Rational Design of Benzobisheterocycle Metallo-ß-Lactamase Inhibitors: A Tricyclic Scaffold Enhances Potency against Target Enzymes.

Antimicrobial resistance is a global public health threat. Metallo-ß-lactamases (MBLs) inactivate ß-lactam antibiotics, including carbapenems, are disseminating among Gram-negative bacteria, and lack clinically useful inhibitors. The evolving bisthiazolidine (BTZ) scaffold inhibits all three MBL subclasses (B1-B3). We report design, synthesis, and evaluation of BTZ analogues. Structure-activity relationships identified the BTZ thiol as essential, while carboxylate is replaceable, with its removal enhancing potency by facilitating hydrophobic interactions within the MBL active site. While the introduction of a flexible aromatic ring is neutral or detrimental for inhibition, a rigid (fused) ring generated nM benzobisheterocycle (BBH) inhibitors that potentiated carbapenems against MBL-producing strains. Crystallography of BBH:MBL complexes identified hydrophobic interactions as the basis of potency toward B1 MBLs. These data underscore BTZs as versatile, potent broad-spectrum MBL inhibitors (with activity extending to enzymes refractory to other inhibitors) and provide a rational approach to further improve the tricyclic BBH scaffold.

Correction: 2-Mercaptomethyl-thiazolidines use conserved aromatic-S interactions to achieve broad-range inhibition of metallo-ß-lactamases.

[This corrects the article DOI: 10.1039/D0SC05172A.].

2-Mercaptomethyl-thiazolidines use conserved aromatic-S interactions to achieve broad-range inhibition of metallo-ß-lactamases.

Infections caused by multidrug resistant (MDR) bacteria are a major public health threat. Carbapenems are among the most potent antimicrobial agents that are commercially available to treat MDR bacteria. Bacterial production of carbapenem-hydrolysing metallo-ß-lactamases (MBLs) challenges their safety and efficacy, with subclass B1 MBLs hydrolysing almost all ß-lactam antibiotics. MBL inhibitors would fulfil an urgent clinical need by prolonging the lifetime of these life-saving drugs. Here we report the synthesis and activity of a series of 2-mercaptomethyl-thiazolidines (MMTZs), designed to replicate MBL interactions with reaction intermediates or hydrolysis products. MMTZs are potent competitive inhibitors of B1 MBLs in vitro (e.g., K i = 0.44 µM vs. NDM-1). Crystal structures of MMTZ complexes reveal similar binding patterns to the most clinically important B1 MBLs (NDM-1, VIM-2 and IMP-1), contrasting with previously studied thiol-based MBL inhibitors, such as bisthiazolidines (BTZs) or captopril stereoisomers, which exhibit lower, more variable potencies and multiple binding modes. MMTZ binding involves thiol coordination to the Zn(ii) site and extensive hydrophobic interactions, burying the inhibitor more deeply within the active site than d/l-captopril. Unexpectedly, MMTZ binding features a thioether-π interaction with a conserved active-site aromatic residue, consistent with their equipotent inhibition and similar binding to multiple MBLs. MMTZs penetrate multiple Enterobacterales, inhibit NDM-1 in situ, and restore carbapenem potency against clinical isolates expressing B1 MBLs. Based on their inhibitory profile and lack of eukaryotic cell toxicity, MMTZs represent a promising scaffold for MBL inhibitor development. These results also suggest sulphur-π interactions can be exploited for general ligand design in medicinal chemistry.

Cross-class metallo-ß-lactamase inhibition by bisthiazolidines reveals multiple binding modes.

Metallo-ß-lactamases (MBLs) hydrolyze almost all ß-lactam antibiotics and are unaffected by clinically available ß-lactamase inhibitors (ßLIs). Active-site architecture divides MBLs into three classes (B1, B2, and B3), complicating development of ßLIs effective against all enzymes. Bisthiazolidines (BTZs) are carboxylate-containing, bicyclic compounds, considered as penicillin analogs with an additional free thiol. Here, we show both l- and d-BTZ enantiomers are micromolar competitive ßLIs of all MBL classes in vitro, with Kis of 6-15 µM or 36-84 µM for subclass B1 MBLs (IMP-1 and BcII, respectively), and 10-12 µM for the B3 enzyme L1. Against the B2 MBL Sfh-I, the l-BTZ enantiomers exhibit 100-fold lower Kis (0.26-0.36 µM) than d-BTZs (26-29 µM). Importantly, cell-based time-kill assays show BTZs restore ß-lactam susceptibility of Escherichia coli-producing MBLs (IMP-1, Sfh-1, BcII, and GOB-18) and, significantly, an extensively drug-resistant Stenotrophomonas maltophilia clinical isolate expressing L1. BTZs therefore inhibit the full range of MBLs and potentiate ß-lactam activity against producer pathogens. X-ray crystal structures reveal insights into diverse BTZ binding modes, varying with orientation of the carboxylate and thiol moieties. BTZs bind the di-zinc centers of B1 (IMP-1; BcII) and B3 (L1) MBLs via the free thiol, but orient differently depending upon stereochemistry. In contrast, the l-BTZ carboxylate dominates interactions with the monozinc B2 MBL Sfh-I, with the thiol uninvolved. d-BTZ complexes most closely resemble ß-lactam binding to B1 MBLs, but feature an unprecedented disruption of the D120-zinc interaction. Cross-class MBL inhibition therefore arises from the unexpected versatility of BTZ binding.

Bisthiazolidines: A Substrate-Mimicking Scaffold as an Inhibitor of the NDM-1 Carbapenemase.

Pathogenic Gram-negative bacteria resistant to almost all ß-lactam antibiotics are a major public health threat. Zn(II)-dependent or metallo-ß-lactamases (MBLs) produced by these bacteria inactivate most ß-lactam antibiotics, including the carbapenems, which are "last line therapies" for life-threatening Gram-negative infections. NDM-1 is a carbapenemase belonging to the MBL family that is rapidly spreading worldwide. Regrettably, inhibitors of MBLs are not yet developed. Here we present the bisthiazolidine (BTZ) scaffold as a structure with some features of ß-lactam substrates, which can be modified with metal-binding groups to target the MBL active site. Inspired by known interactions of MBLs with ß-lactams, we designed four BTZs that behave as in vitro NDM-1 inhibitors with Ki values in the low micromolar range (from 7 ± 1 to 19 ± 3 µM). NMR spectroscopy demonstrated that they inhibit hydrolysis of imipenem in NDM-1-producing Escherichia coli. In vitro time kill cell-based assays against a variety of bacterial strains harboring blaNDM-1 including Acinetobacter baumannii show that the compounds restore the antibacterial activity of imipenem. A crystal structure of the most potent heterocycle (L-CS319) in complex with NDM-1 at 1.9 Å resolution identified both structural determinants for inhibitor binding and opportunities for further improvements in potency.

Discovering Echinococcus granulosus thioredoxin glutathione reductase inhibitors through site-specific dynamic combinatorial chemistry.

In this study, we report a strategy using dynamic combinatorial chemistry for targeting the thioredoxin (Trx)-reductase catalytic site on Trx glutathione reductase (TGR), a pyridine nucleotide thiol-disulfide oxido-reductase. We chose Echinococcus granulosus TGR since it is a bottleneck enzyme of platyhelminth parasites and a validated pharmacological target. A dynamic combinatorial library (DCL) was constructed based on thiol-disulfide reversible exchange. We demonstrate the use of 5-thio-2-nitrobenzoic acid (TNB) as a non-covalent anchor fragment in a DCL templated by E. granulosus TGR. The heterodimer of TNB and bisthiazolidine (2af) was identified, upon library analysis by HPLC (IC50 = 24 µM). Furthermore, 14 analogs were synthetically prepared and evaluated against TGR. This allowed the study of a structure-activity relationship and the identification of a disulfide TNB-tricyclic bisthiazolidine (2aj) as the best enzyme inhibitor in these series, with an IC50 = 24 µM. Thus, our results validate the use of DCL for targeting thiol-disulfide oxido-reductases.

[Cardiovascular risk factors and apolipoproteic profile in a group of adults treated in a public health center in Carabobo state, Venezuela]. / Factores de riesgo cardiovascular y perfil apolipoprotéico en un grupo de adultos atendidos en un centro público de salud del estado Carabobo, Venezuela.

OBJECTIVES: To compare serum levels of apolipoproteins A-I and B as well as Apo B/Apo A-I and HDL cholesterol/Apo A-I ratios by age, gender and cardiovascular risk factors in individuals treated at a Venezuelan public health center. MATERIALS AND METHODS: We determined in 221 individuals (44.0 ± 15.5 years) of both genders blood pressure, waist circumference (WC), lipid profile and apolipoproteins A-I and B; body mass index (BMI) was calculated from weight and height; smoking habit, alcohol intake and consumption pattern were established. RESULTS: 27.5% of individuals had low levels of Apo A-I, 45.2% high Apo B and 60.6% high Apo B/Apo A-I ratio. Serum levels of apolipoproteins and Apo B/Apo A-I ratio did not vary with age or gender, while the ratio HDL cholesterol/Apo A-I decreased with the age. Obese individuals, smokers, hypertensive, hypercholesterolemics, hypertriglyceridemics or with low HDL cholesterol showed higher Apo B and Apo B/Apo A-I ratio. Older individuals, smokers or individuals with increased LDL cholesterol and triglycerides showed lower HDL cholesterol/Apo A-I ratio. Consumption of three or more alcoholic drinks/day was associated with decreased Apo B. CONCLUSIONS: These results show high prevalence of altered apolipoprotein profile, which is associated with major cardiovascular risk factors. The results support the inclusion of the evaluated apolipoproteins in laboratory determinations made in public health centers in Venezuela.

LDL pequeña y densa en adultos y su relación con factores de riesgo cardiovascular tradicionales

Objetivos: Establecer la presencia de lipoproteína de baja densidad pequeña y densa (LDLpd) en suero y su relación con factores de riesgo cardiovascular tradicionales en adultos. Métodos: Se estudiaron 78 mujeres y 73 hombres con promedio de edad de 39,9±14,9 años (rango: 20-84 años), los cuales asistieron a un centro de salud del Edo. Carabobo, Venezuela. Se registró hábito tabáquico, presión arterial y medidas antropométricas. Se obtuvo muestra de sangre en ayunas en la que se cuantificó colesterol total y fraccionado y triglicéridos mediante métodos enzimáticos-colorimétricos y se detectó LDLpd a través de electroforesis en gel de poliacrilamida en gradiente. El consumo de alcohol y su patrón de ingesta se registró mediante el Test de Identificación de Desórdenes del Uso del Alcohol (AUDIT). Resultados: Se detectó LDLpd en 45,7% de los individuos, siendo más frecuente en las mujeres que en los hombres (57,7% vs. 32,9%). La presencia de LDLpd se asoció significativamente con el aumento de la edad, índice de masa corporal, circunferencia de cintura, colesterol total, LDL colesterol y triglicéridos así como con la disminución de HDL colesterol. La presencia de LDLpd fue más frecuente entre los fumadores, hipertensos y aquellos individuos que consumieron alcohol en mayor cantidad y frecuencia. La presencia de LDLpd en suero fue predicha significativamente por la edad y los niveles de triglicéridos y HDL colesterol. Conclusiones: En este estudio, la presencia de LDLpd en suero fue frecuente en los individuos estudiados y se encontró relacionada con los factores de riesgo cardiovascular tradicionales evaluados.

Objectives: To establish the presence of small dense Low Density Lipoproteins (sdLDL) in serum and possible relation with traditional cardiovascular risk factors in adult individuals. Methods:We studied 78 women and 73 men with a mean age of 39.9 ± 14.9 years (range: 20-84 years) who attended to a health center of Edo. Carabobo, Venezuela. Measures were recorded smoking habit, blood pressure and anthropometric . After informed consent, patients were clinically evaluated and. Total and fractionated cholesterol and triglycerides were determined in serum by enzymatic-colorimetric methods. The presence of serum sdLDL was detected by polyacrylamide gradient gel electrophoresis. Alcohol consumption and drinking pattern were recorded by Alcohol Use Disorders Identification Test (AUDIT). Results: sdLDL was detected in 45.7% of individuals, being more prevalent in women than in men (57.7% vs. 32.9%). The presence of sdLDL in serum was significantly associated with the increasing age, body mass index, waist circumference, total cholesterol, LDL cholesterol, triglycerides and the decrease of HDL cholesterol. The presence of sdLDL was more common among smokers, hypertensives and those individuals who consumed alcohol in more quantity and frequency. Age, triglyceride and HDL cholesterol significantly predicted the presence of sdLDL. Conclusions: In this study, the presence of serum sdLDL was common in study subjects and related to traditional cardiovascular risk factors.

Factores de riesgo cardiovascular y perfil apolipoprotéico en un grupo de adultos atendidos en un centro público de salud del estado Carabobo, Venezuela / Cardiovascular risk factors and apolipoproteic profile in a group of adults treated in a public health center in Carabobo state, Venezuela

Objetivos. Comparar los niveles séricos de las apolipoproteínas A-I y B así como las relaciones Apo B/Apo A-I y HDL colesterol/Apo A-I según edad, sexo y factores de riesgo cardiovascular en individuos atendidos en un centro público de salud venezolano. Materiales y métodos. Se determinó la presión arterial, la circunferencia de cintura (CC), el perfil lipídico y las apolipoproteínas A-I y B en 221 individuos (44,0±15,5 años) de ambos sexos; también se calculó el índice de masa corporal (IMC) a partir del peso y la talla y se estableció hábito al tabaco, la ingesta de bebidas alcohólicas y el patrón de su consumo. Resultados. El 27,5 por ciento presentó concentraciones bajas de Apo A-I, 45,2 por ciento Apo B elevada y 60,6 por ciento relación Apo B/Apo A-I alta. Los niveles séricos de las apolipoproteínas y la relación Apo B/Apo A-I no variaron con la edad o sexo, mientras que la relación HDL colesterol/Apo A-I disminuyó al elevarse la edad. Los individuos obesos, fumadores, hipertensos, hipercolesterolémicos, hipertrigliceridémicos o con HDL colesterol bajo mostraron cifras más elevadas de Apo B y Apo B/Apo A-I. La relación HDL colesterol/Apo A-I disminuyó con la edad, el nivel de habito al tabaco y el aumento de LDL-C y triglicéridos. El consumo de tres o más bebidas alcohólicas/día se asoció con disminución de Apo B. Conclusiones. Se demostró alta prevalencia de perfil apolipoprotéico alterado, lo cual se asoció con los principales factores de riesgo cardiovascular. Los resultados del estudio apoyan la inclusión de las apolipoproteínas evaluadas en las determinaciones de laboratorio realizadas en los centros públicos de atención de salud venezolanos.

Objectives. To compare serum levels of apolipoproteins A-I and B as well as Apo B/Apo A-I and HDL cholesterol/Apo A-I ratios by age, gender and cardiovascular risk factors in individuals treated at a Venezuelan public health center. Materials and methods. We determined in 221 individuals (44.0 ± 15.5 years) of both genders blood pressure, waist circumference (WC), lipid profile and apolipoproteins A-I and B; body mass index (BMI) was calculated from weight and height; smoking habit, alcohol intake and consumption pattern were established. Results. 27.5 percent of individuals had low levels of Apo A-I, 45.2 percent high Apo B and 60.6 percent high Apo B/Apo A-I ratio. Serum levels of apolipoproteins and Apo B/Apo A-I ratio did not vary with age or gender, while the ratio HDL cholesterol/Apo A-I decreased with the age. Obese individuals, smokers, hypertensive, hypercholesterolemics, hypertriglyceridemics or with low HDL cholesterol showed higher Apo B and Apo B/Apo A-I ratio. Older individuals, smokers or individuals with increased LDL cholesterol and triglycerides showed lower HDL cholesterol/Apo A-I ratio. Consumption of three or more alcoholic drinks/day was associated with decreased Apo B. Conclusions. These results show high prevalence of altered apolipoprotein profile, which is associated with major cardiovascular risk factors. The results support the inclusion of the evaluated apolipoproteins in laboratory determinations made in public health centers in Venezuela.