Amino acid-derived phthalimide and saccharin derivatives as inhibitors of human leukocyte elastase, cathepsin G, and proteinase 3

Cristiano ML, Rijo P, Pombeiro AJL. In Vitro Assessment of Antimicrobial, Antioxidant, and Cytotoxic Properties of Saccharin-Tetrazolyl and -Thiadiazolyl Derivatives: The Simple Dependence of the pH Value on Antimicrobial Activity

The antimicrobial, antioxidant, and cytotoxic activities of a series of saccharin-tetrazolyl and -thiadiazolyl analogs were examined. The assessment of the antimicrobial properties of the referred-to molecules was completed through an evaluation of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against Gram-positive and Gram-negative bacteria and yeasts. Scrutiny of the MIC and MBC values of the compounds at pH 4.0, 7.0, and 9.0 against four Gram-positive strains revealed high values for both the MIC and MBC at pH 4.0 (ranging from 0.98 to 125 µg/mL) and moderate values at pH 7.0 and 9.0, exposing strong antimicrobial activities in an acidic medium. An antioxidant activity analysis of the molecules was performed by using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, which showed high activity for the TSMT (N-(1-methyl-2H-tetrazol-5-yl)-N-(1,1-dioxo-1,2-benzisothiazol-3-yl) amine, 7) derivative (90.29% compared to a butylated hydroxytoluene positive control of 61.96%). Besides, the general toxicity of the saccharin analogs was evaluated in an Artemia salina model, which displayed insignificant toxicity values. In turn, upon an assessment of cell viability, all of the compounds were found to be nontoxic in range concentrations of 0-100 µg/mL in H7PX glioma cells. The tested molecules have inspiring antimicrobial and antioxidant properties that represent potential core structures in the design of new drugs for the treatment of infectious diseases.

Organic reactions in ionic liquids: N-alkylation of cyclic imides with alkyl halides promoted by potassium fluoride

An ionic liquid based on 1-butyl-3-methylimidazolium hexafluorophosphate is used as an efficient reusable reaction medium in the N-alkylation of cyclic imides with alkyl halides promoted by fluoride ion.

Discovery and Biological Evaluation of Potent and Selective N-Methylene Saccharin-Derived Inhibitors for Rhomboid Intramembrane Proteases

Rhomboids are intramembrane serine proteases and belong to the group of structurally and biochemically most comprehensively characterized membrane proteins. They are highly conserved and ubiquitously distributed in all kingdoms of life and function in a wide range of biological processes, including epidermal growth factor signaling, mitochondrial dynamics, and apoptosis. Importantly, rhomboids have been associated with multiple diseases, including Parkinson's disease, type 2 diabetes, and malaria. However, despite a thorough understanding of many structural and functional aspects of rhomboids, potent and selective inhibitors of these intramembrane proteases are still not available. In this study, we describe the computer-based rational design, chemical synthesis, and biological evaluation of novel N-methylene saccharin-based rhomboid protease inhibitors. Saccharin inhibitors displayed inhibitory potency in the submicromolar range, effectiveness against rhomboids both in vitro and in live Escherichia coli cells, and substantially improved selectivity against human serine hydrolases compared to those of previously known rhomboid inhibitors. Consequently, N-methylene saccharins are promising new templates for the development of rhomboid inhibitors, providing novel tools for probing rhomboid functions in physiology and disease.

2015 Philip S. Portoghese Medicinal Chemistry Lectureship. Curing Hepatitis C Virus Infection with Direct-Acting Antiviral Agents: The Arc of a Medicinal Chemistry Triumph

The development of direct-acting antiviral agents that can cure a chronic hepatitis C virus (HCV) infection after 8-12 weeks of daily, well-tolerated therapy has revolutionized the treatment of this insidious disease. In this article, three of Bristol-Myers Squibb's HCV programs are summarized, each of which produced a clinical candidate: the NS3 protease inhibitor asunaprevir (64), marketed as Sunvepra, the NS5A replication complex inhibitor daclatasvir (117), marketed as Daklinza, and the allosteric NS5B polymerase inhibitor beclabuvir (142), which is in late stage clinical studies. A clinical study with 64 and 117 established for the first time that a chronic HCV infection could be cured by treatment with direct-acting antiviral agents alone in the absence of interferon. The development of small molecule HCV therapeutics, designed by medicinal chemists, has been hailed as "the arc of a medical triumph" but may equally well be described as "the arc of a medicinal chemistry triumph".

A comparative QSAR on 1,2,5-thiadiazolidin-3-one 1,1-dioxide compounds as selective inhibitors of human serine proteinases

Selective inhibitors of target serine proteinases have a potential therapeutic role for the treatment of various inflammatory and related diseases. We develop a comparative quantitative structure-activity relationships based analysis on compounds embodying the 1,2,5-thiadiazolidin-3-one 1,1-dioxide scaffold. By means of classical Molecular Dynamics we obtain the conformation of each lowest-energy molecular structure from which we derive more than a thousand of structural descriptors necessary for building predictive QSAR models. We resort to two different modeling approaches with the purpose of testing the consistency of our results: (a) multivariable linear regressions based on the replacement method and forward stepwise regression, and (b) the calculation of flexible descriptors with the CORAL program. All the models are properly validated by means of standard procedures. The resulting QSAR models are supposed to be of great utility for the rational search and design (including synthesis and/or in vitro biochemical studies) of new effective non-peptidyl inhibitors of serine proteinases.

Inhibitors of human neutrophil elastase based on a highly functionalized N-amino-4-imidazolidinone scaffold

A series of compounds based on the N-amino-4-imidazolidinone scaffold was synthesized and screened against human neutrophil elastase (HNE). These studies lead to the identification of a selective, low micromolar reversible competitive inhibitor of HNE.

Utilization of the 1,2,3,5-thiatriazolidin-3-one 1,1-dioxide scaffold in the design of potential inhibitors of human neutrophil proteinase 3

The S' subsites of human neutrophil proteinase 3 (Pr 3) were probed by constructing diverse libraries of compounds based on the 1,2,3,5-thiatriazolidin-3-one 1,1-dioxide using combinational and click chemistry methods. The multiple points of diversity embodied in the heterocyclic scaffold render it well-suited to the exploration of the S' subsites of Pr 3. Molecular modeling studies suggest that further exploration of the S' subsites of Pr 3 using the aforementioned heterocyclic scaffold may lead to the identification of highly selective, reversible competitive inhibitors of Pr 3.

6-Substituted 2-oxo-2H-1-benzopyran-3-carboxylic acid as a core structure for specific inhibitors of human leukocyte elastase

Pyridyl esters of 6-substituted 2-oxo-2H-1-benzopyran-3-carboxylic acid were designed as mechanism-based inhibitors of human leukocyte elastase. Compounds of series 4 specifically inhibited this enzyme. Several of the tested compounds (series 2 and 3) acted as powerful time-dependent inhibitors of both human leukocyte elastase and alpha-chymotrypsin; some compounds of these series inhibited thrombin. Trypsin was not inhibited. A transient inactivation was observed for human leukocyte elastase (k(i)/K(I) = 107 000 M(-1). s(-1) for 4c) and thrombin (k(i)/K(I) = 7 200 M(-1).s(-1) for 3b) as demonstrated by spontaneous or hydroxylamine-accelerated reactivation, irrespective of the nature of the substituent at the 6-position. Conversely, alpha-chymotrypsin was irreversibly inhibited by 6-chloromethyl derivatives (k(i)/K(I) = 107 400 M(-1). s(-1) for 3b). The presence of a latent alkylating function at the 6-position (chloromethyl group) was required for leading to this inactivation. In the absence of such an alkylating function (series 4), human leukocyte elastase was specifically inhibited suggesting that this new series of human leukocyte elastase inhibitors may be of potential therapeutic interest in degradative and degenerative processes involving this enzyme.