Synthesis and evaluation of a new series of tri-, di-, and mono-N-alkylcarbamylphloroglucinols as conformationally constrained inhibitors of cholesterol esterase.
1,3,5-Tri-N-alkylcarbamylphloroglucinols (1-4) are synthesized as conformationally constrained analogs of triacylglycerols (TGs) to probe Jenck's proximity effect in the cholesterol esterase inhibition. For the cholesterol esterase inhibition, inhibitors 1-4 are 220-760-fold more potent than 1,2,3-tri-N-alkylcarbamylglycerols (13-15) that are substrate analogs of TG. Comparison of tridentate inhibitors 1-4, bidentate inhibitors 3,5-di-N-n-alkylcarbamyloxyphenols (5-8) and monodentate inhibitors 5-N-n-alkylcarbamyloxyresorcinols (9-12) indicates that inhibitory potencies are as followed: tridentate inhibitor > bidentate inhibitor > monodentate inhibitor. The log k(i)  and pK(i)  values of tridentate inhibitors, bidentate inhibitors, and monodentate inhibitors are linearly correlated with the alkyl chain length indicating a common mechanism in each inhibition. Also, positive slopes of these correlations indicate that the longer chain inhibitors bind more tightly to the enzyme than the shorter ones. Molecular dockings of tridentate 1, bidentate 5, and monodentate 9 into the X-ray crystal structure of cholesterol esterase suggest that one carbamyl group in the cis form of the inhibitor binds to the acyl chain-binding site of the enzyme. The second carbamyl groups in the trans forms of inhibitors 1 and 5 bind to the second acyl chain-binding site of the enzyme. The third carbamyl group in the trans form of inhibitor 1 binds to the third acyl chain-binding site of the enzyme. Moreover, the configuration of the inhibitor in the enzyme-inhibitor complex is the (1,3,5)-(cis, trans, trans)-tricarbamate form that mimics the (+gauche, -gauche)-conformation of TG.
Department of Internal Medicine, Chung Shan Medical University Hospital, School of Medicine, Chung-Shan Medical University, Taichung 402, Taiwan.
Ming-Cheng
MC
Lin
Gin-Zen
GZ
Lin
Ching-In
CI
Hwang
Shuo-Yung
SY
Jian
James
J
Lin
Yu-Fong
YF
Shen
Gialih
G
Lin
D000818:Animals; D002219:Carbamates / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D062105:Molecular Docking Simulation; D010179:Pancreas / Q000201:enzymology; D010636:Phenols / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D011487:Protein Conformation; D002787:Sterol Esterase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D013552:Swine
D002219:Carbamates; D004791:Enzyme Inhibitors; D010636:Phenols; D002787:Sterol Esterase