The Importance of Substituent Position for Antibacterial Activity in the Group of Thiosemicarbazide Derivatives.

The search for new antibacterial compounds is still a huge challenge for scientists. Each new chemotherapy drug is not 100% effective when introduced into treatment. Bacteria quickly become resistant to known structures. One promising group of new compounds is thiosemicarbazides. In the presented work, we looked for the relationship between structure and antibacterial activity within the group of thiosemicarbazide derivatives. This is a continuation of our previous work. Here, we decided to check to what extent the position of the 3-methoxyphenyl substituent affects potency. We obtained new structures that differ in the positions of the substituent in the thiosemicarbazide skeleton. Based on the obtained results of the biological tests, it can be concluded that the substituent in position 1 of thiosemicarbazide derivatives significantly determines their activity. Generally, among the substituents used, trifluoromethylphenyl turned out to be the most promising. The MIC values for compounds with this substituent are 64 µg/mL towards Staphylococci sp. Using molecular docking, we tried to explain the mechanism behind the antibacterial activity of the tested compounds.

Synthesis and spectroscopic characterization of 13 C4 -labeled 4-cyano-2-oxobutyraldehyde semicarbazone: A metabolite of nitrofurazone.

Nitrofurazone usage in food-producing animals is prohibited in most countries, including the United States. Regulatory agencies regularly monitor its use in domestic, export/import animals' food products by measuring the semicarbazide (SEM) metabolite as a biomarker of nitrofurazone exposure. However, the use of SEM is controversial because it is also produced in food naturally and thus gives false positive results. A cyano-metabolite, 4-cyano-2-oxobutyraldehyde semicarbazone (COBS), is proposed as an alternate specific marker of nitrofurazone to distinguish nitrofurazone from treated or untreated animals. A synthetic method was developed to produce COBS via metallic hydrogenation of nitrofurazone. The product was isolated and characterized by one- and two-dimensional nuclear magnetic spectroscopy (NMR) experiments, Fourier-transform infrared spectroscopy (FT-IR), and mass spectrometry. The developed synthetic procedure was further extended to synthesize isotopically labeled 4-[13 C]-cyano-2-oxo- [2, 3, 4-13 C3 ]-butyraldehyde semicarbazone. Labeled COBS is useful as an internal standard for its quantification in food-producing animals. Thus, the developed method provides a possibility for its commercial synthesis to procure COBS. This is the first synthesis of the alternate specific marker metabolite of nitrofurazone for possible usage in regulatory analysis to solve a real-world problem.

4-Arylthiosemicarbazide derivatives - Pharmacokinetics, toxicity and anti-Toxoplasma gondii activity in vivo.

The increasing resistance of Toxoplasma gondii to drugs and side effects of therapy indicate that specific treatment for these parasites is still needed. The 4-arylthiosemicarbazide derivatives seem to be a solution to this challenge because they have low cytotoxicity against host cells and high anti-T. gondii activity. The molecular mechanism for these compounds is related to the inhibition of tyrosine amino acids involved in the proliferation and parasitophorous vacuole formation. The pharmacokinetic analysis shows that 1-(4-Methylimidazol-5-oyl)-4-(4-nitrophenyl)thiosemicarbazide and 4-(3-Iodophenyl)-1-(4-methylimidazol-5-oyl)thiosemicarbazide administered intragastrically pass into the bloodstream and cross the blood-brain barrier, and the absorption of both compounds is first-order absorption. Toxicity analysis shows that our derivatives possess lower toxicity than the routinely used drugs trimethoprim, sulfadiazine and pyrimethamine, as was observed in the level of liver enzymes and creatinine. Both derivatives are highly potent antiparasitic agents against T. gondii, prolonged survival and cure parasite-infected mice. Additionally, significant reductions in cyst formation in the brain and heart were observed, but the highest decreases were noted in muscle and the level of bradyzoites was similar to these observed in mice treated with commercially used drugs. Collectively, the obtained results support the conclusion that both compounds are highly efficacious in a mouse model of acute and chronic toxoplasmosis.

Synthesis, characterization, DFT calculation, antioxidant activity, ADMET and molecular docking of thiosemicarbazide derivatives and their Cu (II) complexes.

In this work, new thiosemicarbazides (ECA-1, ECA-2) and their Cu (II) complexes (ECA-1-Cu, ECA-2-Cu) were synthesized and their structures were characterized by 1H NMR, 13C NMR, FT-IR, LC-MS, UV-Vis, and thermogravimetric analysis methods. Also, the surface morphology of the all compounds were examined by SEM (Scanning Electron Microscope). In the second stage, in vitro antioxidant capacity of the obtained compounds was investigated. The evaluation of the antioxidant properties of both synthesized ligands and complexes in this study was carried out by DPPH and FRAP methods. According to the results, both complexes exhibited more antioxidant capacity than the corresponding ligands. When antioxidant effects are compared for DPPH (SC50 = 5.27 ± 0.05 µM) and for FRAP (7845.69 ± 16.75 mmolTE/g), compound ECA-2-Cu appears to have the best inhibition effect. The complexes were found non-electrolytic in nature with melting point of above 250 °C, and electronic spectra and magnetic behavior demonstrated that the complexes were found to be tetrahedral geometry. Further, in silico the ADMET properties which studies are a significant role in improving and predicting drug compounds were calculated using web-based platforms. The theoretical calculations were made using the method of Density Functional Theory (Frontier molecular orbital analyze and Nonlinear optical properties). Also, molecular docking studies were performed to evaluate the binding interactions between the ligand and complex compounds and Human Peroxiredoxin 2. Both in vitro and in silico results indicated that synthesized compounds could act as potent antioxidant agents.

Optimized Synthesis of New Thiosemicarbazide Derivatives with Tuberculostatic Activity.

Original results are presented in the field of research that addresses the extension of the reaction of residue of acyl-thiosemicarbazide fixation on the structure of 5-nitrobenzimidazole by a sulphonic group. The aim of the study is the increase of new thiosemicarbazide derivatives' applicative potential in the field of biochemistry, with a wide range of medical applications. The newly obtained compounds were characterized by using elemental analysis and spectral analysis (FT-IR and 1H NMR). A study regarding the optimization of the chemical reactions was made. The performed in vitro biological tests confirmed the tuberculostatic activity of three newly obtained compounds against Mycobacterium tuberculosis.

Schiff base 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide up-regulates the antioxidant status and inhibits the progression of Ehrlich solid tumor in mice.

Cisplatin is an approved cancer therapeutic drug used to treat many solid tumors but its accumulation in the kidney, which causes nephrotoxicity, limits its clinical use. Therefore, investigators seek new alternatives to cisplatin that may be more effective and/or safer. Thiosemicarbazides are of great significance due to their expected biological activity including anticancer activities. The aim of this work is the study of the antitumor effect of Schiff base 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide (HEPTS) on Ehrlich solid tumor-bearing mice in comparison to cancer therapeutic drug cisplatin. The experiment was run using sixty adult female Swiss albino mice. Mice were allocated into six groups (n = 10 mice). Healthy control, EAC control (untreated tumor), EAC + cisplatin, EAC + HEPTS, Healthy + HEPTS, and Healthy + solvent. After scarification, blood samples, liver organs, and solid tumors were collected. Tumor weights and volumes were registered. The concentrations of malondialdehyde (MDA), reduced glutathione (GSH), SOD, catalase (CAT), total antioxidant capacity (TAC), nitric oxide (NO), uric acid, creatinine, and urea were assessed. Median survival time (MST) and the percentage increase in lifespan (%ILS) were also calculated. Treatment of tumorized mice with HEPTS significantly reduced both tumor volume and weight while it significantly increased the MST, antioxidant marks and prolonged the %ILS. It also, significantly reduced MAD, creatinine, urea, uric acid, and NO levels. Compared to cisplatin, HEPTS effects were better. Our results recommend HEPTS as one of the probable cisplatin-alternatives for tumor treatment after more validation.

Synthesis and Antinociceptive Effect of Some Thiazole-Piperazine Derivatives: Involvement of Opioidergic System in the Activity.

In this study, we aimed to design and synthesize novel molecules carrying both the thiazole and piperazine rings in their structures and to investigate their antinociceptive activity. Targeted compounds were obtained by reacting thiosemicarbazide derivative and appropriate 2-bromoacetophenone in ethanol. The structures of the obtained compounds were determined using data from various spectroscopic methods (IR, 1H-NMR, 13C-NMR, and LCMSMS). Experimental data from in vivo tests showed that test compounds 3a-3c, 3f, and 3g (50 mg/kg) significantly prolonged reaction times of animals in tail-clip and hot-plate tests compared to the controls, indicating that these compounds possess centrally mediated antinociceptive activities. Furthermore, these compounds reduced the number of writhing behaviors in the acetic acid-induced writhing tests, showing that the compounds also possess peripheral antinociceptive activity. In the mechanistic studies, naloxone pre-treatments abolished the antinociceptive activities of compounds 3a-3c, 3f, and 3g, indicating that opioidergic mechanisms were involved in their antinociceptive effects. Molecular docking studies demonstrating significant interactions between the active compounds and µ- and δ-opioid receptor proteins supported the pharmacological findings. This study is the first showing that molecules designed to bear thiazole and piperazine moieties together on their structure exert centrally and peripherally mediated antinociceptive effects by activating the opioid system.

4-Arylthiosemicarbazide derivatives as a new class of tyrosinase inhibitors and anti-Toxoplasma gondii agents.

We report herein anti-proliferation effects of 4-arylthiosemicarbazides, with a cyclopentane substitution at N1 position, on highly virulent RH strain of Toxoplasma gondii. Among them, the highest in vitro anti-Toxoplasma activity was found with the meta-iodo derivative. Further experiments demonstrated inhibitory effects of thiosemicarbazides on tyrosinase (Tyr) activity, and good correlation was found between percentage of Tyr inhibition and IC50Tg. To confirm the concept that thiosemicarbazides are able to disrupt tyrosine metabolism in Toxoplasma tachyzoites, the most potent Tyr inhibitors were tested for their efficacy of T. gondii growth inhibition. All of them significantly reduced the number of tachyzoites in the parasitophorous vacuoles (PVs) compared to untreated cells, as well as inhibited tachyzoites growth by impeding cell division. Collectively, these results indicate that compounds with the thiosemicarbazide scaffold are able to disrupt tyrosine metabolism in Toxoplasma tachyzoites by deregulation of their crucial enzyme tyrosine hydroxylase (TyrH).

Thiosemicarbazide Derivatives Decrease the ATPase Activity of Staphylococcus aureus Topoisomerase IV, Inhibit Mycobacterial Growth, and Affect Replication in Mycobacterium smegmatis.

Compounds targeting bacterial topoisomerases are of interest for the development of antibacterial agents. Our previous studies culminated in the synthesis and characterization of small-molecular weight thiosemicarbazides as the initial prototypes of a novel class of gyrase and topoisomerase IV inhibitors. To expand these findings with further details on the mode of action of the most potent compounds, enzymatic studies combined with a molecular docking approach were carried out, the results of which are presented herein. The biochemical assay for 1-(indol-2-oyl)-4-(4-nitrophenyl) thiosemicarbazide (4) and 4-benzoyl-1-(indol-2-oyl) thiosemicarbazide (7), showing strong inhibitory activity against Staphylococcus aureus topoisomerase IV, confirmed that these compounds reduce the ability of the ParE subunit to hydrolyze ATP rather than act by stabilizing the cleavage complex. Compound 7 showed better antibacterial activity than compound 4 against clinical strains of S. aureus and representatives of the Mycobacterium genus. In vivo studies using time-lapse microfluidic microscopy, which allowed for the monitoring of fluorescently labelled replisomes, revealed that compound 7 caused an extension of the replication process duration in Mycobacterium smegmatis, as well as the growth arrest of bacterial cells. Despite some similarities to the mechanism of action of novobiocin, these compounds show additional, unique properties, and can thus be considered a novel group of inhibitors of the ATPase activity of bacterial type IIA topoisomerases.

Synthesis of new 1,2,4-triazole-(thio)semicarbazide hybrid molecules: Their tyrosinase inhibitor activities and molecular docking analysis.

Tyrosinase inhibition is very important in controlling melanin synthesis. If melanin synthesis is not controlled in metabolism, an unwanted increase in melanin synthesis occurs. As melanin plays a role in the formation of skin color, its unusual levels cause some skin disorders such as pregnancy scars, age spots, and especially skin cancer (melanoma). However, the tyrosinase activity is also related to Parkinson's disease and some neurodegenerative diseases. For all these reasons, the medicinal as well as the cosmetic industries focus on research on tyrosinase inhibitors for the treatment of skin disorders and some neurodegenerative diseases. In this study, 32 new 1,2,4-triazole-(thio)semicarbazide hybrid molecules (6a-p and 7a-p) were synthesized, starting from 4-amino-1-pentyl-3-phenyl-1H-1,2,4-triazole-5(4H)-one. These compounds were evaluated for their inhibitory activity against mushroom tyrosinase. The results indicated that 6h, 6m, 6n, and 6p exhibited the most effective inhibitory activity, with IC50 values of 0.00162 ± 0.0109, 0.00166 ± 0.0217, 0.00165 ± 0.019, and 0.00197 ± 0.0063 µM, respectively, compared with kojic acid as the reference drug (IC50 = 14.09 ± 0.02 µM). Also, molecular docking analyses were performed to suggest possible binding poses for the ligands. As a result, derivatives 6h, 6m, 6n, and 6p can be used as promising tyrosinase inhibitor candidates in the medicinal, cosmetics, or food industries.

Electrochemiluminescence biosensor for microRNA determination based on AgNCs@MoS2 composite with (AuNPs-Semicarbazide)@Cu-MOF as coreaction accelerator.

A novel electrochemiluminescence (ECL) biosensor was fabricated for miRNA-162a detection by using silver nanoclusters/molybdenum disulfide (AgNCs@MoS2) as an ECL material, peroxodisulfate (S2O82-) as a co-reactant, and semicarbazide (Sem) as a co-reaction accelerator. Firstly, hairpin probe Ha modified on AgNCs@MoS2/GCE was unfolded based on its hybridization with target microRNA. Then, the unfolded Ha can further be hybridized with another hairpin DNA of Hb on (AuNPs-semicarbazide)@Cu-MOF, resulting in the release of target microRNA, which further causes a cyclic hybridization. This creates more (AuNPs-semicarbazide)@Cu-MOF on the electrode surface, achieving cyclic hybridization signal amplification. Strikingly, due to the presence of Sem, accelerating the reduction of S2O82- and resulting in the generation of more oxidant intermediates of SO42-, the amount of excited states of Agincreases to further amplify the ECL signal. The biosensor exhibited high sensitivity with a low LOD of 1.067 fM, indicating that the introduction of co-reaction accelerators can provide an effective method for signal amplification. The applicability of this method was assessed by investigating the effect of Pb(II) ion on miRNA-162a expression level in maize seedling leaves. A novel electrochemiluminescence biosensor was fabricated for miRNA-162a detection by using silver nanoclusters/molybdenum disulfide as an ECL material, peroxodisulfate as a co-reactant, and semicarbazide as a co-reaction accelerator.

Optimized reducing-end labeling of cellulose nanocrystals: Implication for the structure of microfibril bundles in plant cell walls.

A strategy to optimize the labeling of the reducing end of native cellulose nanocrystals (CNCs) with gold nanoparticles (AuNPs) was developed and used to investigate the arrangement of the elementary crystallites constituting these biosourced particles. First, CNCs pre-functionalized with thiosemicarbazide molecules were reacted with presynthesized AuNPs. A second method consisted in synthesizing AuNPs in situ from soluble gold derivatives in the presence of CNCs regioselectively functionalized with thiosemicarbazide molecules. Transmission electron microscopy images revealed that the direct reaction resulted in a low labeling yield and the undesired formation of AuNP aggregates. Oppositely, unprecedent high labeling yields were achieved through the in situ growth approach, with a vast majority of CNCs bearing one or several AuNPs on one end. These results evidence that cotton-derived CNCs are composed of the unidirectional assembly of chemically polar elementary crystallites, implying that the acid hydrolysis isolates fragments of microfibril bundles present in the cell walls.

Thiosemicarbazide binds with the dicopper center in the competitive inhibition of mushroom tyrosinase enzyme: Synthesis and molecular modeling of theophylline analogues.

Theophylline is long known for its anti-ageing and anti-oxidative properties. Moreover, Tyrosinase is a crucial enzyme that regulates the melanin synthetic pathway, which is involved in various physiological metabolic processes including aging. The current paper describes the synthesis of various heterocyclic systems coupled with theophylline moiety along with their tyrosinase inhibition activity in view to identify the potent nucleus. Around 19 compounds were synthesized and screened for enzyme inhibition. Based on the current study, it is suggested that compound 18 having thiosemicarbazide has strong enzyme inhibition potential. The enzyme kinetics and docking studies provide important insights into how the compound interacts with the mushroom tyrosinase active site. The work will provide clue to developing new, potent tyrosinase inhibitors for drug development.

Design, synthesis and evaluation of carbazole derivatives as potential antimicrobial agents.

Five series of novel carbazole derivatives containing an aminoguanidine, dihydrotriazine, thiosemicarbazide, semicarbazide or isonicotinic moiety were designed, synthesised and evaluated for their antimicrobial activities. Most of the compounds exhibited potent inhibitory activities towards different bacterial strains (including one multidrug-resistant clinical isolate) and one fungal strain with minimum inhibitory concentrations (MICs) between 0.5 and 16 µg/ml. Compounds 8f and 9d showed the most potent inhibitory activities (MICs of 0.5-2 µg/ml). Furthermore, compounds 8b, 8d, 8f, 8k, 9b and 9e with antimicrobial activities were not cytotoxic to human gastric cancer cell lines (SGC-7901 and AGS) or a normal human liver cell line (L-02). Structure-activity relationship analyses and docking studies implicated the dihydrotriazine group in increasing the antimicrobial potency and reducing the toxicity of the carbazole compounds. In vitro enzyme activity assays suggested that compound 8f binding to dihydrofolate reductase might account for the antimicrobial effect.

Docking and QSAR of Aminothioureas at the SARS-CoV-2 S-Protein-Human ACE2 Receptor Interface.

Docking of over 160 aminothiourea derivatives at the SARS-CoV-2 S-protein-human ACE2 receptor interface, whose structure became available recently, has been evaluated for its complex stabilizing potency and subsequently subjected to quantitative structure-activity relationship (QSAR) analysis. The structural variety of the studied compounds, that include 3 different forms of the N-N-C(S)-N skeleton and combinations of 13 different substituents alongside the extensive length of the interface, resulted in the failure of the QSAR analysis, since different molecules were binding to different parts of the interface. Subsequently, absorption, distribution, metabolism, and excretion (ADME) analysis on all studied compounds, followed by a toxicity analysis using statistical models for selected compounds, was carried out to evaluate their potential use as lead compounds for drug design. Combined, these studies highlighted two molecules among the studied compounds, i.e., 5-(pyrrol-2-yl)-2-(2-methoxyphenylamino)-1,3,4-thiadiazole and 1-(cyclopentanoyl)-4-(3-iodophenyl)-thiosemicarbazide, as the best candidates for the development of future drugs.

N-monosubstituted thiosemicarbazide as novel Ure inhibitors: synthesis, biological evaluation and molecular docking.

Background: Identification of novel Ure inhibitors with high potency has received considerable attention. Methodology & results: Ure inhibition was determined using the indophenol method, the affinities to Ure were estimated via surface plasmon resonance. Seventeen new plus ten known N-monosubstituted thiosemicarbazides were synthesized and identified as novel Ure inhibitors. Out of these compounds, compound b5 shows excellent activity against both crude Ure from Helicobacter pylori (IC50 = 0.04 µM) and Ure in living cell (IC50 = 0.27 µM), with the potency being over 600-fold higher than clinical used drug acetohyroxamic acid, respectively. Surface plasmon resonance demonstrated the high affinity (Kd.#x00A0;= 6.32 nM) of b5 to Ure. Conclusion: This work provides a class of novel and promising Ure inhibitors.

In Vivo Targeting Using Arylboronate/Nopoldiol Click Conjugation.

Bioorthogonal click reactions yielding stable and irreversible adducts are in high demand for in vivo applications, including in biomolecular labeling, diagnostic imaging, and drug delivery. Previously, we reported a novel bioorthogonal "click" reaction based on the coupling of ortho-acetyl arylboronates and thiosemicarbazide-functionalized nopoldiol. We now report that a detailed structural analysis of the arylboronate/nopoldiol adduct by X-ray crystallography and 11B NMR reveals that the bioorthogonal reactants form, unexpectedly, a tetracyclic adduct through the cyclization of the distal nitrogen into the semithiocarbazone leading to a strong B-N dative bond and two new 5-membered rings. The cyclization adduct, which protects the boronate unit against hydrolytic breakdown, sheds light on the irreversible nature of this polycondensation. The potential of this reaction to work in a live animal setting was studied through in vivo capture of fluorescently labeled molecules in vivo. Arylboronates were introduced into tissues through intradermal injection of their activated NHS esters, which react with amines in the extracellular matrix. Fluorescently labeled nopoldiol molecules were administered systemically and were efficiently captured by the arylboronic acids in a location-specific manner. Taken together, these in vivo proof-of-concept studies establish arylboronate/nopoldiol bioorthogonal chemistry as a candidate for wide array of applications in chemical biology and drug delivery.

Blocking of negative charged carboxyl groups converts Naja atra neurotoxin to cardiotoxin-like protein.

Naja atra cobrotoxin and cardiotoxin 3 (CTX3) exhibit neurotoxicity and cytotoxicity, respectively. In the present study, we aimed to investigate whether the carboxyl groups of cobrotoxin play a role in structural constraints, thereby preventing cobrotoxin from exhibiting cytotoxic activity. Six of the seven carboxyl groups in cobrotoxin were conjugated with semicarbazide. Measurement of circular dichroism spectra and Trp fluorescence quenching showed that the gross conformation of semicarbazide-modified cobrotoxin (SEM-cobrotoxin) and cobrotoxin differed. In sharp contrast to cobrotoxin, SEM-cobrotoxin demonstrated membrane-damaging activity and cytotoxicity, which are feature more characteristic of CTX3. Furthermore, both SEM-cobrotoxin and CTX3 induced cell death through AMPK activation. Analyses of the interaction between polydiacetylene/lipid vesicles and fluorescence-labeled lipids revealed that SEM-cobrotoxin and cobrotoxin adopted different membrane-bound states. The structural characteristics of SEM-cobrotoxin were similar to those of CTX3, including trifluoroethanol (TFE)-induced structural transformation and membrane binding-induced conformational change. Conversely, cobrotoxin was insensitive to the TFE-induced effect. Collectively, the data of this study indicate that blocking negatively charged residues confers cobrotoxin with membrane-damaging activity and cytotoxicity. The findings also suggest that the structural constraints imposed by carboxyl groups control the functional properties of snake venom α-neurotoxins during the divergent evolution of snake venom neurotoxins and cardiotoxins.

Thiosemicarbazides: Updates on Antivirals Strategy.

The challenges of viral infection have increased in recent decades due to the emergence of resistance, cross-resistance and drying up of antiviral drug discovery. Many neglected tropical viruses including the chikungunya virus, dengue virus & Japanese encephalitis virus have gradually become global pathogens. This has further increased the burden of viral infection which necessitates the continuous development of antiviral therapy. The antiviral chemistry began with the development of thiosemicarbazide derived thiosemicarbazones as antiviral. Although very few thiosemicarbazides have progressed into clinical application, it still inspires antiviral development. During last 3 decades (1990- 2020), several efforts have been made to develop suitable antiviral by using thiosemicarbazide scaffold. Its hybridization with other pharmacophores has been used as a strategy to enhance safety and efficacy. Cyclization and substitution of thiosemicarbazides have also been used to develop potent antiviral. With the ability to form coordinate bonds, thiosemicarbazides have been used either as metal complex or chelator against viruses. This work is an attempt to systematically review the research on the use of thiosemicarbazides as an antiviral scaffold. It also reviews the structure-activity relationship and translational suitability of thiosemicarbazide derived compounds.

Virtual screening identifies broad-spectrum ß-lactamase inhibitors with activity on clinically relevant serine- and metallo-carbapenemases.

Bacteria are known to evade ß-lactam antibiotic action by producing ß-lactamases (BLs), including carbapenemases, which are able to hydrolyze nearly all available ß-lactams. The production of BLs represents one of the best known and most targeted mechanisms of resistance in bacteria. We have performed the parallel screening of commercially available compounds against a panel of clinically relevant BLs: class A CTX-M-15 and KPC-2, subclass B1 NDM-1 and VIM-2 MBLs, and the class C P. aeruginosa AmpC. The results show that all BLs prefer scaffolds having electron pair donors: KPC-2 is preferentially inhibited by sulfonamide and tetrazole-based derivatives, NDM-1 by compounds bearing a thiol, a thiosemicarbazide or thiosemicarbazone moiety, while VIM-2 by triazole-containing molecules. Few broad-spectrum BLs inhibitors were identified; among these, compound 40 potentiates imipenem activity against an NDM-1-producing E. coli clinical strain. The binary complexes of the two most promising compounds binding NDM-1 and VIM-2 were obtained at high resolution, providing strong insights to improve molecular docking simulations, especially regarding the interaction of MBLs with inhibitors.