- C-6α- vs C-7α-Substituted Steroidal Aromatase Inhibitors: Which Is Better? Synthesis, Biochemical Evaluation, Docking Studies, and Structure-Activity Relationships
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C-6α and C-7α androstanes were studied to disclose which position among them is more convenient to functionalize to reach superior aromatase inhibition. In the first series, the study of C-6 versus C-7 methyl derivatives led to the very active compound 9 with IC50 of 0.06 μM and Ki = 0.025 μM (competitive inhibition). In the second series, the study of C-6 versus C-7 allyl derivatives led to the best aromatase inhibitor 13 of this work with IC50 of 0.055 μM and Ki = 0.0225 μM (irreversible inhibition). Beyond these findings, it was concluded that position C-6α is better to functionalize than C-7α, except when there is a C-4 substituent simultaneously. In addition, the methyl group was the best substituent, followed by the allyl group and next by the hydroxyl group. To rationalize the structure-activity relationship of the best inhibitor 13, molecular modeling studies were carried out.
- Roleira, Fernanda M. F.,Varela, Carla,Amaral, Cristina,Costa, Saul C.,Correia-Da-Silva, Georgina,Moraca, Federica,Costa, Giosuè,Alcaro, Stefano,Teixeira, Natércia A. A.,Tavares Da Silva, Elisiário J.
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p. 3636 - 3657
(2019/04/26)
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- Direct organocatalytic stereoselective transfer hydrogenation of conjugated olefins of steroids
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Kinetically controlled and organocatalytic syn-selective transfer hydrogenation has been successfully demonstrated for the reduction of the enone functional group of various steroids. Herein, diastereoselective synthesis of many 5β-steroids have been reported through organocatalysis, which have broad medicinal and pharmaceutical applications. The mechanistic studies and the selectivity of the products clearly indicated that the catalyst 1b·d-CSA is mild enough to activate the various chiral cyclic enones through iminium ion formation during the organocatalytic transfer hydrogenations with Hantzsch ester 2a as a hydrogen source. Further, clear evidence for the selective formation of intermediate iminium species [I]+ have been characterized through on-line monitoring of controlled experiments by NMR and ESI-HRMS analyses.
- Ramachary, Dhevalapally B.,Sakthidevi, Rajasekar,Reddy, P. Srinivasa
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p. 13497 - 13506
(2013/09/02)
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- Microbial transformation of 3-hydroxy-5,6-cyclopropanocholestanes - An alternative route to 6-methylsteroids
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Incubation of 3β-hydroxy-5,6α-cyclopropano-5α-cholestane (4), 3β-hydroxy-5,6β-cyclopropano-5β-cholestane (5), and 3β-hydroxy-5,6α-cyclopropano-5α-cholest-7-ene (6) with Mycobacterium sp. (NRRL B-3805) gave a mixture of side chain cleaved 17-keto steroids as the major products in 52, 57, and 69% yields, respectively. Among these 17-keto steroids, the cyclopropyl ring eliminated product, androst-4-ene-3,17-dione (9), was isolated in 6, 4, and 8% yields, respectively. A cyclopropyl ring migration product, 6α,7α-cyclopropanoandrost-4-ene-3,17-dione (16), was isolated from the incubation mixture of 6 in 4% yield, also 10% yield of 16 was obtained when 5,6α-cyclopropano-5α-androst-7-ene-3,17-dione (12) was incubated. The cyclopropyl ring opening and subsequent reduction followed by oxidation of the two major biotransformation products, 5,6β-cyclopropano-5β-androsta-3,17-dione (10) and 5,6α-cyclopropano-5α-androsta-3,17-dione (7), gave 6β- and 6α-methylandrost-4-ene-3,17-dione in 60, and 45% yields, respectively. (C) 2000 Elsevier Science Inc.
- Yan, Jiann-Long,Lee, Shoei-Sheng,Wang
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p. 863 - 870
(2007/10/03)
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- 6-Alkyl- and 6-Arylandrost-4-ene-3,17-diones as Aromatase Inhibitors. Synthesis and Structure-Activity Relationships
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Two series of 6β- and 6α-substituted androst-4-ene-3,17-diones (5 and 6) were synthesized as aromatase inhibitors to gain insights of structure-activity relationships of varying substituents (methyl, ethyl, n-propyl, isopropyl, n-butyl, phenyl, benzyl, vi
- Numazawa, Mitsuteru,Oshibe, Mariko
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p. 1312 - 1319
(2007/10/02)
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- Synthesis and aromatase inhibition by potential metabolites of exemestane (6-methylenandrosta-1,4-diene-3,17-dione)
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Exemestane (6-methylenandrosta-1,4-diene-3,17-dione; FCE 24304) is an orally active irreversible aromatase inhibitor which is in phase II clinical evaluation for the potential therapy of postmenopausal breast cancer. A series of exemestane analogs, with modifications at the 6-methylene group and with additional reduction at the 17-keto group, were synthesized as potential metabolites and tested in vitro for their effect on human placental aromatase. All these new analogs were found to be less potent in inhibiting aromatase than exemestane. The most effective compound was the 17β-hydroxy- derivative (compound 2), which is 2.6-fold less potent than exemestane [50% inhibitory concentration (IC50) 69 and 27 nM, respectively]. The various C- 6 modified derivatives of the 17-oxo series were found to inhibit the aromatase enzyme in the following descending order: 6-methylene (exemestane) > 6-spirooxirane (6) > 6β-hydroxymethyl (11) > 6-hydroxymethyl (7) > 6β- carboxy (13), showing IC50 values of 27, 206, 295, 2,300, and 7,200 nM, respectively. The 17β-hydroxy analogs of some of the above mentioned compounds were also synthesized (3, 4, 12) and found to be 3-8-fold less potent than the corresponding 17-keto analogs.
- Buzzetti,Di Salle,Longo,Briatico
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p. 527 - 532
(2007/10/02)
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