Deciphering the Mechanism of Carbonic Anhydrase Inhibition with Coumarins and Thiocoumarins

Abstract

Coumarin derivatives were recently shown to constitute a totally new class of inhibitors of the zinc metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1), being hydrolyzed within the CA active site to 2-hydroxycinnamic acids. We explore here a new series of variously substituted coumarins and a thiocoumarin for their interaction with 13 mammalian CA isoforms, detecting low nanomolar and isoform selective inhibitors. The mechanism of action of this class of inhibitors is delineated in detail by resolving the X-ray crystal structure of CA II in complex with trans-2-hydroxy-cinnamic acid, the in situ hydrolysis product of simple coumarin. Thiocoumarins also act as efficient CAIs, similarly to coumarins. The versatility of the (thio)coumarin chemistry, the cis-trans isomerization evidenced here, and easy derivatization of the (thio)coumarin rings, coupled with the nanomolar inhibition range of several isozymes, afford isoform-selective CAIs with various biomedical applications, which render these classes of compounds superior to the clinically used sulfonamides.

Carbonic anhydrase inhibition and cytotoxicity studies of Mannich base derivatives of thymol

“…Stock solutions of inhibitor (0.1 mM) were prepared in distilled-deionized water and dilutions up to 0.01 nM were done thereafter with the assay buffer. Inhibitor and enzyme solutions were preincubated together for 15 33 , and represent the mean from at least three different determinations. All CA isoforms were recombinant ones obtained in-house as reported earlier 34 .…”

Multimeric xanthates as carbonic anhydrase inhibitors

“…coumarins 3 and lacosamide 4 , inhibit the enzyme activity by occluding the entrance of the catalytic site and ortho-substituted benzoic acid derivatives can inhibit CA without entering the active site at all 5 . However, most CAIs act by binding either to the Zn(II) cation, inside of the active site and crucial for the catalytic activity, or to the water molecule coordinated to it 6 . Namely, the classical sulfonamides and their isosteres, phenols, thiophenols, polyamines, and metal complexing anions.…”

Synthesis of novel acridine bis-sulfonamides with effective inhibitory activity against the carbonic anhydrase isoforms I, II, IX and XII

“…21,22 In this context many efforts have been made for the development of specific CAIs, and some remarkable results have been achieved in the last 15 years since the introduction of the tail approach. [20][21][22] Moreover novel CAIs classes such as the polyamines, 23 phenols, 24 dithiocarbamates, 25 xanthates, 26 coumarins, thiocoumarins, 2-thioxo-coumarins and coumarin oximes 16,[27][28][29] were identified and their inhibition mechanisms of many of these compounds were determined by means of X-ray crystallography CA II adducts. 21,24,25 Considering the interest in sulfonamide CAIs, in this study we investigate a new class of acridine bis-sulfonamides which have been designed by an approach of multicomponent reactions.…”