anti-TB Activity Research Articles

Lipid droplets help anti-TB drug efficacy

Microbiology Improving chemotherapies against intracellular pathogens requires understanding how antibiotic distribution within infected cells affects efficacy. Greenwood et al. developed an approach to visualize antibiotics in human macrophages infected with the tubercle bacillus (see the Perspective by Smith and Aldridge). They showed that the antitubercular (anti-TB) drug bedaquiline accumulated in host lipid droplets. Lipid droplets seemed to act as an antibiotic reservoir that could be transferred to bacteria during host lipid consumption. Indeed, alterations in host lipid droplet content affected the anti-TB activity of bedaquiline against intracellular bacilli. Science , this issue p. [1279][1]; see also p. [1234][2] [1]: /lookup/doi/10.1126/science.aat9689 [2]: /lookup/doi/10.1126/science.aay0211

Population pharmacokinetics of efavirenz in HIV and TB/HIV coinfected children: the significance of genotype-guided dosing

The current WHO weight-based dosing recommendations for efavirenz result in a wide variability of drug exposure in children. Our objectives are to characterize the effects of rifampicin- and isoniazid-containing anti-TB therapy and CYP2B6 activity on efavirenz concentrations in children, using non-linear mixed-effects modelling. This is a pharmacokinetic (PK) substudy of a prospective study that examined the interactions between anti-TB therapy and efavirenz in HIV-infected children with and without TB. PK samples were obtained 4 weeks after starting efavirenz (PK1) and repeated 4 weeks after completing TB therapy (PK2) in TB/HIV coinfected patients. Drug concentrations were measured using LC-MS/MS. Composite CYP2B6 516/983/15582 genotype was determined. Population PK modelling was performed in Monolix. Simulations were performed to obtain the predicted mid-dose concentrations (C12). One hundred and five HIV-infected Ghanaian children (46 with TB/HIV) were included. The median age and weight were 7 years and 19 kg. The efavirenz concentrations over time were adequately described using a one-compartment model. Weight, composite CYP2B6 genotype and PK visit had a significant influence on the PK parameters, while TB therapy had no significant effect. Simulations showed adequate C12 for intermediate composite CYP2B6 metabolizers only. Our model showed that rifampicin- and isoniazid-containing anti-TB therapy does not influence efavirenz PK parameters. On the other hand, it describes the effect of efavirenz autoinduction after completing TB treatment. In addition, dosing efavirenz in children based only on weight results in a large variability in drug exposure. We propose dose adjustments for slow and extensive composite CYP2B6 metabolizers.

Identifying Regimens Containing TBI-166, a New Drug Candidate against Mycobacterium tuberculosis In Vitro and In Vivo.

TBI-166, derived from riminophenazine analogues, is under development in a phase I clinical trial in China. TBI-166 showed more potent anti-tuberculosis (anti-TB) activity than did clofazimine in in vitro and animal experiments. To identify potent regimens containing TBI-166 in TB chemotherapy, TBI-166 was assessed for pharmacological interactions in vitro and in vivo with several anti-TB drugs, including isoniazid (INH), rifampin (RFP), bedaquiline (BDQ), pretomanid (PMD), linezolid (LZD), and pyrazinamide (PZA). Using an in vitro checkerboard method, we found that TBI-166 did not show antagonism or synergy with the tested drugs. The interaction relationship between TBI-166 and each drug was indifferent. In in vivo experiments, aerosol infection models with BALB/c and C3HeB/FeJNju mice were established, testing drugs were administered either individually or combined in treatments containing TBI-166 and one, two, or three other drugs, and the bactericidal activities were determined after 4- and 8-week therapeutic treatments. In BALB/c mice, five TBI-166-containing regimens-TBI-166+BDQ, TBI-166+PZA, TBI-166+BDQ+LZD, TBI-166+BDQ+PMD, and TBI-166+BDQ+PMD+LZD-showed significantly more potent efficacy after 4 weeks of treatment compared to the control regimen, INH+RFP+PZA. At the end of an 8-week treatment, lung log CFU counts decreased to undetectable levels in mice treated with each of the five regimens. The rank order of the potency of the five regimens was as follows: TBI-166+BDQ+LZD > TBI-166+BDQ > TBI-166+PZA > TBI-166+BDQ+PMD+LZD > TBI-166+BDQ+PMD. In C3HeB/FeJNju mice, TBI-166+BDQ+LZD was also the most effective of the TBI-166-containing regimens. In conclusion, five potent chemotherapy regimens that included TBI-166 were identified. The TBI-166+BDQ+LZD regimen is recommended for further testing in a TBI-166 phase IIb clinical trial.

Synthesis, characterization, crystal structure biological activity of 4-{2-[5-(4-fluoro-phenyl)- [1,3,4]oxadiazol-2-ylsulfanyl]-ethyl}-morpholine

4-{2-[5-(4-Fluoro-phenyl)- [1,3,4]oxadiazol-2-ylsulfanyl]-ethyl}-morpholine (3) was synthesized by refluxing 1,3,4 oxadiazole-2-thiol with 4-(2-chloroethyl) morpholine hydrochloride. It was characterized by NMR, IR, and Mass spectral studies and finally the structure was confirmed by single crystal X-ray diffraction studies. From single crystal X-ray diffraction results that the compound belongs to monoclinic system with the following lattice parameters a = 13.0734 (4) Å, b = 11.4788 (4) Å, c = 9.7771 (3) Å and residual factor R = 0.048. The synthesized 4-{2-[5-(4-Fluoro-phenyl)- [1,3,4]oxadiazol-2-ylsulfanyl]-ethyl}-morpholine was also screened for biological activity such as antibacterial, antioxidant, anti-TB, anti-diabetic and molecular docking studies for InhA protein. compound 3 showed the remarkable anti-tb activity with MIC 3.12 μg/ml concentration and superior anti-microbial activity, its MIC values are lower than the standard.

Synthesis, Screening and Docking Analysis of Hispolon Pyrazoles and Isoxazoles as Potential Antitubercular Agents.

Hispolons are natural products known to possess cytoprotective, antioxidant and anti-cancer activities. We have found recently anti TB activity in these compounds. Efforts were made to optimize the structure with bioisosteric replacement of 1,3-diketo functional group with the corresponding pyrazole and isoxazole moieties. The goal of this paper is designing new hispolon isoxazole and pyrazole and the evaluation of their biological activities. The designed compounds were prepared using classical organic synthesis methods. The anti- TB activity was evaluated using the MABA method. A total of 44 compounds were synthesized (1a- 1v and 2a-2v) and screened for anti TB activity and antibacterial activity. The compounds 1b and 1n showed the highest potency with MIC 1.6µg/mL against M. tuberculosis H37Rv. Bioisosteric replacement of 1,3-diketo functional group in hispolons with pyrazole or isoxazole rings have resulted in potent anti TB molecules. Docking simulations of these compounds on mtFabH enzyme resulted in a clear understanding of bioactivity profiles of these compounds. Docking scores are in good agreement with the anti TB activity obtained for these compounds. Computational studies and in vitro screening results indicate mtFabH as the probable target of these compounds.

Computational, crystallographic studies, cytotoxicity and anti-tubercular activity of substituted 7-methoxy-indolizine analogues.

Indolizines are heteroaromatic compounds, and their synthetic analogues have reportedly showed promising pharmacological properties. In this study, a series of synthetic 7-methoxy-indolizine derivatives were synthesised, characterised and evaluated for in vitro whole-cell anti-tuberculosis (TB) screening against susceptible (H37Rv) and multi-drug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB) using the resazurin microplate assay method. The cytotoxicity was evaluated using the MTT assay. In silico molecular-docking study was conducted for compounds 5a-j against enoyl-[acyl-carrier] protein reductase, a key enzyme of the type II fatty acid synthesis that has attracted much interest for the development of novel anti-TB compounds. Thereafter, molecular dynamic (MD) simulation was undertaken for the most active inhibitors. Compounds 5i and 5j with the methoxy functional group at the meta position of the benzoyl group, which was at the third position of the indolizine nucleus, demonstrated encouraging anti-TB activity against MDR strains of MTB at 16 μg/mL. In silico studies showed binding affinity within the range of 7.07–8.57 kcal/mol, with 5i showing the highest binding affinity. Hydrogen bonding, π-π- interactions, and electrostatic interactions were common with the active site. Most of these interactions occurred with the catalytic amino acids (Pro193, Tyr158, Phe149, and Lys165). MD simulation showed that 5j possessed the highest binding affinity toward the enzyme, according to the two calculation methods (MM/PBSA and MM/GBSA). The single-crystal X-ray studies of compounds 5c and 5d revealed that the molecular arrangements in these two structures were mostly guided by C-H···O hydrogen-bonded dimeric motifs and C-H···N hydrogen bonds, while various secondary interactions (such as π···π and C-H···F) also contributed to crystal formation. Compounds 5a, 5c, 5i, and 5j exhibited no toxicity up to 500 μg/mL. In conclusion, 5i and 5j are promising anti-TB compounds that have shown high affinity based on docking and MD simulation results.

Development and validation of a multiplex UHPLC-MS/MS method for the determination of the investigational antibiotic against multi-resistant tuberculosis macozinone (PBTZ169) and five active metabolites in human plasma

The emergence of Mycobacterium tuberculosis strains resistant to current first-line antibiotic regimens constitutes a major global health threat. New treatments against multidrug-resistant tuberculosis (MDR-TB) are thus eagerly needed in particular in countries with a high MDR-TB prevalence. In this context, macozinone (PBTZ169), a promising drug candidate with an unique mode of action and highly potent in vitro tuberculocidal properties against MDR Mycobacterium strains, has now reached the clinical phase and has been notably tested in healthy male volunteers in Switzerland. To that endeavor, a multiplex UHPLC-MS/MS method has been developed for the sensitive and accurate human plasma levels determination of PBTZ169 along with five metabolites retaining in vitro anti-TB activity. Plasma protein precipitation with methanol was carried out as a simplified sample clean-up procedure followed by direct injection of the undiluted supernatant for the bioanalysis of the six analytes within 5 min, using 1.8 μm reversed-phase chromatography coupled to triple quadrupole mass spectrometry employing electrospray ionization in the positive mode. Stable isotopically-labelled PBTZ169 was used as internal standard (ISTD), while metabolites could be reliably quantified using two unlabeled chemical analogues selected as ISTD from a large in-house analogous compounds library. The overall methodology was fully validated according to current recommendations (FDA, EMEA) for bioanalytical methods, which include selectivity, carryover, qualitative and quantitative matrix effect, extraction recovery, process efficiency, trueness, precision, accuracy profiles, method and instrument detection limits, integrity to dilution, anticoagulant comparison and short- and long-term stabilities. Stability studies on the reduced metabolite H2-PBTZ169 have shown no significant impact on the actual PBTZ169 concentrations determined with the proposed assay. This simplified, rapid, sensitive and robust methodology has been applied to the bioanalysis of human plasma samples collected within the frame of a phase I clinical study in healthy volunteers receiving PBTZ169.

Design, synthesis, antitubercular and antibacterial activities of pyrrolo[3,2-b]pyridine-3-carboxamide linked 2-methoxypyridine derivatives and in silico docking studies

A novel series pyrrolo[3,2-b]pyridine-3-carboxamide linked 2-methoxypyridine derivatives have been designed, synthesized and confirmed by FT-IR, 1H NMR, 13C NMR, 19F NMR, MS, and elemental analysis. The synthesized compounds were screened for their antitubercular activity using microplate alamar blue assay method and antibacterial activity. Among the tested compounds, 4- fluorophenyl (8m), 4- chlorophenyl (8n) and 4-methoxyphenyl (8i) showed potent anti-TB activity (3.12 µg/mL) in comparison with reference drug, Pyrazinamide ((3.12 µg/mL). In addition, all compounds were docked into DprE1 (PDB code: 4KW5) to explore their binding interactions at the active site. The compounds exhibited essential key interactions as that of reported DprE1 inhibitors and hence, the synthesized compounds may be considered as molecular scaffolds for antitubercular activity. Compounds, 4-chlorophenyl (8n) and 4-flurophenyl (8m) showed significant antibacterial activity against Escherichia coli and Staphylococcus aureus strains. In silico prediction of toxicities, druglikeness and drug score profiles of the tested compounds are promising.

Targeting HIV-TB coinfection by developing novel piperidin-4-substituted imines: Design, synthesis, in vitro and in silico studies.

Tuberculosis is the "Achilles heel" of the human immunodeficiency (HIV) ministration. HIV-positive people are 16-27 times more prone to contract tuberculosis. But the adverse interaction between antiretroviral drugs and antitubercular drugs has made it necessary to look for a single drug regimen for HIV-TB coinfection. Piperidine derivatives have been reported as anti-HIV and anti-TB agents. This inspired us to design, synthesize, and characterize a series of 3,5-bis(furan-2-ylmethylidene)-piperidin-4-substituted imines (R1-R25) and these were further screened for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv and anti-HIV activity. Molecular docking studies showed energetically favorable binding interactions with both EACP reductase (1ZID.pdb) and reverse-transcriptase (1REV.pdb) targets. The compounds R7, R12, R17, R18, R19, R20 were found to be more potent as anti-TB agents than ethambutol (MIC 3.125 μg/ml). Compound R7 was found to be moderately active with an IC50 of 2.1 ± 0.04 μM in multicycle infection assays, in comparison with the standard drug, zidovudine (IC50 = 5.7 ± 0.04 nM), used as anti-HIV drug. The cytotoxicity assay was done on Vero, MT-2, and TZM-bl cells to assess the safety of these compounds and they were found to be safe. From the above results, R7 seems to be a promising lead for anti-HIV and anti-TB activity.

Design, synthesis and biological evaluation of substituted 2-amino-1,3-thiazine derivatives as antituberculosis and anti-cancer agents

A series of substituted 2-amino-1,3-thiazines were synthesized as amides (9a-9i), carbamates (9j-9m), sulfonamides (9n-9o) and urea derivatives (9p-9q) by treating the compound 7 with acid chlorides (8a-8i), chloroformates (8j-8m), sulfonyl chlorides (8n-8o) and isocyanates (8p-8q) respectively. The synthesized compounds (9a-9q) were screened for antituberculosis activity against Mycobacterium tuberculosis H37Rv ATCC 27294 and the results show that some of these derivatives possess good activity against Mycobacterium tuberculosis H37Rv ATCC 27294. A few also display promising cytotoxic activity against human breast cancer MCF-7 and human esophageal cancer EC-9706 cell lines. Regarding both biological profiles 9b, 9m and 9h are the most active for anti-cancer, anti-TB activity.

Synthesis and Structural Elucidation of Novel Benzothiazole Derivatives as Anti-tubercular Agents: In-silico Screening for Possible Target Identification.

Benzothiazole derivatives are known for anti-TB properties. Based on the known anti-TB benzothiazole pharmacophore, in the present study, we described the synthesis, structural elucidation, and anti-tubercular screening of a series of novel benzothiazole (BNTZ) derivatives (BNTZ 1-7 and BNTZ 8-13). The study aims to carry out the development of benzothiazole based anti-TB compounds. Title compounds are synthesized by microwave method and purified by column chromatography. Characterization of the compounds is achieved by FT-IR, NMR (1H and 13C), LCMS and elemental analysis. Screening of test compounds for anti-TB activity is achieved by Resazurin Microplate Assay (REMA) Plate method. It was noted that the BNTZ compound with an isoquinoline nucleus (BNTZ 9) exhibited remarkable anti-tubercular activity at 8 µg/mL against both the susceptible strain H37Rv and the multi-drug resistant tuberculosis strains of Mycobacterium tuberculosis. On the other hand, the BNTZ compound with a naphthalene nucleus (BNTZ 2) revealed anti-tubercular activity at 6 µg/mL and 11 µg/mL against both the susceptible strain H37Rv and the multi-drug resistant tuberculosis strains of M. tuberculosis, respectively. One of the selected BNTZ derivatives BNTZ 13 was used for single crystal X-ray studies. To identify the appropriate target for potent BNTZ compounds from the series, molecular modeling studies revealed the multiple strong binding of several BNTZs with mycobacterium lysine-ɛ-aminotransferase and decaprenyl-phosphoryl-β-D-ribose 2'-oxidase. The interaction is derived by forming favorable hydrogen bonds and stacking interactions. This new class of BNTZ compounds gave promising anti-tubercular actions in the low micromolar range, and can be further optimized on a structural basis to develop promising, novel, BNTZ pharmacophore-based anti-tubercular drugs.

Biosynthetic and Synthetic Strategies for Assembling Capuramycin-Type Antituberculosis Antibiotics.

Mycobacterium tuberculosis (Mtb) has recently surpassed HIV/AIDS as the leading cause of death by a single infectious agent. The standard therapeutic regimen against tuberculosis (TB) remains a long, expensive process involving a multidrug regimen, and the prominence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) strains continues to impede treatment success. An underexplored class of natural products—the capuramycin-type nucleoside antibiotics—have been shown to have potent anti-TB activity by inhibiting bacterial translocase I, a ubiquitous and essential enzyme that functions in peptidoglycan biosynthesis. The present review discusses current literature concerning the biosynthesis and chemical synthesis of capuramycin and analogs, seeking to highlight the potential of the capuramycin scaffold as a favorable anti-TB therapeutic that warrants further development.

Benzofuran-isatin-imine hybrids tethered via different length alkyl linkers: Design, synthesis and in vitro evaluation of anti-tubercular and anti-bacterial activities as well as cytotoxicity

Herein we report the design and synthesis of twenty-two novel benzofuran-isatin-imine hybrids 7a-v tethered through propylene, butylene, pentylene and hexylene, and for the evaluation of their in vitro anti-tubercular and anti-bacterial activities as well as cytotoxicity. All benzofuran-isatin-imine hybrids exhibited considerable in vitro anti-TB (MIC: <0.016–0.218 μg/mL and 0.062–14.15 μg/mL against drug-sensitive and MDR MTB, respectively) and anti-bacterial (MIC: 0.25–64 μg/mL and 0.06–16 μg/mL against Gram-positive and Gram-negative strains, respectively) activities. All of them also showed acceptable cytotoxicity towards VERO (CC50: 8–128 μg/mL). The most active hybrid 7j (MIC: <0.016, 0.062 and 0.16 μg/mL, respectively) was >4.8 and ≥ 48 folds more potent than the first line anti-TB agents RIF and INH against both drug-sensitive MTB H37Rv and MDR-TB isolates, respectively. Moreover, hybrid 7j also demonstrated promising anti-bacterial activities with MIC values of ≤1 μg/mL against the majority of the tested Gram-negative and Gram-positive pathogens, which was comparable to vancomycin (MIC: 0.5–4 μg/mL) and CPFX (MIC: 0.125–8 μg/mL) against Gram-positive bacteria, but slightly less potent than CPFX (MIC: ≤0.03–0.5 μg/mL) against Gram-negative bacteria. The results indicated that benzofuran-isatin-imine hybrids could act as candidates for the development of anti-TB and anti-bacterial agents.

ANALYSIS OF BIOLOGICAL ACTIVITY AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY STUDY OF CONVENTIONAL EXTRACTION OF VITEX NEGUNDO LINN. LEAVES

Objective: The main objective of the present work is to carry out the biological activity, gas chromatography-mass spectrometry (GC-MS) studies for the possible compounds present in Vitex negundo.Methods: The aqueous extract of V. negundo Linn. was screened for biological activities such as antimicrobial, antituberculosis (TB), antimalarial, and antioxidant activities. The GC-MS analysis was carried out.Results: The result shows that leaf extract is effective against Escherichia Coli and Bacillus subtitus while negative results for anti-TB and anti-malarial activity. The antioxidant activity of the leave extract is excellent.Conclusion: The compounds present in the leaf extract of V. negundo are responsible for possessing the biological activity.

ANALYSIS OF BIOLOGICAL ACTIVITY AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY STUDY OF CONVENTIONAL EXTRACTION OF VITEX NEGUNDO LINN. LEAVES

Objective: The main objective of the present work is to carry out the biological activity, gas chromatography-mass spectrometry (GC-MS) studies for the possible compounds present in Vitex negundo.Methods: The aqueous extract of V. negundo Linn. was screened for biological activities such as antimicrobial, antituberculosis (TB), antimalarial, and antioxidant activities. The GC-MS analysis was carried out.Results: The result shows that leaf extract is effective against Escherichia Coli and Bacillus subtitus while negative results for anti-TB and anti-malarial activity. The antioxidant activity of the leave extract is excellent.Conclusion: The compounds present in the leaf extract of V. negundo are responsible for possessing the biological activity.

Sulfisoxazole Guanidinyl Derivatives: Synthesis, Characterization and Docking Studies for potential Anti-TB agents

Guanidine’s are major functionality in natural and synthetic compound, which exhibit a variety of activities like antidiabetic, antimicrobial, antiviral, anticancer, antibiotic and anti-inflammatory etc. The wide spread of guanidine compounds in the field of pharmaceutical, makes them as one of the attractive pharmacophores. The presence of the -CN3 group in guanidine compounds makes them to have efficient affinity towards various substituents with wide range of biochemical activities. In the present study, novel Sulfisoxazole guanidinyl derivatives were synthesized and characterized by LCMS and NMR spectral studies. The synthesized compounds were screened for anti-TB and anti-oxidant activities. It was found that compounds with electron donating groups exhibited superior activity.

Antitubercular Activity of the Fungus Gliocladium sp. MR41 Strain.

Tuberculosis (TB) is a leading cause of death worldwide from infectious diseases and its inadequate treatment has led to emergence of resistant strains. The emergence of these strains renders the search for new drugs for the treatment of TB. The aim of this study was the evaluation of the anti-TB activity of the extract from fungus Gliocladium sp. MR41, and bioassay-guided fractionation and identification of majority compounds was carried out. Fungal strain culture was lyophilized and extracted by maceration in Ethyl Acetate (EtOAc). This extract was fractionated by liquid-liquid partitioning and chromatographic techniques, and the compounds were identified by their spectroscopic data. Furthermore, the EtOAc extract, fractions, and pure compounds were tested on Mycobacterium tuberculosis using the Microplate Alamar Blue Assay. From the bioactive AcetoNitrile Fraction (AcNF; MIC = 3.13 µg/mL) of the EtOAc extract, four compounds were isolated: ergosterol (1), ergosterol-5, 8-peroxide (2), 1, 6-di-O-acetyl-2,3,4,5-tetrahydroxy-hexane (3), and allitol (4). Only 2 exhibited potent activities against M. tuberculosis (MIC = 0.78 µg/mL). Additionally, this is the first report, to our knowledge, of polyols 3 and 4 from this fungus.

Facile synthesis of 1,4-benzodiazepine-2,5-diones and quinazolinones from amino acids as anti-tubercular agents

A family of 1,4-benzodiazepine-2,5-diones and quinazolinones with diverse substituents at C-3 position are synthesized by novel, simple and convenient methodology using H2PtCl6as catalyst and were all screened for anti-TB activity.

Synthesis, Screening and Docking Analysis of Novel Benzimidazolium and Benzotriazolium Compounds as Potent Anti Tubercular Agents

Introduction: Tuberculosis is an infectious bacterial disease that mainly affects the lungs. Globally, there are about 10.5 million new cases and about 1.5 million deaths reported each year as per science daily research news in 2017.Objective:One of the biggest problems of Tuberculosis is the lack of effective treatments. Bedaquiline (2013) and Delaminid (2014) are the only two agents approved for TB after Rifampicin. This clearly shows the need for new lead molecules to fight against TB.Methodology:A series of benzimidazolium and benzotriazolium derivatives were synthesized and the structures were confirmed by their IR, 1H NMR,13C NMR and mass spectral data. They were tested for in vitro antitubercular activity by MABA Assay, MTT Assay and axenic culture assay. To determine selective TB activity, they were also tested for antimicrobial activity and cytotoxicity. Docking simulations and drug-inhibitor combination studies were conducted to know the probable mechanism of action.Results:Among the synthesized compounds B10, B11, B13, B14, B22, B23, B24, B25, B26 and B27 showed excellent anti TB activity with an MIC 3.12-0.8 µg/mL. Among these, compound 1,3- bis(4-chlorobenzyl)-1H-benzo[d]imidazol-3-ium chloride (B11) has shown selective anti TB activity against Mycobacterium tuberculosis H37Rv (0.8µg/mL) in MABA assay. This compound hasn’t shown any antimicrobial (at 100μg/mL) and cytotoxicity (at 10µM). Docking studies and drug-inhibitor combination studies indicated that the compounds might act via enzymes involved in the cell division process.Conclusion:In conclusion, we synthesized molecules with potent and selective anti TB activity.

A Nanostructured Lipid System to Improve the Oral Bioavailability of Ruthenium(II) Complexes for the Treatment of Infections Caused by Mycobacterium tuberculosis.

Tuberculosis (TB) is an infectious, airborne disease caused by the bacterium Mycobacterium tuberculosis that mainly affects the lungs. Fortunately, tuberculosis is a curable disease, and in recent years, death rates for this disease have decreased. However, the existence of antibiotic-resistant strains and the occurrence of co-infections with human immunodeficiency virus (HIV), have led to increased mortality in recent years. Another area of concern is that one-third of the world′s population is currently infected with M. tuberculosis in its latent state, serving as a potential reservoir for active TB. In an effort to address the failure of current TB drugs, greater attention is being given to the importance of bioinorganic chemistry as an ally in new research into the development of anti-TB drugs. Ruthenium (Ru) is a chemical element that can mimic iron (Fe) in the body. In previous studies involving the following heteroleptic Ru complexes, [Ru(pic)(dppb)(bipy)]PF6 (SCAR1), [Ru(pic)(dppb)(Me-bipy)]PF6 (SCAR2), [Ru(pic)(dppb)(phen)]PF6 (SCAR4), cis-[Ru(pic)(dppe)2]PF6 (SCAR5), and [Ru(pic)(dppe)(phen)]PF6 (SCAR7), we observed excellent anti-TB activity, moderate cell-toxicity, and a lack of oral bioavailability in an in vivo model of these complexes. Therefore, the objective of this study was to evaluate the toxicity and oral bioavailability of these complexes by loading them into a nanostructured lipid system. The nanostructured lipid system was generated using different ratios of surfactant (soybean phosphatidylcholine, Eumulgin®, and sodium oleate), aqueous phase (phosphate buffer with a concentration of 1X and pH 7.4), and oil (cholesterol) to generate a system for the incorporation of Ru(II) compounds. The anti-TB activity of the compounds was determined using a microdilution assay with Resazurin (REMA) against strains of M. tuberculosis H37Rv and clinical isolates resistant. Cytotoxicity assay using J774.A1 cells (ATCC TIB-67) and intra-macrophage activity were performed. The oral bioavailability assay was used to analyze blood collected from female BALB/C mice. Plasma collected from the same mice was analyzed via inductively coupled plasma mass spectrometry (ICP-MS) to quantify the number of Ru ions. The complexes loaded into the nanostructured lipid system maintained in vitro activity and toxicity was found to be reduced compared with the compounds that were not loaded. The complexes showed intra-macrophagic activity and were orally bioavailable.