Novel Organic Salts Based on Mefloquine: Synthesis, Solubility, Permeability, and In Vitro Activity against Mycobacterium tuberculosis.

The development of novel pharmaceutical tools to efficiently tackle tuberculosis is the order of the day due to the rapid development of resistant strains of Mycobacterium tuberculosis. Herein, we report novel potential formulations of a repurposed drug, the antimalarial mefloquine (MFL), which was combined with organic anions as chemical adjuvants. Eight mefloquine organic salts were obtained by ion metathesis reaction between mefloquine hydrochloride ([MFLH][Cl]) and several organic acid sodium salts in high yields. One of the salts, mefloquine mesylate ([MFLH][MsO]), presented increased water solubility in comparison with [MFLH][Cl]. Moreover, all salts with the exception of mefloquine docusate ([MFLH][AOT]) showed improved permeability and diffusion through synthetic membranes. Finally, in vitro activity studies against Mycobacterium tuberculosis revealed that these ionic formulations exhibited up to 1.5-times lower MIC values when compared with [MFLH][Cl], particularly mefloquine camphorsulfonates ([MFLH][(1R)-CSA], [MFLH][(1S)-CSA]) and mefloquine HEPES ([MFLH][HEPES]).

Novel 2-Nitroimidazole and Imidazooxazole Derivatives and their Activity against Trypanosoma cruzi and Mycobacterium tuberculosis.

BACKGROUND: Tuberculosis (TB) is one of the top ten causes of death worldwide, while Chagas disease (CD) is the parasitic disease that kills the largest number of people in the Americas. TB is the leading cause of death for patients with AIDS; it kills 1.5 million people and causes 10 million new cases every year. The lack of newly developed chemotherapeutic agents and insufficient access to health care services for a diagnosis increase the incidence of multidrug-resistant TB (MDRTB) cases. Although CD was identified in 1909, the chronic stages of the disease still lack adequate treatment. OBJECTIVE: The purpose of this work was to design and synthesize two new series of 2-nitroimidazole 5a-e and imidazooxazoles 6a-e with 1H-1,2,3-triazolil nucleus and evaluate their activities against Tc and Mycobacterium tuberculosis (Mtb). METHODS: Two series of five compounds were synthesized in a 3 or 4-step route in moderated yields, and their structures were confirmed by NMR spectral data analyses. The in vitro antitrypanosomal evaluation of products was carried out in an intracellular model using L929 cell line infected with trypomastigotes and amastigote forms of Tc of ß-galactosidase-transfected Tulahuen strain. Their antimycobacterial activity was evaluated against Mtb strain H37Rv. RESULTS: In general, 2-nitroimidazolic derivatives proved to be more potent in regard to antitrypanocidal and antimycobacterial activity. The non-cytotoxic 2-nitroimidazole derivative 5b was the most promising with a half maximum inhibitory concentration of 3.2 µM against Tc and a minimum inhibitory concentration of 65.3 µM against Mtb. CONCLUSION: Our study reinforced the importance of 2-nitroimidazole and 1H-1,2,3-triazole nuclei in antimicrobial activity. In addition, derivative 5b proved to be the most promising, presenting important activity against Tc and Mtb and could be used as a starting point for the development of new agents against these diseases.

Mefloquine synergism with anti-tuberculosis drugs and correlation to membrane effects: Biologic, spectroscopic and molecular dynamics simulations studies.

Studies displaying the combination of mefloquine (MFL) with anti-tuberculosis (TB) substances are limited in the literature. In this work, the effect of MFL-association with two first-line anti-TB drugs and six fluoroquinolones was evaluated against Mycobacterium tuberculosis drug resistant strains. MFL showed synergistic interaction with isoniazid, pyrazinamide, and several fluoroquinolones, reaching fractional inhibitory concentration indexes (FICIs) ranging from 0.03 to 0.5. In order to better understand the observed results, two approaches have been explored: (i) spectroscopic responses attributed to the effect of MFL on physicochemical properties related to a liposomal membrane model composed by soybean asolectin; (ii) molecular dynamics (MD) simulation data regarding MFL interaction with a membrane model based on PIM2, a lipid constituent of the mycobacterial cell wall. FTIR and NMR data showed that MFL affects expressively the region between the phosphate and the first methylene groups of soybean asolectin membranes, disordering these regions. MD simulations results detected high MFL density in the glycolipid interface and showed that the drug increases the membrane lateral diffusion, enhancing its permeability. The obtained results suggest that synergistic activities related to MFL are attributed to its effect of lipid disorder and membrane permeability enhancement.

Synthesis, Antitrypanosomal and Antimycobacterial Activities of Coumarin N-acylhydrazonic Derivatives.

BACKGROUND: Near to 5-7 million people are infected with T. cruzi in the world, and about 10,000 people per year die of problems associated with this disease. METHODS: Herein, the synthesis, antitrypanosomal and antimycobacterial activities of seventeen coumarinic N-acylhydrazonic derivatives have been reported. RESULTS: These compounds were synthesized using methodology with reactions global yields ranging from 46%-70%. T. cruzi in vitro effects were evaluated against trypomastigote and amastigote, forming M. tuberculosis activity towards H37Rv sensitive strain and resistant strains. DISCUSSION: Against T. cruzi, the more active compounds revealed only moderate activity IC50/96h~20 µM for both trypomastigotes and amastigotes intracellular forms. (E)-2-oxo-N'- (3,4,5-trimethoxybenzylidene)-2H-chromene-3-carbohydrazide showed meaningful activity in INH resistant/RIP resistant strain. CONCLUSION: These compound acting as multitarget could be good leads for the development of new trypanocidal and bactericidal agents.

Benzoylthioureas: Design, Synthesis and Antimycobacterial Evaluation.

BACKGROUND: New drugs and strategies to treat tuberculosis (TB) are urgently needed. In this context, thiourea derivatives have a wide range of biological activities, including anti-TB. This fact can be illustrated with the structure of isoxyl, an old anti-TB drug, which has a thiourea as a pharmacophore group. OBJECTIVE: The aim of this study is to describe the synthesis and the antimycobacterial activity of fifty-nine benzoylthioureas derivatives. METHODS: Benzoylthiourea derivatives have been synthesized and evaluated for their activity against Mycobacterium tuberculosis using the MABA assay. After that, a structure-activity relationship study of this series of compounds has been performed. RESULTS AND DISCUSSION: Nineteen compounds exhibited antimycobacterial activity between 423.1 and 9.6 µM. In general, we observed that the presence of bromine, chlorine and t-Bu group at the para-position in benzene ring plays an important role in the antitubercular activity of Series A. These substituents were fixed at this position in benzene ring and other groups such as Cl, Br, NO2 and OMe were introduced in the benzoyl ring, leading to the derivatives of Series B. In general, Series B was less cytotoxic than Series A, which indicates that the presence of a substituent at benzoyl ring contributes to an improvement in both antimycobacterial activity and toxicity profiles. CONCLUSION: Compound 4c could be considered a good prototype to be submitted to further structural modifications in the search for new anti-TB drugs, since it is 1.8 times more active than the first line anti-TB drug ethambutol and 0.65 times less active than isoxyl.

Cutaneous tuberculosis in Rio de Janeiro, Brazil: description of a series of 75 cases.

BACKGROUND: Brazil is one of the highest tuberculosis (TB) burden countries of the world. Cutaneous tuberculosis (CTB) is a rare form of extrapulmonary manifestation of tuberculosis. This study aimed to describe the clinico-evolutive, laboratory and therapeutic aspects of CTB cases among patients from a cohort with TB in Rio de Janeiro, Brazil. METHODS: Cases of diagnosed CTB with microbiologic confirmation or clinical response to anti-tuberculous treatment associated with positive smear or histopathological findings between the years 2000 and 2016 were selected. RESULTS: Seventy-five patients with CTB were included, most were women (58.7%) with a median age of 42 years. CTB diagnosis was based on culture in only 42.7% of the cases. Scrofuloderma represented 50.7% of the cases, followed by erythema induratum of Bazin (EIB) (18.7%), tuberculous gumma (13.3%), lupus vulgaris (8%), TB verrucosa cutis (4%), orificial TB (2.7%) and associated forms (2.7%). Other TB presentations were pulmonary (22.7%), mammary (6.6%) and osteoarticular (4%). All patients who completed the treatment (97.3%) had their lesions healed. Only two patients (2.6%) needed to change the therapy due to adverse reactions. Fifty percent of EIB patients presented recurrence. CONCLUSIONS: These data highlight the diversity of CTB presentations and the importance of the skin to assist in early identification and treatment of TB. More studies are necessary to improve the knowledge on EIB for a better approach towards these patients, mainly in cases of recurrence.

Synthesis and Antibacterial Activity of Mefloquine-Based Analogs Against Sensitive and Resistant Mycobacterium tuberculosis Strains.

Background and Introduction: Mefloquine, a drug used to prevent and treat malaria is described possessing activity against the Mycobacterium tuberculosis (Mtb) as well as against multidrugresistant tuberculosis (MDR) and other types of bacteria. Despite their importance, few compounds based on the Mefloquine nucleus have been synthesized and evaluated against TB. MATERIALS AND METHODS: For the synthesis of all the compounds based on the Mefloquine nucleus we used a synthetic route which utilized the key derivative 4-methoxy-2,8-bis(trifluoromethyl)quinoline 2 as starting material. The compounds 3 (a-c), 4 (a-b) were synthesized after one step by reaction of 2 with appropriate amines substituted. The chloro derivatives 5 and 6 were obtained from compounds 4b and 4a by treatment with SOCl2 in CH2Cl2 at reflux in 75 and 80% yield, respectively. The analogue 6 was converted to 7 after treatment with ethanolamine under heating at 90oC in 64% yield and to the azido derivative 8 in 56% after reaction with sodium azide in MeOH at reflux for 2 h. The analogue 9 was obtained after reaction of 5 with ethanolamine at 90oC for 1 h in 90% yield. All the new compounds were identified by detailed spectral data, including 1H NMR, 13C NMR and high resolution mass spectra. All the compound were evaluated for their in vitro antibacterial activity against sensitive Mycobacterium tuberculosis ATCC 27294, using the microplate Alamar Blue assay (MABA). The more active compounds 3c, 7, and 9 were also evaluated against resistant strain SR 2571/0215 (resistant to Rifampicin and Isoniazid) by above method. All compounds were tested against three cancer cell lines: SF-295 (glioblastoma), HCT-116 (colon) and PC-3 (prostate) using the MTT assay. RESULTS: All the planned ten compounds were synthetically obtained in good global yield, displaying activity against sensitive Mycobacterium tuberculosis in vitro, with exception of one, with MIC values between 37.2 and 154.8 µM. The compounds 3c (37.2 µM), 7 (68.1 µM) and 9 (65.6 µM) showed the highest activity in this series with MIC values similar when compare to the standard Mefloquine (30 - 60 µM), being 3c the most potent. The more active compounds 3c, 7, and 9 were also evaluated against resistant strain, displaying MIC of 37.2, 136.2 and 65.6 µM, respectively. All compounds were tested against three cancer cell lines and showed low cytotoxicity. CONCLUSION: All synthesized compounds, with the exception of 5, exhibited activity against the Mtb. Compound 3c was the most potent against resistant and sensitive Mtb in this series, with MIC value of 37.2 µM. All compounds showed low cytotoxicity. These findings could be considered a good model to develop possible lead compounds in the fight against TB based on Mefloquine nucleus.

Anti-Mycobacterial Evaluation of 7-Chloro-4-Aminoquinolines and Hologram Quantitative Structure-Activity Relationship (HQSAR) Modeling of Amino-Imino Tautomers.

In an ongoing research program for the development of new anti-tuberculosis drugs, we synthesized three series (A, B, and C) of 7-chloro-4-aminoquinolines, which were evaluated in vitro against Mycobacterium tuberculosis (MTB). Now, we report the anti-MTB and cytotoxicity evaluations of a new series, D (D01-D21). Considering the active compounds of series A (A01-A13), B (B01-B13), C (C01-C07), and D (D01-D09), we compose a data set of 42 compounds and carried out hologram quantitative structure-activity relationship (HQSAR) analysis. The amino-imino tautomerism of the 4-aminoquinoline moiety was considered using both amino (I) and imino (II) forms as independent datasets. The best HQSAR model from each dataset was internally validated and both models showed significant statistical indexes. Tautomer I model: leave-one-out (LOO) cross-validated correlation coefficient (q²) = 0.80, squared correlation coefficient (r²) = 0.97, standard error (SE) = 0.12, cross-validated standard error (SEcv) = 0.32. Tautomer II model: q² = 0.77, r² = 0.98, SE = 0.10, SEcv = 0.35. Both models were externally validated by predicting the activity values of the corresponding test set, and the tautomer II model, which showed the best external prediction performance, was used to predict the biological activity responses of the compounds that were not evaluated in the anti-MTB trials due to poor solubility, pointing out D21 for further solubility studies to attempt to determine its actual biological activity.

Synthesis, Antitubercular and Anticancer Activities of p-nitrophenylethylenediamine-derived Schiff Bases.

BACKGROUND: Schiff bases have been greatly studied in biological field due to their wide range of pharmacological activities, such as antitubercular and antitumour. In the search of novel antitubercular agents, several compounds containing pharmacophoric group of ethambutol have been synthesized and evaluated against mycobacteria species causing tuberculosis. In this work, we investigate whether ethylenediamine, Schiff base as well as nitro group together could contribute to the formation of novel molecules with dual biological activities: antitubercular and anticancer. METHODS: A series of Schiff bases (3-12) derived from p-nitrophenylethylenediamine (1) as well as N1,N2-bis(4-nitrophenyl)ethane-1,2-diamine (2) were synthetized and assayed for their action against Mycobacterium tuberculosis H37Rv strain and the human tumour cell lines SF-295 (glioblastoma multiforme), HCT-116 (colon adenocarcinoma) and OVCAR-8 (ovarian cancer). RESULTS: Among the compounds that showed antimycobacterial effects, 4 was more active than ethambutol, the antitubercular drug used as positive control. Also, compounds 1, 8, 10 and 12 were able to reduce strongly the viability of the tumour cell lines at 5 µgmL-1. CONCLUSION: According to studies, some modifications on p-nitrophenylethylenediamine (1) were an effective strategy to obtain compounds with antiproliferactive activities. Also, Schiff base 4 proved to be the lead antitubercular compound.

Synthesis and evaluation of copper(II) complexes with isoniazid-derived hydrazones as anticancer and antitubercular agents.

In this study, the N,N,O metal chelator 2-pyridinecarboxaldehydeisonicotinoyl hydrazone (HPCIH, 1) and its derivatives 2-acetylpyridine-(HAPIH 2), 2-pyridineformamide-(HPAmIH, 3) and pyrazineformamide-(HPzAmIH, 4) were employed in the synthesis of four copper(II) complexes, [Cu(HPCIH)Cl2]·0.4H2O (5), [Cu(HAPIH)Cl2]·1.25H2O (6), [Cu(HPAmIH)Cl2]·H2O (7) and [Cu(HPzAmIH)Cl2]·1.25H2O (8). The compounds were assayed for their action toward Mycobacterium tuberculosis H37Rv ATCC 27294 strain and the human tumor cell lines OVCAR-8 (ovarian cancer), SF-295 (glioblastoma multiforme) and HCT-116 (colon adenocarcinoma). All copper(II) complexes were more effective in reducing growth of HCT-116 and SF-295 cells than the respective free hydrazones at 5 µg/mL, whereas only complex 7 was more cytotoxic toward OVCAR-8 lines than its ligand HPAmIH. 6 proved to be cytotoxic at submicromolar doses, whose IC50 values (0.39-0.86 µM) are similar to those ones found for doxorubicin (0.23-0.43 µM). Complexes 5 and 6 displayed high activity against M. tuberculosis (MIC = 0.85 and 1.58 µM, respectively), as compared with isoniazid (MIC = 2.27 µM), which suggests the compounds are attractive candidates as antitubercular drugs.

Anti-tuberculosis evaluation and conformational study of N-acylhydrazones containing the thiophene nucleus.

A series of N-acylhydrazonyl-thienyl derivatives (compounds 2 and 3), mainly of the type 2-(aryl-CH=N-NHCOCH2 )-thiene (2: aryl = substituted-phenyl; 3: aryl = heteroaryl) were evaluated against Mycobacterium tuberculosis. Particularly active compound was 3 (heteroaryl = 5-nitrothien-2-yl or 5-nitrofuran-2-yl) with MIC values of 8.5 and 9.0 µM, respectively. Moderately active compounds were compound 3 (heteroaryl = pyridin-2-yl) and compound 2 containing aryl = 2- or 4-hydroxyphenyl groups, with MIC values between 170 and 408 µM. Compound 2 containing OMe, H, F, Cl, Br, CN, and NO2 substituents and compound 3 (heteroaryl = furan-2-yl, thien-2-yl, pyrrol-2-yl, imidazol-2-yl, pyridin-3-yl, and pyridin-4-yl) were all inactive. Clearly, there is no correlation of activity with the electronic effects of the substituents. The activities suggest different modes of biological action of the compounds having nitro-heteroaryl groups, on the one hand, and the 2-hydroxyphenyl or pyridin-2-yl substituents, on the other hand. Compounds having 2- or 4-hydroxyphenyl, 2-hydroxy-5-nitrophenyl, or 4-hydroxy-3-chlorophenyl were less cytotoxic than ethambutol. It is important to notice that compound 3 (aryl = 5-NO2 -furan-2-yl) exhibited a promising therapeutic index (TI = 1093.90), with a value 4.4 less than that of ethambutol. Compounds 2 and 3 exist in DMSO or MeOD solutions as mixtures of EC(O)N /EC=N and ZC(O)N /EC=N conformers.

Syntheses and antimycobacterial activities of [(2S,3R)-2-(amino)-4-(arenesulfonamido)-3-hydroxy-1-phenylbutane derivatives.

The syntheses of hydroxyethylsulfonamides, (2S,3R)-tert-butyl N-[4-(N-benzyl-4-R-phenylsulfonamido)-3- hydroxy-1-phenylbutan-2-yl]carbamates and (5) (2S,3R)-2-amino-4-[N-benzyl-4-R-benzenesulfonamido]-3-hydroxy-1- phenylbutane hydrochlorides (6), derived from (2S,3S)-Boc-phenylalanine epoxide, are reported. None of the compounds, containing the Boc group, showed activity against M. tuberculosis ATTC 27294, while compounds 6 did, with the most active compounds having R = p-Cl, p-Br and p-Me. Results indicate that the presence of a free amino group at C2 and the sulphonamide moiety are important for biological activity. The antimycobacterial activity of compounds 6 correlated well with the calculated lipophilicities, but not with the electronic effects of the substituents, R. All compounds 6 were highly cytotoxic against the hepatoma cell lineage Hep G2 A16. The X-ray crystal structure of compound [(6: R = Me).H2O] is also reported. In the propeller-like conformation adopted by the cation, the amino and hydroxy groups have a cis arrangement, and thus are suitably placed to form 5- membered chelates.

Experimental and theoretical NMR determination of isoniazid and sodium p-sulfonatocalix[n]arenes inclusion complexes.

In this work the inclusion complex formation of isoniazid with sodium p-sulfonatocalix[n]arenes is reported aiming to improve the physicochemical and biopharmaceutical properties of isoniazid a first line antibuberculosis drug. The architectures of the complexes were proposed according to NMR data Job plot indicating details on the insertion of the isoniazid in the calix[n]arenes cavities. DFT theoretical NMR calculations were also performed for sodium p-sulfonatocalix[4]arene complex with isoniazid, with various modes of complexation being considered, to provide support for the experimental proposal. A comparison between experimental and theoretical ¹H NMR chemical shifts profiles allowed for the inclusion complex characterization confirming the isoniazid inclusion mode which is preferentially through the hydrazide moiety. The remarkable agreement between experimental and theoretical NMR profiles adds support to their use in the structural characterization of inclusion compounds. Antibacterial activity was evaluated and the results indicated the inclusion complexes as a potential strategy for tuberculosis treatment.

Mefloquine-oxazolidine derivatives, derived from mefloquine and arenecarbaldehydes: In vitro activity including against the multidrug-resistant tuberculosis strain T113.

Ten new mefloquine-oxazolidine derivatives, 4-[(1S,8aR)-3-(aryl)hexahydro[1,3]oxazolo[3,4-a]pyridin-1-yl]-2,8-bis(trifluoromethyl)quinoline (1: aryl=substituted phenyl) and 4-[(1S,8aR)-3-(heteroaryl)hexahydro[1,3]oxazolo[3,4-a]pyridin-1-yl]-2,8-bis(trifluoromethyl)quinoline [2: heteroaryl=5-nitrothien-2-yl (2a); 5-nitrofuran-2-yl (2b) and 4H-imidazol-2-yl) (2c)], have been synthesized and evaluated against Mycobacterium tuberculosis. Compounds 1f (aryl=3-ethoxyphenyl), 1g (Ar=3,4,5-(MeO)(3)-C(6)H(2)) and 2c were slightly more active than mefloquine (MIC=33µM) with MICs=24.5, 22.5 and 27.4, respectively, whereas compounds 1e (aryl=3,4-(MeO)(2)-C(6)H(3)) and 2a (MICs=11.9 and 12.1µM, respectively) were ca. 2.7 times more active than mefloquine, with a better tuberculostatic activity than the first line tuberculostatic agent ethambutol (MIC=15.9). The compounds were also assayed against the MDR strain T113 and the same MICs were observed. Thus the new derivatives have advantages over such anti-TB drugs as isoniazid, rifampicin, ethambutol and ofloxacin, for which this strain is resistant. The most active compounds were not cytotoxic to Murine Macrophages Cells in a concentration near their MIC values.

Synthesis and antitubercular activity of novel amino acid derivatives.

In this work, 17 new N-acylhydrazone derivatives of amino acids have been evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. The compounds 8b, 8e, 8f, 9a-d, and 10c exhibited an important minimum inhibitory concentration activity between 12.5 and 50 µg/mL, which can be compared with that of the tuberculostatic drug d-cycloserine (20 µg/mL).

Synthesis, antitubercular activity, and SAR study of N-substituted-phenylamino-5-methyl-1H-1,2,3-triazole-4-carbohydrazides.

Tuberculosis treatment remains a challenge that requires new antitubercular agents due to the emergence of multidrug-resistant Mycobacterium strains. This paper describes the synthesis, the antitubercular activity and the theoretical analysis of N-substituted-phenylamino-5-methyl-1H-1,2,3-triazole-4-carbohydrazides (8a-b, 8e-f, 8i-j and 8n-o) and new analogues (8c-d, 8g-h, 8l-m and 8p-q). These derivatives were synthesized in good yields and some of them showed a promising antitubercular profile. Interestingly the N-acylhydrazone (NAH) 8n was the most potent against the Mycobacterium tuberculosis H37Rv strain (MIC=2.5 µg/mL) similar to or better than the current drugs on the market. The theoretical structure-activity relationship study suggested that the presence of the furyl ring and the electronegative group (NO(2)) as well as low lipophilicity and small volume group at R position are important structural features for the antitubercular profile of these molecules. NMR spectra, IR spectra and elemental analyses of these substances are reported.

Antitubercular activity of new coumarins.

The present article describes a series of 21 N '-benzylidene-2-oxo-2H-chromene-3-carbohydrazides 4a-4v, which were synthesized and evaluated for their cell viabilities in non-infected and Mycobacterium bovis Bacillus Calmette-Guerin-infected macrophages. Subsequently, the non-cytotoxic compounds 4c, 4g, 4h, 4j, 4l and 4t were assessed against Mycobacterium tuberculosis ATCC 27294 using the microplate Alamar Blue assay and the activity expressed as the minimum inhibitory concentration in µg/mL. These compounds exhibited a significant activity (50-100 µg/mL) when compared to the first-line drugs, such as pyrazinamide (PZA >100 µg/mL). These results could be considered a good starting point for further studies to develop new lead compounds to treat multidrug-resistant tuberculosis.

Synthesis and anti-mycobacterial activity of novel amino alcohol derivatives.

Thirteen new hydroxyethylamines have been synthesized from reactions of (2S,3S)Boc-phenylalanine epoxide, piperonylamine and arenesulfonyl chlorides in good yields. These compounds were evaluated as antibacterial agents against Mycobacterium tuberculosis H37Rv using the Alamar Blue susceptibility test and their activity expressed as the minimum inhibitory concentration (MIC) in µM. Two amino alcohols displayed significant activity when compared with first line drug ethambutol (EMB). Therefore this class of compounds could be a good starting point to develop new lead compounds in the treatment of tuberculosis.

Synthesis and antitubercular activity of new mefloquine-oxazolidine derivatives.

In this work, we report the synthesis and the antitubercular evaluation of 16 new mefloquine derivatives, formed from reactions between mefloquine and benzaldehydes, with the activity expressed as the minimum inhibitory concentration (MIC) in µM. The compounds were non-cytotoxic and exhibited an important activity (12.6 µM). The appreciable activity of these compounds can be considered an important finding for the rational design of new leads for anti-TB compounds.

Synthesis and antitubercular activity of heteroaromatic isonicotinoyl and 7-chloro-4-quinolinyl hydrazone derivatives.

Two series of N'-(E)-heteroaromatic-isonicotinohydrazide derivatives (3a-f and 4a-b) and 1-(7-chloroquinolin-4-yl)-2-[(heteroaromatic)methylene]hydrazone derivatives (5a-f and 6a-b) have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Several compounds were noncytotoxic and exhibited significant minimum inhibitory concentration (MIC) activity (3.12, 2.50, 1.25, or 0.60 microg/mL), which can be compared to that of the first-line drugs ethambutol (3.12 microg/mL) and rifampicin (2.0 microg/ml). These results can be considered an important starting point for the rational design of new leads for anti-TB compounds.