- Stereospecific reduction of 5β-reduced steroids by human ketosteroid reductases of the AKR (aldo-keto reductase) superfamily: Role of AKR1C1-AKR1C4 in the metabolism of testosterone and progesterone via the 5β-reductase pathway
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Active sex hormones such as testosterone and progesterone are metabolized to tetrahydrosteroids in the liver to terminate hormone action. One main metabolic pathway, the 5β-pathway, involves 5β-steroid reductase (AKR1D1, where AKR refers to the aldo-keto reductase superfamily), which catalyses the reduction of the 4-ene structure, and ketosteroid reductases (AKR1C1-AKR1C4), which catalyse the subsequent reduction of the 3-oxo group. The activities of the four human AKR1C enzymes on 5β-dihydrotestosterone, 5β-pregnane-3,20-dione and 20α-hydroxy-5β-pregnan-3-one, the intermediate 5β-dihydrosteroids on the 5β-pathway of testosterone and progesterone metabolism, were investigated. Product characterization by liquid chromatography-MS revealed that the reduction of the 3-oxo group of the three steroids predominantly favoured the formation of the corresponding 3α-hydroxy steroids. The stereochemistry was explained by molecular docking. Kinetic properties of the enzymes identified AKR1C4 as the major enzyme responsible for the hepatic formation of 5β-tetrahydrosteroid of testosterone, but indicated differential routes and roles of human AKR1C for the hepatic formation of 5β-tetrahydrosteroids of progesterone. Comparison of the kinetics of the AKR1C1-AKR1C4-catalysed reactions with those of AKR1D1 suggested that the three intermediate 5β-dihydrosteroids derived from testosterone and progesterone are unlikely to accumulate in liver, and that the identities and levels of 5β-reduced metabolites formed in peripheral tissues will be governed by the local expression of AKR1D1 and AKR1C1-AKR1C3. The Authors Journal compilation 2011 Biochemical Society.
- Jin, Yi,Mesaros, A. Clementina,Blair, Ian A.,Penning, Trevor M.
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experimental part
p. 53 - 61
(2012/06/15)
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- METHODS OF NEUROPROTECTION USING NEUROPROTECTIVE STEROIDS AND A VITAMIN D
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Described herein are compositions and methods for treating or preventing nervous system injury. In particular, the methods and compositions relate to the use of at least one neuroprotective steroid, such as progesterone, and vitamin D.
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- METABOLISM AND CONJUGATION OF PROGESTERONE BY BOVINE LIVER AND ADIPOSE TISSUES, IN VITRO
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The ability of bovine liver and fat to metabolize progesterone and also to form glucuronide conjugates with these progestins in vitro was investigated.Tissue supernatants were incubated with progesterone, UDP-glucuronic acid, and a NADPH generating system for 5 hr, at 37 deg C.Steroids were identified by thin-layer chromatography, high performance liquid chromatography, and recrystallization to a constant specific activity.The total original radioactivity which could not be removed by exhaustive ether extraction (presumptive conjugates) was 44.7 +/- 14.2percent in liver, 5.0 +/- 3.6percent in subcutaneous fat, and 3.7 +/- 2.2percent in kidney fat samples.Progestins identified in liver samples include 5β-pregnane-3α,20α-diol (free and conjugate), 5β-pregnane-3α,20β-diol (free and conjugate), 3α-hydroxy-5β-pregnan-20-one (free and conjugate), 3β-hydroxy-5β-pregnan-20-one (free), 5β-pregnane-3,20-dione (free), and progesterone (conjugate).Progestins identified in both the free and conjugate fractions of subcutaneous fat and kidney fat samples include progesterone, 3α-hydroxy-5β-pregnan-20-one, 20β-hydroxy-4-pregnen-3-one, and 20α-hydroxy-4-pregnen-3-one.Differences due to sex of bovine used were noted.These results confirm the ability of bovine liver to readily metabolize progesterone and form glucuronide conjugates of these compounds and suggest that adipose tissues take an active role in these actions in cattle.
- Clemens, J. D.,Estergreen, V. L.
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p. 287 - 306
(2007/10/02)
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- TOTAL SYNTHESIS OF (+)-5α-DIHYDROPREGNENOLONE VIA ACETYLENE-CATION CYCLIZATION
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The stereoselective total synthesis of (+)-5α-dihydropregnenolone 7 via acetylene-cation cyclization of 6, which was readily prepared from the optically active D-ring aromatic steroid 1, is described.
- Kametani, Tetsuji,Suzuki, Koji,Nemoto, Hideo
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p. 1469 - 1470
(2007/10/02)
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