Exploring Scaffold Hopping for Novel 2-(Quinolin-4-yloxy)acetamides with Enhanced Antimycobacterial Activity.

Utilizing a scaffold-hopping strategy from the drug candidate telacebec, a novel series of 2-(quinolin-4-yloxy)acetamides was synthesized and evaluated as inhibitors of Mycobacterium tuberculosis (Mtb) growth. These compounds demonstrated potent activity against drug-sensitive and multidrug-resistant strains (MIC ≤ 0.02 µM). Leading compounds were evaluated against a known qcrB resistant strain (T313A), and their loss in activity suggested that the cytochrome bc1 complex is the likely target. Additionally, these structures showed high selectivity regarding mammalian cells (selectivity index > 500) and stability across different aqueous media. Furthermore, some of the synthesized quinolines demonstrated aqueous solubility values that exceeded those of telacebec, while maintaining low rates of metabolism. Finally, a selected compound prevented Mtb growth by more than 1.7 log10 colony forming units in a macrophage model of tuberculosis (TB) infection. These findings validate the proposed design and introduce new 2-(quinolin-4-yloxy)acetamides with potential for development in TB drug discovery campaigns.

Novel 4-aminoquinolines: Synthesis, inhibition of the Mycobacterium tuberculosis enoyl-acyl carrier protein reductase, antitubercular activity, SAR, and preclinical evaluation.

Herein a series of 4-aminoquinolines were synthesized in an attempt to optimize and study the structural features related to LABIO-17 biological activity, a Mycobacterium tuberculosis NADH-dependent enoyl-acyl carrier protein reductase (MtInhA) inhibitor previously identified by a virtual-ligand-screening approach. Structure-activity relationships led to novel submicromolar inhibitors of MtInhA and potent antitubercular agents. The lead compound is 87-fold more potent as enzymatic inhibitors and 32-fold more potent against M. tuberculosis H37Rv strain in comparison with LABIO-17. These molecules were also active against multidrug-resistant strains, devoid of apparent toxicity to mammalian cells and showed favorable in vitro ADME profiles. Additionally, these compounds were active in an intracellular model of tuberculosis (TB) infection, showed no genotoxicity signals, satisfactory absorption parameters and absence of in vivo acute toxicity. Finally, treatment with selected 4-aminoquinoline for two weeks produced bacteriostatic effect in a murine model of TB. Taken together, these findings indicate that this chemical class may furnish candidates for the future development of drug-sensitive and drug-resistant tuberculosis treatments.

Antitubercular Activity of Novel 2-(Quinoline-4-yloxy)acetamides with Improved Drug-Like Properties.

Using cycloalkyl and electron-donating groups to decrease the carbonyl electrophilicity, a novel series of 2-(quinoline-4-yloxy)acetamides was synthesized and evaluated as in vitro inhibitors of Mycobacterium tuberculosis (Mtb) growth. Structure-activity relationship studies led to selective and potent antitubercular agents with minimum inhibitory concentrations in the submicromolar range against drug-sensitive and drug-resistant Mtb strains. An evaluation of the activity of the lead compounds against a spontaneous qcrB mutant strain indicated that the structures targeted the cytochrome bc 1 complex. In addition, selected molecules inhibited Mtb growth in a macrophage model of tuberculosis infection. Furthermore, the leading compound was chemically stable depending on the context and showed good kinetic solubility, high permeability, and a low rate of in vitro metabolism. Finally, the pharmacokinetic profile of the compound was assessed after oral administration to mice. To the best of our knowledge, for the first time, a 2-(quinoline-4-yloxy)acetamide was obtained with a sufficient exposure, which may enable in vivo effectiveness and its further development as an antituberculosis drug candidate.

Evaluation of 3-Deoxy-D-Arabino-Heptulosonate 7-Phosphate Synthase (DAHPS) as a Vulnerable Target in Mycobacterium tuberculosis.

Tuberculosis (TB) remains one of the leading causes of death due to a single pathogen. The emergence and proliferation of multidrug-resistant (MDR-TB) and extensively drug-resistant strains (XDR-TB) represent compelling reasons to invest in the pursuit of new anti-TB agents. The shikimate pathway, responsible for chorismate biosynthesis, which is a precursor of important aromatic compounds, is required for Mycobacterium tuberculosis growth. The enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (MtbDAHPS) catalyzes the first step in the shikimate pathway and it is an attractive target for anti-tubercular agents. Here, we used a CRISPRi system to evaluate the DAHPS as a vulnerable target in M. tuberculosis. The silencing of aroG significantly reduces the M. tuberculosis growth in both rich medium and, especially, in infected murine macrophages. The supplementation with amino acids was only able to partially rescue the growth of bacilli, whereas the Aro supplement (aromix) was enough to sustain the bacterial growth at lower rates. This study shows that MtbDAHPS protein is vulnerable and, therefore, an attractive target to develop new anti-TB agents. In addition, the study contributes to a better understanding of the biosynthesis of aromatic compounds and the bacillus physiology. IMPORTANCE Determining the vulnerability of a potential target allows us to assess whether its partial inhibition will impact bacterial growth. Here, we evaluated the vulnerability of the enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS) from M. tuberculosis by silencing the DAHPS-coding aroG gene in different contexts. These results could lead to the development of novel and potent anti-tubercular agents in the near future.

Synthesis and Antimycobacterial Evaluation of N-(4-(Benzyloxy)benzyl)-4-aminoquinolines.

Tuberculosis remains a global health problem that affects millions of people around the world. Despite recent efforts in drug development, new alternatives are required. Herein, a series of 27 N-(4-(benzyloxy)benzyl)-4-aminoquinolines were synthesized and evaluated for their ability to inhibit the M. tuberculosis H37Rv strain. Two of these compounds exhibited minimal inhibitory concentrations (MICs) similar to the first-line drug isoniazid. In addition, these hit compounds were selective for the bacillus with no significant change in viability of Vero and HepG2 cells. Finally, chemical stability, permeability and metabolic stability were also evaluated. The obtained data show that the molecular hits can be optimized aiming at the development of drug candidates for tuberculosis treatment.

Short-chain fatty acid acetate triggers antiviral response mediated by RIG-I in cells from infants with respiratory syncytial virus bronchiolitis.

BACKGROUND: Gut microbiota-derived short-chain fatty-acid (SFCA) acetate protects mice against RSV A2 strain infection by increasing interferon-ß production and expression of interferon-stimulated genes (ISGs). However, the role of SFCA in RSV infection using strains isolated from patients is unknown. METHODS: We first used RSV clinical strains isolated from infants hospitalized with RSV bronchiolitis to investigate the effects of in vitro SCFA-acetate treatment of human pulmonary epithelial cells. We next examined whether SCFA-acetate treatment is beneficial in a mouse model of RSV infection using clinical isolates. We sought to investigate the relationship of gut microbiota and fecal acetate with disease severity among infants hospitalized with RSV bronchiolitis, and whether treating their respiratory epithelial cells with SCFA-acetate ex-vivo impacts viral load and ISG expression. We further treated epithelial cells from SARS-CoV-2 infected patients with SCFA-acetate. FINDINGS: In vitro pre-treatment of A549 cells with SCFA-acetate reduced RSV infection with clinical isolates and increased the expression of RIG-I and ISG15. Animals treated with SCFA-acetate intranasally recovered significantly faster, with reduction in the RSV clinical isolates viral load, and increased lung expression of IFNB1 and the RIG-I. Experiments in RIG-I knockout A549 cells demonstrated that the protection relies on RIG-I presence. Gut microbial profile was associated with bronchiolitis severity and with acetate in stool. Increased SCFA-acetate levels were associated with increasing oxygen saturation at admission, and shorter duration of fever. Ex-vivo treatment of patients' respiratory cells with SCFA-acetate reduced RSV load and increased expression of ISGs OAS1 and ISG15, and virus recognition receptors MAVS and RIG-I, but not IFNB1. These SCFA-acetate effects were not found on cells from SARS-CoV-2 infected patients. INTERPRETATION: SCFA-acetate reduces the severity of RSV infection and RSV viral load through modulation of RIG-I expression. FUNDING: FAPERGS (FAPERGS/MS/CNPq/SESRS no. 03/2017 - PPSUS 17/2551-0001380-8 and COVID-19 20/2551-0000258-6); CNPq 312504/2017-9; CAPES) - Finance Code 001.

Application of cellulosic materials as supports for single-step purification and immobilization of a recombinant ß-galactosidase via cellulose-binding domain.

This study aimed to develop single-step purification and immobilization processes on cellulosic supports of ß-galactosidase from Kluyveromyces sp. combined with the Cellulose-Binding Domain (CBD) tag. After 15 min of immobilization, with an enzymatic load of 150 U/gsupport, expressed activity values reached 106.88 (microcrystalline cellulose), 115.03 (alkaline nanocellulose), and 108.47 IU/g (acid nanocellulose). The derivatives produced were less sensitive to the presence of galactose in comparison with the soluble purified enzyme. Among the cations assessed (Na+, K+, Mg2+, and Ca2+), magnesium provided the highest increase in the enzymatic activity of ß-galactosidases immobilized on cellulosic supports. Supports and derivatives showed no cytotoxic effect on the investigated cell cultures (HepG2 and Vero). Derivatives showed high operational stability in the hydrolysis of milk lactose and retained from 53 to 64% of their hydrolysis capacity after 40 reuse cycles. This study obtained biocatalyzers with promising characteristics for application in the food industry. Biocatalyzers were obtained through a low-cost one-step sustainable bioprocess of purification and immobilization of a ß-galactosidase on cellulose via CBD.

One-step purification of a recombinant beta-galactosidase using magnetic cellulose as a support: Rapid immobilization and high thermal stability.

For the first time, this work reported the one-step purification and targeted immobilization process of a ß-galactosidase (Gal) with the Cellulose Binding Domain (CBD) tag, by binding it to different magnetic cellulose supports. The process efficiency after ß-galactosidase-CBD immobilization on magnetic cellulose-based supports showed values of approximately 90% for all evaluated enzymatic loads. Compared with free Gal, derivatives showed affinity values between ß-galactosidase and the substrate 1.2 × higher in the lactose hydrolysis of milk. ß-Galactosidase-CBD's oriented immobilization process on supports increased the thermal stability of the immobilized enzyme by up to 7 × . After 15 cycles of reuse, both enzyme preparations showed a relative hydrolysis percentage of 50% of lactose in milk. The oriented immobilization process developed for purifying recombinant proteins containing the CBD tag enabled the execution of both steps simultaneously and quickly and the obtention of ß-galactosidases with promising catalytic characteristics for application in the food and pharmaceutical industries.

Synthesis and Antimycobacterial Activity of 3-Phenyl-1H-indoles.

Tuberculosis has been described as a global health crisis since the 1990s, with an estimated 1.4 million deaths in the last year. Herein, a series of 20 1H-indoles were synthesized and evaluated as in vitro inhibitors of Mycobacterium tuberculosis (Mtb) growth. Furthermore, the top hit compounds were active against multidrug-resistant strains, without cross-resistance with first-line drugs. Exposing HepG2 and Vero cells to the molecules for 72 h showed that one of the evaluated structures was devoid of apparent toxicity. In addition, this 3-phenyl-1H-indole showed no genotoxicity signals. Finally, time-kill and pharmacodynamic model analyses demonstrated that this compound has bactericidal activity at concentrations close to the Minimum Inhibitory Concentration, coupled with a strong time-dependent behavior. To the best of our knowledge, this study describes the activity of 3-phenyl-1H-indole against Mtb for the first time.

Targeting thymidine phosphorylase inhibition in human colorectal cancer xenografts.

Human thymidine phosphorylase (hTP) is overexpressed in several solid tumors and is commonly associated with aggressiveness and unfavorable prognosis. 6-(((1,3-Dihydroxypropan-2-yl)amino)methyl)-5-iodopyrimidine-2,4(1H,3H)-dione (CPBMF-223) is a noncompetitive hTP inhibitor, which has been described as a tumor angiogenesis inhibitor. The present study investigated the effects of CPBMF-223 in a xenograft tumor induced by human colorectal carcinoma cells (HCT-116). Additionally, CPBMF-223 capacity to reduce cell migration, its toxicological profile, and pharmacokinetic characteristics, were also evaluated. The intraperitoneal treatment with CPBMF-223 markedly prevented the relative tumor growth with an efficacy similar to that observed for 5-fluorouracil. Interestingly, number of vessels were significantly decreased in the treated groups. Moreover, CPBMF-223 significantly reduced the migration of cell line HCT-116. In the Ames assay and in an acute oral toxicity test, the molecule did not alter any evaluated parameter. Using the zebrafish toxicity model, cardiac and locomotor parameters were slightly changed. Regarding the pharmacokinetics profile, CPBMF-223 showed clearance of 9.42 L/h/kg after intravenous administration, oral bioavailability of 13.5%, and a half-life of 0.75 h. Our findings shed new light on the role of hTP in colorectal cancer induced by HCT-116 cell in mice, pointing out CPBMF-223 as, hopefully, a promising drug candidate.

Design, synthesis, and evaluation of new 2-(quinoline-4-yloxy)acetamide-based antituberculosis agents.

Using a classical molecular simplification approach, a series of 36 quinolines were synthesized and evaluated as in vitro inhibitors of Mycobacterium tuberculosis (M. tuberculosis) growth. Structure-activity relationship (SAR) studies leaded to potent antitubercular agents, with minimum inhibitory concentration (MIC) values as low as 0.3 µM against M. tuberculosis H37Rv reference strain. Furthermore, the lead compounds were active against multidrug-resistant strains, without cross-resistance with some first- and second-line drugs. Testing the molecules against a spontaneous mutant strain containing a single mutation in the qcrB gene (T313A) indicated that the synthesized quinolines targeted the cytochrome bc1 complex. In addition, leading compounds were devoid of apparent toxicity to HepG2 and Vero cells and showed moderate elimination rates in human liver S9 fractions. Finally, the selected structures inhibited M. tuberculosis growth in a macrophage model of tuberculosis infection. Taken together, these data indicate that this class of compounds may furnish candidates for the future development of antituberculosis drugs.

Nonclinical evaluation of IQG-607, an anti-tuberculosis candidate with potential use in combination drug therapy.

New effective compounds to treat tuberculosis are urgently needed. IQG-607 is an orally active anti-tuberculosis drug candidate, with promising preliminary safety profile and anti-mycobacterial activity in both in vitro and in vivo models of tuberculosis infection. Here, we evaluated the mutagenic and genotoxic effects of IQG-607, and its interactions with CYP450 isoforms. Moreover, we describe for the first time a combination study of IQG-607 in Mycobacterium tuberculosis-infected mice. Importantly, IQG-607 had additive effects when combined with the first-line anti-tuberculosis drugs rifampin and pyrazinamide in mice. IQG-607 presented weak to moderate inhibitory potential against CYP450 isoforms 3A4, 1A2, 2C9, 2C19, 2D6, and 2E1. The Salmonella mutagenicity test revealed that IQG-607 induced base pair substitution mutations in the strains TA100 and TA1535. However, in the presence of human metabolic S9 fraction, no mutagenic effect was detected in any strain. Additionally, IQG-607 did not increase micronucleus frequencies in mice, at any dose tested, 25, 100, or 250 mg/kg. The favorable activity in combination with first-line drugs and mild to moderate toxic events described in this study suggest that IQG-607 represents a candidate for clinical development.

Design of Novel Inhibitors of Human Thymidine Phosphorylase: Synthesis, Enzyme Inhibition, in Vitro Toxicity, and Impact on Human Glioblastoma Cancer.

Overexpressed human thymidine phosphorylase (hTP) has been associated with cancer aggressiveness and poor prognosis by triggering proangiogenic and antiapoptotic signaling. Designed as transition-state analogues by mimicking the oxacarbenium ion, novel pyrimidine-2,4-diones were synthesized and evaluated as inhibitors of hTP activity. The most potent compound (8g) inhibited hTP in the submicromolar range with a noncompetitive inhibition mode with both thymidine and inorganic phosphate substrates. Furthermore, compound 8g was devoid of apparent toxicity to a panel of mammalian cells, showed no genotoxicity signals, and had low probability of drug-drug interactions and moderate in vitro metabolic rates. Finally, treatment with 8g (50 mg/(kg day)) for 2 weeks (5 days/week) significantly reduced tumor growth using an in vivo glioblastoma model. To the best of our knowledge, this active compound is the most potent in vitro hTP inhibitor with a kinetic profile that cannot be reversed by the accumulation of any enzyme substrates.

Toxicological evaluation of a standardized hydroethanolic extract from leaves of Plantago australis and its major compound, verbascoside.

ETHNOPHARMACOLOGICAL RELEVANCE: Plantago australis is a perennial plant widely distributed in Latin America, and its seeds and leaves are used in folk medicine to treat many diseases and conditions. Among its various chemical compounds, verbascoside is one of the most present, and has several pharmacological activities described, but there is not much information about its toxicity. AIMS OF THE STUDY: The aims of this study were to optimize the extraction of verbascoside from P. australis leaves with ultrasound methods, to develop a validated HPLC method to quantify verbascoside, and to evaluate the toxicological safety of the extract and verbascoside using in vitro and in vivo assays. MATERIALS AND METHODS: Dried leaves of P. australis were submitted to different extraction methods (percolation and ultrasound). The optimization of the ultrasound extraction was carried out by complete factorial design (22) and response surface methodology (RSM), followed by HPLC analysis for marker compounds. HPLC analysis was performed to verify the presence of the marker compounds aucubin, baicalein, oleanolic acid, ursolic acid and verbascoside. Mutagenicity was assessed by Salmonella/microsome mutagenicity assay. Cytotoxicity and genotoxicity were evaluated in V79 cells by reduction of tetrazolium salt (MTT) and neutral red uptake (NRU) assays, and alkaline comet assay, respectively. Verbascoside phototoxicity was assessed in 3T3 cells by the NRU phototoxicity assay. Wistar rats were used to perform the acute and sub-chronic toxicity tests. RESULTS: Among the marker compounds, only verbascoside was found in the hydroethanolic extract of P. australis leaves (PAHE); its highest concentration was obtained with the ultrasound-assisted extraction (UAE) method, optimized in 40 min and 25 °C, and the method validation was successfully applied. Neither PAHE nor verbascoside showed mutagenic or genotoxic activities. Cytotoxicity assays demonstrated that both PAHE and verbascoside reduced cell viability only at the highest concentrations, and verbascoside had no phototoxic properties. The in vivo toxicity evaluation of PAHE suggested that the LD50 is higher than 5000 mg/Kg, indicating that this extract is safe for use. In addition, no signs of toxicity were found in subchronic exposure. CONCLUSION: The HPLC method to quantify verbascoside was validated, and the extraction of verbascoside from P. australis leaves through ultrasound method was optimized, yielding an extract with 6% verbascoside. Our results suggest the toxicological safety of PAHE and verbascoside, corroborating the use of P. australis in folk medicine, and also indicate verbascoside as a potential ingredient in topical formulations.

Hunter syndrome: Long-term idursulfase treatment does not protect patients against DNA oxidation and cytogenetic damage.

Mucopolysaccharidosis type II (MPS II or Hunter syndrome) is an inborn error of metabolism characterized by the accumulation of glycosaminoglycans (GAG) in lysosomes. Enzyme replacement therapy (ERT) can reduce GAG storage, ameliorate symptoms, and slow disease progression. Oxidative damages may contribute to the MPS II pathophysiology, and treatment with ERT might reduce the effects of oxidative stress. We evaluated levels of DNA damage (including oxidative damage) and chromosome damage in leukocytes of long-term-treated MPS II patients, by applying the buccal micronucleus cytome assay. We observed that, despite long-term ERT, MPS II patients had higher levels of DNA damage and higher frequencies of micronuclei and nuclear buds than did control. These genetic damages are presumably due to oxidation: we also observed increased levels of oxidized guanine species in MPS II patients. Therapy adjuvant to ERT should be considered, in order to decrease oxidative damage and cytogenetic alterations.

Pre-clinical evaluation of quinoxaline-derived chalcones in tuberculosis.

New effective compounds for tuberculosis treatment are needed. This study evaluated the effects of a series of quinoxaline-derived chalcones against laboratorial strains and clinical isolates of M. tuberculosis. Six molecules, namely N5, N9, N10, N15, N16, and N23 inhibited the growth of the M. tuberculosis H37Rv laboratorial strain. The three compounds (N9, N15 and N23) with the lowest MIC values were further tested against clinical isolates and laboratory strains with mutations in katG or inhA genes. From these data, N9 was selected as the lead compound for further investigation. Importantly, this chalcone displayed a synergistic effect when combined with moxifloxacin. Noteworthy, the anti-tubercular effects of N9 did not rely on inhibition of mycolic acids synthesis, circumventing important mechanisms of resistance. Interactions with cytochrome P450 isoforms and toxic effects were assessed in silico and in vitro. The chalcone N9 was not predicted to elicit any mutagenic, genotoxic, irritant, or reproductive effects, according to in silico analysis. Additionally, N9 did not cause mutagenicity or genotoxicity, as revealed by Salmonella/microsome and alkaline comet assays, respectively. Moreover, N9 did not inhibit the cytochrome P450 isoforms CYP3A4/5, CYP2C9, and CYP2C19. N9 can be considered a potential lead molecule for development of a new anti-tubercular therapeutic agent.

Wound healing and anti-inflammatory activities induced by a Plantago australis hydroethanolic extract standardized in verbascoside.

ETHNOPHARMACOLOGICAL RELEVANCE: Plantago australis is a popular plant found to be widely spread in Latin America. In folk medicine, the seeds and leaves are used mainly for anti-inflammatory, wound healing, among others. The verbascoside, a phenolic glycoside, is an active chemical component described in this species of plant, which has antioxidant, anti-inflammatory and healing effects. PURPOSE: The aim of the present study was to evaluate whether P. australis hydroethanolic extract (PAHE) standardized in verbascoside could promote wound healing associated with anti-inflammatory action within both in vitro and in vivo models. METHODS: For the wound healing activity, we used a Scratch Test, an assay capable of evaluating the migratory ability of keratinocyte cells (HaCat) in vitro and thereby confirming the activity in rats. For the anti-inflammatory activity, the inflammation was induced with LPS in microglial murine cells (N9). Inflammatory mediators (IL-6, IL-10, IL-12p70, INFγ, MCP-1 and TNFα) were measured and the activity of superoxide dismutase (SOD), catalase (CAT), and mitochondrial membrane potential were evaluated. In addition, using paw edema induced by carrageenan in rats, the anti-inflammatory activity in vivo was analyzed. RESULTS: The PAHE and verbascoside, induced a significant increase in migration of keratinocytes, at all concentrations tested when compared to the negative control. The wound healing activity in vivo showed that the PAHE accelerated the process. The treatments with PAHE and verbascoside induce increases in the antioxidants enzymes, suggesting a possible activation of these enzymes. However, this did not result in an increase in the expression of inflammatory mediators in microglial cells. In LPS activated cells the verbascoside displayed a significant reduction of TNFα, IL-6, IL-12p70, MCP-1 and INFγ, while the PAHE only displayed statistically significant reduction in TNFα. Interestingly, both the compounds could reduce the oxidative parameters in N9 cells activated by LPS. Additionally, pretreatment with PAHE inhibited the paw edema in rats. CONCLUSION: The results suggest that PAHE has wound healing activity, improving cells migration and, as well as was able to reverse the oxidation effect in LPS-activated N9 cells. The wound-healing and anti-inflammatory activities of PAHE were confirmed in vivo. In addition, the presence of verbascoside can be related to PAHE effects, since this compound was capable of increase keratinocytes migration and inhibiting inflammation mediators.

1H-Benzo[d]imidazoles and 3,4-dihydroquinazolin-4-ones: Design, synthesis and antitubercular activity.

Using a classical hybridization approach, a series of 1H-benzo[d]imidazoles and 3,4-dihydroquinazolin-4-ones were synthesized (39 examples) and evaluated as inhibitors of Mycobacterium tuberculosis growth. Chemical modification studies yielded potent antitubercular agents with minimum inhibitory concentration (MIC) values as low as 0.24 µM against M. tuberculosis H37Rv strain. Further, the synthesized compounds were active against four drug-resistant strains containing different levels of resistance for the first line drugs. These molecules were devoid of apparent toxicity to HepG2, HaCat, and Vero cells with IC50s > 30 µM. Viability in mammalian cell cultures was evaluated using MTT and neutral red assays. In addition, some 3,4-dihydroquinazolin-4-ones showed low risk of cardiac toxicity, no signals of neurotoxicity or morphological alteration in zebrafish (Danio rerio) toxicity models. 3,4-Dihydroquinazolin-4-ones 9q and 9w were considered the lead compounds of these series of molecules with MIC values of 0.24 µM and 0.94 µM against M. tuberculosis H37Rv, respectively. Taken together, these data indicate that this class of compounds may furnish candidates for future development of novel anti-TB drugs.

Preclinical pharmacokinetic profiling of IQG-607, a potential oral metallodrug to treat tuberculosis.

IQG-607 is an analog of isoniazid with anti-tuberculosis activity. This work describes the development and validation of an HPLC method to quantify pentacyano(isoniazid)ferrate(II) compound (IQG-607) and the pharmacokinetic studies of this compound in mice. The method showed linearity in the 0.5-50µg/mL concentration range (r=0.9992). Intra- and inter-day precision was <5%, and the recovery ranged from 92.07 to 107.68%. IQG-607 was stable in plasma for at least 30days at -80°C and, after plasma processing, for 4h in the auto-sampler maintained on ice (recovery >85%). The applicability of the method for pharmacokinetic studies was determined after intravenous (i.v.) and oral (fasted and fed conditions) administration to mice. IQG-607 levels in plasma were quantified at time points for up to 2.5h. A short half-life (t1/2) (1.14h), a high clearance (CL) (3.89L/h/kg), a moderate volume of distribution at steady state (Vdss) of 1.22L/kg, were observed after i.v. (50mg/kg) administration. Similar results were obtained for oral administration (250mg/kg) under fasted and fed conditions. The oral bioavailability (F), approximately 4%, was not altered by feeding. Plasma protein binding was 88.87±0.9%. The results described here provide novel insights into a pivotal criterion to warrant further efforts to be pursued towards attempts to translate this chemical compound into a chemotherapeutic agent to treat TB.

Inhibitory activity of pentacyano(isoniazid)ferrate(II), IQG-607, against promastigotes and amastigotes forms of Leishmania braziliensis.

M. tuberculosis and parasites of the genus Leishmania present the type II fatty acid biosynthesis system (FASII). The pentacyano(isoniazid)ferrate(II) compound, named IQG-607, inhibits the enzyme 2-trans-enoyl-ACP(CoA) reductase from M. tuberculosis, a key component in the FASII system. Here, we aimed to evaluate the inhibitory activity of IQG-607 against promastigote and amastigote forms of Leishmania (Viannia) braziliensis isolated from patients with different clinical forms of L. braziliensis infection, including cutaneous, mucosal and disseminated leishmaniasis. Importantly, IQG-607 inhibited the proliferation of three different isolates of L. braziliensis promastigotes associated with cutaneous, mucosal and disseminated leishmaniasis. The IC50 values for IQG-607 ranged from 32 to 75 µM, for these forms. Additionally, IQG-607 treatment decreased the proliferation of intracellular amastigotes in infected macrophages, after an analysis of the percentage of infected cells and the number of intracellular parasites/100 cells. IQG-607 reduced from 58% to 98% the proliferation of L. braziliensis from cutaneous, mucosal and disseminated strains. Moreover, IQG-607 was also evaluated regarding its potential toxic profile, by using different cell lines. Cell viability of the lineages Vero, HaCat and HepG2 was significantly reduced after incubation with concentrations of IQG-607 higher than 2 mM. Importantly, IQG-607, in a concentration of 1 mM, did not induce DNA damage in HepG2 cells, when compared to the untreated control group. Future studies will confirm the mechanism of action of IQG-607 against L. braziliensis.