 DOI: 10.1016/0022-4731(89)90513-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The biochemical pathway leading to the 16-unsaturated C19 steroids--known as sex pheromone (precursors) in pig and man--is still a matter of dispute. In the 16-ene-synthetase process, via which 5,16-androstadien-3 beta-ol (ADL) or 4,16-androstadien-3-one (ADN) are biosynthesized from pregnenolone (P5) or progesterone (P4), a number of 2 or even 3 step conversions have been suggested in porcine tests, including 20 beta-reduction, 21-hydroxylation and 16,17-dehydrogenation. Studying the 16-ene-synthetase reaction in human testicular homogenates, we adduced evidence for the hypothesis that ADL is synthesized from P5 in a single step, not requiring separate intermediates. Our proposal for the 16-ene-synthetase mechanism also explains why, at least in our hands, synthesis of ADL is always accompanied by co-synthesis of its satellite 5-androstene-3 beta,17 alpha-diol (epiA5): both steroids are synthesized as a mere consequence of the fact that the proposed elimination and substitution reactions for the synthesis of ADL and epiA5, respectively, are competitive processes.
Collapse
Affiliation(s)
- J J Weusten
- Department of Medicine, St. Radboud Hospital, University of Nijmegen, The Netherlands
| | | | | | | | | | | |
Collapse
|
3
|
Kwan TK, Taylor NF, Watson D, Gower DB. Gas chromatographic-mass spectrometric study of metabolites of C21 and C19 steroids in neonatal porcine testicular microsomes. Biochem J 1985; 227:909-16. [PMID: 3159382 PMCID: PMC1144921 DOI: 10.1042/bj2270909] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
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.
Collapse
|
4
|
Kwan TK, Orengo C, Gower DB. Biosynthesis of androgens and pheromonal steroids in neonatal porcine testicular preparations. FEBS Lett 1985; 183:359-64. [PMID: 3857187 DOI: 10.1016/0014-5793(85)80810-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The biosynthesis of testosterone and 4-androstene-3,17-dione and some 16-androstenes has been studied in homogenates or subcellular fractions of testes from 3-week-old Landrace piglets. Pregnenolone was converted into 5,16-androstadien-3 beta-ol, 4,16-androstadien-3-one, 5 alpha-androst-16-en-3-one and 5 alpha-androst-16-en-3 alpha- and 3 beta-ols, but the quantities were some 50 times less than those formed in the mature boar testis. Androgens were also formed in the microsomal fractions but the quantities of 4-androstene-3,17-dione (from side-chain cleavage of 17-hydroxyprogesterone) and of testosterone (from reduction of 4-androstene-3,17-dione) were 50-70 times lower than in the adult animal. The kinetic parameters and cofactor preference of the 3 alpha- and 3 beta-hydroxysteroid dehydrogenases were determined in the cytosolic, microsomal and mitochondrial fractions of neonatal porcine testes.
Collapse
|
5
|
Testosterone and the incidence of boar taint: Effects of testosterone or testosterone propionate on the incidence of boar taint in implanted barrows. Meat Sci 1985; 13:237-45. [DOI: 10.1016/0309-1740(85)90093-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/1984] [Indexed: 11/20/2022]
|
6
|
Chapter 5 Amphibian Alkaloids. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/s0099-9598(08)60051-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
|
7
|
Andresen Ø, Bakke H. 5alpha-androstenone in fat from boars selected for rate of gain and thickness of back fat, and from boars used in artificial insemination service. Acta Vet Scand 1976. [PMID: 1211326 DOI: 10.1186/bf03546642] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
8
|
Andresen O, Bakke H. 5alpha-androstenone in fat from boars selected for rate of gain and thickness of back fat, and from boars used in artificial insemination service. Acta Vet Scand 1975; 16:492-502. [PMID: 1211326 PMCID: PMC8396101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Large variations in the level of 5α-androstenone in fat from different boars have been found. No significant difference in the level of 5α-androstenone was detected in fat from boars selected for high rate of gain and low back fat (HP-line), low rate of gain and high degree of fatness (LP-line) and a control group maintained without deliberate selection (GL-line). In boars used in artificial insemination service relatively high levels of 5α-androstenone in fat were observed, and in these animals a significant (P < 0.05) positive regression of 5α-androstenone level on age was found. Positive but non-significant regression coefficients were found between number of services which the boars had performed and level of 5α-androstenone in fat from the same animals.
Collapse
|
9
|
Studies on the metabolism of the odoriferous ketones, 5α-androst-16-en-3-one and 4,16-androstadien-3-one by the nasal epithelium of the mature and immature sow. ACTA ACUST UNITED AC 1974. [DOI: 10.1016/0005-2760(74)90143-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
10
|
Katkov T, Booth WD, Gower DB. The metabolism of 16-androstenes in boar salivary glands. BIOCHIMICA ET BIOPHYSICA ACTA 1972; 270:546-56. [PMID: 4403376 DOI: 10.1016/0005-2760(72)90120-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
11
|
Brophy PJ, Gower BD. 16-unsaturated C 19 3-oxo steroids as metabolic intermediates in boar testis. Biochem J 1972; 128:945-52. [PMID: 4404770 PMCID: PMC1173914 DOI: 10.1042/bj1280945] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
1. The formation of the two 16-unsaturated alcohols 5alpha-androst-16-en-3alpha-ol and 5alpha-androst-16-en-3beta-ol from [5alpha-(3)H]5alpha-androst-16-en-3-one has been demonstrated in boar testis homogenates. 2. The optimum yield (23%) of the 3alpha-alcohol was obtained in the presence of NADPH, whereas that for the 3beta-alcohol (74%) was obtained when NADH was the added cofactor. 3. The two alcohols were not interconvertible. 4. Prolonged storage of boar testis tissue at -20 degrees C abolished the ability to form all androst-16-enes except androsta-4,16-dien-3-one from [4-(14)C]progesterone. 5. The production of 5alpha-androst-16-en-3-one and the two alcohols from [7alpha-(3)H]androsta-4,16-dien-3-one only occurred when fresh tissue was used, whereas reduction of [5alpha-(3)H]5alpha-androst-16-en-3-one was unaffected by storage of testis at -20 degrees C. 6. NADPH was the preferred cofactor for the reduction of androsta-4,16-dien-3-one. 7. The previously established conversion of androsta-5,16-dien-3beta-ol into androsta-4,16-dien-3-one was shown to be reversible, NADH and NADPH being equally effective cofactors. 8. Pathways of biosynthesis of 5alpha-androst-16-en-3alpha- and 3beta-ols, with the C(19) 3-oxo steroids as intermediates, are presented.
Collapse
|
12
|
Loke KH, Gower DB. The intermediary role of 5-pregnene-3 ,20 -diol in the biosynthesis of 16-unsaturated C 19 steroids in boar testis. Biochem J 1972; 127:545-51. [PMID: 4403927 PMCID: PMC1178696 DOI: 10.1042/bj1270545] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
1. The possible involvement of 5-pregnene-3beta,20beta-diol in 16-unsaturated C(19) steroid biosynthesis has been investigated. 2. 5,16-Androstadien-3beta-ol (andien-beta) formation from [4-(14)C]pregnenolone (3beta-hydroxy-5-pregnen-20-one), 5-pregnene-3beta,20alpha-diol and 5-pregnene-3beta,20beta-diol was studied in homogenates of boar testis and the mean yields obtained were 25.6, 2.7 and 16.0% respectively. 3. Short-term kinetic studies with pregnenolone and 5-pregnene-3beta,20beta-diol separately and together suggested that the latter compound might be an intermediate in the biosynthesis of andien-beta. 4. In agreement with this interpretation, radioactive 5-pregnene-3beta,20beta-diol has been isolated during andien-beta biosynthesis from [4-(14)C]pregnenolone in the presence of NADPH, more radioactivity being trapped under limiting conditions of andien-beta formation with NADH present as cofactor. 5. Further, 5-pregnene-3beta,20beta-diol and andien-beta have been shown to inhibit the formation of the 16-unsaturated C(19) steroid from [4-(14)C]pregnenolone, the yield of radioactive 5-pregnene-3beta,20beta-diol increasing in the presence of added unlabelled andien-beta. 6. It is concluded that there may be two pathways leading to 16-unsaturated C(19) steroid formation from pregnenolone, one of these involving 5-pregnene-3beta,20beta-diol as an intermediate. Possible mechanisms are presented and discussed.
Collapse
|
13
|
Gower DB. 16-Unsaturated C 19 steroids. A review of their chemistry, biochemistry and possible physiological role. JOURNAL OF STEROID BIOCHEMISTRY 1972; 3:45-103. [PMID: 4561286 DOI: 10.1016/0022-4731(72)90011-8] [Citation(s) in RCA: 202] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
14
|
Gower DB, Loke KH. Studies on the subcellular location and stability of the enzyme system involved in the biosynthesis of 5,16-androstadien-3 -ol from 3 -hydroxy-5-pregnen-20-one (pregnenolone). BIOCHIMICA ET BIOPHYSICA ACTA 1971; 250:614-6. [PMID: 5132916 DOI: 10.1016/0005-2744(71)90267-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
15
|
Abstract
Batrachotoxin has been shown to be a pyrrolecarboxylic ester of a novel steroidal base with unique and selective actions on a variety of electrogenic membranes. The effects of batrachotoxin in neuromuscular preparations both pre- and postsynaptically, in nerve axons, in superior cervical ganglion, in heart Purkinje fibers, and in brain slices appear to be due to the selective and irreversible increase in permeability of membranes to sodium ions. The subsequent effects of this increase in Na(+) permeability evoked by batrachotoxin-such as membrane depolarization, enhanced spontaneous transmitter release, muscle contracture, and enhanced formation of cyclic AMP in brain slices-may be blocked reversibly by tetrodotoxin.
Collapse
|
16
|
Lippman V, Lieberman S. Steroidal free radicals as possible intermediates in the biosynthesis of C19-delta 16-steroids. Proc Natl Acad Sci U S A 1970; 67:1754-60. [PMID: 5275374 PMCID: PMC283423 DOI: 10.1073/pnas.67.4.1754] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Treatment of deoxycorticosterone with reagents that abstract a hydrogen atom from the C-21-hydroxyl group leads to the formation of androsta-4,16-dien-3-one. In vitro incubations of [1,2-(3)H]deoxycorticosterone with homogenates of boar testis tissue produce the tritiated dienone. This reaction can be formulated as an abstraction of hydrogen from the C-21-hydroxyl group to form a C-21-alkoxy radical, followed by a 1,5-H.shift from the C-16 atom and beta-scission of the C-16-alkoxy radical leading to the loss of a C(2) fragment (C-20 and C-21) with the formation of the double bond between C-16 and C-17. Both the chemical model and the in vitro experiment support further the thesis [Lieberman, S., L. Bandy, V. Lippman, and K. D. Roberts, Biochem. Biophys. Res. Commun., 34, 367 (1969)] that biosynthetic reactions in which molecular oxygen reacts with steroids (for example, side-chain cleavage or hydroxylation) involve steroidal free radicals.
Collapse
|
17
|
Wilkinson M, Coombs MM, Gower DB. The synthesis and purification of 4-[14C]- and 7α[3H]-androsta-4,16-dien-3-one. ACTA ACUST UNITED AC 1970. [DOI: 10.1002/jlcr.2590060413] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
18
|
|
19
|
Abstract
1. The metabolism of [4-(14)C]pregnenolone to androst-16-enes has been studied in short-term incubations of boar testis tissue. With fresh tissue androsta-5,16-dien-3beta-ol (8%) and 5alpha-androst-16-en-3beta-ol (2%) were formed. Tissue that had been stored at -20 degrees C was still capable of metabolizing pregnenolone to androsta-5,16-dien-3beta-ol. 2. NADPH was essential for the formation of androsta-5,16-dien-3beta-ol from pregnenolone; NADH had less activity and ATP was not necessary for the reaction. 3. [4-(14)C]Androsta-5,16-dien-3beta-ol, prepared biosynthetically from [4-(14)C]pregnenolone, was shown to be converted by boar testis preparations into androsta-4,16-dien-3-one (31%) if NAD(+) was present or into 5alpha-androst-16-en-3beta-ol (4%) if NADPH was present. 4. 17alpha-Hydroxyandrost-4-en-3-one and 3beta,17alpha-dihydroxypregn-5-en-20-one were considered as possible precursors for androst-16-ene formation, but both were shown to be ineffective. 5. No radioactivity was incorporated into androst-5-en-3beta-ol used to trap any corresponding (14)C-labelled compound formed from [4-(14)C]pregnenolone.
Collapse
|
20
|
Smith SW, Axelrod LR. Studies on the metabolism of steroid hormones and their precursors by the human placenta at various stages of gestation. 3. In vitro metabolism of 3 beta, 17 alpha-dihydroxy-pregn-5-ene-20-one. Steroids 1970; 15:421-32. [PMID: 4906385 DOI: 10.1016/s0039-128x(70)80059-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
21
|
Katkov T, Gower DB. The biosynthesis of 3-beta-hydroxyandrosta-5,16-diene and its further metabolism in boar testis. Biochem J 1969; 115:16P. [PMID: 5353505 PMCID: PMC1185167 DOI: 10.1042/bj1150016pa] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
22
|
Katkov T, Gower DB. The biosynthesis of 5 alpha-androst-16-en-3-one from progesterone by boar testis homogenate. BIOCHIMICA ET BIOPHYSICA ACTA 1968; 164:134-6. [PMID: 5692903 DOI: 10.1016/0005-2760(68)90082-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
|
23
|
Gower DB, Thomas BS. Gas-liquid chromatography of androst-16-enes as trimethylsilyl and chloromethyldimethylsilyl ethers. J Chromatogr A 1968; 36:338-40. [PMID: 5683241 DOI: 10.1016/s0021-9673(01)92951-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
|
24
|
Ahmad N, Gower DB. The biosynthesis of some androst-16-enes from C21 and C19 steroids in boar testicular and adrenal tissue. Biochem J 1968; 108:233-41. [PMID: 4233122 PMCID: PMC1198798 DOI: 10.1042/bj1080233] [Citation(s) in RCA: 47] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
1. The formation of androst-16-enes from [4-(14)C]progesterone has been investigated with long-term incubations and short-term kinetic studies. After 4hr., 1.7 and 10.3% respectively of 3alpha- and 3beta-hydroxy-5alpha-androst-16-enes were formed in boar testis minces, but much smaller yields were obtained in boar adrenal. Both tissues formed small quantities of androsta-4,16-dien-3-one. 2. The amounts of androst-4-ene-3,17-dione and testosterone isolated were small, suggesting that androst-16-ene formation may occur preferentially in the boar testis. 3. In the absence of tissue no radioactive androst-16-enes were formed. 4. Incubation of both [4-(14)C]pregnenolone and [7alpha-(3)H]progesterone resulted in 3alpha- and 3beta-hydroxy-5alpha-androst-16-enes containing (3)H/(14)C ratios of near unity and confirmed that both C(21) steroids were precursors. A similar incubation with 17alpha-hydroxy[4-(14)C]-progesterone and [7alpha-(3)H]progesterone gave the same Delta(16)-alcohols, but they contained only (3)H, indicating that side-chain cleavage of pregnenolone and progesterone occurred before 17alpha-hydroxylation. 5. Dehydroepiandrosterone, testosterone, testosterone acetate and 16-dehydroprogesterone were not found to be precursors of Delta(16)-steroids. 6. A pathway is proposed for the biosynthesis of 3alpha- and 3beta-hydroxy-5alpha-androst-16-enes from pregnenolone and progesterone; this may involve androsta-4,16-dien-3-one as an intermediate, but excludes 17alpha-hydroxyprogesterone, testosterone and dehydroepiandrosterone.
Collapse
|