- Oxidation of dihydrotestosterone by human cytochromes P450 19A1 and 3A4
-
Dihydrotestosterone is a more potent androgen than testosterone and plays an important role in endocrine function. We demonstrated that, like testosterone, dihydrotestosterone can be oxidized by human cytochrome P450 (P450) 19A1, the steroid aromatase. The products identified include the 19-hydroxy-and 19-oxo derivatives and the resulting Δ1,10-, Δ5,10-, and Δ9,10-dehydro 19-norsteroid products (loss of 19-methyl group). The overall catalytic efficiency of oxidation was ～10-fold higher than reported for 3α-reduction by 3α-hydroxysteroid dehydrogenase, the major enzyme known to deactivate dihydrotestosterone. These and other studies demonstrate the flexibility of P450 19A1 in removing the 1- and 2-hydrogens from 19-norsteroids, the 2-hydrogen from estrone, and (in this case) the 1-, 5β-, and 9β-hydrogens of dihydrotestosterone. Incubation of dihydrotestosterone with human liver microsomes and NADPH yielded the 18- and 19-hydroxy products plus the Δ1,10-dehydro 19-nor product identified in the P450 19A1 reaction. The 18- and 19-hydroxylation reactions were attributed to P450 3A4, and 18- and 19-hydroxydihydrotestosterone were identified in human plasma and urine samples. The change in the pucker of the A ring caused by reduction of the Δ4,5 bond is remarkable in shifting the course of hydroxylation from the 6β-, 2β-, 1β-, and 15β-methylene carbons (testosterone) to the axial methyl groups (18, 19) in dihydrotestosterone and demonstrates the sensitivity of P450 3A4, even with its large active site, to small changes in substrate structure.
- Cheng, Qian,Sohl, Christal D.,Yoshimoto, Francis K.,Guengerich, F. Peter
-
p. 29554 - 29567,14
(2012/12/12)
-
- Oxidation of dihydrotestosterone by human cytochromes P450 19A1 and 3A4
-
Dihydrotestosterone is a more potent androgen than testosterone and plays an important role in endocrine function. We demonstrated that, like testosterone, dihydrotestosterone can be oxidized by human cytochrome P450 (P450) 19A1, the steroid aromatase. The products identified include the 19-hydroxy-and 19-oxo derivatives and the resulting Δ1,10-, Δ5,10-, and Δ9,10-dehydro 19-norsteroid products (loss of 19-methyl group). The overall catalytic efficiency of oxidation was ～10-fold higher than reported for 3α-reduction by 3α-hydroxysteroid dehydrogenase, the major enzyme known to deactivate dihydrotestosterone. These and other studies demonstrate the flexibility of P450 19A1 in removing the 1- and 2-hydrogens from 19-norsteroids, the 2-hydrogen from estrone, and (in this case) the 1-, 5β-, and 9β-hydrogens of dihydrotestosterone. Incubation of dihydrotestosterone with human liver microsomes and NADPH yielded the 18- and 19-hydroxy products plus the Δ1,10-dehydro 19-nor product identified in the P450 19A1 reaction. The 18- and 19-hydroxylation reactions were attributed to P450 3A4, and 18- and 19-hydroxydihydrotestosterone were identified in human plasma and urine samples. The change in the pucker of the A ring caused by reduction of the Δ4,5 bond is remarkable in shifting the course of hydroxylation from the 6β-, 2β-, 1β-, and 15β-methylene carbons (testosterone) to the axial methyl groups (18, 19) in dihydrotestosterone and demonstrates the sensitivity of P450 3A4, even with its large active site, to small changes in substrate structure.
- Cheng, Qian,Sohl, Christal D.,Yoshimoto, Francis K.,Guengerich, F. Peter
-
p. 29554 - 29567
(2013/01/14)
-
- 11β-alkyl-Δ9-19-nortestosterone derivatives: High-affinity ligands and potent partial agonists of the androgen receptor
-
We report the synthesis of novel steroidal androgen receptor ligands comprising 11β-alkyl-Δ9-derivatives of 19-nortestosterone. These compounds are structurally related to the antiprogestin, antiglucocorticoid, and antiandrogen drug mifepristone (RU486). Nortestosterone analogues bearing 11β-octyl and 11β-decyl side-chains bind tightly to recombinant AR protein (IC50 = 6.6 nM and IC50 = 0.8 nM), block AR dimerization, exhibit activity against LNCaP prostate cancer cells, and comprise partial AR agonists with low antiglucocorticoid activity.
- Muddana, Smita S.,Price, Aimee M.,MacBride, Megan M.,Peterson, Blake R.
-
p. 4985 - 4988
(2007/10/03)
-
- 19-hydroxy-5β,19-cyclosteroids: Synthesis, isomerization and ring opening
-
19(R/S)-Hydroxy-5β,19-cyclosteroids have been synthesised from the 19-formyl 4-en-3-one by reductive cyclization with zinc in aqueous acetic acid. Treatment of the aldehyde with lithium in liquid ammonia also gave the 19(R)-hydroxy-5β,19-cyclosteroid together with the 17β-hydroxy analogue. The 19(R)-alcohol is isomerized to the 19(S)-alcohol in either dilute acidic or basic media via the 3-hydroxy-3,5-cyclosteroid. The 19(S)-alcohol is in equilibrium with its 3-hemiketal. Treatment of the 19(R)-alcohol with methanolic HCl gave the 19(R)- and 19(S)-methyl ethers, the 3-methyl ether 19-ketal and the 3α-methoxy-3β,5β-cyclosteroid. Further rearrangements of the 19(R)- and 19(S)-alcohols take place on more vigorous treatment with acid or base to give cyclopropanol ring-opened aldehydes including a 5β-methyl-A-norsteroid. Metal hydride reduction of the 3-ketone in the 19(R)-alcohol gave only the 3β-alcohol whereas the 19(S)-alcohol gave both the 3α- and 3β-alcohols. Acid treatment of the 3β-alcohols gave products with retention of configuration at C-5 and C-19 while base-catalysed ring opening gave inversion at C-5. Ring opening mainly involved breaking of the 5,19-bond, however, the 19(S)-alcohol also resulted in 10,19-bond cleavage. Structures were established by NMR measurements.
- Templeton, John F.,Ling, Yangzhi,Lin, Weiyang,Majgier-Baranowska, Helena,Marat, Kirk
-
p. 1895 - 1904
(2007/10/03)
-
- Suicide inhibitors of aromatase
-
Thiol-substituted synthetic steriod hormones or androgens having a testosterone ring system backbone are used to inhibit aromatase''s catalyzed conversion of C 19 androgens having a A 4,3-ketone group to estrogens in the treatment of estrogen-dependent tumors, such as metastatic breast cancer in postmenopausal females.The compounds have the general formula: STR1 wherein R 1 =a thiol, such as --SH or --CH 2 SH, and R 2 =OH or =O. The preferred synthetic hormones are 17β-hydroxy-10β-mercaptoestr-4-en-3-one, 19-mercaptoandrost-4-en-3,17-dione, and 10β-mercaptoandrost-4-en-3,17-dione.
- -
-
-
