Synthesis of C-2 and C-4 deuterium-labeled estradiol-17 beta

Estradiol-17 beta labeled with deuterium in the positions 2 or 4 can be prepared from 2-chloromercurio-1,3,5(10)-estratriene-3,17 beta-diol 3-methyl ether 17-acetate or 4-chloromercurio-1,3,5(10)-estratriene-3,17 beta-diol, respectively, in refluxing CH3COO(2)H/(2)H2O. The same reaction performed on 4-acetoxymercurio-1,3,5(10)-estratriene-3,17 beta-diol afforded 2,4-dideuterio-estradiol-17 beta in good yields.     

Metabolism of 17 alpha-methyltestosterone in the rabbit: C-6 and C-16 hydroxylated metabolites

17 alpha-Methyltestosterone and the reduced metabolites, 17 alpha-methyl-5 alpha-androstane-3 alpha, 17 beta-diol, 17 alpha-methyl-5 alpha-androstane-3 beta, 17 beta-diol and 17 alpha-methyl-5 beta-androstane-3 alpha, 17 beta-diol, together with three hydroxylated metabolites, 17 alpha-methyl-5 beta-androstane-3 alpha, 16 alpha, 17 beta-triol, 17 alpha-methyl-5 beta-androstane-3 alpha, 16 beta, 17 beta-triol and a new metabolite, 17 alpha-methyl-5 alpha-androstane-3 beta, 6 alpha, 17 beta-triol, were isolated and identified in the urine of rabbits dosed with 17 alpha-methyltestosterone. No hydroxylated 5 alpha-metabolite of 17 alpha-methyltestosterone has been identified previously. No of 17 alpha-methyltestosterone has been identified previously. No evidence for epimerization at the C-17 position was observed.     

Synthesis of C-5'-alkyl substituted 17-spirofuran 19-norsteroids

A number of new steroidal 17-spirofuran derivatives of the 19-nor series containing Me, Et or (i)Pr-substituents in the heterocyclic moiety has been prepared, which are expected to have a strong progestagenic activity. The proposed approach made use of the 1-3-dipolar cycloaddition of low-molecular nitrile oxides with steroidal acetylenic alcohols followed by transformation of the isoxazole side chain.     

Biosynthesis of ent-kauranes: Evidence for a C-17, C-16 hydrogen 1,2-shift

The incorporation of ent-kaurenoic acid into the derived hydroxy acid and dihydroxy acid by Beyeria calycina has been studied. The biosynthesis of the hydroxy acid involves a hydrogen 1,2-shift from the C-17 position of ent-kaurenoic acid.     

A straightforward chemical synthesis of 17-ketosteroids by cleavage of the C-17-dihydroxy acetone side chain in corticosteroids

A facile and convenient approach to 17-ketosteroids is described. Treatment of steroids containing the C-17-dihydroxy acetone side chain with an excess of sodium methoxide in dry 1,4-dioxane under reflux, affords high yields of the corresponding 17-ketosteroids that are recovered as pure products, without the need of further purification.     

Synthesis and biological properties of novel glucocorticoid androstene C-17 furoate esters

A series of novel corticosteroid derivatives featuring C-17 furoate ester functionality have been synthesised. Profiling in vitro and in vivo has resulted in the identification of a compound with a longer duration of action and a lower oral side effect profile in rodents compared to budesonide.     

Comparative dose-effect studies with four C-17-spirosteroidal mineralocorticoid synthesis inhibitors

Interference of three spirolactones and a spiro-oxazolidine with mineralocorticoid biosynthesis in the concentration range of 10(-4)-10(-10) M has been studied in isolated dispersed z. glomerulosa cells. Inhibitory effects on several enzyme activities involved in the late steps of aldosterone synthesis have been determined. Different patterns of enzyme inhibition could be observed for each inhibitor. The points of interference were mostly related to cytochrome P450-C11-activities (i.e. 11 beta-/18-hydroxylation and 18-OH-oxidation).     

The naturally occurring C-17 fatty acid esters of estradiol are long-acting estrogens

C-17 fatty acid esters of estradiol are naturally occurring biosynthetic metabolites of estradiol. A representative component of this family of esters, estradiol-17-stearate, was studied in order to determine the estrogenic properties of these unusual hydrophobic steroids. Following the classical estrogen bioassay, a solution of this ester in oil was injected subcutaneously into immature rats once a day for 3 days. There was little effect on the uterus on the first day after the third injection. However, on subsequent days a large stimulation of uterine growth occurred. The course of this estrogenic effect was exactly opposite to that obtained with estradiol. In order to eliminate the possibility that this effect on the time course of estrogenic stimulation was caused by increased solubility of the hydrophobic esters in the carrier oil, the steroids were administered to adult ovariectomized animals in aqueous medium via a single intravenous injection. The uterotrophic response to estradiol was maximal at 12 h and was completely dissipated in 48-60 h. Estradiol-17-stearate produced a uterotrophic effect of twice the duration of estradiol. In the immature rat, aqueous intravenous injections of estradiol-17-stearate produced a greater uterotrophic effect than estradiol and this effect was still maximal 96 h later. In addition, this single injection of estradiol-17-stearate advanced the time of vaginal opening, a marker for puberty in the female rat. The mechanism of the prolonged estrogenic stimulation was investigated by studying the steroidal content of the uterus after injecting [3H]estradiol and [3H]estradiol-17 -stearate i.v. into immature rats. At 1 and 4 h there was significantly more radioactivity in the uteri of the [3H]estradiol treated animals. At later times (8 h and onwards) the total radioactivity in the uterus did not differ appreciably between the two groups. However at these later times, the amount of [3H]estradiol was far greater in the uteri of animals receiving [3H]estradiol-17-stearate. Consequently, the prolonged estrogenic effects of the endogenous C-17 fatty acid esters of estradiol are caused by the increased duration of the estrogenic signal. It is hypothesized that one of the roles of the fatty acid is to protect the steroid nucleus from metabolism and thereby prolong the life of the parent C18 steroid. Thus, the results of these experiments are consistent with the family of endogenous alkyl esters of estradiol having a physiological role as long-acting estrogens.     

Fermentation conditions and properties of a chitosanase from Acinetobacter sp. C-17

A species of bacterium with high chitosanase activity was isolated from soil samples in Haiyan City, China, and identified as an Acinetobacter species. This strain, named Acinetobacter sp. strain C-17, produced a chitosanase that was inducible and secreted into the medium. The optimal conditions for enzyme production were cells used to inoculate a medium containing 1% chitosan (pH 7.0) followed by culture at 30 degrees C. The chitosanase activity reached 1.7 U/ml when strain C-17 was incubated in a 250-ml flask under the optimal conditions for 24 h, and reached 2.8 U/ml when cells were incubated in a 3-l fermentor. The optimal pH and temperature for hydrolysis of chitosanase were 7.0 and 36 degrees C, respectively. The chitosanase activity was stable in the pH range of 5-8 and temperature range of 30-40 degrees C. The chitosanase of the strain was extracted by zinc acetate and ammonium sulfate precipitation. The molecular mass was estimated to be 35.4 kDa by SDS-PAGE.     

Mechanism-based inactivation of bovine adrenal cytochromes P450 C-21 and P450 17 alpha by 17 beta-substituted steroids

A series of progesterone derivatives has been studied as potential inactivators of the bovine adrenocortical cytochromes P450, P450 17 alpha, and P450 C-21. Replacement of the 21-methyl group of progesterone with a difluoromethyl group resulted in a selective inactivator of P450 C-21 in a reconstituted system. The loss of 21-hydroxylase activity caused by this compound exhibits a number of characteristics of mechanism-based inactivation including NADPH dependence, pseudo-first-order kinetics, saturability, irreversibility, and protection by substrate. In addition to the difluoro compound, 21,21-dichloroprogesterone, the acetylenic compound pregn-4-en-20-yn-3-one, and the olefinic compound pregna-4,20-dien-3-one all inactivate P450 C-21. In contrast, the only compound to inactivate the rabbit adrenal progesterone 21-hydroxylase is 21,21-dichloroprogesterone. In binding studies, the 21,21-dihalo steroids produce a greater maximal type I spectral shift of P450 C-21 than the two 17 beta-unsaturated steroids. The dihalo compounds inactivate P450 C-21 by both heme destruction and protein modification as shown by significant decreases in residual 21-hydroxylase activity and spectrally detectable P450 after incubation with P450 C-21 in a reconstituted system. Liquid chromatographic and mass spectral analyses of the organic extracts from these incubations showed that 21-pregnenoic acid is a major metabolite of the dihalo compounds with a partition ratio of 5 nmol of acid produced/nmol of P450 C-21 inactivated. This supports the hypothesis that inactivation proceeds in part through an acyl halide intermediate. In contrast, the acetylenic compound pregn-4-en-20-yn-3-one inactivates P450 C-21 mainly by protein modification, producing an NADPH-dependent irreversible type I spectral shift. The stoichiometry of inactivation is approximately 1.5 nmol of compound bound/nmol of enzyme inactivated, indicating selective modification of the enzyme at or near the substrate binding site.     

Simultaneous regioselective protection of phenyl 1-thioglucosides at the C-3 and C-6 or at the C-2 and C-6 hydroxy groups

Simultaneous regioselective 3,6- or 2,6-selective protection of 1-thio-beta- or alpha-D-glucopyranosides is described. The C-3 and C-6 hydroxy groups of the beta-thioglucoside were selectively protected with triisopropylsilyl or tert-butyldiphenylsilyl trifluoromethanesulfonate. The C-2 and C-6 hydroxy groups of the alpha-thioglucoside were selectively protected with tert-butyldiphenylsilyl trifluoromethanesulfonate.