Derivatives of pyridine and thiazole hybrid: Synthesis, DFT, biological evaluation via antimicrobial and DNA cleavage activity

Synthesis, Antimicrobial Evaluation, and In Silico Studies of 2-Substituted-Phenyl-3-(5-Aryl/Heteroaryl Substituted Thiazol-2-yl) Thiazolidin-4-One Derivatives

In a one-pot reaction involving 3-(2-aminothiazol-5-yl)-2H-chromen-2-one/5-(naphthalen-1-yl)thiazol-2-amines 5-6 with various substituted aldehydes and mercaptoacetic acid, we obtained the corresponding 2-(4-substituted-phenyl)-3-[5-(2-oxo-2H-chromen-3-yl)thiazol-2-yl] thiazolidin-4-ones 8(a-h) and 2-(4-substituted-phenyl)-3-[5-(naphthalen-1-yl)thiazol-2-yl] thiazolidin-4-ones 9(a-h). The antimicrobial activity of all compounds was evaluated against Pseudomonas aeruginosa (MTCC-424), Salmonella typhi (MTCC-531), Staphylococcus aureus (MTCC-737), and Candida albican (MTCC-227). Molecular docking further supported the findings, which showed that the compounds 8d and 9d had excellent antibacterial action against all tested pathogens.

Design, synthesis and characterization of tetra substituted 2,3-dihydrothiazole derivatives as DNA and BSA targeting agents: advantages of the visible-light-induced multicomponent approach

This report describes the visible-light-induced one-pot multicomponent regioselective synthesis of a series of 5-aroyl-3-((arylidene)amino)-2-((arylidene)hydrazono)-4-methyl-2,3-dihydrothiazoles as DNA and BSA targeting agents. The multicomponent condensation of thiocarbohydrazide and aldehydes with α-bromo-1,3-diketones, generated in situ by the bromination of unsymmetrical 1,3-diketones with NBS using white LED light as an environmental friendly source in the presence of EtOAc solvent furnished the titled 2,3-dihydrothiazole derivatives in excellent yields. The exact regioisomeric structure was identified unambiguously by employing multinuclear 2D-NMR spectroscopy [1H-13C] HMBC; [1H-13C] HMQC and [1H-15N] HMBC. Furthermore, the binding characteristics of the synthesized 2,3-dihydrothiazole derivatives were assessed with double-stranded calf-thymus DNA duplex (ct-DNA) and bovine serum albumin (BSA). Initial screening of all the synthesized 2,3-dihydrothiazole derivatives using various in silico techniques including molecular reactivity analysis, Lipinski rule and molecular docking, concluded 5-(4'-chlorobenzoyl)-3-((4''-methoxybenzylidene)amino)-2-(4'''-methoxybenzylidene)hydrazono)-4-methyl-2,3-dihydrothiazole derivative 6a as the most suitable compound for studying binding interaction with DNA and BSA. Additionally, to illustrate the ex vivo binding mode of 6a with DNA and BSA, several spectroscopic techniques viz. UV-visible, circular dichroism (CD), steady-state fluorescence and competitive displacement assays were carried out.

Unlocking the biological potential of transition metal complexes with Thiosemicarbazone ligands: Insights from computational studies

In the previous study, the synthesis and characterization of 4-(3-fluorophenyl)-3-thiosemicarbazide and benzaldehyde derivatives based thiosemicarbazone ligands and their Co(II), Ni(II), Cu(II), Zn(II) complexes were carried out to evaluate their malarial and oxidant and inflammatory inhibition abilities, demonstrating that these compounds have robust efficacy for these ailments. In the present research, to find out a combating agent against breast cancer, tuberculosis, bacterial and fungal ailments, the compounds were tested through MTT, microplate alamar blue and serial dilution protocols. ADMET and DFT investigation were analyzed against highly bioactive compounds (2, 7-10) to give a new insight about compound's reactivity, stability and drug likeness properties. Furthermore, activity results shows that the ligand (2) and its complexes demonstrate greater efficacy compared to ligand (1) and its complexes. The Cu(II) (9) and Zn(II) (10) complexes were observed as highly efficient for breast cancer (MCF-7 cell line), TB (H37Rv strain), bacterial and fungal ailments in comparison of standard drugs with 0.029 ± 0.001 μM IC50 value for (9) in anticancer activity and 0.0034 ± 0.0017 μmol/mL MIC value for (10) in anti-tuberculosis activity. In the molecular docking investigation, the various kind of binding interactions and lowest binding affinity of (9) (against 4RJ3 (-10.0 kcal/mol), 2VCJ (-7.9 kcal/mol)) and (10) (-7.8 and -8.3 kcal/mol for 5V3Y and 3PTY protein) support their bioactivity. This research highlights the pharmaceutical importance of transition metal complexes having thiosemicarbazones, presenting a significant approach for the discovery of potent anti-infectious agent.

New insides into chimeric and hybrid azines derivatives with antifungal activity

During the last decades, five or six member rings azaheterocycles compounds appear to be an extremely valuable source of antifungal agents. Their use seems to be a very attractive solution in antifungal therapy and to overcome antifungal resistance in agriculture. The present review highlights the main results obtained in the field of hybrid and chimeric azine (especially pyridine, quinoline, phenanthroline, bypyridine, naphthyridine and their fused derivatives) derivatives presented in scientific literature from the last 10 years, with emphasis on antifungal activity of the mentioned compounds. A special attention was played to hybrid and chimeric azole-azine class, having in view the high antifungal potential of azoles.

An Overview of the Structure-Activity Relationship in Novel Antimicrobial Thiazoles Clubbed with Various Heterocycles (2017-2023)

Antimicrobial resistance is an increasing problem for global public health. One of the strategies to combat this issue is the synthesis of novel antimicrobials through rational drug design based on extensive structure-activity relationship studies. The thiazole nucleus is a prominent feature in the structure of many authorized antimicrobials, being clubbed with different heterocycles. The purpose of this review is to study the structure-activity relationship in antimicrobial thiazoles clubbed with various heterocycles, as reported in the literature between 2017 and 2023, in order to offer an overview of the last years in terms of antimicrobial research and provide a helpful instrument for future research in the field.

Recent Literature on the Synthesis of Thiazole Derivatives and their Biological Activities

The thiazole ring is naturally occurring and is primarily found in marine and microbial sources. It has been identified in various compounds such as peptides, vitamins (thiamine), alkaloids, epothilone, and chlorophyll. Thiazole-containing compounds are widely recognized for their antibacterial, antifungal, anti-inflammatory, antimalarial, antitubercular, antidiabetic, antioxidant, anticonvulsant, anticancer, and cardiovascular activities. The objective of this review is to present recent advancements in the discovery of biologically active thiazole derivatives, including their synthetic methods and biological effects. This review comprehensively discusses the synthesis methods of thiazole and its corresponding biological activities within a specific timeframe, from 2017 until the conclusion of 2022.

Thiadiazole and Thiazole Derivatives as Potential Antimicrobial Agents

BACKGROUND

This review summarizes data on heterocyclic systems with thiadiazole and thiazole fragments in molecules as promising antimicrobial agents.

INTRODUCTION

Thiadiazole and thiazole backbones are the most favored and well-known heterocycles, a common and essential feature of various drugs. These scaffolds occupy a central position and are the main structural components of numerous drugs with a wide spectrum of action. These include antimicrobial, antituberculous, anti-inflammatory, analgesic, antiepileptic, antiviral, and anticancer agents.

METHOD

The research is based on bibliosemantic and analytical methods using bibliographic and abstract databases, as well as databases of chemical compounds.

RESULT

This review reports on thiadiazole and thiazole derivatives, which have important pharmacological properties. We are reviewing the structural modifications of various thiadiazole and thiazole derivatives, more specifically, the antimicrobial activity reported over the last years, as we have taken this as our main research area. 80 compounds were illustrated, and various derivatives containing hydrazone bridged thiazole and pyrrole rings, 2-pyridine and 4-pyridine substituted thiazole derivatives, compounds containing di-, tri- and tetrathiazole moieties, spiro-substituted 4- thiazolidinone-imidazoline-pyridines were analyzed. Derivatives of 5-heteroarylidene-2,4- thiazolidinediones, fluoroquinolone-thiadiazole hybrids, and others.

CONCLUSION

1,3,4-thiadiazoles and thiazoles are valuable resource for researchers engaged in rational drug design and development in this area.

Design, synthesis, in vitro, and in silico evaluations of kojic acid derivatives linked to amino pyridine moiety as potent tyrosinase inhibitors

In the present study, novel series of kojic acid derivatives conjugated to amino pyridine moiety were designed and synthesized to explore their inhibitory activity against tyrosinase. To this end, the structure of all derivatives was characterized by 1H NMR, 13C NMR, FT-IR, and elemental analysis. Next, all derivatives were evaluated against tyrosinase compared to the kojic acid as positive control and exhibited different inhibitory potencies. Furthermore, the antioxidant potential of all derivatives was determined. The kinetic analysis of the most active agent revealed that 3-hydroxy-6-(hydroxymethyl)-2-((3-nitrophenyl)(pyridin-2-ylamino)methyl)-4H-pyran-4-one (4h) binds to the enzyme in the uncompetitive mode of action. The docking analysis and molecular dynamic simulations showed considerable binding affinity and significant interactions with tyrosinase enzyme to target the melanogenesis pathway, proposing them as potent candidates to control hyperpigmentation in the future.

Exploration of Thiourea-Based Scaffolds for the Construction of Bacterial Ureases Inhibitors

A series of 32 thiourea-based urease inhibitors were synthesized and evaluated against native bacterial enzyme and whole cells of Sporosarcina pasteurii and Proteus mirabilis strains. The proposed inhibitors represented structurally diverse thiosemicarbazones and thiocarbohydrazones, benzyl-substituted thiazolyl thioureas, 1H-pyrazole-1-carbothioamides, and dihydropirimidine-2(1H)-thiones. Kinetic characteristics with purified S. pasteurii enzyme determined low micromolar inhibitors within each structural group. (E)-2-(1-Phenylethylidene)hydrazine-1-carbothioamide 19 (Ki = 0.39 ± 0.01 μM), (E)-2-(4-methylbenzylidene)hydrazine-1-carbothioamide 16 (Ki = 0.99 ± 0.04 μM), and N'-((1E,2E)-1,3-diphenylallylidene)hydrazinecarbothiohydrazide 29 (Ki = 2.23 ± 0.19 μM) were used in modeling studies that revealed sulfur ion coordination of the active site nickel ion and hydrogen bonds between the amide group and the side chain of Asp363 and Ala366 carbonyl moiety. Whole-cell studies proved the activity of compounds in Gram-positive and Gram-negative microorganisms. Ureolysis control observed in P. mirabilis PCM 543 (e.g., IC50 = 304 ± 14 μM for 1-benzyl-3-(4-(4-hydroxyphenyl)thiazol-2-yl)thiourea 52) is a valuable achievement, as urease is recognized as a major virulence factor of this urinary tract pathogen.

Synthesis and antimicrobial activity of new series of thiazoles, pyridines and pyrazoles based on coumarin moiety

Microbial infections are currently a widespread disease in hospitals and community health centres and are a major cause of death worldwide. In pursuit of searching new antimicrobial agents, coumarin linked to thiazoles, pyridines and pyrazoles have been developed and evaluated for their antimicrobial properties against two Gram + bacteria, two Gram - bacteria as well as two fungi. Some of the prepared coumarins displayed high to moderate activity against the tested microorganisms with respect to the reference drugs. However, compound 3 exhibited antimicrobial effect equal to the reference drug Ciprofloxacin for Gram - baceria Enterobacter cloacae. Compound 12 was found to be the most potent compound against Bacillus pumilis with MIC of 7.69 (µmol/ml). Compounds 3, 4 and 12 showed remarkable activity against Streptococcus faecalis with MIC of 14.34, 3.67 and 15.36 (µmol/ml), respectively. Regarding Escherichia coli, most compounds recorded high to moderate MIC values (4.73-45.46 µmol/ml). Moreover, in case of E. cloacae compound 9 was the most potent compound with MIC value of 22.76 (µmol/ml).

Transition metal complexes as self-activating chemical nucleases: proficient DNA cleavage without any exogenous redox agents

Chemical nucleases have found potential applications in the research fields of chemistry, biotechnology and medicine. A variety of metal complexes have been explored as good to outstanding therapeutic agents for DNA cleavage activity most likely via hydrolytic, oxidative or photoinduced cleavage pathways. However, most of these DNA cleaving agents lack their utility in in vivo applications due to their dependence on exogenous oxidants or reductants to achieve successful DNA damage. In view of addressing these issues, the development of metal complexes/organic molecules serving as self-activating chemical nucleases has received growing attention from researchers. In only the last decade, this field has dramatically expanded for the usage of chemical nucleases as therapeutic agents for DNA damage. The present study provides an overview of the opportunities and challenges in the design and development of self-activating chemical nucleases as improved DNA therapeutic candidates in the absence of an external redox agent. The reports on DNA nuclease activity via self-activation, especially with copper, zinc and iron complexes, and their mechanistic investigation have been discussed in this review article.

Metabolomics analysis of the effect of acidification on rhizosphere soil microecosystem of tea tree

Acidification can seriously affect the growth of tea trees and the yield and quality of tea leaves. In this study, we analyzed the effects of acidification on the physicochemical properties, microorganisms and metabolites of tea rhizosphere soils with different pH values, and the results showed that with the increase of soil pH, the organic matter content, cation exchange capacity, microbial biomass carbon, microbial biomass nitrogen, microbial respiration intensity, bacterial number and actinomyces number in tea rhizosphere soil all showed an increasing trend, while the fungi number decreased. The results of soil metabolite analysis showed that 2376, 2377 and 2359 metabolites were detected in tea rhizosphere soil with pH values of 3.29, 4.74 and 5.32, respectively, and the number of similar compounds reached 2331, accounting for more than 98%. The results of soil metabolite content analysis showed that with the increase of soil pH, the total contents of metabolite of tea rhizosphere soil increased significantly. The results of correlation analysis between physicochemical indexes of soil and microorganisms and soil metabolites showed that physicochemical indexes of soil and microorganisms were significantly correlated with 221 soil metabolites, among which 55 were significantly positively correlated and 166 were significantly negatively correlated. Based on correlation interaction network analysis, 59 characteristic compounds were obtained and divided into 22 categories, among which 7 categories compounds showed a significant increasing trend with the increase of soil pH, while the other 15 categories compounds showed the opposite trend. Based on the functional analysis of characteristic metabolites, this study found that with the increase of soil pH in tea rhizosphere, the diversity and number of soil microorganisms increased, and the cyclic ability of C and N of tea rhizosphere soil was enhanced, which in turn might lead to the enhancement of resistance of tea tree and promote the growth of tea tree.

Synthesis, computational study, solvatochromism and biological studies of thiazole-owing hydrazone derivatives

In the present work, we have synthesized thiazole-hydrazone conjugates 5(a–h) and characterized them using various analytical techniques such as UV, IR, NMR, and mass spectrometry. Solvatochromic properties were evaluated in ten solvents with different polarity and quantum chemical parameters using a DFT study. The antibacterial activity results revealed that compounds 5c, 5d and 5g exhibited good efficacy and that the remaining compounds displayed significant activity. The synthesized compounds were screened for their cytotoxic activity against HepG2 and MCF-7 cell lines, and all the synthesized compounds exhibited significant potency towards the screened cancer cell lines. The anti-inflammatory efficacy of the synthesized thiazole derivatives was determined against MMP-2 and MMP-9, and some of the compounds showed significant activity. Furthermore, the in silico molecular docking was performed with the COX-2 receptor.

Effect of Arylazo Sulfones on DNA: Binding, Cleavage, Photocleavage, Molecular Docking Studies and Interaction with A375 Melanoma and Non-Cancer Cells

A set of arylazo sulfones, known to undergo N-S bond cleavage upon light exposure, has been synthesized, and their activity in the dark and upon irradiation towards DNA has been investigated. Their interaction with calf-thymus DNA has been examined, and the significant affinity observed (most probably due to DNA intercalation) was analyzed by means of molecular docking "in silico" calculations that pointed out polar contacts, mainly via the sulfonyl moiety. Incubation with plasmid pBluescript KS II revealed DNA cleavage that has been studied over time and concentration. UV-A irradiation considerably improved DNA damage for most of the compounds, whereas under visible light the effect was slightly lower. Moving to in vitro experiments, irradiation was found to slightly enhance the death of the cells in the majority of the compounds. Naphthylazosulfone 1 showed photo-disruptive effect under UV-A irradiation (IC₅₀ ~13 μΜ) followed by derivatives 14 and 17 (IC₅₀ ~100 μΜ). Those compounds were irradiated in the presence of two non-cancer cell lines and were found equally toxic only upon irradiation and not in the dark. The temporal and spatial control of light, therefore, might provide a chance for these novel scaffolds to be useful for the development of phototoxic pharmaceuticals.

Discovery and biosynthesis of karnamicins as angiotensin converting enzyme inhibitors

Angiotensin-converting enzyme inhibitors are widely used for treatment of hypertension and related diseases. Here, six karnamicins E₁-E₆ (1-6), which bear fully substituted hydroxypyridine and thiazole moieties are characterized from the rare actinobacterium Lechevalieria rhizosphaerae NEAU-A2. Through a combination of isotopic labeling, genome mining, and enzymatic characterization studies, the programmed assembly of the fully substituted hydroxypyridine moiety in karnamicin is proposed to be due to sequential operation of a hybrid polyketide synthase-nonribosomal peptide synthetase, two regioselective pyridine ring flavoprotein hydroxylases, and a methyltransferase. Based on AlphaFold protein structures predictions, molecular docking, and site-directed mutagenesis, we find that two pyridine hydroxylases deploy active site residues distinct from other flavoprotein monooxygenases to direct the chemo- and regioselective hydroxylation of the pyridine nucleus. Pleasingly, karnamicins show significant angiotensin-converting enzyme inhibitory activity with IC₅₀ values ranging from 0.24 to 5.81 μM, suggesting their potential use for the treatment of hypertension and related diseases.

QSAR Studies, Molecular Docking, Molecular Dynamics, Synthesis, and Biological Evaluation of Novel Quinolinone-Based Thiosemicarbazones against Mycobacterium tuberculosis

In this study, a series of novel quinolinone-based thiosemicarbazones were designed in silico and their activities tested in vitro against Mycobacterium tuberculosis (M. tuberculosis). Quantitative structure-activity relationship (QSAR) studies were performed using quinolinone and thiosemicarbazide as pharmacophoric nuclei; the best model showed statistical parameters of R² = 0.83; F = 47.96; s = 0.31, and was validated by several different methods. The van der Waals volume, electron density, and electronegativity model results suggested a pivotal role in antituberculosis (anti-TB) activity. Subsequently, from this model a new series of quinolinone-thiosemicarbazone 11a-e was designed and docked against two tuberculosis protein targets: enoyl-acyl carrier protein reductase (InhA) and decaprenylphosphoryl-β-D-ribose-2'-oxidase (DprE1). Molecular dynamics simulation over 200 ns showed a binding energy of -71.3 to -12.7 Kcal/mol, suggesting likely inhibition. In vitro antimycobacterial activity of quinolinone-thiosemicarbazone for 11a-e was evaluated against M. bovis, M. tuberculosis H37Rv, and six different strains of drug-resistant M. tuberculosis. All compounds exhibited good to excellent activity against all the families of M. tuberculosis. Several of the here synthesized compounds were more effective than the standard drugs (isoniazid, oxafloxacin), 11d and 11e being the most active products. The results suggest that these compounds may contribute as lead compounds in the research of new potential antimycobacterial agents.

Hybrid Azine Derivatives: A Useful Approach for Antimicrobial Therapy

Nowadays, infectious diseases caused by microorganisms are a major threat to human health, mostly because of drug resistance, multi-drug resistance and extensive-drug-resistance phenomena to microbial pathogens. During the last few years, obtaining hybrid azaheterocyclic drugs represents a powerful and attractive approach in modern antimicrobial therapy with very promising results including overcoming microbial drug resistance. The emphasis of this review is to notify the scientific community about the latest recent advances from the last five years in the field of hybrid azine derivatives with antimicrobial activity. The review is divided according to the main series of six-member ring azaheterocycles with one nitrogen atom and their fused analogs. In each case, the main essential data concerning synthesis and antimicrobial activity are presented.

A new exploration toward adamantane derivatives as potential anti-MDR agents: Design, synthesis, antimicrobial, and radiosterilization activity as potential topoisomerase IV and DNA gyrase inhibitors

Developing novel antimicrobial agents has become a necessitate due to the increasing rate of microbial resistance to antibiotics. All the newly adamantane derivatives were evaluated for their antimicrobial activities against six MDR clinical pathogenic isolates. The results exhibited that 13 compounds have from potent to good activity. Among those, five derivatives (6, 7, 9, 14a, and 14b) displayed the potent activities against the different isolates tested (MIC < 0.25 µg/ml with bacteria and <8 µg/ml with fungi) compared with Ciprofloxacin (CIP) and Fluconazole (FCA). Additionally, the potent adamantanes showed bactericidal and fungicidal effects based on (MBCs and MFCs) and the time-kill assay. The most active adamantane derivatives 7 and 14b exhibited a synergistic effect of ΣFIC ≤ 0.5 with CIP and FCA against the bacterial and fungal isolates. Moreover, no antagonistic effect appeared for the tested derivatives. Additionally, the interaction of DNA gyrase and topoisomerase IV enzymes with the compounds 6, 7, 9, 14a, and 14b exhibited potent antimicrobial activity using in vitro biochemical assays and gel-based DNA-supercoiling inhibition method. The activity of DNA gyrase and topoisomerase IV enzymes showed inhibitory activity (IC₅₀ ) of 6.20 µM and 9.40 µM with compound 7 and 10.14 µM and 13.28 µM with compound 14b, respectively. Surprisingly, exposing compound 7 to gamma irradiation sterilized and increased its activity. Finally, the in-silico analysis predicted that the most active derivatives had good drug-likeness and safe properties. Besides, molecular docking and quantum chemical studies revealed several important interactions inside the active sites and showed the structural features necessary for activity.

Elhagali G, A. Eyada H, S. Aboul-Magd D, Ragab A. In Vitro Antimicrobial Evaluation, Single-Point Resistance Study, and Radiosterilization of Novel Pyrazole Incorporating Thiazol-4-one/Thiophene Derivatives as Dual DNA Gyrase and DHFR Inhibitors against MDR Pathogens

A series of thiazol-4-one/thiophene-bearing pyrazole derivatives as pharmacologically attractive cores were initially synthesized using a hybridization approach. All structures were confirmed using spectra analysis techniques (IR, ¹H NMR, and ¹³C NMR). In vitro antimicrobial activities, including the minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration (MBC/MFC), and time-kill assay, were evaluated for the most active derivatives 4a, 5a, 7b, 10, and 13. These derivatives were significantly active against the tested pathogens, with compound 7b as the most active derivative (MIC values range from 0.22 to 0.25 μg/mL). In the MBC and MFC, the active target pyrazole derivatives showed -cidal activities toward the pathogenic isolates. Further, the inhibition of biofilm formation of Staphylococcus aureus and Staphylococcus epidermidis was also carried out. Additionally, these derivatives displayed significant antibiofilm potential with a superior % reduction in the biofilm formation compared with Ciprofloxacin. The target derivatives behaved synergistically with Ciprofloxacin and Ketoconazole, reducing their MICs. Hemolytic results revealed that these derivatives were nontoxic with a significantly low hemolytic activity (%lysis range from 3.23 to 15.22%) compared with Triton X-100 and showed noncytotoxicity activity with IC₅₀ values > 60 μM. In addition, these derivatives proved to be active DNA gyrase and DHFR inhibitors with IC₅₀ ranging between 12.27-31.64 and 0.52-2.67 μM, respectively. Furthermore, compound 7b showed bactericidal activity at different concentrations in the time-kill assay. Moreover, a gamma radiation dose of 10.0 kGy was efficient for sterilizing compound 7b and enhancing its antimicrobial activity. Finally, molecular docking simulation of the most promising derivatives exhibited good binding energy with different interactions.

Urea-thiazole/benzothiazole hybrids with a triazole linker: synthesis, antimicrobial potential, pharmacokinetic profile and in silico mechanistic studies

Some urea-thiazole/benzothiazole hybrids with a triazole linker were synthesized via Cu(I)-catalysed click reaction. After successfully analysed by various spectral techniques including FTIR, NMR and HRMS, antimicrobial screening of the synthesized hybrids along with their precursors was carried out against two Gram (+) bacteria (Staphylococcus aureus and Bacillus endophyticus), two Gram (-) bacteria (Escherichia coli and Pseudomonas fluorescens) and two fungi (Candida albicans and Rhizopus oryzae). All the synthesized compounds (4a-4l) displayed better biological response than the standard fluconazole against both of the tested fungi. Compounds 4h and 4j were found to be the most active compounds against R. oryzae and C. albicans, respectively. Molecular docking of hybrid 4j and its alkyne precursor 1b in the active site of C. albicans target sterol 14-α demethylase was also performed and was also supported by molecular dynamics studies. In silico ADME prediction of synthesized urea-thiazole/benzothiazole hybrids with a triazole linker and their alkyne precursors was also predicted.

Pyridine Derivatives-A New Class of Compounds That Are Toxic to E. coli K12, R2-R4 Strains

A preliminary study of 2-amino-4-aryl-3,5-dicarbonitrile-6-thiopyridines as new potential antimicrobial drugs was performed. Special emphasis was placed on the selection of the structure of target pyridine derivatives with the highest biological activity against different types of Gram-stained bacteria by lipopolysaccharide (LPS). Herein, Escherichia coli model strains K12 (without LPS in its structure) and R2–R4 (with different lengths of LPS in its structure) were used. Studied target compounds were provided with yields ranging from 53% to 91% by the lipase-catalyzed one pot multicomponent reaction of various aromatic aldehydes with malononitrile, and thiols. The presented work showed that the antibacterial activity of the studied pyridines depends on their structure and affects the LPS of bacteria. Moreover, the influence of the pyridines on bacteria possessing smooth and rough LPS and oxidative damage to plasmid DNA caused by investigated compounds was indicated. Additionally, the modification of the bacterial DNA with the tested compounds was performed to detect new potential oxidative damages, which are recognized by the Fpg protein. The obtained damage modification values of the analyzed compounds were compared with the modifications after antibiotics were used in this type of research. The presented studies demonstrate that 2-amino-4-aryl-3,5-dicarbonitrile-6-thiopyridines can be used as substitutes for known antibiotics. The observed results are especially important in the case of the increasing resistance of bacteria to various drugs and antibiotics.

Conventional and microwave-assisted organic synthesis of novel antimycobacterial agents bearing furan and pyridine hybrids

Drug resistance in tuberculosis poses a serious threat to humanity because currently available antitubercular drugs are ineffective against Mycobacterium tuberculosis (M. tuberculosis). As a result, the approval of Bedaquiline and Delamanid for the treatment of drug-resistant tuberculosis was accelerated. Still, there is an urgent need to search for new antitubercular drugs with novel mechanisms of action (MoA). Due to this, we have designed a synthetic strategy by utilizing microwave-assisted organic synthesis. We have compared our method with the conventional procedure, and the data show that our procedure is more effective in the preparation of title compounds. A unique series of 1-(2-(furan-2-yl)-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl)-3-(aryl)-prop-2-en-1-ones (5a-o) was synthesized utilizing conventional and microwave-assisted techniques. Synthetic compounds were investigated for antitubercular activity against Mycobacterium TB H₃₇ Ra and Mycobacterium bovis (M. bovis). Compound 5b was reported to be the most effective against M. tuberculosis H₃₇ Ra (97.69 percent inhibition at 30 μg/ml) and M. bovis (97.09 percent inhibition at 30 μg/ml). An in silico binding affinity study of mycobacterial enoyl-acyl carrier protein reductase (InhA) reveals the binding mechanism and thermodynamic interactions that determine these molecule's binding affinity. Compound 5b had a high glide score of -8.991 and low glide energy of -49.893 kcal/mol.

Novel Pyridyl-Oxazole Carboxamides: Toxicity Assay Determination in Fungi and Zebrafish Embryos

Eight novel pyridyl–oxazole carboxamides were evaluated against fungi and displayed good fungicidal activities against Botrytis cinereal and Rhizoctonia solani. Preliminary bioassay results indicated that at 100 mg/L, compounds 6a–6e, 6g and 6h exhibited 100% fungicidal activities against Botrytis cinerea, and the compound 6b to Rhizoctonia solani at 100%. Then, the zebrafish embryo acute toxicity test was performed to assess the toxicity of 6b and 6c. A series of malformations appeared, when the zebrafish embryos were exposed to 6b and 6c, such as delayed yolk sac resorption, significant shortening of body length, pericardial edema, bending spine, lack of melanin, heart hemorrhage, head hemorrhage, delayed swim sac development, yolk malformation and head malformation. In addition, the acute toxicity of 6b to zebrafish embryo is 4.878 mg/L, and 6c is 6.257 mg/L.

Synthesis of Chitosan-La2O3 Nanocomposite and Its Utility as a Powerful Catalyst in the Synthesis of Pyridines and Pyrazoles

Recently, the development of nanocatalysts based on naturally occurring polysaccharides has received a lot of attention. Chitosan (CS), as a biodegradable and biocompatible polysaccharide, is considered to be an excellent template for the design of a hybrid biopolymer-based metal oxide nanocomposite. In this case, lanthanum oxide nanoparticles doped with chitosan at different weight percentages (5, 10, 15, and 20 wt% CS/La2O3) were prepared via a simple solution casting method. The prepared CS/La2O3 nanocomposite solutions were cast in a Petri dish in order to produce the developed catalyst, which was shaped as a thin film. The structural features of the hybrid nanocomposite film were studied by FTIR, SEM, and XRD analytical tools. FTIR spectra confirmed the presence of the major characteristic peaks of chitosan, which were modified by interaction with La2O3 nanoparticles. Additionally, SEM graphs showed dramatic morphological changes on the surface of chitosan, which is attributed to surface adsorption with La2O3 molecules. The prepared CS/La2O3 nanocomposite film (15% by weight) was investigated as an effective, recyclable, and heterogeneous base catalyst in the synthesis of pyridines and pyrazoles. The nanocomposite used was sufficiently stable and was collected and reused more than three times without loss of catalytic activity.

In vitro and in silico assessment of DNA interaction, topoisomerase I and II inhibition properties of chrysosplenetin

Chrysosplenetin is a methoxyflavone with reported anti-cancer effect. We tested its cytotoxic effect on the MCF-7 breast cancer cell line, and determined its effect on DNA intercalation and on the activity of topoisomerases I and II. The compound inhibited proliferation MCF-7 with an IC₅₀ value of 0.29 μM. Chrysosplenetin did not initiate plasmid DNA cleavage but, in a concentration-dependent manner, protected plasmid DNA against damage induced by Fenton reagents. Furthermore, it possessed dual Topoisomerase I and II inhibitory properties. Especially, it inhibited topoisomerase II by 83-96% between the range 12.5-100 μM. In the light of these experimental findings, molecular docking studies were performed to understand binding mode, interactions and affinity of chrysosplenetin with DNA, and with topoisomerases I and II. These studies showed that of 4-chromone core and the hydroxyl and methoxy groups important for both intercalation with DNA and topoisomerase I and II inhibition.

Pyridine- and Thiazole-Based Hydrazides with Promising Anti-inflammatory and Antimicrobial Activities along with Their In Silico Studies

A new class of compounds formed by the linkage of -C(O)-NH- with pyridine and thiazole moieties was designed, synthesized, and characterized by various spectral approaches. The newly characterized compounds were evaluated for their antimicrobial as well as anti-inflammatory properties. The in vitro anti-inflammatory activity of these compounds was evaluated by denaturation of the bovine serum albumin method and showed inhibition in the range of IC50 values-46.29-100.60 μg/mL. Among all the tested compounds, compound 5l has the highest IC50 value and compound 5g has the least IC50 value. On the other hand, antimicrobial results revealed that compound 5j showed the lowest MIC values and compound 5a has the highest MIC values. Furthermore, molecular docking of the active compounds demonstrated a better docking score and interacted well with the target protein. Physicochemical parameters of the titled compounds were found suitable in the reference range only. The in silico molecular docking study revealed their COX-inhibitory action. Compound 5j emerged as a significant bioactive molecule among the synthesized analogues.

Novel molecular discovery of promising amidine-based thiazole analogues as potent dual Matrix Metalloproteinase-2 and 9 inhibitors: Anticancer activity data with prominent cell cycle arrest and DNA fragmentation analysis effects

Thiazole derivatives are known to possess various biological activities such as antiparasitic, antifungal, antimicrobial and antiproliferative activities. Matrix metalloproteinases (MMPs) are important protease target involved in tumor progression including angiogenesis, tissue invasion, and migration. Therefore, MMPs have also been reported as potential diagnostic and prognostic biomarkers in many types of cancer. Herein, new aryl thiazoles were synthesized and evaluated for their anticancer effects on a panel of cancer cell lines including the invasive MDA-MB-231 line. Some of these compounds showed IC₅₀ values in the submicromolar range in anti-proliferative assays. In order to examine the relationship between their anticancer activity and MMPs targets, the compounds were evaluated for their inhibitory effects on MMP-2 and 9. That data obtained revealed that most of these compounds were potent dual MMP-2/9 inhibitors at nanomolar concentrations. Among these, 2-(1-(2-(2-((E)-4-iodobenzylidene)hydrazineyl)-4-methylthiazol-5-yl)ethylidene)hydrazine-1-carboximidamide (4a) was the most potent non-selective dual MMP-2/9 inhibitor with inhibitory concentrations of 56 and 38 nM respectively. When compound 4a was tested in an MDA-MB-231, HCT-116, MCF-7 model, it effectively inhibited tumor growth, strongly induced cancer cell apoptosis, inhibit cell migration, and suppressed cell cycle progression leading to DNA fragmentation. Taken together, the results of our studies indicate that the newly discovered thiazole-based MMP-2/9 inhibitors have significant potential for anticancer treatment.