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At least 19 recordsLinked to original sources
PubMed1992

Kinetic mechanism of reduction of testosterone by hepatic 5 beta-reductase of chicken and inhibition of the reductase activity by a secosteroid, an azasteroid and glycyrrhetinic acid.

The present studies on initial velocity of testosterone reduction by hepatic 5 beta-reductase (4-en-3-oxosteroid 5 beta-reductase) of chicken and mode of inhibition of the 5 beta-reduction by 5 beta-dihydrotestosterone and NADP+ indicated that the reduction of testosterone occurred after the 5 beta-reductase bound firstly to NADPH and then to testosterone, forming a ternary complex. After 5 beta-reduction, 5 beta-dihydrotestosterone and then NADP+ were liberated from the complex, following a mechanism of "ordered Bi-Bi". Effect of (4R)-5,10-seco-19-norpregna-4,5-diene-3,10,20-trione (a steroidal 5 alpha-reductase-inhibitor or Secosteroid), diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carboxamide (the other steroidal 5 alpha-reductase-inhibitor or 4-MA), and glycyrrhetinic acid (3 beta-hydroxy-11-oxoolean-12-en-30-oic acid, a 5 beta-reductase-inhibitor) was examined upon the 5 beta-reductase activity by double reciprocal plots. The mode of inhibition against testosterone by 4-MA and glycyrrhetinic acid was found to be competitive, while that by Secosteroid was non-competitive.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1978

Inhibition of testosterone 5 alpha-reductase by and antiandrogenicity of allenic 3-keto-5,10-secosteroids.

(4R)-5,10-seco-19-norpregna-4,5-diene-3,10,20-trione(II), A 3-keto-5,10-secosteroid which is an irreversible inhibitor of delta 5-3-ketosteroid isomerase was tested for its possible antiandrogenicity in the hamster flank organ test. The organs of female animals topically treated with 4 microgram of testosterone propionate (TP) for 4 weeks enlarged in size and showed pigmentation resembling adult males. When compound II was applied concomitantly with TP, androgenic stimulation was completely blocked and the flank organs remained small like those of female animals. These results suggest that compound II may be a useful anti-androgen when applied topically. It may well act mainly by inhibition of the formation of 5alphs-reduced metabolites was markedly inhibited.

5-alpha Reductase Inhibitors↗
PubMed1979

Selective inhibition by secosteroids of 5 alpha-reductase activity in human sex skin fibroblasts.

The effects of 5,10-secoestra-4,5-diene-3,10,17-trione (Compound I) and 5,10-seco-19-norpregna-4,5-diene,3,10,20-trione (Compound II) on the 5 alpha-reductase activity and on the androgen receptors of normal human sex skin fibroblasts were investigated. The Vmax and Km of the transformation of testosterone to 5 alpha-reduced products was 387 pg/microgram DNA/30 min and 234 X 10(-9)M, respectively. When the inhibitors were introduced in the assay, the 5 alpha-reductase activity was markedly reduced, Compound I being a less potent inhibitor than Compound II. At 15 min, the inhibition was greater than at 30 and 60 min. The Ki for Compound I was 1.60 x 10(-6)M with a Vmax of 83 to 553 pg/microgram DNA/30 min. For Compound II, the Ki was 0.53 x 10(-6)M with a Vmax of 70 to 340 pg/microgram DNA/30 min. The inhibition was of the noncompetitive type. Studies with androgen receptors showed that Compound I had a lower affinity for the receptors than Compound II. The ID50 for 3H-DHT and 3H-T for Compound I were 42.9 x 10(-7)M and 8.6 x 10(-7)M, respectively, whereas for Compound II, they were 10.6 x 10(-7)M and 4.8 x 10(-7)M.

5-alpha Reductase Inhibitors↗
PubMed1983

Studies in antifertility agents--Part XLI : Secosteroids--X : Syntheses of various stereoisomers of (+/-) 2,6 beta -diethyl-7 alpha -ethynyl-3-(p-hydroxyphenyl)-trans-bicyclo[4.3.0]nonan-7 beta-ol.

The syntheses of (+/-) 2 alpha,6 beta -diethyl-7 alpha -ethynyl-3 alpha-(p-hydroxyphenyl)-trans- bicyclo[4.3.0]nonan-7 beta-ol (8), (+/-)2 beta,6 beta-diethyl-7 alpha-ethynyl-3 beta-(p-methoxy-phenyl)-trans-bicyclo[4.3.0]nonan-7 beta-ol 12 and (+/-) 2 alpha,6 beta-diethyl-7 alpha-ethynyl-3 beta-(p-hydroxyphenyl)- trans-bicyclo[4.3.0]nonan-7 beta-ol (18) and their derivatives, which are essentially B-seco-steroids having cis-anti-trans, cis-syn-trans and trans-anti-trans geometries have been carried out. A study of their antiimplantation activities (AI) and receptor binding affinities (RBA) show that trans-anti-trans compounds are biologically most potent, followed by the corresponding cis-anti-trans and cis-syn-trans compounds. The most potent compound 18 is active at 1 mg/kg in rats. Introduction of 7 alpha-ethynyl group increases their AI activity; however, no significant effect on their RBA is observed.

Animals↗
PubMed1984

Phenolic 9,10-secosteroids as products of the catabolism of bile acids by a Pseudomonas sp.

The obligate aerobe, Pseudomonas putida ATCC 31752, efficiently utilises bile acids as a source of carbon and energy for growth and maintenance. When aeration is considerably restricted, a consequence to the catabolism of the bile acids in a fermentor is an accumulation of certain steroidal catabolites. Evidence is presented to show that among these are hydroxy-9,10-seco-1,3,5 (10)-androstratriene-9, 17-diones and those from four of the common bile acids, cholic, chenodeoxycholic, hyodeoxycholic and deoxycholic acids have been isolated and their structures determined. The product of catabolism of hyodeoxycholic acid appears to exist in a hemi-acetal form which readily forms an acetal during isolation procedures. All but one of these are described for the first time.

Bile Acids and Salts↗
PubMed1975

Studies in antifertility agents. 11. Secosteroids. 5. Synthesis of 9,11-secoestradiol.

9,11-Secoestradiol (9) and 11-hydroxy-9,11-secoestradiol (12) have been synthesized starting from 17-acetoxyestradiol 3-methyl ether (1) and found to possess significant antifertility activity in rats. 3-Methoxy-9,11-seco-9-oxo-17beta-acetoxyestra-1,3,5(10)-trien-11-oic acid (2), prepared by CrO3 oxidation of 1, on hydrogenolysis gave methyl 17beta-hydroxy-3-methoxy-9,11-secoestra-1,3,5(10)-triene-11-carboxylate (3). The 17-O-THP derivative of 3 was treated with LiAlH4 to give 17beta-(O-tetrahydropyranyl)-3-methoxy-11-hydroxy-9,11-secoestra-1,3,5(10)-triene (5). The 11-O-mesylate of 5 on LiAlH4 reduction followed by mild acid treatment and demethylation under alkaline conditions gave 9. LiAlH4 reduction of 3 gave 9,11-seco-11-hydroxyestradiol 3-methyl ether (11) which on demethylation gave 9,11-seco-11-hydroxyestradiol (12).

Animals↗