Novel Drug Screening Assay for Acanthamoeba castellanii and the Anti-Amoebic Effect of Carbonic Anhydrase Inhibitors.

Acanthamoeba castellanii is an amoeba that inhabits soil and water in every part of the world. Acanthamoeba infection of the eye causes keratitis and can lead to a loss of vision. Current treatment options are only moderately effective, have multiple harmful side effects, and are tedious. In our study, we developed a novel drug screening method to define the inhibitory properties of potential new drugs against A. castellanii in vitro. We found that the clinically used carbonic anhydrase inhibitors, acetazolamide, ethoxzolamide, and dorzolamide, have promising antiamoebic properties.

Unconventional amino acids in medicinal chemistry: First report on taurine merged within carbonic anhydrase inhibitors.

This study reports the design, synthesis of a series of taurine containing benzenesulfonamide derivatives which were all screened in vitro against the physiological relevant human (h) expressed Carbonic Anhydrase (CA; EC 4.2.1.1) I, II, IX, XII isozymes. Compound 2, 5, 11-16 displayed superior inhibitory activities against the tumor associated hCA IX over the reference drug Acetazolamide (AAZ). Both hCA IX and XII isoforms were selectively inhibited only by compound 3, whereas the chloro-containing compound 12 was showed as the most selective and effective inhibitor profile for the CA IX isoforms. To the best of our knowledge the data reported herein are the first of this kind and introduce in the literature new compounds worth for future development within the Medicinal Chemistry field.

A New Kid on the Block? Carbonic Anhydrases as Possible New Targets in Alzheimer's Disease.

The increase in the incidence of neurodegenerative diseases, in particular Alzheimer's Disease (AD), is a consequence of the world's population aging but unfortunately, existing treatments are only effective at delaying some of the symptoms and for a limited time. Despite huge efforts by both academic researchers and pharmaceutical companies, no disease-modifying drugs have been brought to the market in the last decades. Recently, several studies shed light on Carbonic Anhydrases (CAs, EC 4.2.1.1) as possible new targets for AD treatment. In the present review we summarized preclinical and clinical findings regarding the role of CAs and their inhibitors/activators on cognition, aging and neurodegeneration and we discuss future challenges and opportunities in the field.

Discovery of ß-Adrenergic Receptors Blocker-Carbonic Anhydrase Inhibitor Hybrids for Multitargeted Antiglaucoma Therapy.

The combination of a ß-adrenergic receptors (AR) blocker and a carbonic anhydrase (CA, EC 4.2.1.1) inhibitor in eye drops formulations is one of the most clinically used treatment for glaucoma. A novel approach consisting of single-molecule, multitargeted compounds for the treatment of glaucoma is proposed here by designing compounds which concomitantly interact with the ß-adrenergic and CA targets. Most derivatives of the two series of benzenesulfonamides incorporating 2-hydroxypropylamine moieties reported here exhibited striking efficacy against the target hCA II and XII, whereas a subset of compounds also showed significant modulation of ß1- and ß2-ARs. X-ray crystallography studies provided rationale for the observed hCA inhibition. The best dual-agents decreased IOP more effectively than clinically used dorzolamide, timolol, and the combination of them in an animal model of glaucoma. The reported evidence supports the proof-of-concept of ß-ARs blocker-CAI hybrids for antiglaucoma therapy with an innovative mechanism of action.

Acyl selenoureido benzensulfonamides show potent inhibitory activity against carbonic anhydrases from the pathogenic bacterium Vibrio cholerae.

A series of acyl selenoureido benzensulfonamides was evaluated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors against two Vibrio cholerae such enzymes (VchCAα over VchCAß) belonging to the α- and ß-classes, potential novel targets for anti-infective drugs development. These compounds showed strong inhibitory action against VchCAα over VchCAß and excellent selectivity over the human (h) off-target isoforms hCA I and II. Identification of potent and possibly selective inhibitors of VchCAα and/or VchCAß over the human counterparts may lead to pharmacological tools useful for understanding the physiological role(s) of these under-investigated proteins, possibly involved in the virulence of the bacterium and colonization of the host in bicarbonate rich regions of the gastro-intestinal tract.

Phenols and Polyphenols as Carbonic Anhydrase Inhibitors.

Phenols are among the largest and most widely distributed groups of secondary metabolites within the plant kingdom. They are implicated in multiple and essential physiological functions. In humans they play an important role as microconstituents of the daily diet, their consumption being considered healthy. The physical and chemical properties of phenolic compounds make these molecules versatile ligands, capable of interacting with a wide range of targets, such as the Carbonic Anhydrases (CAs, EC 4.2.1.1). CAs reversibly catalyze the fundamental reaction of CO2 hydration to bicarbonate and protons in all living organisms, being actively involved in the regulation of a plethora of patho/physiological processes. This review will discuss the most recent advances in the search of naturally occurring phenols and their synthetic derivatives that inhibit the CAs and their mechanisms of action at molecular level. Plant extracts or mixtures are not considered in the present review.

An Update on Natural Products with Carbonic Anhydrase Inhibitory Activity.

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO2 hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological processes. They represent a typical example of enzyme convergent evolution, as six genetically unrelated families of such enzymes were described so far. It is more than 70 years that synthetic compounds, mainly sulfonamides, have been used in clinical practice as diuretics and systemic acting antiglaucoma drugs. Recent studies using natural product libraries and isolated constituents from natural sources (such as fungi and plants) have disclosed novel chemotypes possessing carbonic anhydrase inhibition activities. These natural sources offer new opportunities in the search for new and more effective carbonic anhydrase inhibitors, and may serve as new leads for the design and development of future drugs. This review will discuss the most recent advances in the search of naturally occurring products and their synthetic derivatives that inhibit the CAs and their mechanisms of action at molecular level. Plant extracts are not considered in the present review.

Inhibition studies of bacterial, fungal and protozoan ß-class carbonic anhydrases with Schiff bases incorporating sulfonamide moieties.

A series of new Schiff bases derived from sulfanilamide, 3-fluorosulfanilamide or 4-(2-aminoethyl)-benzenesulfonamide containing either a hydrophobic or a hydrophilic tail, have been investigated as inhibitors of three ß-carbonic anhydrases (CA, EC 4.2.1.1) from three different microorganisms. Their antifungal, antibacterial and antiprotozoan activities have been determined against the pathogenic fungus Cryptococcus neoformans, the bacterial pathogen Brucella suis and the protozoan parasite Leishmania donovani chagasi, responsible for Leishmaniasis. The results of these inhibition studies show that all three enzymes were efficiently inhibited by the Schiff base sulfonamides with KI values in the nanomolar or submicromolar range, depending on the nature of the tail, coming from the aryl/heteroaryl moiety present in the starting aldehyde employed in the synthesis. Furthermore, the compounds hereby investigated revealed high ß-CAs selectivity over the ubiquitous, physiologically relevant and off-target human isoforms (CA I and II) and to be more potent as antifungal and antibacterial than as antiprotozoan potential drugs.

Design and synthesis of novel dihydroxyindole-2-carboxylic acids as HIV-1 integrase inhibitors.

In a search for new HIV-1 integrase (IN) inhibitors, we synthesized and evaluated the biological activity of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and a series of its derivatives. These compounds were designed as conformationally constrained analogues of the acrylate moiety of caffeic acid phenethyl ester (CAPE). DHICA, an intermediate in the biosynthesis of melanins, was prepared as a monomeric unit by a novel synthetic route. In order to perform coherent SAR studies, two series of DHICA amides were synthesized. First, to validate the utility of a previously identified three-point pharmacophore based on CAPE in inhibitor design, we prepared a series of benzyl- or phenylethylamine substituted derivatives lacking and containing hydroxyl groups. Second, dimers of DHICA containing various aminoalkylamine linkers were also prepared with a goal to increase potency. All compounds were tested against purified IN and the C65S mutant in enzyme-based assays. They were also tested for cytotoxicity in an ovarian carcinoma cell line and antiviral activity in HIV-1-infected CEM cells. Seven compounds inhibited catalytic activities of purified IN with IC50 values below 10 microM. Further computational docking studies were performed to determine the title compounds' mode of interaction with the IN active site. The residues K156, K159 and D64 were the most important for potency against purified IN.