6 beta-Propynyl-substituted steroids: mechanism-based enzyme-activated irreversible inhibitors of aromatase.
6 beta-Propynyl-substituted steroids: mechanism-based enzyme-activated irreversible inhibitors of aromatase.
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6 β-丙炔基取代类固醇：基于机制的酶激活不可逆芳香酶抑制剂。
DOI：
10.1021/jm970325z
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Abul-Hajj,YJ
中科院分区：
文献类型：
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作者：
Akkani,A;Paterlini,G;Gleason,WB;Ojala,WH;Abul-Hajj,YJ
报道了6-α-和6-β-炔丙基雄烯二酮和雌二酮的合成及其芳香酶抑制谱。目标化合物1和2是在5-α，6-α-环氧双酮6或5-α，6-α-环氧二乙酸酯7中加入炔丙基研磨剂，然后用亚硫酰氯脱水6-β-炔丙基5α-羟基二酮10和11得到的。用盐酸处理6个β-炔丙基类似物1和2，得到相应的6个α-炔丙基异构体3和4。以人胎盘微粒体为酶来源，以[1β-3 H]-4-雄烯二酮为底物，对合成的化合物进行了抑制活性评价。在低产物形成的初始速度测定条件下，这些抑制剂对芳香酶表现出很强的抑制作用，其Kis为10~66 nM，对雄烯二酮的Km为55 nM。6-α-丙烯酰雄酮-4-烯-3，17-二酮和6-α-丙烯酰雄酮-4-烯-3，17-二酮对芳香化酶具有较强的竞争性抑制作用(Ki37和66 nM)。而6-β-丙叉雄酮-4-烯-3，17-二酮(6-β-PAD)和6-β-丙叉-4-烯-3，17-二酮(6β-PED)分别与芳香酶结合，KI分别为10和48 nm，在NADPh存在下，芳香酶迅速失活，呈一级失活，而在没有NADPh存在时未见失活。底物对酶有保护作用，而β-巯基乙醇不起作用，提示6-β-炔丙基类似物6-β-PAD和6-β-PED是基于机理的芳香酶失活剂。能量最小化计算和分子模拟研究表明，6个β-炔丙基类似物中的每一个都有三个全局最小值，其中一个构象被认为是导致芳香酶失活的原因。
The synthesis and aromatase inhibitory profile of 6α- and 6β-propargyl androstenedione and estrenedione are described. The targeted compounds1and2were prepared by addition of the propargyl Gringard to the 5α,6α-epoxy bisketal6or the 5α,6α-epoxy diacetate7followed by dehydration of the 6β-propargyl 5α-hydroxy diones10and11using thionyl chloride. Treatment of the 6β-propargyl analogs1and2with hydrochloric acid gave the corresponding 6α-propargyl isomers3and4. Inhibitory activity of the synthesized compounds was assessed using a human placental microsomal preparation as the enzyme source and [1β-3H]-4-androstenedione as substrate. Under initial velocity assay conditions of low product formation, the inhibitors demonstrated potent inhibition of aromatase, with apparentKis ranging from 10 to 66 nM, with theKmfor androstenedione being 55 nM. 6α-Propargylandrost-4-ene-3,17-dione and 6α-propargylestr-4-ene-3,17-dione were found to be potent competitive inhibitors of aromatase (Ki37 and 66 nM, respectively). On the other hand the 6β-propargylandrost-4-ene-3,17-dione (6β-PAD) and 6β-propargylestr-4-ene-3,17-dione (6β-PED) were found to bind to aromatase with an apparentKiof 10 and 48 nM, respectively, as well as cause rapid time-dependent, first-order inactivation of aromatase in the presence of NADPH, whereas no inactivation was observed in the absence of NADPH. Substrate protects the enzyme from inactivation, but β-mercaptoethanol does not, suggesting that the 6β-propargyl analogs 6β-PAD and 6β-PED are mechanism-based inactivators of aromatase. Energy-minimization calculations and molecular modeling studies indicate three global minima for each of the 6β-propargyl analogs in which one of the conformers is proposed to be responsible for the inactivation of aromatase.