ASSESSMENT OF THE ACTIVE-SITE REQUIREMENTS OF LANOSTEROL 14-ALPHA-DEMETHYLASE - EVALUATION OF NOVEL SUBSTRATE-ANALOGS AS COMPETITIVE INHIBITORS

• Published in: Journal of organic chemistry Vol. 56; no. 3; pp. 1260 - 1266
• Main Authors: TUCK, SF, ROBINSON, CH, SILVERTON, JV
• Format: Journal Article
• Language: English
• Published: WASHINGTON Amer Chemical Soc 01.02.1991; American Chemical Society
• Subjects: Alicyclic compounds, terpenoids, prostaglandins, steroids; Aliphatic, non-condensed and condensed benzenic, and alicyclic compounds; Chemistry; Chemistry, Organic; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Organic chemistry; Organic compounds; Physical Sciences; Physics; Preparations and properties; Science & Technology; Steroids; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; YEAST; ALCOHOLS; MICROSOMAL-ENZYMES; PURIFIED CYTOCHROME-P-45014DM; PURIFICATION; 14-ALPHA-DEMETHYLATION; DERIVATIVES; CHOLESTEROL-BIOSYNTHESIS; 14-ALPHA-METHYL DEMETHYLASE; Steroid; Molecular structure; Aliphatic compound; Cytochrome P450; Enzyme inhibitor; Experimental study; Oxygen heterocycle; X ray diffraction; Biological activity; Primary alcohol; Sulfur heterocycle; Triterpene; Acylate; Homoallylic compound; Crystalline structure
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo00003a059

Lanosterol 14-alpha-demethylase (P450(14DM)), a cytochrome P450 enzyme, is responsible for the first stage in the biosynthesis of cholesterol (1) from lanosterol (2). Inhibitors of P450(14DM) may have therapeutic use in the treatment of familial hypercholesterolemia or as antifungal agents. The specificity of P450(14DM) has been investigated by using substrate analogues modified at the C-32 carbon. The hitherto undescribed 14-alpha-ethyl and 14-alpha-propyl analogues 15 and 13 of lanost-7-en-3-beta-ol, as well as the 14-alpha-ethenyl and 14-alpha-prop-2-enyl analogues 14 and 12, have been synthesized. These all proved to be good competitive inhibitors of the enzyme. A series of 32-oxiranes and 32-thiiranes was then synthesized and evaluated as inhibitors. Oxiranes 4 and 5 were excellent stereoselective competitive inhibitors of P450(14DM). The (2'S)-32-oxirane 4 had K(i) = 0.62-mu-M, and the (2'R)-32-oxirane 5 showed K(i) = 2-mu-M. The (2'R)-32-thiiranyl and (2'S)-32-thiiranyl compounds 10 and 11 were considerably less potent inhibitors. Comparison of the K(i) values for analogues 12-15, also good competitive inhibitors of this enzyme, indicated the P450(14DM) active site to be relatively insensitive to the size and degree of unsaturation of C-14-alpha alkyl substituents up to and including propyl.