Sensitive Mycobacterium Tuberculosis Research Articles

In vitro bioevaluation and docking study of dihydrosphingosine and ethambutol analogues against sensitive and multi-drug resistant Mycobacterium tuberculosis

Tuberculosis remains a major public health problem and one of the top ten causes of death worldwide. The alarming increase in multidrug-resistant and extensively resistant variants (MDR, pre-XDR, and XDR) makes the disease more difficult to treat and control. New drugs that act against MDR/XDR strains are needed for programs to contain this major epidemic. The present study aimed to evaluate new compounds related to dihydro-sphingosine and ethambutol against sensitive and pre-XDR Mycobacterium strains, as well as to characterize the pharmacological activity through in vitro and in silico approaches in mmpL3 protein. Of the 48 compounds analyzed, 11 demonstrated good to moderate activity on sensitive and MDR Mycobacterium tuberculosis (Mtb), with a Minimum Inhibitory Concentration (MIC) ranging from 1.5 to 8 μM. They presented 2 to 14 times greater potency of activity when compared to ethambutol in pre-XDR strain, and demonstrated a selectivity index varying between 2.21 and 82.17. The substance 12b when combined with rifampicin, showed a synergistic effect (FICI = 0.5) on sensitive and MDR Mtb. It has also been shown to have a concentration-dependent intracellular bactericidal effect, and a time-dependent bactericidal effect in M. smegmatis and pre-XDR M. tuberculosis. The binding mode of the compounds in its cavity was identified through molecular docking and using a predicted structural model of mmpL3. Finally, we observed by transmission electron microscopy the induction of damage to the cell wall integrity of M. tuberculosis treated with the substance 12b. With these findings, we demonstrate the potential of a 2-aminoalkanol derivative to be a prototype substance and candidate for further optimization of molecular structure and anti-tubercular activity in preclinical studies.

Tetrahydrobenzo[h]quinoline derivatives as a novel chemotype for dual antileishmanial-antimalarial activity graced with antitubercular activity: Design, synthesis and biological evaluation

Derivatives with tetrahydrobenzo[h]quinoline chemotype were synthesized via one-pot reactions and evaluated for their antileishmanial, antimalarial and antitubercular activities. Based on a structure-guided approach, they were designed to possess antileishmanial activity through antifolate mechanism, via targeting Leishmania major pteridine reductase 1 (Lm-PTR1). The in vitro antipromastigote and antiamastigote activity are promising for all candidates and superior to the reference miltefosine, in a low or sub micromolar range of activity. Their antifolate mechanism was confirmed via the ability of folic and folinic acids to reverse the antileishmanial activity of these compounds, comparably to Lm-PTR1 inhibitor trimethoprim. Molecular dynamics simulations confirmed a stable and high potential binding of the most active candidates against leishmanial PTR1. For the antimalarial activity, most of the compounds exhibited promising antiplasmodial effect against P. berghei with suppression percentage of up to 97.78%. The most active compounds were further screened in vitro against the chloroquine resistant strain P. falciparum, (RKL9) and showed IC50 value range of 0.0198–0.096 μM, compared to IC50 value of 0.19420 μM for chloroquine sulphate. Molecular docking of the most active compounds against the wild-type and quadruple mutant pf DHFR-TS structures rationalized the in vitro antimalarial activity. Some candidates showed good antitubercular activity against sensitive Mycobacterium tuberculosis in a low micromolar range of MIC, compared to 0.875 μM of isoniazid. The top active ones were further tested against a multidrug-resistant strain (MDR) and extensively drug-resistant strain (XDR) of Mycobacterium tuberculosis. Interestingly, the in vitro cytotoxicity test of the best candidates displayed high selectivity indices emphasizing their safety on mammalian cells. Generally, this work introduces a fruitful matrix for new dual acting antileishmanial-antimalarial chemotype graced with antitubercular activity. This would help in tackling drug-resistance issues in treating some Neglected Tropical Diseases.

Development and clinical evaluation of a CRISPR/Cas13a-based diagnostic test to detect Mycobacterium tuberculosis in clinical specimens.

Tuberculosis diagnosis requires rapid, simple and highly sensitive methods. Clustered regularly interspaced short palindromic repeats (CRISPRs) and associated protein (Cas) systems are increasingly being used for clinical diagnostic applications, due to their high flexibility, sensitivity and specificity. We developed a sensitive Mycobacterium tuberculosis (MTB) complex polymerase chain reaction (PCR)-CRISPR/Cas13a detection method (CRISPR-MTB) and then evaluated its performance in detecting MTB in clinical specimens. The conserved MTB IS1081 sequence was used to design CRISPR-derived RNAs (crRNAs) and T7 promoter sequencing-containing PCR primers for use in the CRISPR-MTB assay, then assay performance was evaluated using 401 clinical specimens. The CRISPR-MTB assay provided a low limit of detection of 1 target sequence copy/μL and excellent specificity. Furthermore, use of the assay to detect MTB in bronchoalveolar lavage fluid (BALF), sputum and pus samples provided superior sensitivity (261/268, 97.4%) as compared to sensitivities of acid-fast bacilli (130/268, 48.5%) and mycobacterial culture (192/268, 71.6%) assays, and comparable or greater sensitivity to that of GeneXpert MTB/RIF (260/268, 97.0%). The CRISPR-MTB assay, which provides excellent sensitivity and specificity for MTB detection in sputum, BALF and pus samples, is a viable alternative to conventional tests used to diagnose TB in resource-limited settings.

The small-molecule SMARt751 reverses Mycobacterium tuberculosis resistance to ethionamide in acute and chronic mouse models of tuberculosis.

The sensitivity of Mycobacterium tuberculosis, the pathogen that causes tuberculosis (TB), to antibiotic prodrugs is dependent on the efficacy of the activation process that transforms the prodrugs into their active antibacterial moieties. Various oxidases of M. tuberculosis have the potential to activate the prodrug ethionamide. Here, we used medicinal chemistry coupled with a phenotypic assay to select the N-acylated 4-phenylpiperidine compound series. The lead compound, SMARt751, interacted with the transcriptional regulator VirS of M. tuberculosis, which regulates the mymA operon encoding a monooxygenase that activates ethionamide. SMARt751 boosted the efficacy of ethionamide in vitro and in mouse models of acute and chronic TB. SMARt751 also restored full efficacy of ethionamide in mice infected with M. tuberculosis strains carrying mutations in the ethA gene, which cause ethionamide resistance in the clinic. SMARt751 was shown to be safe in tests conducted in vitro and in vivo. A model extrapolating animal pharmacokinetic and pharmacodynamic parameters to humans predicted that as little as 25 mg of SMARt751 daily would allow a fourfold reduction in the dose of ethionamide administered while retaining the same efficacy and reducing side effects.

Molecular Epidemiology and Polymorphism Analysis in Drug-Resistant Genes in M. tuberculosis Clinical Isolates from Western and Northern India.

IntroductionThe mechanistic details of first line drug (FLD) resistance have been thoroughly explored but the genetic resistance mechanisms of second line injectables, which form the backbone of the combinatorial drug resistant tuberculosis therapy, are partially identified. This study aims to highlight the genetic and spoligotypic differences in the second line drug (SLD) resistant and sensitive Mycobacterium tuberculosis (Mtb) clinical isolates from Mumbai (Western India) and Lucknow (Northern India).MethodsThe rrs, eis, whiB7, tlyA, gyrA and gyrB target loci were screened in 126 isolates and spoligotyped.ResultsThe novel mutations were observed in whiB7 loci (A43T, C44A, C47A, G48T, G59A and T152G in 5’-UTR; A42C, C253T and T270G in gene), tlyA (+CG200, G165A, C415G, and +G543) and gyrB (+G1359 and +A1429). Altogether, the rrs, eis, and whiB7 loci harbored mutations in ~86% and ~47% kanamycin resistant isolates from Mumbai and Lucknow, respectively. Mumbai strains displayed higher prevalence of mutations in gyrA (~85%) and gyrB loci (~13%) as compared to those from Lucknow (~69% and ~3.0%, respectively). Further, spoligotyping revealed that Beijing lineage is distributed equally amongst the drug resistant strains of Mumbai and Lucknow, but EAI-5 is existed at a higher level only in Mumbai. The lineages Manu2, CAS1-Delhi and T1 are more prevalent in Lucknow.ConclusionBesides identifying novel mutations in whiB7, tlyA and gyrB target loci, our analyses unveiled a potential polymorphic and phylogeographical demarcation among two distinct regions.

Molecular studies on extra-pulmonary tuberculosis among patients attending Aminu Kano Teaching Hospital, Kano, Kano State, Nigeria

In 2010 World Health Organization reported that, one third of the World population had tuberculosis, and it is among the infectious disease with significant morbidity and mortality. Mycobacterium tuberculosis is a successful pathogen that has evolved several mechanisms to manipulate the host immune response. The purpose of this study was to determine the incidence of extra-pulmonary TB in patient that visited DOTs clinic, Aminu Kano Teaching Hospital, Kano Nigeria for treatment. A prospective cross-sectional laboratory based study that involved the use of questionnaire and consent/assent form prior to sample collection. Extra pulmonary tuberculosis samples were tested by MTB/RIF assay using GeneXpert. Descriptive statistics was used to analyzed the data obtained and results were given in charts and tables. Out of 71 samples analyzed along with positive control (H37RV) and molecular grade water as a negative control, 3 (4.2 %) samples had extra-pulmonary TB, among which 2 (2.8 %) were from urine samples and 1 (1.4 %) from acetic fluid. This study shows the existence of extra-pulmonary tuberculosis in the study area; and the tuberculosis was sensitive Mycobacterium tuberculosis. It is therefore important to make screening of patients with sign and symptoms of extra pulmonary tuberculosis using Xpert MTB/RIF assay as regular method for extra pulmonary tuberculosis diagnosis. This will be achieved through enlightenment of the clinicians in our health facilities, our States and local governments should strengthen the laboratory capacity for diagnosis and make the services available and reachable to the patients who need them.

Modern approaches to pharmacotherapy of tuberculosis infection in children

Anti-TB drugs for children: Aetiotropic therapy is used for the treatment of tuberculosis (TB) in children, as well as in adult patients. Anti-tuberculosis drugs (anti-TB drugs) are divided into 3 lines, taking into account drug sensitivity in Mycobacterium tuberculosis (MBT). First-line anti-TBdrugs (basic) are used to treat TB caused by drug-susceptible MBT. Second- and third-line (reserve) drugs are recommended for the treatment of MBT-induced multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB, respectively.
 Stages and regimens to treat tuberculosis: Chemotherapy of tuberculosis in children is carried out in 2 stages (intensive treatment and continuation of treatment) and includes 5 regimens. Each regimen assumes a certain combination of anti-TB drugs, indicating the duration and frequency of their administration. The final chemotherapy regimen is chosen only according to the results of determining the drug sensitivity. To improve the TB epidemic among children, it is important to improve the regimens for the use of anti-TB drugs. The effectiveness of anti-tuberculosis pharmacotherapy is largely determined by the MBT sensitivity and the rational choice of the chemotherapy regimen. The wrong choice of a chemotherapy regimen or its violation threatens to reduce the effectiveness of pharmacotherapy and expand the spectrum of resistance of the pathogen. The development of fixed-dose combination anti-TB drugs and special dosage forms for children will improve the quality of chemotherapy and adherence to treatment. Pharmacoeconomic studies are needed to increase the effectiveness of drug pharmacotherapy for tuberculosis infection in children and to optimize the costs of its implementation.

Pharmacoeconomical aspects of chemotherapy in children at high risk of tuberculosis

AIM: of the study is to analyze the results of pharmacoeconomical studies of preventive chemotherapy in children from high-risk groups of tuberculosis to optimize measures for the prevention of tuberculosis infection in children.
 MATERIALS AND METHODS: Collection, systematization and analysis of data from the scientific literature and the results of their own research on the relevant problem.
 RESULTS: On the problem of chemoprophylaxis of tuberculosis infection in children from high-risk groups, there is insufficient information on the pharmacoeconomical aspects of this problem. Most studies include a pharmacoeconomical assessment of the management of adult patients with tuberculosis infection. There are isolated scientific papers devoted to the pharmacoeconomical analysis of the preventive treatment of latent tuberculosis infection (LTI) in children. Different clinical and economic efficiency of the applied methods of immunodiagnostics and regimens of chemoprophylaxis of tuberculosis in children is shown. To improve the epidemic situation of tuberculosis among children, it is important to improve preventive chemotherapy regimens. Their effectiveness is largely determined by the sensitivity of Mycobacterium tuberculosis (MBT) to anti-tuberculosis drugs (PTP) and the rational choice of a chemotherapy regimen. The current chemoprophylaxis regimens for children with LTI do not take into account the sensitivity of MBT to PTP at a possible source of infection.
 CONCLUSION: The analysis shows the high relevance of pharmacoeconomical studies and the practical significance of the results of such studies for optimizing preventive chemotherapy in children from high-risk groups for tuberculosis. Scientific research on the assessment of the clinical and economic effectiveness of various regimens of chemoprophylaxis of tuberculosis in children allows us to identify the most effective and least expensive ways to prevent tuberculosis through the rational use of medicines and methods of immunodiagnostics.

A multi-targeting pre-clinical candidate against drug-resistant tuberculosis

FNDR-20081 [4-{4-[5-(4-Isopropyl-phenyl)- [1,2,4]oxadiazol-3-ylmethyl]-piperazin-1-yl}-7-pyridin-3-yl-quinoline] is a novel, first in class anti-tubercular pre-clinical candidate against sensitive and drug-resistant Mycobacterium tuberculosis (Mtb). In-vitro combination studies of FNDR-20081 with first- and second-line drugs exhibited no antagonism, suggesting its compatibility for developing new combination-regimens. FNDR-20081, which is non-toxic with no CYP3A4 liability, demonstrated exposure-dependent killing of replicating-Mtb, as well as the non-replicating-Mtb, and efficacy in a mouse model of infection. Whole genome sequencing (WGS) of FNDR-20081 resistant mutants revealed the identification of pleotropic targets: marR (Rv0678), a regulator of MmpL5, a transporter/efflux pump mechanism for drug resistance; and Rv3683, a putative metalloprotease potentially involved in peptidoglycan biosynthesis. In summary, FNDR-20081 is a promising first in class compound with the potential to form a new combination regimen for MDR-TB treatment.

Antimycobacterial Activity and Gas Chromatography-Mass Spectrometry (GC-MS) Analysis of Henna (Lawsonia Inermis) Leaves extract.

Lawsonia inermis or (henna) is used as a cosmetic dye and medicinal plant for its strong antimycobacterial and other therapeutic effects. In this study, we investigated the phytochemical and antimycobacterial activity of L. inermis leaves methanol extract against Rifampicin sensitive and resistant mycobacterium tuberculosis ( M.tb ) strains. Fresh Sudanese henna leaves were collected from the University of Gezira campus garden, shade dried, ground and was extracted by methanol. Crude henna methanolic extract was then tested for antimycobacterial activity against eight M.tb strains sensitive and resistant to rifampicin, using drug susceptibility test. The phytoconstituents were identified by using gas chromatograph interfaced to a mass spectrometer (GC-MS). GC-MS analysis revealed the presence of seven phytochemical components, with prevailing of squalene (34.433%), Lawsone (20.185%) and Coumarin-4-carboxylic acid (23.328%). The crude methanolic extract of henna leaves demonstrated an inhibitory effect on all tested M.tb strains, with antimycobacterial activity being ≤ 50 mg/ml. Henna leaves crude methanolic extract is rich in phytoconstituents that may involve in its remarkable antimycobacterial activity against rifampicin sensitive and resistant M.tb strains.

Tubercular splenic abscess and recurrent acute on chronic tubercular pancreatitis: a rare coincidence in an immune competent child

Tubercular splenic abscess in association with chronic tubercular pancreatitis is scarcely reported in an immune competent child. 12 years old boy had presented with recurrent attacks of upper abdominal pain radiating towards left shoulder. He had multiple hospitalizations with similar complaints. The child had associated anorexia and significant weight loss during the period of his illness. Clinical examination revealed tenderness and muscle guard over the epigastric region. The pancreatic enzymes were markedly raised. Abdominal CT scan had suggested chronic pancreatitis with multiple splenic abscesses. The cartridge- based nucleic acid amplification test (CBNAAT) of the pus aspirated from the abscess confirmed the presence of pan sensitive mycobacterium tuberculosis. Image guided fine needle aspiration biopsy revealed the presence of caseating granulomatous lesion. Treatment with anti-tubercular drugs led to complete clinical recovery and normalization of pancreatic enzymes at follow up. An immunocompetent child had chronic tubercular pancreatitis associated with tubercular splenic abscess.

Antibacterial activity of new substituted 4-N-alkylated-2-trifluoromethyl-quinoline analogues against sensitive and resistant Mycobacterium tuberculosis strains

The emergence of resistant strain has aggravated the tuberculosis situation in the world, running out of control and hard to fight. We evaluate forty new quinoline analogues against sensitive and resistant Mycobacterium tuberculosis (Mtb). The compounds were obtained via synthesis and evaluated against sensitive strain ATCC 27294. Selected compounds were evaluated against resistant strains SR 2571/0215 and T113/09, using the MABA method. The more active compounds were selected for their potential cytotoxic activity against human macrophage cells. Twenty-nine compounds displayed activity against sensitive strain, and thirteen were active against resistant strains. Against sensitive strain, the most promising compounds were 4c and 4d (MIC=9 and 12 μM, respectively). Against resistant strains, the compounds 4a, 4d displayed the best results (MIC=4 and 5 μM, respectively). The active compounds 4a, 4d, 6d, 7c, 8d, and 10d were non-cytotoxic to the host cells at concentrations near to the MIC. The non-cytotoxic compound 4d was the most potent against resistant and sensitive Mtb. These findings contribute to relevant information and perspectives in search of new bioactive compounds against sensitive and resistant TB. Resistant strains have turned tuberculosis a severe disease in the world.

Update on TB Vaccine Pipeline

In addition to antibiotics, vaccination is considered among the most efficacious methods in the control and the potential eradication of infectious diseases. New safe and effective vaccines against tuberculosis (TB) could be a very important tool and are called to play a significant role in the fight against TB resistant to antimicrobials. Despite the extended use of the current TB vaccine Bacillus Calmette-Guérin (BCG), TB continues to be transmitted actively and continues to be one of the 10 most important causes of death in the world. In the last 20 years, different TB vaccines have entered clinical trials. In this paper, we review the current use of BCG and the diversity of vaccines in clinical trials and their possible indications. New TB vaccines capable of protecting against respiratory forms of the disease caused by sensitive or resistant Mycobacterium tuberculosis strains would be extremely useful tools helping to prevent the emergence of multi-drug resistance.

TB or not TB: an uncanny radiology

A 52-year-old male smoker presented with a 2-month history of progressive breathlessness and weight loss. He denied having cough, wheeze, hemoptysis or fever. Although tachypneic (rate 26/min), he was maintaining...

Mitochondrial Free Zn2+ Changes can Play an Important Role in Aging-associated Cardiac Dysfunction Through Increases in Mitochondria-associated ROS Production

Finding a gene or genes that are involved with multidrug resistance will be useful for finding a new target for the treatment of drug resistant tuberculosis. In this study, we aimed to compare the differences of the expression of 15 putative multidrug efflux pump genes in clinically isolated drug sensitive and multidrug resistant (MDR) Mycobacterium tuberculosis isolates, and reference strains. We found that these genes in the drug-sensitive and MDR M. tuberculosis isolates have similar rates of expressions. However, we found the expression levels of the all the genes are significantly higher in the clinical strains compared to the expression level of genes in the reference strains. In addition to this, it is found that standard strain has lower MIC value for the drugs including streptomycin and rifampin compared to the clinical isolate. We presume that the increase of the gene expression in the clinical strains is due to the exposure of antituberculosis drugs during treatment of patients, which cause constitutive expression of efflux systems, which might increase MIC levels of the major anti-tuberculosis drugs.

A CASE OF PANCOAST SYNDROME IN TB

SESSION TITLE: Monday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Tuberculosis is one of the most common systemic infectious disease, and a major public health problem all over the world. It has several forms of presentation and clinical manifestations. Here we present an interesting clinical manifestation of Tuberculosis as Pancoast Syndrome. CASE PRESENTATION: A 55 year old male, smoker for past 30 years, presented with cough with expectoration, left shoulder pain and weakness of left upper limb of 6 months duration. He had irregular treatment for pulmonary tuberculosis two years ago. On examination he had partial ptosis of left eye, enophthalmos, miosis, ipsilateral anhydrosis, and tenderness in left supraclavicular region, wasting of left upper limb muscles. Sputum examination was positive for Acid fast bacilli. Cartridge based Nucleic Acid Amplification Test (CBNAAT) of sputum confirmed Rifampicin sensitive Mycobacterium Tuberculosis. Chest radiograph and CT Chest showed fibrocavitary changes, Cavitary consolidations predominantly involving right lung and mass like lesion in left apical lobe with erosion of left first rib. Histopathological examination with CT guided biopsy of the mass like lesion was negative for malignancy but showed caseous granulomatous inflammation. DISCUSSION: Pancoast syndrome1 refers to a constellation of symptoms of Brachial Neuralgia, Horner’s syndrome and atrophy of muscles of ipsilateral upper limb. Pancoast syndrome is commonly associated with Pancoast tumor of Squamous cell carcinoma , recently adenocarcinoma has emerged as commonest. Other conditions that may result in Pancoast syndrome are (1) Other tumors - primary chest wall and metastatic tumors, pleural mesothelioma, hematologic malignancies, (2) infectious and inflammatory lung diseases – tuberculosis, aspergillosis, echinococcosis, actinomyces and lung abscesses, inflammatory pseudotumor, amyloid nodules and (3) vascular lesions - carotid pseudoaneurysm, hemangioma.These conditions can invade and destruct the apical bony skeleton of the thorax, producing similar clinical and radiographic picture. CONCLUSIONS: We conclude that clinicians need to be aware of the variable manifestations of Tuberculosis. Reference #1: Pancoast HK. Superior pulmonary sulcus tumor: tumor characterized by pain Horner’s syndrome, destruction of bone and atrophy of hand muscles. JAMA 1932;19:1391-6. Reference #2: White HD, White BA, Boethel C, et al. Pancoast’s syndrome secondary to infectious etiologies: a not so uncommon occurrence. Am J Med Sci 2011;341:333-6 Reference #3: Beshay M, Roth T, Stein RM, et al. Tuberculosis presenting as Pancoast tumor. Ann Thorac Surg 2003;76:1733-5 DISCLOSURES: No relevant relationships by ALLWYN VIJAY GOWRI SHANKAR, source=Web Response No relevant relationships by Sagindar Samaraj, source=Web Response

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Evaluation of Some Plant-derived Secondary Metabolites Against Sensitive and Multidrug-resistant Mycobacterium tuberculosis

The results on the bioevaluation of thirty five plant-derived secondary metabolites against one sensitive and three multidrugresistant clinical isolates of Mycobacterium tuberculosis are reported. Results toward the sensitive strain showed that five products gave MIC values of 12.5 µg/mL: the alkaloids 6-methoxydihydrochelerytrine (2) and 6-methoxy-dihydrochelirubine (6), the flavanone pinostrobin (17), 1-hydroxy-benzoisochromanquinone (23) and 23-hydroxy-5a-lanosta7,9(11),24-triene-3-one (33). These were followed by the peracetylstrictosidine lactam (12) and the quinone aloe-emodin (24) which displayed MICs of 6.25 µg/mL. Finally, liriodenine (8) was the most active (MIC: 3.125 µg/mL) of all secondary metabolites. Results with the multidrug-resistant clinical isolates showed that 6-methoxy-dihydrochelirubine (6) was the most active (MIC: 12.5 µg/mL).

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

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. 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. 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.

Ultrastructural analysis of cell wall of drug resistant and sensitive Mycobacterium tuberculosis isolated from cerebrospinal fluid by transmission electron microscope.

Drug-resistant tuberculosis is being increasingly recognized and is one among the leading cause of death worldwide. Remarkable impermeability of cell wall to antituberculous drugs protects the mycobacteria from drug action. The present study analyzed the cell wall thickness among first-line drug resistant and sensitive Mycobacterium tuberculosis (Mtb) isolated from cerebrospinal fluid by transmission electron microscopy (TEM). The average thickness of the cell wall of sensitive isolates was 13.60 ± 0.98 nm. The maximum difference (26.48%) in the cell wall thickness was seen among multi-drug resistant (18.50 ± 1.71 nm) isolates and the least difference (4.14%) was shown by streptomycin-resistant (14.18 ± 1.38 nm) isolates. The ultrastructural study showed evident differences in the cell wall thickness among sensitive and resistant isolates. Preliminary TEM examination of cells indicates that morphological changes occur in the cell wall which might be attributed to the drug resistance. The thickened wall of Mtb appears to help the bacilli to overcome the action of antituberculous drugs.