Chemical synthesis and biological evaluation of triazole derivatives as inhibitors of InhA and antituberculosis agents

1,2,3-Triazole naphthaldehyde compounds and their oxime derivatives: in vitro and in silico DNA binding properties

In this work, we report the synthesis and DNA binding properties of a series of 1,2,3-triazole naphthaldehyde compounds and their oxime derivatives. The 1,2,3-triazole naphthaldehyde compounds (1a-1f) were prepared by the Cu(I) catalysed click reactions. The 1,2,3-triazole naphthaldehyde compounds (1a-1f) were then reacted with hydroxyl amine to yield 1,2,3-triazole oxime compounds (2a-2f). The structures of all compounds were characterized by Fourier-transform ınfrared spectroscopy, Nuclear magnetic resonance and elemental analysis. Crystal structures of compounds 1a, 1c, 1f, 2c and 2d were investigated by single crystal X-ray crystallography. The compounds were evaluated for their DNA binding properties via in vitro spectrophotometric and in silico molecular docking studies. The compounds were found to interact with DNA via a groove binding mode with considerable the binding constants. The groove binding mode of interactions were also suggested by fluorescence ethidium bromide replacement experiments and viscosity studies. Binding interactions of the compounds with DNA have also been studied by molecular docking studies.

Catalase-peroxidase (KatG): a potential frontier in tuberculosis drug development

Mycobacterium tuberculosis (Mtb) depends on the bifunctional enzyme catalase-peroxidase (KatG) for survival within the host. KatG exhibits both catalase and peroxidase activities, serving distinct yet critical roles. While its peroxidase activity is essential for activating the frontline tuberculosis drug isoniazid, its catalase activity protects Mtb from oxidative stress. This bifunctional enzyme is equipped with a unique, protein-derived cofactor, methionine-tyrosine-tryptophan (MYW), which enables catalase activity to efficiently disproportionate hydrogen peroxide in phagocytes. Recent studies reveal that the MYW cofactor naturally exists in a hydroperoxylated form (MYW-OOH) when cell cultures are grown under ambient conditions. New findings highlight a dynamic regulation of KatG activity, wherein the modification of the protein cofactor is removable-from MYW-OOH to MYW-at body temperature or in the presence of micromolar concentrations of hydrogen peroxide. This reversible modification modulates KatG's dual activities: MYW-OOH inhibits catalase activity while enhancing peroxidase activity, demonstrating the chemical accessibility of the cofactor. Such duality positions KatG as a unique target for tuberculosis drug development. Therapeutic strategies that exploit cofactor modification could hold promise, particularly against drug-resistant strains with impaired peroxidase activity. By selectively inhibiting catalase activity, these approaches would render Mtb more vulnerable to oxidative stress while enhancing isoniazid activation-a double-edged strategy for combating tuberculosis.

Cu/N-doped carbon spheres derived from soybean flour as an active green nanocomposite for the synthesis of 1,4-disubstituted 1H-1,2,3-triazole derivatives

Cu immobilized onto N-doped carbon spheres (Cu/N-doped CS) derived from soybean flour was synthesized via the hydrothermal method and certified as a green high-efficiency catalyst for the regioselective synthesis of 1,4-disubstituted 1H-1,2,3-triazoles. The obtained N-doped carbon spheres from a combination of glucose and soy flour have a larger size and suitable affinity for load copper species. The morphology and structure of the as-prepared catalyst have been confirmed based on FT-IR, XRD, FE-SEM, EDX, BET, and ICP-OES characterizations. The catalytic performance of the Cu/N-doped carbon spheroids was investigated experimentally. It was found that the Cu/N-doped CS nanocomposite has a high efficiency and recyclability for 5 cycles without any appreciable loss in its catalytic activity in the synthesis of 1,4-disubstituted 1H-1,2,3-triazoles via the three-component condensation reaction of various epoxide/alkyl or aryl halides, sodium azide, and phenylacetylene in a water medium. Furthermore, significant advantages such as stability, ease of preparation, low cost of the carbon resource, high regioselectivity, and good product yield have been achieved in the heterogeneous catalyst system attractive for large-scale in many industrial products.

Identification of potent indolizine derivatives against Mycobacterial tuberculosis: In vitro anti-TB properties, in silico target validation, molecular docking and dynamics studies

In the current study, two sets of compounds: (E)-1-(2-(4-substitutedphenyl)-2-oxoethyl)-4-((hydroxyimino)methyl)pyridinium derivatives (3a-3e); and (E)-3-(substitutedbenzoyl)-7-((hydroxyimino)methyl)-2-substitutedindolizine-1-carboxylate derivatives (5a-5j), were synthesized and biologically evaluated against two strains of Mycobacterial tuberculosis (ATCC 25177) and multi-drug resistant (MDR) strains. Further, they were also tested in vitro against the mycobacterial InhA enzyme. The in vitro results showed excellent inhibitory activities against both MTB strains and compounds 5a-5j were found to be more potent, and their MIC values ranged from 5 to 16 μg/mL and 16-64 μg/mL against the M. tuberculosis (ATCC 25177) and MDR-TB strains, respectively. Compound 5h with phenyl and 4-fluorobenzoyl groups attached to the 2- and 3-position of the indolizine core was found to be the most active against both strains with MIC values of 5 μg/mL and 16 μg/mL, respectively. On the other hand, the two sets of compounds showed weak to moderate inhibition of InhA enzyme activity that ranged from 5 to 17 % and 10-52 %, respectively, with compound 5f containing 4-fluoro benzoyl group attached to the 3-position of the indolizine core being the most active (52 % inhibition of InhA). Unfortunately, there was no clear correlation between the InhA inhibitory activity and MIC values of the tested compounds, indicating the probability that they might have different modes of action other than InhA inhibition. Therefore, a computational investigation was conducted by employing molecular docking to identify their putative drug target(s) and, consequently, understand their mechanism of action. A panel of 20 essential mycobacterial enzymes was investigated, of which β-ketoacyl acyl carrier protein synthase I (KasA) and pyridoxal-5'-phosphate (PLP)-dependent aminotransferase (BioA) enzymes were revealed as putative targets for compounds 3a-3e and 5a-5j, respectively. Moreover, in silico ADMET predictions showed adequate properties for these compounds, making them promising leads worthy of further optimization.

Self-assembly and antimicrobial activity of cationic gemini surfactants containing triazole moieties

1,2,3-Triazole-based gemini bis-quaternary ammonium surfactants with varying hydrophobic chain length and ethylene or butylene spacers were synthesized and characterized. Their surface and aggregation properties were analyzed using tensiometry and conductimetry. The gemini surfactants showed significantly lower CMC values compared to their single-tail counterparts and conventional gemini surfactants described in the literature. The micellization and surface adsorption processes in water can be tailored according to the hydrophobic chain and the spacer length and were substantially improved by the presence of the heterocycle. These surfactants are active against various Gram-positive and Gram-negative bacterial stains, as well as fungi. The gemini surfactant with tetradecyl chain and ethylene spacer (Bis 14-2-14) exhibited the highest activity against all investigated microbial strains.

An updated review of fatty acid residue-tethered heterocyclic compounds: synthetic strategies and biological significance

Heterocyclic compounds have been featured as the key building blocks for the development of biologically active molecules. In addition to being derived from renewable raw materials, fatty acids possess a variety of biological properties. The two bioactive ingredients are being combined by many researchers to produce hybrid molecules that have a number of desirable properties. Biological activities and significance of heterocyclic derivatives of fatty acids have been demonstrated in a new class of heterocyclic compounds called heterocyclic fatty acid hybrid derivatives. The significance of heterocyclic-fatty acid hybrid derivatives has been emphasized in numerous research articles over the past few years. In this review, we emphasize the development of synthetic methods and their biological evaluation for heterocyclic fatty acid derivatives. These reports, combined with the upcoming compilation, are expected to serve as comprehensive foundations and references for synthetic, preparative, and applicable methods in medicinal chemistry.

Design, synthesis and biological evaluation of benzo-[d]-imidazo-[2,1-b]-thiazole and imidazo-[2,1-b]-thiazole carboxamide triazole derivatives as antimycobacterial agents

In the search for new anti-mycobacterial agents, we revealed the importance of imidazo-[2,1-b]-thiazole and benzo-[d]-imidazo-[2,1-b]-thiazole carboxamide derivatives. We designed, in silico ADMET predicted and synthesized four series of novel imidazo-[2,1-b]-thiazole and benzo-[d]-imidazo-[2,1-b]-thiazole carboxamide analogues in combination with piperazine and various 1,2,3 triazoles. All the synthesized derivatives were characterized by 1H NMR, 13C NMR, HPLC and MS spectral analysis and evaluated for in vitro antitubercular activity. The most active benzo-[d]-imidazo-[2,1-b]-thiazole derivative IT10, carrying a 4-nitro phenyl moiety, displayed IC90 of 7.05 μM and IC50 of 2.32 μM against Mycobacterium tuberculosis (Mtb) H37Ra, while no acute cellular toxicity was observed (>128 μM) towards the MRC-5 lung fibroblast cell line. Another benzo-[d]-imidazo-[2,1-b]-thiazole compound, IT06, which possesses a 2,4-dichloro phenyl moiety, also showed significant activity with IC50 2.03 μM and IC90 15.22 μM against the tested strain of Mtb. Furthermore, the selected hits showed no activity towards a panel of non-tuberculous mycobacteria (NTM), thus suggesting a selective inhibition of Mtb by the tested imidazo-[2,1-b]-thiazole derivatives over the selected panel of NTM. Molecular docking and dynamics studies were also carried out for the most active compounds IT06 and IT10 in order to understand the putative binding pattern, as well as stability of the protein-ligand complex, against the selected target Pantothenate synthetase of Mtb.

Fe3O4@SiO2-PMA-Cu magnetic nanoparticles as a novel catalyst for green synthesis of β-thiol-1,4-disubstituted-1,2,3-triazoles

The magnetic nanoparticles of Fe3O4 were synthesized through a solid-state reaction of hydrated iron (III) chloride, hydrated iron (II) chloride and NaOH, and then purified by calcination at high temperature. In order to protect ferrite nanoparticles from oxidation and agglomeration, and to manufacture a novel catalytic system of anchored copper on the magnetic substrate, the Fe3O4 was core-shelled by adding tetraethyl orthosilicate. Next, the prepared Fe3O4@SiO2 was supported by phosphomolybdic acid (PMA) as the second layer of nanocomposite at 80 °C in 30 h. Eventually, the new nanocomposite of Fe3O4@SiO2-PMA-Cu was successfully synthesized by adding copper (II) chloride solution and solid potassium borohydride. The structure of magnetic nanocatalyst was acknowledged through different techniques such as EDS, VSM, XRD, TEM, FT-IR, XPS, TGA, BET and FESEM. The synthesis of β-thiolo/benzyl-1,2,3-triazoles from various thiiranes, terminal alkynes and sodium azide was catalyzed by Fe3O4@SiO2-PMA-Cu nanocomposite in aqueous medium. In order to obtain the optimum condition, the effects of reaction time, temperature, catalyst amount and solvent were gauged. The recycled catalyst was used for several consecutive runs without any loss of activity.

Emerging impact of triazoles as anti-tubercular agent

Tuberculosis, a disease of poverty is a communicable infection with a reasonably high mortality rate worldwide. 10 Million new cases of TB were reported with approx 1.4 million deaths in the year 2019. Due to the growing number of drug-sensitive and drug-resistant tuberculosis cases, there is a vital need to develop new and effective candidates useful to combat this deadly disease. Despite tremendous efforts to identify a mechanism-based novel antitubercular agent, only a few have entered into clinical trials in the last six decades. In recent years, triazoles have been well explored as the most valuable scaffolds in drug discovery and development. Triazole framework possesses favorable properties like hydrogen bonding, moderate dipole moment, enhanced water solubility, and also the ability to bind effectively with biomolecular targets of M. tuberculosis and therefore this scaffold displayed excellent potency against TB. This review is an endeavor to summarize an up-to-date innovation of triazole-appended hybrids during the last 10 years having potential in vitro and in vivo antitubercular activity with structure activity relationship analysis. This review may help medicinal chemists to explore the triazole scaffolds for the rational design of potent drug candidates having better efficacy, improved selectivity and minimal toxicity so that these hybrid NCEs can effectively be explored as potential lead to fight against M. tuberculosis.

Preparation, characterization and application of MgFe2O4/Cu nanocomposite as a new magnetic catalyst for one-pot regioselective synthesis of β-thiol-1,4-disubstituted-1,2,3-triazoles

Magnesium ferrite magnetic nanoparticles were synthesized by a solid-state reaction of magnesium nitrate, hydrated iron(iii) nitrate, NaOH and NaCl salts and then calcined at high temperatures. In order to prevent oxidation and aggregation of magnesium ferrite particles, and also for preparing a new catalyst of supported copper on the magnetic surface, the MgFe2O4 was covered by copper nanoparticles in alkaline medium. Magnetic nanoparticles of MgFe2O4/Cu were successfully obtained. The structure of the synthesized magnetic nanoparticles was identified using XRD, TEM, EDS, FT-IR, FESEM and VSM techniques. The prepared catalyst was used in the three component one-pot regioselective synthesis of 1,2,3-triazoles in water. The various thiiranes bearing alkyl, allyl and aryl groups with terminal alkynes, and sodium azide in the presence of the MgFe2O4/Cu nanocatalyst were converted to the corresponding β-thiolo/benzyl-1,2,3-triazoles as new triazole derivatives. The effects of different factors such as time, temperature, solvent, and catalyst amount were investigated, and performing the reaction using 0.02 g of catalyst in water at 60 °C was chosen as the optimum conditions. The recovered catalyst was used several times without any significant change in catalytic activity or magnetic property.

Contribution of N-heterocycles towards anti-tubercular drug discovery (2014-2019); predicted and reengineered molecular frameworks

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, responsible for high death frequency every year all over the world. In this regard, efficient drug-design and discovery towards the prevention of M.tb H₃₇ R_v is of prime concern. Prevention of the infection may include vaccination, and the treatment comprises anti-TB drug regimen. However, the vaccine decreases the risk of tuberculosis infection only to some extent, while drug-resistance limits the efficacy of the existing anti-TB agents. Much improvement has to be achieved to overcome pitfalls such as side effects, high-toxicity, low bioavailability, pharmacokinetics and pharmacodynamics, and hence forth in clinical therapeutics. Amongst heterocyclic compounds, N-heterocycles played a pivotal role in drug-design and discovery. A wide range of microbial diseases are being treated by the N-heterocyclic drugs. The present review comprises description of anti-TB effects of the N-heterocycles such as indoles, triazoles, thiazoles, and pyrazoles. The potent anti-TB activity exerted by the derivatives of these heterocycles is evaluated critically alongside emphasizing structure-activity relationship. Besides, docking studies supporting anti-TB activity is supplemented. Alongside this, based on the potent heterocyclic molecules, the molecular frameworks are designed that would bring about enhanced M. tb H₃₇ R_v inhibitory potencies.

COVID-19 therapy: What weapons do we bring into battle?

Urgent treatments, in any modality, to fight SARS-CoV-2 infections are desired by society in general, by health professionals, by Estate-leaders and, mainly, by the scientific community, because one thing is certain amidst the numerous uncertainties regarding COVID-19: knowledge is the means to discover or to produce an effective treatment against this global disease. Scientists from several areas in the world are still committed to this mission, as shown by the accelerated scientific production in the first half of 2020 with over 25,000 published articles related to the new coronavirus. Three great lines of publications related to COVID-19 were identified for building this article: The first refers to knowledge production concerning the virus and pathophysiology of COVID-19; the second regards efforts to produce vaccines against SARS-CoV-2 at a speed without precedent in the history of science; the third comprehends the attempts to find a marketed drug that can be used to treat COVID-19 by drug repurposing. In this review, the drugs that have been repurposed so far are grouped according to their chemical class. Their structures will be presented to provide better understanding of their structural similarities and possible correlations with mechanisms of actions. This can help identifying anti-SARS-CoV-2 promising therapeutic agents.

Multifaceted activity of polyciclic MDR revertant agents in drug-resistant leukemic cells: Role of the spacer

A small library of derivatives carrying a polycyclic scaffold recently identified by us as a new privileged structure in medicinal chemistry was designed and synthesized, aiming at obtaining potent MDR reverting agents also endowed with antitumor properties. In particular, as a follow-up of our previous studies, attention was focused on the role of the spacer connecting the polycyclic core with a properly selected nitrogen-containing group. A relevant increase in reverting potency was observed, going from the previously employed but-2-ynyl- to a pent-3-ynylamino moiety, as in compounds 3d and 3e, while the introduction of a triazole ring proved to differently impact on the activity of the compounds. The docking results supported the data obtained by biological tests, showing, for the most active compounds, the ability to establish specific bonds with P-glycoprotein. Moreover, a multifaceted anticancer profile and dual in vitro activity was observed for all compounds, showing both revertant and antitumor effects on leukemic cells. In this respect, 3c emerged as a "triple-target" agent, endowed with a relevant reverting potency, a considerable antiproliferative activity and a collateral sensitivity profile.

Molecule Property Analyses of Active Compounds for Mycobacterium tuberculosis

Tuberculosis (TB) continues to claim the lives of around 1.7 million people per year. Most concerning are the reports of multidrug drug resistance. Paradoxically, this global health pandemic is demanding new therapies when resources and interest are waning. However, continued tuberculosis drug discovery is critical to address the global health need and burgeoning multidrug resistance. Many diverse classes of antitubercular compounds have been identified with activity in vitro and in vivo. Our analyses of over 100 active leads are representative of thousands of active compounds generated over the past decade, suggests that they come from few chemical classes or natural product sources. We are therefore repeatedly identifying compounds that are similar to those that preceded them. Our molecule-centered cheminformatics analyses point to the need to dramatically increase the diversity of chemical libraries tested and get outside of the historic Mtb property space if we are to generate novel improved antitubercular leads.

First triclosan-based macrocyclic inhibitors of InhA enzyme

Two macrocyclic derivatives based on the triclosan frame were designed and synthesized as inhibitors of Mycobacterium tuberculosis InhA enzyme. One of the two molecules M02 displayed promising inhibitory activity against InhA enzyme with an IC₅₀ of 4.7 μM. Molecular docking studies of these two compounds were performed and confirmed that M02 was more efficient as inhibitor of InhA activity. These molecules are the first macrocyclic direct inhibitors of InhA enzyme able to bind into the substrate pocket. Furthermore, these biaryl ether compounds exhibited antitubercular activities comparable to that of triclosan against M. tuberculosis H37Rv strain.

Novel fatty acid-thiadiazole derivatives as potential antimycobacterial agents

The discovery of antibiotics around the middle twentieth century led to a decrease in the interest in antimycobacterial fatty acids. In order to re-establish the importance of naturally abundant fatty acid, a series of fatty acid-thiadiazole derivatives were designed and synthesized based on molecular hybridization approach. In vitro antimycobacterial potential was established by a screening of synthesized compounds against Mycobacterium tuberculosis H37Rv strain. Among them, compounds 5a, 5d, 5h, and 5j were the most active, with compound 5j exhibiting minimum inhibitory concentration of 2.34 μg/ml against M.tb H37Rv. Additionally, the compounds were docked to determine the probable binding interactions and understand the mechanism of action of most active molecules on enoyl-acyl carrier protein reductases (InhA), which is involved in the mycobacterium fatty acid biosynthetic pathway.

Exploring the Chemistry and Therapeutic Potential of Triazoles: A Comprehensive Literature Review

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Triazole is a valuable platform in medicinal chemistry, possessing assorted pharmacological properties, which could play a major role in the common mechanisms associated with various disorders like cancer, infections, inflammation, convulsions, oxidative stress and neurodegeneration. Structural modification of this scaffold could be helpful in the generation of new therapeutically useful agents. Although research endeavors are moving towards the growth of synthetic analogs of triazole, there is still a lot of scope to achieve drug discovery break-through in this area. Upcoming therapeutic prospective of this moiety has captured the attention of medicinal chemists to synthesize novel triazole derivatives. The authors amalgamated the chemistry, synthetic strategies and detailed pharmacological activities of the triazole nucleus in the present review. Information regarding the marketed triazole derivatives has also been incorporated. The objective of the review is to provide insights to designing and synthesizing novel triazole derivatives with advanced and unexplored pharmacological implications.

In Silico Repositioning of Cannabigerol as a Novel Inhibitor of the Enoyl Acyl Carrier Protein (ACP) Reductase (InhA)

Cannabigerol (CBG) and cannabichromene (CBC) are non-psychoactive cannabinoids that have raised increasing interest in recent years. These compounds exhibit good tolerability and low toxicity, representing promising candidates for drug repositioning. To identify novel potential therapeutic targets for CBG and CBC, an integrated ligand-based and structure-based study was performed. The results of the analysis led to the identification of CBG as a low micromolar inhibitor of the Enoyl acyl carrier protein (ACP) reductase (InhA) enzyme.

CoFe2O4/Cu(OH)2 magnetic nanocomposite: an efficient and reusable heterogeneous catalyst for one-pot synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles from epoxides

A magnetically separable CoFe₂O₄/Cu(OH)₂ nanocomposite was prepared and characterized by various techniques such as FESEM, EDS, TEM, XRD, VSM and FT-IR. This novel composite was used as a heterogeneous catalyst for the regioselective synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles from sodium azide, terminal alkynes and structurally different epoxides in water at 60 °C. The formation of the product proceeds in one pot through a mechanism that involves an in situ generated organic azide intermediate, followed by rapid ring closure with the alkyne component. The simple procedure, short reaction times, perfect regioselectivity, high product yields, and use of a benign solvent and nontoxic catalyst are among the considerable advantages of this protocol. Furthermore, the catalyst was easily separated using an external magnet and reused several times without any significant loss of catalytic activity or magnetic properties.

Magnetically separable CoFe₂O₄/Cu(OH)₂ nanocomposite was prepared and used as a novel heterogeneous catalyst for synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles from epoxides.

Do new N-substituted 3-amino-4-phenyl-5-oxo-pyrazolinecarboxamide derivatives exhibit antitubercular potential?

As a continuation of previous tests concerning new N-substituted 3-amino-4-phenyl-5-oxo-pyrazolinecarboxamide derivatives (R3, R4 and R8) of notable antibacterial activity, their antitubercular potential against different mycobacterial strains was estimated. Tests performed on virulent (reference and clinical) strains of Mycobacterium bovis and Mycobacterium tuberculosis revealed the highest therapeutic potential of R8 derivative: MIC within the range 7.8-15.6 μg/ml and TI (therapeutic index) within the range 46.5-93. Moreover, the synergistic interaction was found between R3, R4 and R8 derivatives and rifampicin, one of the front-line antitubercular drugs. R8/rifampicin mixture in concentrations effective in inhibition of Mycobacterium tuberculosis strain was non-cytotoxic against GMK cells, displaying cell viability approximately 88-97% when compared to control. Molecular docking study enabled to conclude that enoyl acyl carrier protein reductase (InhA) can be considered as a potential molecular target of tested pyrazole derivatives. Although further modifications of chemical structure of the investigated pyrazole derivatives is required, in order to increase their antitubercular efficacy and therapeutic safety, these compounds, in particular R8 compound, can be promising for the treatment of human and bovine tuberculosis.

Theoretical investigation of Banert cascade reaction

Computational inside of Banert cascade reaction for triazole formation is studied with B3LYP/6-31G(d,p) level of theory. The reaction proceeds mainly by SN2 initial chloride displacement rather than SN2'-type attack. Furthermore, according to the rate of reaction calculation, SN2 displacement is much faster than SN2' displacement in the order of 8. The [3,3]-sigmatropic rearrangement for the conversion of propargyl azide into triazafulvene has been proved as the rate-determining step having highest activation energy parameter. Solvent effect on total course of reaction has been found negligible. Furthermore, effects of different density functional theory functionals and functional groups on activation energies of [3,3]-sigmatropic rearrangement of propargyl azide were also studied. BHHLYP, ωB97XD, M062X and BMK calculated ΔG^‡ are consistent with B3LYP.

Structure-based design of bacterial transglycosylase inhibitors incorporating biphenyl, amine linker and 2-alkoxy-3-phosphorylpropanoate moieties

Transglycosylase (TGase) is essential to biosynthesis of peptidoglycan for formation of bacterial cell wall. Moenomycin is a potent TGase inhibitor, but not used in clinic treatment due to its poor pharmacokinetics. The E-F disaccharide, phosphoglycerate and lipid tail in moenomycin are crucial elements for TGase inhibition and antibacterial activity. Based on this scaffold, a series of truncated mimics comprising biphenyl, amine linker and 2-alkoxy-3-phosphorylpropanoate moieties were designed to test their TGase inhibitory activity. In this design, the phosphorylpropanoate group is a surrogate of phosphoglycerate with improved stability. A library of lipid tails can be constructed by a straightforward approach using Cu(I)-catalyzed (3 + 2) cycloaddition reactions, and the as-synthesized triazole ring can provide additional hydrogen bonds in the TGase active site. Our molecular docking experiments reveal that the biphenyl group provides π-π and π-cation interactions to act as a simplified alternative of the C-E disaccharide in moenomycin. To play the role of the oxonium transition state in transglycosylation, the amine linker exists as a positively charged species in physiological condition to attain electrostatic interactions with acidic residues. In this study, two biphenyl-linked 2-alkoxy-3-phosphorylpropanoate compounds (8 and 10) are found to exhibit modest inhibitory activity (IC₅₀ ≈ 150 μM) against the TGase of Acinetobacter baumannii and good antibacterial activity against Staphylococcus aureus (MIC = 6.3 μM).

Mechanochemical Synthesis and Biological Evaluation of Novel Isoniazid Derivatives with Potent Antitubercular Activity

A series of isoniazid derivatives bearing a phenolic or heteroaromatic coupled frame were obtained by mechanochemical means. Their pH stability and their structural (conformer/isomer) analysis were checked. The activity of prepared derivatives against Mycobacterium tuberculosis cell growth was evaluated. Some compounds such as phenolic hydrazine 1a and almost all heteroaromatic ones, especially 2, 5 and 7, are more active than isoniazid, and their activity against some M. tuberculosis MDR clinical isolates was determined. Compounds 1a and 7 present a selectivity index >1400 evaluated on MRC5 human fibroblast cells. The mechanism of action of selected hydrazones was demonstrated to block mycolic acid synthesis due to InhA inhibition inside the mycobacterial cell.

Triazole derivatives and their anti-tubercular activity

Tuberculosis (TB) remains one of the most widespread and leading deadliest diseases, threats one-third of the world's population. Although numerous efforts have been undertaken to develop new anti-TB agents, only a handful of compounds have entered human trials in the past 5 decades. Triazoles including 1,2,3-triazole and 1,2,4-triazole are one of the most important classes of nitrogen containing heterocycles that exhibited various biological activities. Triazole derivatives are regarded as a new class of effective anti-TB candidates owing to their potential anti-TB potency. Thus, molecules containing triazole moiety may show promising in vitro and in vivo anti-TB activities and might be able to prevent the drug resistant to certain extent. This review outlines the advances in the application of triazole-containing hybrids as anti-TB agents, and discusses the structure-activity relationship of these derivatives.

In vitro and in vivo assessments of two novel hydrazide compounds against breast cancer as well as mammary tumor cells

PURPOSE

The hydrazide backbone is a well-known structural core system found in a broad range of biologically activated compounds. Among which, the compounds with anticancer activity have been cited in a number of studies. With this object in mind, we focused on the in vitro and in vivo anticancer potential of two novel hydrazide derivatives bearing furan or thiophen substituents (compounds 1 and 2).

METHODS

The cytotoxic property was evaluated using MTT assay against MCF-7 human breast adenocarcinoma cell line, while the in vivo antitumor activity was investigated in BALB/c mice bearing 4T1 mammary carcinoma cells. Flow cytometry was used for cell cycle analysis, and detection of apoptosis was examined by Annexin-V-FLUOS/PI assay. Protein expression of Bax, Bcl-2 and procaspase-3 was estimated by Western blotting.

RESULTS

Compounds 1 and 2 were found to be cytotoxic towards breast cancer cells presenting IC₅₀ values of 0.7 and 0.18 µM, respectively, and selectivity over normal fibroblast cells. Our findings further indicated that 2 × IC₅₀ concentrations of both compounds induce early stage apoptosis and increase percentage of sub-G1 population in MCF-7 cells at 48 h. An elevation in Bax/Bcl-2 ratio and caspase-3 cleavage suggested that apoptosis induced by the two compounds is through a caspase- and mitochondrial-dependent pathway. In the in vivo study, compounds 1 and 2 at doses of 10 and 1 mg/Kg/day, respectively, significantly hindered the growth of tumor after 3 weeks of i.p. administration, when compared to vehicle-treated mice.

CONCLUSION

Collectively, the great potential exhibited by compound 2 could make it a promising chemotherapeutic candidate for human cancers, especially for breast cancer.

Synthesis, biological evaluation and in silico molecular modeling of pyrrolyl benzohydrazide derivatives as enoyl ACP reductase inhibitors

In efforts to develop lead anti-TB compounds, a novel series of 19 pyrrolyl benzohydrazides were synthesized and screened to target enoyl-ACP reductase enzyme, which is one of the important enzymes involved in type II fatty acid biosynthetic pathway of M. tuberculosis. Pharmacophores were constructed using GALAHAD to generate alignment of data sets and calculated by Pareto ranking. The pharmacophore features were then filtered by Surflex-dock study using enoyl ACP reductase from M. tuberculosis. Compounds 5b and 5d showed H-bonding interactions with Tyr158, Thr196 and co-factor NAD⁺ that fitted well within the binding pocket of InhA. All the synthesized compounds were screened for preliminary antibacterial activities against Gram-positive S. aureus and Gram-negative E. coli and M. tuberculosis H₃₇Rv to evaluate their antitubercular activities. Some representative compounds were further tested for mammalian cell toxicity using human lung cancer cell-line (A549) that was found to be nontoxic. These compounds exhibited moderate inhibition activities against InhA.

Antitubercular activity of 1,2,3-triazolyl fatty acid derivatives

A collection of 1,2,3-triazoles unsaturated fatty acid mimics were efficiently synthesized by click chemistry. The 1,4-disubstituted analogs prepared covered different alkyl chain lengths and triazole positions. The compounds were subsequently tested against Mycobacterium tuberculosis, being most of them active with some of the analogs displaying activity at micromolar concentration. The most potent member of the series has the triazole moiety on the C-2 position with a carbon chain of eight or ten carbon atoms. The 1,5-isomers of the most active analog were significantly less active than the original isomer. The activity of the selected hit was assayed on several clinical MTB multi-drug resistant strains providing the same MIC.