Metallo-β-lactamases (MBLs) hydrolyze almost all β-lactam antibiotics and are unaffected by clinically available β-lactamase inhibitors (βLIs). Active-site architecture divides MBLs into three classes (B1, B2, and B3), complicating development of βLIs 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 βLIs of all MBL classes in vitro, with K i s 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 K i s (0.26-0.36 μM) than D-BTZs (26-29 μM). Importantly, cell-based time-kill assays show BTZs restore β-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 β-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 β-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.carbapenemase | antibiotic resistance | inhibitors | bisthiazolidines | metallo-β-lactamase

Pathogenic Gram-negative bacteria resistant to almost all β-lactam antibiotics are a major public health threat. Zn(II)-dependent or metallo-β-lactamases (MBLs) produced by these bacteria inactivate most β-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 β-lactam substrates, which can be modified with metal-binding groups to target the MBL active site. Inspired by known interactions of MBLs with β-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.

Metallo-β-lactamases (MBLs) are major culprits of resistance to carbapenems in bacteria. A series of thiazolidines are potent MBL inhibitors, restoring the activity of carbapenems. Metal binding and sulphur–π interactions are key to inhibition.

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.

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% presentó concentraciones bajas de Apo A-I, 45,2% Apo B elevada y 60,6% 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.

Novel domino processes that involve sequential reactions via iminium ions derived from b-amino thiols or b-amino alcohols were developed to form bisthiazolidines or bisthiiranes, respectively. The heterocycles were synthesized from readily available starting materials, forming four new chemical bonds in one process without the use of metals. The regioselectivity of the transformation could be explained on the basis of calculations of the coefficients of the frontier orbitals.

β‐Aminothiols (II) and (V) react with 2‐mercaptoacetaldehyde to generate iminium ions which cyclize to novel fused bisthiazolidines.

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