anti-Mycobacterium Tuberculosis Activity Research Articles

Evaluation of the anti-mycobacterium tuberculosis activity and in vivo acute toxicity of Annona sylvatic.

BackgroundThe recent emergence of extensively multidrug-resistant Mycobacterium tuberculosis strains has further complicated the control of tuberculosis. There is an urgent need for the development of new molecular candidates antitubercular drugs. Medicinal plants have been an excellent source of leads for the development of drugs. The aim of this study was to evaluate the in vitro activity of 28 alcoholic extracts and essential oils of native and exotic Brazilian plants against Mycobacterium tuberculosis and to further study these extracts through chemical fractionation, the isolation of their constituents, and an evaluation of the in vivo acute toxicity of the active extracts. To the best of our knowledge this is the first chemical characterization, antituberculosis activity and acute toxicity evaluation of Annona sylvatica.MethodsThe anti-mycobacterial activity of these extracts and their constituent compounds was evaluated using the resazurin reduction microtiter assay (REMA). To investigate the acute toxicity of these extracts in vivo, female Swiss mice were treated with the extracts at doses of 500, 1000 and 2000 mg · kg-1 of body weight. The extracts were characterized by LC-MS, and the constituents were isolated and identified by chromatographic analysis of spectroscopic data.ResultsOf the 28 extracts, the methanol extract obtained from the leaves of Annona sylvatica showed anti-mycobacterial activity with an minimal inhibitory concentration (MIC) of 184.33 μg/mL, and the ethyl acetate fraction (EAF) resulting from liquid-liquid partitioning of the A. sylvatica extract showed an MIC of 115.2 μg/mL. The characterization of this extract by LC-MS identified flavonoids and acetogenins as its main constituents. The phytochemical study of the A. sylvatica EAF resulted in the isolation of quercetin, luteolin, and almunequin.ConclusionsAmong the compounds isolated from the EAF, luteolin and almunequin were the most promising, with MICs of 236.8 μg/mL (827.28 μM) and 209.9 μg/mL (328.48 μM), respectively. The acute administration of the EAF fraction in doses of 500, 1000, and 2000 mg · kg-1 of body weight did not cause signs of toxicity in the treated animals.

ChemInform Abstract: Carbamidocyclophanes F and G with anti‐Mycobacterium tuberculosis Activity from the Cultured Freshwater Cyanobacterium Nostoc sp.

AbstractCarbamidocyclophane F (Ia) shows a potent anti‐Mycobacterium tuberculosis activity in the microplate Alamar blue assay and low‐oxygen‐recovery assay with MIC values of 0.8 and 5.4 μM, respectively.

Evaluating the anti Mycobacterium tuberculosis activity of Alpinia galanga (L.) Willd. axenically under reducing oxygen conditions and in intracellular assays

BackgroundIn tuberculosis (TB), the steadily increasing bacterial resistance to existing drugs and latent TB continue to be major concerns. A combination of conventional drugs and plant derived therapeutics can serve to expand the antimicrobial spectrum, prevent the emergence of drug resistant mutants and minimize toxicity. Alpinia galanga, used in various traditional medicines, possesses broad spectrum antibacterial properties. The study was undertaken to assess the antimycobacterial potential of A. galanga in axenic (under aerobic and anaerobic conditions) and intracellular assays.MethodsPhytochemical analysis was done using HPTLC. The acetone, aqueous and ethanolic extracts (1, 10, 25, 50 and 100 μg/ml) of A. galanga were tested axenically using Microplate Alamar Blue Assay (MABA) against Mycobacterium tuberculosis (M.tb) H37Rv and three drug sensitive and three multi drug resistant clinical isolates. The activity of the extracts was also evaluated intracellularly in A549 cell line against these strains. The extracts active under intracellular conditions were further tested in an axenic setup under reducing oxygen concentrations using only H37Rv.Results1´ acetoxychavicol acetate, the reference standard used, was present in all the three extracts. The acetone and ethanolic extracts were active in axenic (aerobic and anaerobic) and intracellular assays. The aqueous extract did not demonstrate activity under the defined assay parameters.ConclusionA. galanga exhibits anti M.tb activity with multiple modes of action. Since the activity of the extracts was observed under reducing oxygen concentrations, it may be effective in treating the dormant and non-replicating bacteria of latent TB. Though the hypothesis needs further testing, A. galanga being a regular dietary component may be utilized in combination with the conventional TB therapy for enhanced efficacy.

Carbamidocyclophanes F and G with anti-Mycobacterium tuberculosis activity from the cultured freshwater cyanobacterium Nostoc sp.

Two new (1 and 2) and three known (3–5) carbamidocyclophanes were isolated from a cultured freshwater cyanobacterium Nostoc sp. (UIC 10274) obtained from a sample collected at Des Plaines, Illinois. Their planar structures and stereoconfigurations were determined by extensive spectroscopic analysis including 1D/2D NMR experiments, HRESIMS as well as CD spectroscopy. Carbamidocyclophane F (1) showed potent anti-Mycobacterium tuberculosis activity in the microplate Alamar blue assay and low-oxygen-recovery assay with MIC values of 0.8 and 5.4μM, respectively. Carbamidocyclophane F (1) also displayed antimicrobial activities against the gram positive bacteria Staphylococcus aureus and Enterococcus faecalis with MIC values of 0.1 and 0.2μM, respectively. Carbamidocyclophane F (1) and Carbamidocyclophane G (2) both showed antiproliferative activity against MDA-MB-435 and HT-29 human cancer cell lines with IC50 values in the range from 0.5 to 0.7μM.

New Approaches to Tuberculosis - Novel Drugs Based on Drug Targets Related to Toll-Like Receptors in Macrophages

Tuberculosis (TB) is one of the most important health concerns in the world, causing serious levels of morbidity and mortality, particularly in many developing countries. Unfortunately, the development of new anti-TB drugs with superior chemotherapeutic and prophylactic activity has been very slow. Thus, it is urgently necessary to develop novel kinds of antituberculosis drugs that exert their anti-Mycobacterium tuberculosis (MTB) activity through unique drug targets expressed by MTB organisms. At present, the drug targets of most current anti-TB drugs are primarily bacterial metabolic reactions and cell components that are indispensable to the growth and survival of MTB organisms in extracellular milieus, particularly in culture media. To develop novel and unique anti-TB drugs in the future, it is desirable to highlight the drug targets related to the bacterial ability to survive and replicate in host macrophages by escaping from a macrophage's bacterial killing mechanism during infection inside such phagocytes. For this purpose, it is reasonable to focus our research efforts on mycobacterial virulence factors that cross-talk and interfere with signaling pathways of host macrophages, because such virulence factors will provide intracellular milieus favorable to intramacrophage survival and growth of MTB. In this chapter, based on such a viewpoint and strategy, the present status of worldwide research on novel potential drug targets related to Toll-like receptor in the MTB pathogen will be described.

Hytramycins V and I, Anti-Mycobacterium tuberculosis Hexapeptides from a Streptomyces hygroscopicus Strain

Thirty-five thousand actinomycete extracts were screened for anti-Mycobacterium tuberculosis (M. tb) activity, followed by C18 cartridge fractionation of 37 prioritized extracts. Based on MICs against replicating and nonreplicating M. tb, and IC50 values against Vero cells to generate selectivity indices, seven fractions from seven different strains were selected for further examination. When cultured in G.S.S. media and extracted with ethyl acetate, the Streptomyces hygroscopicus strain ECUM 14046 yielded an extract with promising anti-M. tb activity and a well-defined chromatographic profile. Fractionation by preparative HPLC and subsequent structure elucidation of two active fractions using 1D- and 2D-NMR and MS methods revealed the presence of two cyclohexapeptides, hytramycins V and I, each containing three unusual piperazic acid moieties. The use of (1)H iterative full spin analysis (HiFSA) on both hytramycins confirmed that quantum mechanics-simulated spectra match the experimental data, and all J(H,H) and δH values are consistent with the proposed structures. The absolute configuration of each amino acid moiety was determined by Marfey's method. The MICs against replicating and, more importantly, nonreplicating M. tb fall into the range of some existing second-line anti-TB drugs, such as streptomycin and capreomycin, respectively. The activities were maintained against M. tb strains that represent the major global clades, as well as H37Rv-isogenic strains that are resistant to individual clinical anti-TB drugs.

Manganese(II) complexes with thiosemicarbazones as potential anti-Mycobacterium tuberculosis agents

Through a systematic variation on the structure of a series of manganese complexes derived from 2-acetylpyridine-N(4)-R-thiosemicarbazones (Hatc-R), structural features have been investigated with the aim of obtaining complexes with potent anti-Mycobacterium tuberculosis activity. The analytical methods used for characterization included FTIR, EPR, UV–visible, elemental analysis, cyclic voltammetry, magnetic susceptibility measurement and single crystal X-ray diffractometry. Density functional theory (DFT) calculations were performed in order to evaluate the contribution of the thiosemicarbazonate ligands on the charge distribution of the complexes by changing the peripheral groups as well as to verify the Mn–donor atoms bond dissociation predisposition. The results obtained are consistent with the monoanionic N,N,S-tridentate coordination of the thiosemicarbazone ligands, resulting in octahedral complexes of the type [Mn(atc-R)2], paramagnetic in the extension of 5 unpaired electrons, whose EPR spectra are consistent for manganese(II). The electrochemical analyses show two nearly reversible processes, which are influenced by the peripheral substituent groups at the N4 position of the atc-R1− ligands. The minimal inhibitory concentration (MIC) of these compounds against M. tuberculosis as well as their in vitro cytotoxicity on VERO and J774A.1 cells (IC50) was determined in order to find their selectivity index (SI) (SI=IC50/MIC). The results evidenced that the compounds described here can be considered as promising anti-M. tuberculosis agents, with SI values comparable or better than some commercial drugs available for the tuberculosis treatment.

Anti-tuberculosis neolignans from Piper regnellii

The present study determined the anti-Mycobacterium tuberculosis activities of supercritical CO2 extracts, neolignans eupomatenoid-5 (1), conocarpan (4) and eupomatenoid-3 (7) and their derivatives (2, 3, 5, 6, and 8) from Piper regnellii, as well as their cytotoxicities. The supercritical CO2 extract from leaves was purified by chromatographic methods, yielding compounds (1), (4) and (7), which were identified by 1H NMR and comparison with literature data. Anti-M. tuberculosis activity (H37Rv and clinical isolates) was evaluated using a resazurin microtiter assay plate (REMA) to determine the MIC. The cytotoxicity assay was carried out in macrophages J774G.8 by sulforhodamine B colorimetric assay. The supercritical CO2 extracts from leaves and stems, and compound (4) showed activity against M. tuberculosis (MIC 15.6μg/ml). Compound (1) showed the best activity (MIC 1.9μg/ml), with good SI. Compounds (7) and (8) showed low activity against M. tuberculosis H37Rv. The derivative compounds did not show increased anti-M. tuberculosis activity. This is the first report, to our knowledge, to describe neolignans from P. regnellii with activity against M. tuberculosis, and compound (1) is a potential candidate for future antituberculosis drugs.

Chemical composition of hexane extract of Citrus aurantifolia and anti-Mycobacterium tuberculosis activity of some of its constituents.

The main aim of this study was to isolate and characterize the active compounds from the hexane extract of the fruit peels of Citrus aurantiifolia, which showed activity against one sensitive and three monoresistant (isoniazid, streptomycin or ethambutol) strains of Mycobacterium tuberculosis H37Rv. The active extract was fractionated by column chromatography, yielding the following major compounds: 5-geranyloxypsoralen (1); 5-geranyloxy-7-methoxycoumarin (2); 5,7-dimethoxycoumarin (3); 5-methoxypsoralen (4); and 5,8-dimethoxypsoralen (5). The structures of these compounds were elucidated by 1D and 2D NMR spectroscopy. In addition, GC-MS analysis of the hexane extract allowed the identification of 44 volatile compounds, being 5,7-dimethoxycoumarin (15.79%), 3-methyl-1,2-cyclopentanedione (8.27%), 1-methoxy-ciclohexene (8.0%), corylone (6.93%), palmitic acid (6.89%), 5,8-dimethoxypsoralen (6.08%), α-terpineol (5.97%), and umbelliferone (4.36%), the major constituents. Four isolated coumarins and 16 commercial compounds identified by GC-MS were tested against M. tuberculosis H37Rv and three multidrug-resistant M. tuberculosis strains using the Microplate Alamar Blue Assay. The constituents that showed activity against all strains were 5 (MICs = 25–50 μg/mL), 1 (MICs = 50–100 μg/mL), palmitic acid (MICs = 25–50 μg/mL), linoleic acid (MICs = 50–100 μg/mL), oleic acid (MICs = 100 μg/mL), 4-hexen-3-one (MICs = 50–100 μg/mL), and citral (MICs = 50–100 μg/mL). Compound 5 and palmitic acid were the most active ones. The antimycobacterial activity of the hexane extract of C. aurantifolia could be attributed to these compounds.

Anti-Mycobacterium tuberculosis activity of extracts with a new benzoic acid derivative from Piper diospyrifolium by supercritical carbon dioxide

Anti-Mycobacterium tuberculosis activity of extracts with a new benzoic acid derivative from Piper diospyrifolium by supercritical carbon dioxide

Screening a library of 1600 adamantyl ureas for anti-Mycobacterium tuberculosis activity in vitro and for better physical chemical properties for bioavailability

Adamantyl ureas were previously identified as a group of compounds active against Mycobacterium tuberculosis in culture with minimum inhibitor concentrations (MICs) below 0.1μg/ml. These compounds have been shown to target MmpL3, a protein involved in secretion of trehalose mono-mycolate. They also inhibit both human soluble epoxide hydrolase (hsEH) and M. tuberculosis epoxide hydrolases. However, active compounds to date have high cLogP’s and are poorly soluble, leading to low bioavailability and thus limiting any therapeutic application. In this study, a library of 1600 ureas (mostly adamantyl ureas), which were synthesized for the purpose of increasing the bioavailability of inhibitors of hsEH, was screened for activity against M. tuberculosis. 1-Adamantyl-3-phenyl ureas with a polar para substituent were found to retain moderate activity against M. tuberculosis and one of these compounds was shown to be present in serum after oral administration to mice. However, neither it, nor a closely related analog, reduced M. tuberculosis infection in mice. No correlation between in vitro potency against M. tuberculosis and the hsEH inhibition were found supporting the concept that activity against hsEH and M. tuberculosis can be separated. Also there was a lack of correlation with cLogP and inhibition of the growth of M. tuberculosis. Finally, members of two classes of adamantyl ureas that contained polar components to increase their bioavailability, but lacked efficacy against growing M. tuberculosis, were found to taken up by the bacterium as effectively as a highly active apolar urea suggesting that these modifications to increase bioavailability affected the interaction of the urea against its target rather than making them unable to enter the bacterium.

Anti-Mycobacterium tuberculosis activity of fungus Phomopsis stipata.

Our purpose was to determine the anti-Mycobacterium tuberculosis activity of the metabolites produced by the endophitic fungus Phomopsis stipata (Lib.) B. Sutton, (Diaporthaceae), cultivated in different media. The antimycobacterial activity was assessed through the Resazurin Microtiter Assay (REMA) and the cytotoxicity test performed on macrophage cell line. The extracts derived from fungi grown on Corn Medium and Potato Dextrose Broth presented the smallest values of Minimum Inhibitory Concentration (MIC) and low cytotoxicity, which implies a high selectivity index. This is the first report on the chemical composition and antitubercular activity of metabolites of P. stipata, as well as the influence of culture medium on these properties.

Eucapsitrione, an Anti-Mycobacterium tuberculosis Anthraquinone Derivative from the Cultured Freshwater Cyanobacterium Eucapsis sp.

Eucapsitrione (1), an anthraquinone derivative with an indeno-anthracene-trione skeleton, was isolated from the cyanobacterium Eucapsis sp. (UTEX 1519) by bioassay-guided fractionation. The chemical structure was determined by analyzing MS and 1D and 2D NMR spectroscopic data. Eucapsitrione (1) showed anti-Mycobacterium tuberculosis activity in the microplate Alamar blue assay and low-oxygen-recovery assay with MIC values of 3.1 and 6.4 microM, respectively.

Palladium(II) complexes with thiosemicarbazones: syntheses, characterization and cytotoxicity against breast cancer cells and Anti-Mycobacterium tuberculosis activity

Three PdII complexes were prepared from N(4)-substituted thiosemicarbazones: [Pd(aptsc)(PPh3)](NO3)•H2O, 1, [Pd(apmtsc)(PPh3)](NO3), 2, and [Pd(apptsc)(PPh3)](NO3)•H2O, 3, where PPh3 = triphenylphosphine; Haptsc = 2-acetylpyridine-thiosemicarbazone; Hapmtsc = 2-acetylpyridine-N(4)-methyl-thiosemicarbazone and Happtsc = 2-acetylpyridine-N(4)-phenyl-thiosemicarbazone. All complexes were characterized by elemental analysis, IR, UV-Vis, ¹H and 31P{¹H} NMR spectroscopies, and had their crystalline structures determined by X-ray diffractometry from single crystals. The monoanionic thiosemicarbazonate ligands act in a tridentate mode, binding to the metal through the pyridine nitrogen, the azomethine nitrogen and the sulfur atoms. The cytotoxic activity against the breast cancer cell line MDA-MB231 and the anti-Mycobacterium tuberculosis H37Rv ATCC 27294 activity were evaluated for the compounds. All PdII complexes were highly active against the studied cell line, presenting similar values of IC50, around 5 µmol L-1, while the clinically applied antitumor agent cisplatin was inactive. The compounds show remarkable anti-M. tuberculosis activities, presenting MIC values comparable or better than some commercial anti-M tuberculosis drugs.

Ruthenium (II) phosphine/picolinate complexes as antimycobacterial agents

The synthesis, characterization and the anti-Mycobacterium tuberculosis (MTB) activities of three ruthenium complexes containing the 2-pyridinecarboxylic acid anion (picolinate), with formulae cis- [Ru(pic)(dppm)2]PF6 (1), cis- [Ru(pic)(dppe)2]PF6 (2) and [Ru(pic)2(PPh3)2] (3) [pic=2-pyridinecarboxylate; dppm=bis(diphenylphosphino)methane; dppe=1,2-bis(diphenylphosphino)ethane; PPh3=triphenylphosphine] are reported in this article. The complexes were characterized by elemental analysis, spectroscopic and electrochemical techniques. Their in vitro antimycobacterial activity was determinated as the Minimum Inhibitory Concentration (MIC) for MTB cell growth, measured by the REMA method. The best MICs were found for complexes (1) and (2), with values of 0.78 and 0.26μg/mL, respectively. The results are comparable to or better than “first line” or “second line” drugs commonly used in the treatment of TB.

Synthesis and in vitro anti Mycobacterium tuberculosis activity of a series of phthalimide derivatives

New phthalimide derivatives were easily prepared through condensation of phthalic anhydride and selected amines with variable yields (70–90%). All compounds ( 3a– l) were evaluated against Mycobacterium tuberculosis H 37Rv using Alamar Blue susceptibility. The compounds 3c, 3i, and 3l have the minimum inhibitory concentrations (MICs) of 3.9, 7.8, and 5.0 μg/mL, respectively, and could be considered new lead compounds in the treatment of tuberculosis and multi-drug resistant tuberculosis.

Evaluation of anti-Mycobacterium tuberculosis activity of Campomanesia adamantium (Myrtaceae)

The anti-Mycobacterium tuberculosis activity of Campomanesia adamantium fruits extracts were evaluated. Six compounds, identified as flavanones and chalcones were quantified by HPLC-DAD-UV. Promising antitubercular activity was observed with ethyl acetate extract (MIC 62.5 μg/mL) and their fractions (MIC values ranging from 39 to above 250 μg/mL). The better MIC result of 39 μg/mL was associated with two fractions that contain bigger amounts of 5,7-dihydroxy-6, 8-di-C-methylflavanone and 2’,4’-dihydroxy-3’,5’dimethyl-6’-methoxychalcone. These compounds exhibited MICs >250 and 62.5 μg/mL, respectively, while their mixtures showed values ranging from 62.5 to 7.8 μg/mL, demonstrating a synergism between them.

Antimycobacterial pyrroles: synthesis, anti-Mycobacterium tuberculosis activity and QSAR studies

A number of known antifungal pyrrole derivatives and some newly synthesized compounds (5–33) were tested in vitro against Mycobacterium tuberculosis CIP 103471. The majority of tested compounds were efficient antimycobacterial agents showing MIC values ranging from 0.5 to 32 μg/mL. A 3-D-QSAR study has been performed on these pyrrole derivatives to correlate their chemical structures with their observed inhibiting activity against M. tuberculosis. Due to the absence of information on a putative receptor responsible for this activity, classical quantitative structure–activity relationships (QSAR) and comparative molecular field analysis (CoMFA) have been applied. A model able to well correlate the antimycobacterial activity with the chemical structures of pyrrole derivatives 5–33 has been developed which is potentially helpful in the design of novel and more potent antituberculosis agents. The combination of CoMFA with classical QSAR descriptors led to a better hybrid 3-D-QSAR model, that successfully explains the structure–activity relationships (r2=0.86) of the training set. A comparison between the QSAR, CoMFA and mixed QSAR–CoMFA models is also presented. The hybrid model is to be preferred, however, because of its lowest values of the average absolute error of prediction toward a limited external test set.