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International audience; The ever-evolving research in the field of antitubercular agents has led to the identification of several new potential drug classes. Among them, 5-phenyl-furan-2-carboxylic acids have emerged as innovative potential therapeutics, targeting iron acquisition in mycobacterial species. In our efforts to characterize the molecular interactions between these compounds and their protein target (MbtI from M. tuberculosis) by means of co-crystallization experiments, we unexpectedly obtained the structure of 5-(4-nitrophenyl)furan-2-carboxylic acid (1). Herein, we describe the preparation of the compound and its analysis by 1H NMR, 13C NMR, HRMS, and SC-XRD.

5-Phenyl-furan-2-carboxylic acids have emerged as a new, promising class of antimycobacterial agents that have the ability to interfere with iron homeostasis. Considering the lack of structural data on these compounds, we analyzed the crystal of a fluorinated ester derivative of 5-(4-nitrophenyl)furan-2-carboxylic acid, one of the most potent candidates in the series. Here, we describe the preparation of methyl 5-(2-fluoro-4-nitrophenyl)furan-2-carboxylate (1) and its analysis by 1H-NMR, 13C-NMR, HRMS, and SC-XRD.

The synthesis of a collection of enantiomerically pure, systematically substituted hydantoins as structural privileged universal mimetic scaffolds is presented. It relies on a chemoselective condensation/cyclization domino process between isocyanates of quaternary or unsubstituted α-amino esters and

The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) infections is one of the most crucial challenges currently faced by the scientific community. Developments in the fundamental understanding of their underlying mechanisms may open new perspectives in drug discovery. In this review, we conducted a systematic literature search in PubMed, Web of Science, and Scopus, to collect information on innovative strategies to hinder iron acquisition in bacteria. In detail, we discussed the most interesting targets from iron uptake and metabolism pathways, and examined the main chemical entities that exhibit anti-infective activities by interfering with their function. The mechanism of action of each drug candidate was also reviewed, together with its pharmacodynamic, pharmacokinetic, and toxicological properties. The comprehensive knowledge of such an impactful area of research will hopefully reflect in the discovery of newer antibiotics able to effectively tackle the antimicrobial resistance issue.

Mycobacterial resistance is a rapidly increasing phenomenon requiring the identification of new drugs effective against multidrug-resistant pathogens. The inhibition of protein tyrosine phosphatase B (MptpB), which interferes with host immune responses, may provide a new strategy to fight tuberculosis (TB), while preventing cross-resistance issues. On this basis, starting from a virtual screening (VS) campaign and subsequent structure elucidation studies guided by X-ray analyses, an unexpected γ-lactone derivative (compound 1) with a significant enzymatic activity against MptpB was identified. The structural characterization of compound 1 was described by means of NMR spectroscopy, HRMS, single crystal X-ray diffraction and Hirshfeld surface analysis, allowing a detailed conformational investigation. Notably, the HPLC separation of (±)-1 led to the isolation of the most active isomer, which emerged as a very promising MptpB inhibitor, with an IC

The elucidation of the structure of enzymes and their complexes with ligands continues to provide invaluable insights for the development of drugs against many diseases, including bacterial infections. After nearly three decades since the World Health Organization’s (WHO) declaration of tuberculosis (TB) as a global health emergency, Mycobacterium tuberculosis (Mtb) continues to claim millions of lives, remaining among the leading causes of death worldwide. In the last years, several efforts have been devoted to shortening and improving treatment outcomes, and to overcoming the increasing resistance phenomenon. The structural elucidation of enzyme-ligand complexes is fundamental to identify hot-spots, define possible interaction sites, and elaborate strategies to develop optimized molecules with high affinity. This review offers a critical and comprehensive overview of the most recent structural information on traditional and emerging mycobacterial enzymatic targets. A selection of more than twenty enzymes is here discussed, with a special emphasis on the analysis of their binding sites, the definition of the structure–activity relationships (SARs) of their inhibitors, and the study of their main intermolecular interactions. This work corroborates the potential of structural studies, substantiating their relevance in future anti-mycobacterial drug discovery and development efforts.

Vecuronium bromide (Piperidinium, 1-[(2β,3α,5α,16β,17β)-3,17-bis(acetyloxy)-2-(1-piperidinyl)androstan-16-yl]-1-methyl-, bromide; Norcuron®) has been extensively used in anesthesiology practice as neuromuscular blocking agent since its launch on the market in 1982. However, a detailed crystallographic and NMR analysis of its advanced synthetic intermediates is still lacking. Hence, with the aim of filling this literature gap, vecuronium bromide was prepared starting from the commercially available 3β-hydroxy-5α-androstan-17-one (epiandrosterone), implementing some modifications to a traditional synthetic procedure. A careful NMR study allowed the complete assignment of the 1H, 13C, and 15N NMR signals of vecuronium bromide and its synthetic intermediates. The structural and stereochemical characterization of 2β,16β-bispiperidino-5α-androstane-3α,17β-diol, the first advanced synthetic intermediate carrying all the stereocenters in the final configuration, was described by means of single-crystal X-ray diffraction and Hirshfeld surface analysis, allowing a detailed conformational investigation.

SIRT5 is a member of the Sirtuin family, a class of deacetylating enzymes consisting of seven isoforms, involved in the regulation of several processes, including gene expression, metabolism, stress response, and aging. Considering that the anomalous activity of SIRT5 is linked to many pathological conditions, we present herein an overview of the most interesting modulators, with the aim of contributing to further development in this field.

For centuries, natural products (NPs) have served as powerful therapeutics against a variety of human ailments. Nowadays, they still represent invaluable resources for the treatment of many diseases, including bacterial infections. After nearly three decades since the World Health Organization's (WHO) declaration of tuberculosis (TB) as a global health emergency, Mycobacterium tuberculosis (Mtb) continues to claim millions of lives, remaining among the leading causes of death worldwide. In the last years, several efforts have been devoted to shortening and improving treatment outcomes, and to overcoming the increasing resistance phenomenon. Nature has always provided a virtually unlimited source of bioactive molecules, which have inspired the development of new drugs. NPs are characterized by an exceptional chemical and structural diversity, the result of millennia of evolutionary responses to various stimuli. Thanks to their favorable structural features and their enzymatic origin, they are naturally prone to bind proteins and exhibit bioactivities. Furthermore, their worldwide distribution and ease of accessibility has contributed to promote investigations on their activity. Overall, these characteristics make NPs excellent models for the design of novel therapeutics. This review offers a critical and comprehensive overview of the most promising NPs, isolated from plants, fungi, marine species, and bacteria, endowed with inhibitory properties against traditional and emerging mycobacterial enzymatic targets. A selection of 86 compounds is here discussed, with a special emphasis on their biological activity, structure-activity relationships, and mechanism of action. Our study corroborates the antimycobacterial potential of NPs, substantiating their relevance in future drug discovery and development efforts.

New Pt(II) complexes (Pt-1-3) bearing 1,2,5-oxadiazole ligands (1-3) were synthesized, characterized and evaluated for their ability to disrupt STAT3 dimerization. Ligand 3·HCl showed cytotoxic effects on HCT-116 cells (IC50 = 95.2 μM) and a selective ability to interact with STAT3 (IC50 = 8.2 μM) versus STAT1 (IC50 > 30 μM). Its corresponding platinum complex Pt-3 exhibited an increased cytotoxicity (IC50 = 18.4 μM) and a stronger interaction with STAT3 (IC50 = 1.4 μM), leading to inhibition of its signaling pathway. Pt-3 was also evaluated in cell-based assays for its action on p53 expression and on STAT3 phosphorylation. In syngeneic murine Lewis lung carcinoma (LLC) implanted in C57BL/6 mice, Pt-3 showed a higher antitumor activity with fewer side effects than cisplatin.

A novel one-pot multicomponent reaction to synthesize substituted imidazopyrazines is described. In brief, 1H-(imidazol-5-yl)-N-substituted methanamines react with aldehydes and isocyanides in methanol at room temperature to give imidazopyrazine derivatives in excellent yields. The imidazole nitrogen atom was able to intercept the nascent nitrilium ion, channeling the reaction toward to the sole formation of imidazopyrazines, suppressing the competitive formation of other possible side products deriving from the reaction with the high-energy nitrilium ion. The number of examples and the variability of the nature of isocyanides, aldehydes, and amine components herein employed, witness the robustness of this novel methodology.

Considering aryl azides as electrophilic partners for the TosMIC mediated Van Leusen reaction, a novel multicomponent synthesis of 4-tosyl-1-arylimidazoles is reported. In this transformation, two molecules of TosMIC participate in the reaction mechanism in two different ways, with the second molecule undergoing a novel type of fragmentation resulting in the incorporation of a C-H into the final product.

Three chiral derivatives of the alkaloid sparteine (bispidines), characterized by the 3,7-diazabicyclo[3.3.1]nonane moiety, were designed as efficient ligands in a number of enantioselective reactions due to their metal coordination properties. A full evaluation of the 3D properties of the compounds was carried out, as the geometrical features of the bicyclic framework are strictly related to the efficiency of the ligands in the asymmetric catalysis. The selected molecules have different molecular complexity for investigating the effects of different chiral groups on the bicycle conformation. We report here a thorough analysis of their molecular arrangement, by NMR spectroscopy, single crystal X-ray crystallography, and computational techniques, which put in evidence their conformational preferences and the parameters needed for the design of more efficient ligands in asymmetric synthetic routes. The results confirmed the high molecular flexibility of the compounds, and indicated how to achieve a control of the chair-chair/boat-chair conformational ratio, by adjusting the relative size of the substituents on the piperidine nitrogens.

The first asymmetric, Brønsted acid catalyzed Biginelli-like reaction of a ketone has been developed, employing N-substituted isatins as carbonyl substrates, and urea and alkyl acetoacetates as further components. BINOL-derived phosphoric acid catalysts have been used to achieve the synthesis of a small library of chiral, enantioenriched spiro(indoline-pyrimidine)-diones derivatives. The absolute configuration of the new spiro stereocenter was assessed on diastereoisomeric derivatives through computer-assisted NMR spectroscopy. X-ray diffractometry allowed the disclosure of the overall molecular conformation in the solid state and the characterization of the crystal packing of a Br-substituted Biginelli-like derivative, while computational studies on the reaction transition state allowed us to rationalize the stereochemical outcome.

Signal transducer and activator of transcription 3 (STAT3) is a validated anticancer target due to the relationship between its constitutive activation and malignant tumors. Through a virtual screening approach on the STAT3-SH2 domain, 5,6-dimethyl-1H,3H-2,1,3-benzothiadiazole-2,2-dioxide (1) was identified as a potential STAT3 inhibitor. Some benzothiadiazole derivatives were synthesized by employing a versatile methodology, and they were tested by an AlphaScreen-based assay. Among them, benzosulfamide 1 showed a significant activity with an IC50 = 15.8 &plusmn, 0.6 &micro, M as a direct STAT3 inhibitor. Notably, we discovered that compound 1 was also able to interact with cysteine residues located around the SH2 domain. By applying mass spectrometry, liquid chromatography, NMR, and UV spectroscopy, an in-depth investigation was carried out, shedding light on its intriguing and unexpected mechanism of interaction.

6-Hydroxy-2-methylbenzofuran-4-carboxylic acid was synthesized in two steps, starting from 3,5-dihydroxybenzoate. The product was obtained through a direct thermal one-pot cyclization with propargyl bromide, followed by a base-catalyzed hydrolysis. Its molecular structure was elucidated by means of mono- and bidimensional NMR techniques, ESI-MS, FT-IR and single-crystal X-ray diffraction.

We report on the virtual screening, synthesis, and biological evaluation of new furan derivatives targeting Mycobacterium tuberculosis salicylate synthase (MbtI). A receptor-based virtual screening procedure was applied to screen the Enamine database, identifying two compounds, I and III, endowed with a good enzyme inhibitory activity. Considering the most active compound I as starting point for the development of novel MbtI inhibitors, we obtained new derivatives based on the furan scaffold. Among the SAR performed on this class, compound la emerged as the most potent MbtI inhibitor reported to date (K-i = 5.3 mu M). Moreover, compound la showed a promising antimycobacterial activity (MIC99 = 156 mu M), which is conceivably related to mycobactin biosynthesis inhibition. (C) 2018 Elsevier Masson SAS. All rights reserved.

Background:Since Signal Transducer and Activator of Transcription 3 (STAT3) is a transcription factor which plays an important role in multiple aspects of cancer, including progression and migration, and it is constitutively activated in various human tumors, STAT3 inhibition has emerged as a validated strategy for the treatment of several malignancies. The aim of this review is to provide an update on the identification of new promising direct inhibitors targeting STAT3 domains, as potential anticancer agents.Methods:A thorough literature search focused on recently reported STAT3 direct inhibitors was undertaken. We considered the relevant developments regarding the STAT3 domains, which have been identified as potential drug targets.Results:In detail, 135 peer-reviewed papers and 7 patents were cited; the inhibitors we took into account targeted the DNA binding domain (compounds were grouped into natural derivatives, small molecules, peptides, aptamers and oligonucleotides), the SH2 binding domain (natural, semi-synthetic and synthetic compounds) and specific residues, like cysteines (natural, semi-synthetic, synthetic compounds and dual inhibitors) and tyrosine 705.Conclusion:The huge number of direct STAT3 inhibitors recently identified demonstrates a strong interest in the investigation of this target, although it represents a challenging task considering that no drug targeting this enzyme is currently available for anticancer therapy. Notably, many studies on the available inhibitors evidenced that some of them possess a dual mechanism of action.

A collection of systematically substituted 3-cyclo-butylcarbamoyl hydantoins was synthesized by a regioselective multicomponent domino process followed by easy coupling reactions. Calculations, NMR studies and X-ray analysis show that these scaffolds are able to project their side chains similar to common secondary structures, such as the α-helix and β-turn, with favourable enthalpic and entropic profiles.

Three new ureido-pyridazinone derivatives, which are structurally related to the known STAT3 inhibitor AVS-0288, were designed by taking into account the structure–activity relationships determined for several ureido-oxadiazole derivatives previously studied by our group. Their synthesis was first attempted through suitable 5-aminopyridazinone intermediates (6a and 6b), which molecular structures were confirmed by means of X-ray diffraction data on 6a. Amine functionalization was unsuccessful, therefore, an alternative method was devised. Dual-luciferase and AlphaScreen-based assays were used to test their activity. The obtained data were rationalized on the basis of a modeling study, which focused our attention on the geometrical preferences of the ureido moiety. Computational results seem to indicate that both the 1,2,5-oxadiazole ring and the extended ZZ arrangement are essential and probably act in a synergistic way to confer significant activity against STAT3.

A novel one-pot multicomponent synthesis of heteroarylogous 1H-indole-3-carboxamidines starting from readily available N-alkyl-N-(1H-indol-2-ylmethyl)amines, isocyanides, and carbonyl compounds is reported. The strategy exploits the ability of the indole nucleus to interrupt the classical Ugi reaction, by intercepting the nascent nitrilium ion.

Cortexolone-17α-propionate (CP) is a topically active antiandrogen useful in the treatment of skin disorders. In the solid state, three anhydrous forms of this drug (CPI, CPII and CPIII) occur, together with one hydrated crystal (CPW). The single crystal structure of the monohydrated phase, CPW, compared with that of the anhydrous form CPIII, shows a markedly different solid state behavior. These latter pseudopolymorphic forms have also been fully characterized by spectroscopic methods.

A novel interrupted Ugi reaction between ortho -sulfonylaminated aryl aldehydes, secondary amines, and isocyanides affords in good to high yields N -alkyl-2,3-diaminoindoles, providing access to a so far unexplored area of the indole chemical space. With only one single chemical operation, this novel reaction affords a broad gamma of substituted 2,3-diaminoindoles with five points of diversity. The success of this novel multicomponent transformation lies in presence of the amphoteric sulfonylamino group, which sequentially acts as a Bronsted acids and as a nucleophile the lack of need for additional catalysts and the high atom economy, with the loss of only one molecule of water, renders this approach a very effective one.

An efficient Ugi three-component reaction of a preformed chiral ketimine derived from isatin with various isonitrile and acid components has been developed. The reactions proceeded smoothly and in a stereocontrolled manner with regard to the new center of the Ugi products due to the stereoinduction of the amine chiral residue. A wide variety of novel chiral 3,3-disubstituted 3-aminooxindoles were obtained, a selection of which were subjected to post-Ugi transformations, paving the way to application as peptidomimetics.

The reaction of the diazonium salt 12 derived from N-(2-aminophenyl)-N,3 -dimethyl-1-phenyl- 1H-pyrazole-5-carboxamide with copper sulfate and sodium chloride in the presence of ascorbic acid afforded the unexpected products 3,5-dimethyl-1-phenyl-1,5-dihydro-4H-pyrazolo(4,3-c)- quinolin-4-one ( 17 ) and N-methyl-2-(3-methyl-1-phenyl-1H-pyrazol-5-yl)aniline ( 19 ), accompanied by N-(2-chlorophenyl)-N,3-dimethyl-1-phenyl-1H-pyrazole-5-carboxamide ( 18 ). Products 17 and 19 are formed via a non-classical Pschorr reaction. The formation of 17 represents an alternative to the literature synthesis of this biologically active compound. The molecular structure of 18 was confirmed by single-crystal X-ray analysis.

Signal Transducer and Activator of Transcription 3 (STAT3) is a cytoplasmic factor that mediates intracellular signaling commonly generated at cell surface receptors and transmits it to the nucleus. In previous research studies we synthesized several molecules inhibiting STAT3 and among them oxadiazole MD77 and pyridazinone I showed an interesting activity. For the first one, a direct inhibition mechanism was determined, while I interfered within the STAT3 pathway at a different level. In order to discover novel compounds possibly endowed with an improved activity, we decided to merge their scaffolds on the basis of their calculated conformational properties. Therefore we designed and synthesized the chimera diastereomers 3-oxo-N-(4-(trifluoromethyl)phenyl)-2,3,4,4a,5,6-hexahydrobenzo[h]cinnoline-6-carboxamide (1, 2) and 3-oxo-N-(4-(trifluoromethyl)phenyl)-2,3,5,6-tetrahydrobenzo[h]cinnoline-6-carboxamide (3) as racemate and their enantiomeric separation was performed. Modeling studies and theoretical prediction of [α]D values were carried out beside NMR studies which allowed us to assign 1 and 2 relative configurations.

By capitalizing on the different reactivity of nitrile N-oxides with isocyanides and amine, α-oximinoamidines, a so far elusive class of compounds, have been synthesized in a straightforward way by reacting isocyanides, syn-chlorooximes, and amines in a multicomponent fashion.

Tuberculosis nowadays ranks as the second leading cause of death from an infectious disease worldwide. In the last twenty years, this disease has again started to spread mainly for the appearance of multi-drug resistant forms. Therefore, new targets are needed to address the growing emergence of bacterial resistance and for antitubercular drug development. Efficient iron acquisition is crucial for the pathogenesis of Mycobacterium tuberculosis, because it serves as cofactor in many essential biological processes, including DNA biosynthesis and cellular respiration. Bacteria acquire iron chelating non-heme iron from the host using the siderophore mycobactins and carboxymycobactins and by the uptake of heme iron released by damaged red blood cells, through several acquisition systems. Drug discovery focused its efforts on the inhibition of MbtI and MbtA, which are are two enzymes involved in the mycobactin biosynthetic pathway. In particular, MbtI inhibitors have been studied in vitro, while MbtA inhibitors showed activity also in infected mice. Another class of compounds, MmpL3 inhibitors, showed antitubercular activity in vitro and in vivo, but their mechanism of action seems to be off-target. Some compounds inhibiting 4’-phosphopantetheinyl transferase were discovered but not tested on in vivo assays. The available data reported in this study based on inhibitors and gene deletion studies, suggest that targeting iron acquisition systems could be considered a promising antitubercular strategy. Due to their redundancy, the relative importance of each pathway for Mycobacterium tuberculosis survival has still to be determined. Thus, in vivo studies with new, potent and specific inhibitors are needed to highlight target selection.

New N-methyl and N-ethyl substitutions in the indazole nucleus are reported by reacting 3-(2-aminobenzamido)indazole and the appropriate trimethyl/triethyl orthobenzoate. Single crystal X-ray analysis confirms the N-ethylation position for the 3-(1-ethyl-1H-indazol-3-yl)-2-phenylquinazolin-4(3H)-one derivative 3f. Compounds 11a-d and 3a-d were tested to evaluate their antimicrobial, their antiproliferative activity and their COX inhibitory activities showing scarce or moderately antiproliferative activity and some inhibitory activity against COX-1 and COX-2.

The novel one-pot multicomponent reaction is based on the reaction of N-alkyl-N-(1H-indol-2-ylmethyl)amines, with various carbonyl compounds, such as aldehydes including formaldehyde or cyclohexenone, and variously functionalized isocyanides.

6,17α-Dimethyl-4,6-pregnadiene-3,20-dione (medrogestone, 2) is for a long time known steroid endowed with progestational activity. In order to study its crystallographic and NMR spectroscopic properties with the aim to fill the literature gap, we prepared medrogestone following a traditional procedure. A careful NMR study allowed the complete assignment of the (1)H and (13)C NMR signals not only of medrogestone but also of its synthetic intermediates. The structural and stereochemical characterizations of medrogestone together with its precursor 17α-methyl-3-ethoxy-pregna-3,5-dien-20-one were described by means of X-ray analysis, allowing a deepened conformational investigation.

Synthetically useful aminodioximes are prepared via a novel three-component reaction among Z-chlorooximes, isocyanides, and hydroxylamines by exploiting the preferential attack of isocyanides to nitrile N-oxides via a [3 + 1] cycloaddition reaction. The results of quantum mechanical studies of the reaction mechanism are also discussed. Furthermore, the one-pot conversion of aminodioximes to 1,2,3-oxadiazole-5-amines via Mitsunobu–Beckmann rearrangement is reported for the first time.