In Situ Selection of Lead Compounds by Click Chemistry:  Target-Guided Optimization of Acetylcholinesterase Inhibitors

• Published in: Journal of the American Chemical Society Vol. 127; no. 18; pp. 6686 - 6692
• Main Authors: Krasiński, Antoni, Radić, Zoran, Manetsch, Roman, Raushel, Jessica, Taylor, Palmer, Sharpless, K. Barry, Kolb, Hartmuth C.
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 11.05.2005; Amer Chemical Soc
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Binding Sites; Biological and medical sciences; Chemistry; Chemistry, Multidisciplinary; Cholinesterase Inhibitors - chemistry; Cholinesterase Inhibitors - pharmacology; Combinatorial Chemistry Techniques - methods; Enzymes and enzyme inhibitors; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Heterocyclic compounds; Hydrolases; Mice; Miscellaneous; Organic chemistry; Phenanthridines - chemistry; Phenanthridines - pharmacology; Physical Sciences; Preparations and properties; Science & Technology; Stereoisomerism; Tacrine - analogs & derivatives; Tacrine - pharmacology; Triazoles - chemistry; Triazoles - pharmacology; LIBRARIES; ACTIVE-SITE; COMBINATORIAL; BINDING-SITE; GENERATION; HIGHLY POTENT; ACHE INHIBITORS; MASS-SPECTROMETRY; DISCOVERY; ENZYME-INHIBITORS; Five membered ring; Enantioselectivity; Enzyme; Nitrogen heterocycle; Combinatorial chemistry; Enzyme inhibitor; Esterases; Tetracyclic compound; Acetylcholinesterase; Carboxylic ester hydrolases; Organic synthesis; Phenanthridine derivatives; Triazole derivatives; Hydrolases; Aromatic compound; Chemical properties; Mass spectrometry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja043031t

The target-guided, in situ click chemistry approach to lead discovery has been successfully employed for discovering acetylcholinesterase (AChE) inhibitors by incubating a selected enzyme/tacrine azide combination with a variety of acetylene reagents that were not previously known to interact with the enzyme's peripheral binding site. The triazole products, formed by the enzyme, were identified by HPLC-mass spectrometry analysis of the crude reaction mixtures. The target-guided lead discovery search was also successful when performed with reagent mixtures containing up to 10 components. From 23 acetylene reagents, the enzyme selected two phenyltetrahydroisoquinoline (PIQ) building blocks that combined with the tacrine azide within the active center gorge to form multivalent inhibitors that simultaneously associate with the active and peripheral binding sites. These new inhibitors are up to 3 times as potent as our previous phenylphenanthridinium-derived compounds, and with dissociation constants as low as 33 femtomolar, they are the most potent noncovalent AChE inhibitors known. In addition, the new compounds lack a permanent positive charge and aniline groups and possess fewer fused aromatic rings. Remarkably, despite the high binding affinity, the enzyme displayed a surprisingly low preference for one PIQ enantiomer over the other.