Novel thienocycloalkylpyridazinones as useful scaffolds for acetylcholinesterase inhibition and serotonin 5-HT6 receptor interaction.

A library of eighteen thienocycloalkylpyridazinones was synthesized for human acetylcholinesterase (hAChE) and butyrylcholinesterase (hBChE) inhibition and serotonin 5-HT6 receptor subtype interaction by following a multitarget-directed ligand approach (MTDL), as a suitable strategy for treatment of Alzheimer's disease (AD). The novel compounds featured a tricyclic scaffold, namely thieno[3,2-h]cinnolinone, thienocyclopentapyridazinone and thienocycloheptapyridazinone, connected through alkyl chains of variable length to proper amine moieties, most often represented by N-benzylpiperazine or 1-(phenylsulfonyl)-4-(piperazin-1-ylmethyl)-1H-indole as structural elements addressing AChE and 5-HT6 interaction, respectively. Our study highlighted the versatility of thienocycloalkylpyridazinones as useful architectures for AChE interaction, with several N-benzylpiperazine-based analogues emerging as potent and selective hAChE inhibitors with IC50 in the 0.17-1.23 µM range, exhibiting low to poor activity for hBChE (IC50 = 4.13-9.70 µM). The introduction of 5-HT6 structural moiety phenylsulfonylindole in place of N-benzylpiperazine, in tandem with a pentamethylene linker, gave potent 5-HT6 thieno[3,2-h]cinnolinone and thienocyclopentapyridazinone-based ligands both displaying hAChE inhibition in the low micromolar range and unappreciable activity towards hBChE. While docking studies provided a rational structural explanation for AChE/BChE enzyme and 5-HT6 receptor interaction, in silico prediction of ADME properties of tested compounds suggested further optimization for development of such compounds in the field of MTDL for AD.

Quinoxaline-based efflux pump inhibitors restore drug susceptibility in drug-resistant nontuberculous mycobacteria.

Nontuberculous mycobacteria (NTM) comprise several ubiquitous, environmentally localized bacteria that may be responsible for serious human diseases. NTM-associated pulmonary infections largely affect individuals with underlying respiratory disease or chronic disease and immunosuppressed patients. Mycobacterium simiae and M. abscessus are two NTMs responsible for lung disease in immunocompetent and immunocompromised individuals. In this study, two NTM strains were isolated from two patients admitted to an Italian hospital and were identified as M. simiae and M. abscessus. The two NTMs were tested for drug susceptibility against different antibiotics. To restore drug susceptibility, a new series of 2-aryl-3-phenoxymethyl-quinoxaline derivatives (QXs) was designed, synthesized, and investigated as efflux pump inhibitors (EPIs) against two clinical isolates of the above-cited NTMs, evaluating how EPIs can influence the drug minimal inhibitory concentration values and, therefore, the activity. The different\ resistance levels tracked in the clinical strains were reduced by EPIs, and in several cases, the susceptibility was completely restored. QXs also resulted as potential chemical probes to be used in drug susceptibility tests to identify the resistance origin when detected.

Tricyclic Pyrazole-Based Compounds as Useful Scaffolds for Cannabinoid CB1/CB2 Receptor Interaction.

Cannabinoids comprise different classes of compounds, which aroused interest in recent years because of their several pharmacological properties. Such properties include analgesic activity, bodyweight reduction, the antiemetic effect, the reduction of intraocular pressure and many others, which appear correlated to the affinity of cannabinoids towards CB1 and/or CB2 receptors. Within the search aiming to identify novel chemical scaffolds for cannabinoid receptor interaction, the CB1 antagonist/inverse agonist pyrazole-based derivative rimonabant has been modified, giving rise to several tricyclic pyrazole-based compounds, most of which endowed of high affinity and selectivity for CB1 or CB2 receptors. The aim of this review is to present the synthesis and summarize the SAR study of such tricyclic pyrazole-based compounds, evidencing, for some derivatives, their potential in the treatment of neuropathic pain, obesity or in the management of glaucoma.

Biological Effects on µ-Receptors Affinity and Selectivity of Arylpropenyl Chain Structural Modification on Diazatricyclodecane Derivatives.

Opioid analgesics are clinically used to relieve severe pain in acute postoperative and cancer pain, and also in the long term in chronic pain. The analgesic action is mediated by µ-, δ-, and κ-receptors, but currently, with few exceptions for k-agonists, µ-agonists are the only ones used in therapy. Previously synthesized compounds with diazotricyclodecane cores (DTDs) have shown their effectiveness in binding opioid receptors. Fourteen novel diazatricyclodecanes belonging to the 9-propionyl-10-substituted-9,10-diazatricyclo[4.2.1.12,5]decane (compounds 20-23, 53, 57 and 59) and 2-propionyl-7-substituted-2,7-diazatricyclo[4.4.0.03,8]decane (compounds 24-27, 54, 58 and 60) series, respectively, have been synthesized and their ability to bind to the opioid µ-, δ- and κ-receptors was evaluated. Five of these derivatives, compounds 20, 21, 24, 26 and 53, showed µ-affinity in the nanomolar range with a negligible affinity towards δ- and κ-receptors and high µ-receptor selectivity. The synthesized compounds showed µ-receptor selectivity higher than those of previously reported methylarylcinnamyl analogs.

Synthesis, biological evaluation and docking studies of a novel class of sulfur-bridged diazabicyclo[3.3.1]nonanes.

A small library of 3-thia-7,9-diazabicyclo[3.3.1]nonanes was synthesized and their opioid receptors affinity and selectivity evaluated. Among these novel sulfur-bridged compounds, the (E) 9-[3'-(3-chlorophenyl)-but-2'-en-1'-yl]-7-propionyl-3-thia-7,9-diazabicyclo[3.3.1]nonane 2i emerged as the derivative with the highest µ receptor affinity (Ki = 85 nM) and selectivity (Ki µ/δ = 58.8, Ki µ/κ > 117.6). The antinociceptive activity of 2i was also evaluated in acute thermal pain. Docking studies disclosed the specific pattern of interactions of these derivatives.

Development of Oxygen-Bridged Pyrazole-Based Structures as Cannabinoid Receptor 1 Ligands.

In this work, the synthesis of the cannabinoid receptor 1 neutral antagonists 8-chloro-1-(2,4-dichlorophenyl)-N-piperidin-1-yl-4,5-dihydrobenzo-1H-6-oxa-cyclohepta[1,2-c]pyrazole-3-carboxamide 1a and its deaza N-cyclohexyl analogue 1b has led to a deepening of the structure-activity studies of this class of compounds. A series of novel 4,5-dihydrobenzo-oxa-cycloheptapyrazoles analogues of 1a,b, derivatives 1c-j, was synthesized, and their affinity towards cannabinoid receptors was determined. Representative terms were evaluated using in vitro tests and isolated organ assays. Among the derivatives, 1d and 1e resulted in the most potent CB1 receptor ligands (KiCB1 = 35 nM and 21.70 nM, respectively). Interestingly, both in vitro tests and isolated organ assays evidenced CB1 antagonist activity for the majority of the new compounds, excluding compound 1e, which showed a CB1 partial agonist behaviour. CB1 antagonist activity of 1b was further confirmed by a mouse gastrointestinal transit assay. Significant activity of the new CB1 antagonists towards food intake was showed by preliminary acute assays, evidencing the potentiality of these new derivatives in the treatment of obesity.

Risk of hypertension with ramucirumab-based therapy in solid tumors: data from a literature based meta-analysis.

Ramucirumab is a monoclonal antibody against Vascular Endothelial Growth Factor Receptor-2 (VEGFR-2) approved for the treatment of several solid tumours. As shown in recent trials results, new-onset hypertension is one of the most frequent adverse events associated with ramucirumab therapy. Recent studies looked at the quantification of the risk of hypertension in patients receiving other anti-angiogenesis medications. We conducted a meta-analysis of randomized clinical trials with the aim to investigate the incidence and quantify the risk of new-onset hypertension of any grade in patients treated with ramucirumab. Our research suggests that hypertension is frequently associated with ramucirumab therapy, with an OR of 3.60 for any grade of hypertension and an even stronger correlation with grade 3-4 hypertension (OR 4.16). These data suggest that a strict monitoring, as well as early intervention protocols, are recommended in patients receiving the drug.

Multicenter External Validation of a Nomogram for Predicting Positive Prostate-specific Membrane Antigen/Positron Emission Tomography Scan in Patients with Prostate Cancer Recurrence.

BACKGROUND: A nomogram has recently been developed to predict 68Ga-labeled prostate-specific membrane antigen (PSMA)-11 positron emission tomography (PET)/computed tomography (PSMA-PET) results in recurrent prostate cancer (PCa) patients. OBJECTIVE: To perform external validation of the original nomogram in a multicentric setting. DESIGN, SETTING, AND PARTICIPANTS: A total of 1639 patients who underwent PSMA-PET for prostate-specific antigen (PSA) relapse after radical therapy were retrospectively included from six high-volume PET centers. The external cohort was stratified according to clinical setting categories: group 1: first-time biochemical recurrence (n = 774); group 2: PSA relapse after salvage therapy (n = 499); group-3: biochemical persistence after radical prostatectomy (n = 210); and group-4: advanced-stage PCa before second-line systemic therapies (n = 124). INTERVENTION: PSMA-PET in recurrent PCa. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: PSMA-PET detection rate was assessed in the overall population and in each subgroup. A multivariable logistic regression model was produced to evaluate the predictors of a positive scan. The performance characteristics of the model were assessed by quantifying the predictive accuracy (PA) according to model calibration. The Youden's index was used to find the best nomogram's cutoff. Decision curve analysis (DCA) was implemented to quantify the nomogram's clinical net benefit. RESULTS AND LIMITATIONS: In the external cohort, the overall detection rate was 53.8% versus 51.2% in the original population. At multivariate analysis, International Society of Urological Pathology grade group, PSA, PSA doubling time, and clinical setting were independent predictors of a positive scan (all p ≤ 0.02). The PA of the nomogram was identical to the original model (82.0%); the model showed an optimal calibration curve. The best nomogram's cutoff was 55%. In the DCA, the nomogram revealed clinical net benefit when the threshold nomogram probabilities were ≥20%. The retrospective design is a major limitation. CONCLUSIONS: The original nomogram exhibited excellent characteristics on external validation. The incidence of a false negative scan can be reduced if PSMA-PET is performed when the predicted probability is ≥20%. PATIENT SUMMARY: A nomogram has been developed to predict prostate-specific membrane antigen/positron emission tomography (PSMA-PET) results for recurrent prostate cancer (PCa). The nomogram represents an easy tool in the decision-making process of recurrent PCa.

Design, Synthesis, and Antiviral Activities of New Benzotriazole-Based Derivatives.

Several human diseases are caused by enteroviruses and are currently clinically untreatable, pushing the research to identify new antivirals. A notable number of benzo[d][1,2,3]triazol-1(2)-yl derivatives were designed, synthesized, and in vitro evaluated for cytotoxicity and antiviral activity against a wide spectrum of RNA positive- and negative-sense viruses. Five of them (11b, 18e, 41a, 43a, 99b) emerged for their selective antiviral activity against Coxsackievirus B5, a human enteroviruses member among the Picornaviridae family. The EC50 values ranged between 6 and 18.5 µM. Among all derivatives, compounds 18e and 43a were interestingly active against CVB5 and were selected to better define the safety profile on cell monolayers by transepithelial resistance test (TEER). Results indicated compound 18e as the hit compound to investigate the potential mechanism of action by apoptosis assay, virucidal activity test, and the time of addition assay. CVB5 is known to be cytotoxic by inducing apoptosis in infected cells; in this study, compound 18e was proved to protect cells from viral infection. Notably, cells were mostly protected when pre-treated with derivative 18e, which had, however, no virucidal activity. From the performed biological assays, compound 18e turned out to be non-cytotoxic as well as cell protective against CVB5 infection, with a mechanism of action ascribable to an interaction on the early phase of infection, by hijacking the viral attachment process.

Novel 1,3,4-oxadiazole chalcogen analogues: Synthesis and cytotoxic activity.

A small library of novel 1,3,4-oxadiazole bioisosteres was synthesized and their cytotoxic activity evaluated in vitro. Five of the new derivatives (3, 6, 11, 14 and 15) showed high potency against different human cancer cell lines, with 14 being the most interesting compound endowed with IC50 ranging from 0.005 to 0.091 µM. Preliminary SAR studies have suggested that the-chlorine atom in ortho position of the phenyl ring on the 1,3,4-selenadiazole is important for antitumor potency in vitro. Notably, these new compounds showed stronger anti-tumor activity than the previously synthesized and published oxadiazole lead compound 2. Furthermore, the cytotoxic effect was only relevant in tumor cells compared to human primary cells. These results suggest that the nature of the selenadiazole and thiadiazole rings may be even more important for antitumor potency in vitro than the nature of the previously described oxadiazole. All five compounds resulted in a G2/M arrest of the cell cycle and activated an apoptotic response. The colony formation assay showed the long-term effect of the compounds on tumor lines in vitro. Immunofluorescence analysis of ß-tubulin indicated that all compounds interacted with micro-tubulin organization and mitotic spindle formation causing aberrant cell formation. For these reasons, the new molecules 3, 6, 11, 14 and 15 could be good candidates in preventive and chemotherapeutic strategies.

Quinoline tricyclic derivatives. Design, synthesis and evaluation of the antiviral activity of three new classes of RNA-dependent RNA polymerase inhibitors.

In this study three new classes of linear N-tricyclic compounds, derived by condensation of the quinoline nucleus with 1,2,3-triazole, imidazole or pyrazine, were synthesized, obtaining triazolo[4,5-g]quinolines, imidazo[4,5-g]quinolines and pyrido[2,3-g]quinoxalines, respectively. Title compounds were tested in cell-based assays for cytotoxicity and antiviral activity against RNA viruses representative of the three genera of the Flaviviridae family, that is BVDV (Pestivirus), YFV (Flavivirus) and HCV (Hepacivirus). Quinoline derivatives were also tested against representatives of other RNA virus families containing single-stranded, either positive-sense (ssRNA(+)) or negative-sense (RNA(-)), and double-stranded genomes (dsRNA), as well as against representatives of two DNA virus families. Some quinolines showed moderate, although selective activity against CVB-5, Reo-1 and RSV. However, derivatives belonging to all classes showed activity against BVDV. Among the most potent were the bis-triazoloquinoline 1m, the imidazoquinolines 2e and 2h, and the pyridoquinoxalines 4h, 4j and 5n (EC(50) range 1-5 µM). When tested in a replicon assay, compound 2h was the sole derivative to also display anti-HCV activity (EC(50)=3.1 µM). In enzyme assays, 1m, 2h, 5m and 5n proved to be potent inhibitors of the BVDV RNA-dependent RNA polymerase (RdRp), while only 2h also inhibited the recombinant HCV enzyme.

Discovery of potent pteridine reductase inhibitors to guide antiparasite drug development.

Pteridine reductase (PTR1) is essential for salvage of pterins by parasitic trypanosomatids and is a target for the development of improved therapies. To identify inhibitors of Leishmania major and Trypanosoma cruzi PTR1, we combined a rapid-screening strategy using a folate-based library with structure-based design. Assays were carried out against folate-dependent enzymes including PTR1, dihydrofolate reductase (DHFR), and thymidylate synthase. Affinity profiling determined selectivity and specificity of a series of quinoxaline and 2,4-diaminopteridine derivatives, and nine compounds showed greater activity against parasite enzymes compared with human enzymes. Compound 6a displayed a K(i) of 100 nM toward LmPTR1, and the crystal structure of the LmPTR1:NADPH:6a ternary complex revealed a substrate-like binding mode distinct from that previously observed for similar compounds. A second round of design, synthesis, and assay produced a compound (6b) with a significantly improved K(i) (37 nM) against LmPTR1, and the structure of this complex was also determined. Biological evaluation of selected inhibitors was performed against the extracellular forms of T. cruzi and L. major, both wild-type and overexpressing PTR1 lines, as a model for PTR1-driven antifolate drug resistance and the intracellular form of T. cruzi. An additive profile was observed when PTR1 inhibitors were used in combination with known DHFR inhibitors, and a reduction in toxicity of treatment was observed with respect to administration of a DHFR inhibitor alone. The successful combination of antifolates targeting two enzymes indicates high potential for such an approach in the development of previously undescribed antiparasitic drugs.

Synthesis, Antitumor and Antiviral In Vitro Activities of New Benzotriazole-Dicarboxamide Derivatives.

Cancer and viral infections continue to threaten humankind causing death worldwide. Hence, the discovery of new anticancer and antiviral agents still represents a major scientific goal. Heterocycles designed to mimic the chemical structure of natural pyrimidines and purines have been designed over the years, exerting their activity acting as false substrates on several different targets. We reported a series of bis-benzotriazole-dicarboxamide derivatives which inhibit viral helicase of poliovirus, and hence we planned structure modifications to obtain different series of new dicarboxamides. Here, the synthesis and characterization of 56 new compounds: 31 bis-benzotriazole dicarboxamides and 25 mono-substituted acidic derivatives are reported. The synthesized compounds were tested for their antiviral and antitumor activity. Mostly, compounds 4a, 4c and 4d showed antiviral activity against tested Picornaviruses, Coxsackievirus B5 and Poliovirus-1. Likewise, four derivatives (3b, 3d, 4d, 9b) showed notable antiproliferative activity inhibiting cell growth in two distinct antitumor screenings. Compound 3b was selected as the antitumor lead compound for the wide range of activity and the potency proved. The lead compound was proved to induce apoptosis in SK-MES1 tumor cells, in a dose-dependent manner.

Hexanol-Based Supramolecular Solvents Tool for the Determination of 11 Illicit Phenethylamines in Oral Fluid by LC-MS/MS.

Monitoring of new phenethylamine designer drugs in oral fluid (OF) is a crucial aim in workplace testing and driving under the influence of drug programs. In this study a simple and very quick method for the quantification of 11 illicit drugs in OF, which gave negative results to immunoassay tests, is proposed. Sample treatment and extraction of analytes were simultaneously achieved by applying supramolecular solvents (SUPRAS) tool. Chromatographic separation and compounds quantification were carried out by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Efficacy of cleaning-up/extraction of this SUPRAS approach was fully confirmed by recovery and matrix effect results. The entire analytical procedure was validated following the international guidelines. The SUPRAS extraction coupled with LC-MS/MS resulted in powerful tool for the control of phenethylamines abuse, with rapid run time and minimal sample preparation. The use of this methodology could be easily extended to monitoring of other drugs of abuse.

5,6-Dichloro-2-phenyl-benzotriazoles: New Potent Inhibitors of Orthohantavirus.

Orthohantaviruses, previously known as hantaviruses (family Hantaviridae, order Bunyavirales), are emerging zoonoses hosted by different rodent and insectivore species. Orthohantaviruses are transmitted by aerosolized excreta (urine, saliva and feces) of their reservoir hosts. When transmitted to humans, they cause hemorrhagic fever with renal syndrome (HFRS) in Asia and Europe and hantavirus (cardio) pulmonary syndrome (HPS) in the Americas. Clinical studies have shown that early treatments of HFRS patients with ribavirin (RBV) improve prognosis. Nevertheless, there is the need for urgent development of specific antiviral drugs. In the search for new RNA virus inhibitors, we recently identified a series of variously substituted 5,6-dichloro-1(2)-phenyl-1(2)H-benzo[d][1,2,3]triazole derivatives active against the human respiratory syncytial virus (HRSV). Interestingly, several 2-phenyl-benzotriazoles resulted in fairly potent inhibitors of the Hantaan virus in a chemiluminescence focus reduction assay (C-FRA) showing an EC50 = 4-5 µM, ten-fold more active than ribavirin. Currently, there are no FDA approved drugs for the treatment of orthohantavirus infections. Antiviral activities and cytotoxicity profiles suggest that 5,6-dichloro-1(2)-phenyl-1(2)H-benzo[d][1,2,3]triazoles could be promising candidates for further investigation as a potential treatment of hantaviral diseases.

Preliminary Anti-Coxsackie Activity of Novel 1-[4-(5,6-dimethyl(H)- 1H(2H)-benzotriazol-1(2)-yl)phenyl]-3-alkyl(aryl)ureas.

BACKGROUND: Coxsackievirus infections are associated with cases of aseptic meningitis, encephalitis, myocarditis, and some chronic disease. METHODS: A series of benzo[d][1,2,3]triazol-1(2)-yl derivatives (here named benzotriazol-1(2)-yl) (4a-i, 5a-h, 6a-e, g, i, j and 7a-f, h-j) were designed, synthesized and in vitro evaluated for cytotoxicity and antiviral activity against two important human enteroviruses (HEVs) members of the Picornaviridae family [Coxsackievirus B 5 (CVB-5) and Poliovirus 1 (Sb-1)]. RESULTS: Compounds 4c (CC50 >100 µM; EC50 = 9 µM), 5g (CC50 >100 µM; EC50 = 8 µM), and 6a (CC50 >100 µM; EC50 = 10 µM) were found active against CVB-5. With the aim of evaluating the selectivity of action of this class of compounds, a wide spectrum of RNA (positive- and negativesense), double-stranded (dsRNA) or DNA viruses were also assayed. For none of them, significant antiviral activity was determined. CONCLUSION: These results point towards a selective activity against CVB-5, an important human pathogen that causes both acute and chronic diseases in infants, young children, and immunocompromised patients.

Enhancement of antimicrobial activity of pump inhibitors associating drugs.

INTRODUCTION: with the continuous emergence of pathogenic resistance to conventional drugs through efflux pumps, increasing efforts are directed toward discovering efflux inhibitory molecules. METHODOLOGY: in this study three P-glycoprotein (P13CP, P22CP, P34CP) efflux-inhibitors (EIs), belonging to the series of phenoxymethylquinoxalines capable to restore/potentiate the antiproliferative activity of doxorubicin and vincristine against human tumor cell lines and different antibiotics against clinical isolates, were investigated on 10 clinical strains of Candida and 12 clinical and ATCC strains of Gram positive and Gram-negative bacteria. RESULTS: MFC values of FLC were reduced in all Candida strains by the P22CP and P34CP inhibitors, and in 5/10 fungal strains by the P13CP inhibitor. CONCLUSION: novel antibiotics with new modes of action are urgently required to suppress the rise of MDR bacteria. An alternative approach would be to identify molecules that can interfere with the process of efflux.

Poly (ethyl 2-cyanoacrylate) nanoparticles (PECA-NPs) as possible agents in tumor treatment.

Tumor eradication has many challenges due to the difficulty of selectively delivering anticancer drugs to malignant cells avoiding contact with healthy tissues/organs. The improvement of antitumor efficacy and the reduction of systemic side effects can be achieved using drug loaded nanoparticles. In this study, poly (ethyl 2-cyanoacrylate) nanoparticles (PECA-NPs) were prepared using an emulsion polymerization method and their potential for cancer treatment was investigated. The size, polydispersity index and zeta potential of prepared nanoparticles are about 80 nm, 0.08 and -39.7 mV, respectively. The stability test shows that the formulation is stable for 15 days, while an increase in particle size occurs after 30 days. TEM reveals the spherical morphology of nanoparticles; furthermore, FTIR and 1H NMR analyses confirm the structure of PECA-NPs and the complete polymerization. The nanoparticles demonstrate an in vitro concentration-dependent cytotoxicity against human epithelial colorectal adenocarcinoma cell lines (Caco-2), as assessed by MTT assay. The anticancer activity of PECA-NPs was studied on 3D tumor spheroids models of hepatocellular carcinoma (HepG2) and kidney adenocarcinoma cells (A498) to better understand how the nanoparticles could interact with a complex structure such as a tumor. The results confirm the antitumor activity of PECA-NPs. Therefore, these systems can be considered good candidates in tumor treatment.

Novel N-aryl nicotinamide derivatives: Taking stock on 3,6-diazabicyclo[3.1.1]heptanes as ligands for neuronal acetylcholine receptors.

We designed the synthesis of a small library of 3-substituted-3,6-diazabicyclo[3.1.1]heptanes whose affinity on neuronal nicotinic receptors (nAChRs) was evaluated. Among the synthesized compounds, the 5-(3,6-diazabicyclo[3.1.1]heptane-3-yl)-N-(2-fluorophenyl)nicotinamide 43 proved to be the most interesting compound with α4ß2Ki value of 10 pM and a very high α7/α4ß2 selectivity. Furthermore, compounds 35, 39 and 43 elicited a selective partial agonist activity for α4ß2 nAChR subtype. Finally, in this paper we also report the conclusions on the 3,6-diazabicyclo[3.1.1]heptanes as ligands for nAChRs, resulting from our consolidated structure activity relationship (SAR) studies on this template.

Design, synthesis and antitubercular activity of 4-alkoxy-triazoloquinolones able to inhibit the M. tuberculosis DNA gyrase.

A number of new F-triazolequinolones (FTQs) and alkoxy-triazolequinolones (ATQs) were designed, synthesized and evaluated for their activity against Mycobacterium tuberculosis H37Rv. Five out of 21 compounds exhibited interesting minimum inhibitory concentration (MIC) values (6.6-57.9 µM), ATQs generally being more potent than FTQs. Two ATQs, 21a and 30a, were endowed with the best anti-Mtb potency (MIC = 6.9 and 6.6 µM, respectively), and were not cytotoxic in a Vero cell line. Tested for activity against M. tuberculosis DNA gyrase in a DNA supercoiling activity assay, 21a and 30a showed IC50 values (27-28 µM) comparable to that of ciprofloxacin (10.6 µM). 21a was next selected for screening against several Mtb strains obtained from clinical isolates, including multi-drug-resistant (MDR) variants. Importantly, this compound was effective in all cases, with very promising MIC values (4 µM) in the case of some isoniazid/rifampicin-resistant Mtb strains. Finally, computer-based simulations revealed that the binding mode of 21a in the Mtb gyrase cleavage core complexed with DNA and the relevant network of intermolecular interactions are utterly similar to those described for ciprofloxacin, yielding a molecular rationale for the comparable anti-mycobacterial and DNA gyrase inhibition activity of this quinolone.