Resistant Strains Of Mycobacteria Research Articles

Rosmarinic acid and its derivative’s duel as antitubercular agents: insights from computational prediction to functional response in vitro

Tuberculosis is one of the most dreadful infectious diseases, afflicting global populations with anguish. With the emergence of multi-drug resistant strains of mycobacteria, the imperative for new anti-tuberculosis drugs has grown exponentially. Thus, the current study delves into evaluating the impact of Perovskia abrotanoides and its active metabolites-namely, rosmarinic acid and its derivatives-against strains of Mycobacterium tuberculosis (Mtb). Through the use of the CRI assay, the antimycobacterial potential of the high-altitude medicinal plant P. abrotanoides was gauged, while docking and molecular dynamics simulations unveiled plausible targets. Of these, the peak antimycobacterial effectiveness was observed in the P. abrotanoides ethyl acetate extract with 125 µg/mL as minimum inhibitory concentration against various strains of M. tuberculosis, encompassing H37Rv and strains resistant to multiple drugs. Following bioassay-guided fractionation and isolation, rosmarinic acid and rosmarinic acid methyl ester emerged as potent molecules against H37Rv and multidrug-resistant M. tuberculosis strains; minimum inhibitory concentration ranging from 15 to 32 µg/mL. Additionally, out of 22 targets explored, Mtb lipoamide dehydrogenase (PDB: 3II4) and Rv2623 (PDB: 3CIS) were forecasted as potential Mtb targets for rosmarinic acid and rosmarinic acid methyl ester, respectively, a supposition further affirmed by molecular simulations (100 ns). The stability of both complexes throughout the simulation was measured by protein backbone root-mean-square deviation, substantiating their roles as respective targets for antimycobacterial activities. Communicated by Ramaswamy H. Sarma

Problems of anti-tuberculosis therapy in patients on hemodialysis

The objective: to determine possibility of prescribing and safety of various anti-tuberculosis drugs and their combinations as part of a therapeutic or preventive course of anti-tuberculosis therapy (ATBT) in patients with end-stage chronic kidney disease (CKD) receiving hemodialysis replacement therapy in the settings with high prevalence of drug resistant strains of Mycobacterium tuberculosis.Subjects and Methods. 42 patients receiving hemodialysis replacement therapy were followed-up by Central Tuberculosis Research Institute: of them, 31 (73.8%) had active tuberculosis and 11 (26.2%) had residual post-tuberculous changes in the respiratory organs. During the follow-up, the nature and severity of adverse reactions to anti-tuberculosis drugs were assessed.Results. In the patients with end-stage CKD suffering from respiratory tuberculosis, drug resistant strains prevailed – 68.2%. Some of adverse events developed when taking anti-tuberculosis drugs were as follows: deterioration of uremia in 20.5% of cases, cardiovascular complications – in 17.9%, and neurotoxic reactions – in 15.4%. Progression of uremia occurred more often in the followed-up patients taking anti-tuberculosis drugs versus hepatotoxic reactions (p = 0.02). When treating tuberculosis patients with end-stage CKD, isoniazid was discontinued due to adverse events in 12.8% of cases and pyrazinamide in 12.8% of cases, other drugs were discontinued less frequently. Compilation of individual regimens of anti-tuberculosis drugs with the consideration of drug susceptibility testing results, contraindications, and concomitant diseases made it possible to provide an adequate anti-tuberculosis therapy for patients with end-stage CKD with tuberculosis infection in 92.9% of cases for a period of more than 6 months.

Natural phytocompounds physalin D, withaferin a and withanone target L-asparaginase of Mycobacterium tuberculosis: a molecular dynamics study

Tuberculosis is a major infectious disease that is responsible for high mortality in humans. The reason for the global burden is the emergence of new antibiotic resistant strains of Mycobacteria that showed resistance against the currently given therapy. It is identified that the pathogen utilizes the L-asparaginase enzyme as a virulence factor for survival benefits inside the host. Therefore, L-asparaginase of Mycobacterium tuberculosis is a promising therapeutic drug target. In view of the light, the present study explores thirty phytocompounds from medicinal plants to determine the binding affinity in the catalytic site of L-asparaginase. The studies initiated with the construction of the 3 D structure of L-asparaginase using homology modeling. Using the robustness of molecular docking with binding energy cut-off value < −9.0 kcal/mol and 100 ns molecular dynamics simulations, three phytocompounds viz., Physalin D (−9.11 kcal/mol), Withanone (−9.45 kcal/mol) and Withaferin A (−9. 67 kcal/mol) showed strong binding potential compared to the product, L-aspartate (−5.87 kcal/mol). The active site residues identified are Thr 12, Asp 51, Ser 53, Thr 84, Asp 85, and Lys 157. Upon MD simulations, the phytocompounds and the product L-aspartate remain present in the same catalytic pocket of the enzyme. The RMSD, RMSF, radius of gyration and H-bond analysis of enzyme ligand complexes efficiently showed the stability of ligands at the docked site. Further, ADME studies distinctly demonstrate the potential of selected phytoconstituents as therapeutics. Thus, serve as safe and low-cost alternatives to chemical compounds to be used in combination therapy for treatment of tuberculosis. Communicated by Ramaswamy H. Sarma

Exploring disordered loops in DprE1 provides a functional site to combat drug-resistance in Mycobacterium strains

As an anti-tuberculosis target, DprE1 contains two flexible loops (Loop I and Loop II) which have never been exploited for developing DprE1 inhibitors. Here Leu317 in Loop II was discovered as a new functional site to combat drug-resistance in Mycobacterium strains. Based on TCA1, LZDT1 was designed to optimize the hydrophobic interaction with Leu317. A subsequent biochemical and cellular assay displayed increased potency of LZDT1 in inhibiting DprE1 and killing drug-sensitive/-resistant Mycobacterium strains. The improved activity of LZDT1 and its analogue LZDT2 against multidrug resistant tuberculosis was particularly highlighted. For LZDT1, its enhanced interaction with Leu317 also impaired the drug-insensitivity of DprE1 caused by Cys387 mutation. A new nonbenzothiazole lead (LZDT10) with reduced Cys387-dependence was further produced by optimizing interactions with Leu317, improvement directions for LZDT10 were discussed as well. Our research underscores the value of potential functional sites in disordered loops, and affords a feasible way to develop these functional sites into opportunities for drug-resistance management.

Synthesis and evaluation of α-aminoacyl amides as antitubercular agents effective on drug resistant tuberculosis

The development of an effective antitubercular agent is a challenge due to the complex nature of tuberculosis. Herein, we report the synthesis and evaluation of α-aminoacyl amides as antitubercular agents. The systematic medicinal chemistry approach led to identification of optimal substitutions required for the activity. Compound 11l was identified as antitubercular lead with drug like properties. Further, 11l selectively inhibited M. tuberculosis H37Rv with MIC value of 0.78 μM and was found to be non-toxic to CHOK1 cells. The lead compound inhibited multidrug resistant and Pre-Extensively drug resistant strains of Mycobacterium at 2 μg/mL and 8 μg/mL respectively.

Scientific rationale for traditional use of plants to treat tuberculosis in the eastern region of the OR Tambo district, South Africa

Ethnopharmacological relevanceTuberculosis (TB) remains a major health problem for humans worldwide, and was responsible for 1.4 million human deaths in 2015 alone. Although there is treatment for TB, emerging multi-drug, extensively drug and totally drug resistant forms of this disease, as well as co-infection with human immunodefiency virus (HIV) continue to worsen the situation. South Africa is among countries with reported traditional use and published documentation of such knowledge concerning the use of plants against TB. Based on a previous study where plants used traditionally for treating TB in the eastern region of OR Tambo district, South Africa, were documented, the present study aimed to determine the antimycobacterial effect, cytotoxicity and genotoxicity of plants selected from that list. Material and methodsAcetone, 70% ethanol, cold and hot water extracts were tested for antimycobacterial activity against saprophytic Mycobacterium species including M. aurum, M. bovis BCG, M. gordonae, M. fortuitum, and M. smegmatis using a microdilution method. Extracts with MIC values less than 1 mg/ml against at least three Mycobacterium strains were evaluated for antimycobacterial activity against pathogenic Mycobacterium strains including M. tuberculosis H37RV, M. tuberculosis and M. bovis, cytotoxicity (against Vero monkey kidney and bovine dermis cells), and genotoxicity (against Salmonella typhimurium TA98 and TA100). ResultsThe MIC values of the extracts ranged from 0.02 to 2.50 mg/ml, LC50 values of twenty-nine extracts ranged from 0.001 to > 1 mg/ml and the highest selectivity index was 79.50, an extremely promising value. Phymaspermum acerosum roots and leaves (ethanol and water) extracts had the best MIC value (0.02 mg/ml) against at least one Mycobacterium strain. It was interesting to note the lack of cytotoxicity of these extracts with the highest selectivity index value of 39.75. Pterocelastrus echinatus bark acetone and Protorhus longifolia leaf hot water extracts were the most cytotoxic with LC50 = 0.001 and 0.008 mg/ml, respectively, whereas Pittosporum viridiflorum bark water extract was genotoxic. Among non-pathogenic strains, M. gordonae, M. aurum, M. smegmatis showed good correlation of activity with pathogenic M. tuberculosis H37Rv, M. tuberculosis and M. bovis, however, M. aurum was the best predictor with Mycobacterium tuberculosis H37Rv (correlation coefficient value = 0.73). ConclusionThe results indicate that Heteromorpha trifoliata and Phymaspermum acerosum should be investigated further for antimycobacterial efficacy against drug resistant strains of Mycobacterium.

Revisiting Activation of and Mechanism of Resistance to Compound IQG-607 in Mycobacterium tuberculosis.

IQG-607 is a metal complex previously reported as a promising anti-tuberculosis (TB) drug against isoniazid (INH)-resistant strains of Mycobacterium tuberculosis Unexpectedly, we found that INH-resistant clinical isolates were resistant to IQG-607. Spontaneous mutants resistant to IQG-607 were subjected to whole-genome sequencing, and all sequenced colonies carried alterations in the katG gene. The katG(S315T) mutation was sufficient to confer resistance to IQG-607 in both MIC assays and inside macrophages. Moreover, overexpression of the InhA(S94A) protein caused IQG-607's resistance.

Design, Synthesis and Evaluation of Antitubercular Activity of Novel 1,2,4-Triazoles Against MDR Strain of Mycobacterium tuberculosis

Emergence of various forms of resistant strains of Mycobacterium tuberculosis led to the exploration of drugs with novel mechanism of action. Recently econazole, an azole based antitubercular agent, attracted major attention for targeting mycobacterial cytochrome P450. In the present study, we designed novel 1,2,4-triazole derivatives based on econazole moiety and evaluated them for in vitro antitubercular activity against M. tuberculosis H37Rv and multi-drug resistant (MDR) strains of Mycobacterium.

Structural insights of Mycobacterium GTPase-Obg and anti-sigma-F factor Usfx interaction.

An essential protein for bacterial growth, GTPase-Obg (Obg), is known to play an unknown but crucial role in stress response as its expression increases in Mycobacterium under stress conditions. It is well reported that Obg interacts with anti-sigma-F factor Usfx; however, a detailed analysis and structural characterization of their physical interaction remain undone. In view of above-mentioned points, this study was conceptualized for performing binding analysis and structural characterization of Obg-Usfx interaction. The binding studies were performed by surface plasmon resonance, while in silico docking analysis was done to identify crucial residues responsible for Obg-Usfx interaction. Surface plasmon resonance results clearly suggest that N-terminal and G domains of Obg mainly contribute to Usfx binding. Also, binding constants display strong affinity that was further evident by intermolecular hydrogen bonds and hydrophobic interactions in the predicted complex. Strong interaction between Obg and Usfx supports the view that Obg plays an important role in stress response, essentially required for Mycobacterium survival. As concluded by various studies that Obg is crucial for Mycobacterium survival under stress, this structural information may help us in designing novel and potential inhibitors against resistant Mycobacterium strains.

Constraints of Drug Resistance in Mycobacterium tuberculosis - Prospects for Pharmacological Reversion of Susceptibility to Antibiotics

Emergence of multidrug resistant strains ofMycobacterium tuberculosis(MDR-TB) threatens humanity. This problem was complicated by the crisis in development of new anti-tuberculosis antibiotics. Induced reversion of drug resistance seems promising to overcome the problem. Successful clinical trial of a new anti-tuberculosis nanomolecular complex FS-1 has demonstrated prospectively of this approach in combating MDR-TB. Several clinical MDR-TB cultures were isolated from sputum samples prior and in the process of the clinical trial. Every isolate was tested for susceptibility to antibiotics and then they were sequenced for comparative genomics. It was found that the treatment with FS-1 caused an increase in the number of antibiotic susceptible strains among Mtb isolates that was associated with a general increase of genetic heterogeneity of the isolates. Observed impairing of phthiocerol dimycocerosate biosynthesis by disruptive mutations inppsACDsubunits indicated a possible virulence remission for the sake of persistence. It was hypothesized that the FS-1 treatment eradicated the most drug resistant Mtb variants from the population by aggravating the fitness cost of drug resistance mutations. Analysis of distribution of these mutations in the global Mtb population revealed that many of them were incompatible with each other and dependent on allelic states of many other polymorphic loci. The latter discovery may explain the negative correlation between the genetic heterogeneity of the population and the level of drug tolerance. To the best of our knowledge, this work was the first experimental confirmation of the drug induced antibiotic resistance reversion by the induced synergy mechanism that previously was predicted theoretically.

A Review on Effect of Antitubercular Activity on Structural Modification of Isoniazide

Tuberculosis remains the leading cause of mortality worldwide. The facts relating to a front-line antitubercular drug isoniazide and its analogues. The antitubercular pharmacophore moiety of isoniazide has been introduced in various compounds to improve their antitubercular activity against mycobacterium, as well as their multidrug resistant mycobacterium strains. Various compounds like Schiff bases, hydrazones, hydrazides and metal complexes of isoniazid have shown good antitubercular activity. A series of isoniazid analogues have been evaluated for their activity against Mycobacterium tuberculosis. Some compounds exhibited significant antitubercular activity when compared with first line drugs like isoniazid and rifampicin and could be a good starting spot to develop new compounds in the fight against multi-drug resistant tuberculosis.

Fragment-Based De Novo Design of Antimycobacterial Agents and In Vitro Potency Evaluation

Tuberculosis (TB) is an infection with global impact that over time demonstrates enormously high mortality rates. The vital need for improving novel and efficient anti-TB drugs is caused by the rising rate of appearance of Multi Drug Resistant (MDR) strains to the frequently utilized drugs.In addition, the longer periods of therapy and healing, mainly in the immune compromised patients aggrevates the situation. Recent studies indicate that computer-based techniques have been used successfully in the antibacterial research. In our current approach, utilizing combined pattern of computer-based methods as fragment-based de novo design, structure-based docking and scoring, in addition to similaritybased compound searching, led to introduce seven in silico designed compounds with probable antimycobacterial properties. Then, we investigated their potency against sensitive and resistant strains of Mycobacterium sp. in vitro. Findings resulted from antimycobacterial tests and MTT assay indicated that two compounds, 1-amino-4-(phenylamino) anthracene-9,10-dione and 5-fluoroindoline-2,3-dione have useful profile and maybe good candidates for developing novel antimycobacterial drugs.

Biocompatible citric acid‐coated iron oxide nanoparticles to enhance the activity of first‐line anti‐TB drugs in Mycobacterium smegmatis

AbstractBACKGROUNDThe development of drug resistant Mycobacterium strains is a serious health concern causing impairment in tuberculosis (TB) therapy. Using Mycobacterium smegmatis as a model, the possible enhancement in the efficacy of first‐line anti‐TB drugs, isoniazid and rifampicin, is explored by using a combined strategy of treating the cells simultaneously with both drug and nanoparticles. The latter can target the tough cell wall of mycobacteria.RESULTSBiocompatible citric acid‐coated iron oxide (magnetite) nanoparticles (CA‐MNP) were synthesized by a co‐precipitation route with an average diameter of 9 nm. The uptake of nanoparticles by M. smegmatis was proportional to its concentration up to 32 µg mL−1. Real‐time studies on fluorescent tracers demonstrate that the nanoparticles enhance membrane permeability, aiding in a higher influx of drugs into the cells. Intracellular rifampicin levels were enhanced 2‐fold in the presence of CA‐MNP, compared with that in the absence of CA‐MNP. Similarly, reactive oxygen species (ROS) levels, measured as an indication of intracellular isoniazid, increased in cells treated with both nanoparticles and isoniazid, compared with when only the drug was used.CONCLUSIONCA‐MNP in conjunction with either isoniazid or rifampicin displayed a synergistic effect in inhibiting bacterial growth, leading to a 2‐fold reduction in the drug dosage. This study demonstrates that the enhanced uptake of existing anti‐Tb drugs using nanoparticles is a possible option in tuberculosis treatment. © 2015 Society of Chemical Industry

Development of nitroimidazopyrans and nitroimidaoxazoles for tuberculosis chemotherapy

The conventional approach to antitubercular drug development requires introduction of novel molecules for the treatment of resistant mycobacterium strains. The nitroimidazopyrans, nitroimidaoxazoles and other analogs are being studied as antitubercular agents and their characteristics form the basis of this review. These new tuberculosis treatments shorten the duration of treatment and/or reduce the number of doses, improve the coverage of MDR-TB/XDR-TB and are more effective in treatment of latent TB infection.

Antimicrobial and Anti-tubercular Activity of Quinolone Analogues

Background: Quinolones are an important synthetic antimicrobial agents being used over the past three decades. Currently some quinolones are under investigation for the treatment of Mycobacterium tuberculosis and resistant strains of mycobacterium. Results: Their main biological target is the DNA gyrase, a topoisomerase-II encoded by gyrA and gyrB that is essential to maintain the DNA supercoil. The aim of this study is to collect information of the Fluoroquinolones (FQs) which are effective against tuberculosis (TB) and multidrug resistant (MDR-TB), extensively drug resistant-TB (XDR-TB) and latent TB and encourage developing of new QFs which are more effective, less toxic and shorter treatment period. Conclusion: The antitubercular (anti-TB) properties of the quinolone derivatives are as a new class of compounds with potent and selective anti-TB activities. Furthermore, particularly interesting is their activity against multidrug resistance and extensive drug resistance tuberculosis.

A Review of Antimycobacterial Drugs in Development

The needs of newly developed antitubercular agents are required for the control of tuberculosis in the present time. In the discovery of new antitubercular drugs, the emergence of multidrug-resistant (MDR) and extensively drug resistant (XDR) strains of Mycobacterium tuberculosis (Mtb) has encouraged the researchers to intensify the efforts to discover novel antitubercular drugs. These novel drugs will predominantly target the persistent state of mycobacterium strains, which are resistant to conventional drugs including non resistant mycobacterium strains. In the last three to four decades no new effective drug has been developed for the treatment of resistant tuberculosis. However, in recent years, the research and development programs for the control of TB, there is a lot works is going on to enhancement of the anti-TB activity of new drugs particularly against resistant mycobacterium strains. Simultaneously, practical usefulness of some new targets is being identified and validated for the treatment of TB. Some compounds are presently in clinical trials, while others are being investigated in an attempt to explore new compounds for the target based treatment. The present review provides an overview of the new anti-TB agents with different molecular structures that are being clinically used and advanced stages of preclinical as well as clinical stages and also attempted to highlight the efforts that are being made in the development of new drug molecules as lead anti-TB agents.

Targeting multidrug resistant Mycobacterium tuberculosis htra2 with identical chemical entities of fluoroquinolones

Tuberculosis is a highly communicable and chronic respiratory disease caused by pathogenic bacterium Mycobacterium tuberculosis. The drug - resistant species of Mycobacterium tuberculosis are tough to cure due to its resistant activity toward potential drugs. Available inhibitors of tuberculosis include few antimicrobial fluoroquinolone agents like ciprofloxacin, ofloxacin, and moxifloxacin to treat resistant Mycobacterium strains. Literature study elucidates that macromolecular target namely, HtrA2 of Mycobacterium tuberculosis play a dual role of protease and chaperone. These two activities are dependent on temperature, with low temperatures promoting the chaperone function and high temperatures promoting serine protease activity. Under normal physiological conditions HtrA2 acts as a quality control factor and promotes cell survival. In the present investigation, we screened fluoroquinolone such as ciprofloxacin, moxifloxacin and ofloxacin and their analogues based on better Docking score, absorption, distribution, metabolism and excretion screening and Lipinski's rule of 5, to find out their efficiency on resistant strain through in silico study. From the results observed, the analogues are suggested to be potent inhibitors of HtrA2 with sufficient scope for further exploration.

Detección de mutaciones asociadas a cepas multidrogo resistente de Mycobacterium tuberculosis en Chile

The incidence of acquired resistance to antituberculous drugs of Mycobacterium tuberculosis in Chile is approximately 23%.To analyze the mutations associated with drug resistance in drug resistant strains of Mycobacterium tuberculosis.In 28 drug resistant Mycobacterium tuberculosis strains isolated in Chile, genes leading to drug resistance were studied. DNA was amplified by polymerase chain reaction (PCR) and sequencing was carried out using the ABI PRISM big dye terminator cycle sequencing ready reaction kit.In rifampicin-resistant strains, the mutations in rpoβ gene were in the codons S531W/L (56%), D516Y (16%) and D516V (16%). The predominant mutation in katG gene was in the codon S315L (73%) in isoniazid-resistant strains. The mutation S95T was found in the 71% of ciprofloxacin resistant strains. Only one ethambutol resistant strain had the M306I mutation. Three unreported mutations in katG were identified.Drug resistance associated mutations of Mycobacterium tuberculosis isolated in Chile were similar to those reported abroad.

Treatment of Tuberculosis: Use of Active Pharmaceuticals

Tuberculosis (TB) is a highly infectious disease caused by several species of mycobacteria. Multi drug resistant strains of mycobacteria leading to the increase of patient world wide. There is an urgent need for new effective antimicrobial agent to replace those currently in use because of highly toxic. Screening methods available for discovering new chemical entities active against the resistant strains are detailed. The plant origin antimicrobial agents are the valuable anti tubercular drugs. The present review of patent stated several findings from an extensive literature search of semi synthetic, synthetic and natural plants that have been assessed for the antimicrobial activity over 20 years. An attempt has been made to summarize the information in order to highlight those chemical entities and plant species which are of worthy for further investigation as leads to the drug developments. Over 150 chemical entities of semi synthetic and synthetic and over 350 plant species from wide range of families containing various chemical classes of compounds have been cited here which are worthy for the researchers and the industrialist concerned to tuberculosis. The present review includes some patents relevant to the treatment of tuberculosis.

Synthesis and Antiproliferative Activity of 3‐Aryl‐2‐[1H(2H)‐benzotriazol‐1(2)‐yl]acrylonitriles Variously Substituted. Part 4.

AbstractFor Abstract see ChemInform Abstract in Full Text.