Synthesis and antibacterial activity of some novel bis-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and bis-4-thiazolidinone derivatives from terephthalic dihydrazide

Design, synthesis, computational molecular docking studies of novel heterocyclics bearing 1,2,4-triazole, 1,3,4-oxadiazole conjugates as potent antibacterial and antitubercular agents

Herein, we report the synthesis, and characterization of a new series of 1,3,4-oxadiazole and 1,2,4-triazole derivatives based on azaindole acetamides and assigned as potential antibacterial and antitubercular substances. The structures of these compounds were established by 1H NMR, 13C NMR, and HRMS spectral analysis. In preliminary antibacterial studies, analogues 6b, 6d, and 6e were found to be most effective against S. aureus with MIC of 12.5, 6.25, and 12.5 μg/mL, whereas 8d displayed excellent activity against S. aureus, B. subtilis, E. coli bacterial strains with zones of inhibition 12.5, 25, and 12.5 μg/mL respectively. Particularly, the prepared scaffolds 8c, 8d, and 8e showed remarkable antifungal activity with MIC value 12.5, 12.5, and 6.25 μg/mL against A. flavus and 6d, 6c producing an increase in the activity against C. Albicans with zones of inhibition 12.5 and 12.5 μg/mL respectively. Also, through the antitubercular studies, we found that compounds 6e and 8b have a strong activity with M. tuberculosis H37Rv with MICs 3.26, and 6.48 μg/mL, respectively. The protein stability, fluctuations of APO-Protein, and protein-ligand complexes were investigated through Molecular Dynamics (MD) simulations studies using Desmond Maestro 11.3, and potential lead molecules were identified. Our findings were further confirmed using molecular docking, revealing that azaindole based ligand 6e, 6f, and 8a has strong hydrophobic Tyr179, Trp183, Ile177, Ile445, and H-bondings interactions Arg151 and Arg454 through molecular dynamics simulation studies, making it potential biological compound. These compounds were further evaluated for their ADMET and physicochemical properties by using SwissADME.Communicated by Ramaswamy H. Sarma.

Evaluation of Anticancer and Antibacterial Activity of Four 4-Thiazolidinone-Based Derivatives

Heterocycles are commonly known for their unique features, e.g., antibacterial or anticancer properties. Although many synthetic heterocycles, such as 4-thiazolidinone (4-TZD), have been synthesized, their potential applications have not yet been fully investigated. However, many researchers have reported relevant results that can be a basis for the search for new potential drugs. Therefore, the aim of this study was to evaluate the cytotoxic, cytostatic, and antibacterial effects of certain 4-thiazolidinone-based derivatives, Les-3166, Les-5935, Les-6009, and Les-6166, on human fibroblasts (BJ), neuroblastoma (SH-SY5Y), epithelial lung carcinoma (A549), and colorectal adenocarcinoma (CACO-2) cell lines in vitro. All tested compounds applied in a concentration range from 10 to 100 µM were able to decrease metabolic activity in the BJ, A549, and SH-SY5Y cell lines. However, the action of Les-3166 was mainly based on the ROS-independent pathway, similarly to Les-6009. In turn, Les-5935 and Les-6166 were able to promote ROS production in BJ, A549, and SH-SY5Y cells, compared to the control. Les-3166, Les-6009, and Les-6166 significantly increased the caspase-3 activity, especially at the concentrations of 50 µM and 100 µM. However, Les-5935 did not induce apoptosis. Only Les-5935 showed a minor cytostatic effect on SH-SY5Y cells. Additionally, the antibacterial properties of the tested compounds against P. aeruginosa bacterial biofilm can be ranked as follows: Les-3166 > Les-5935 > Les-6009. Les-6166 did not show any anti-biofilm activity. In summary, the study showed that Les-5935, Les-6009, and Les-6166 were characterized by anticancer properties, especially in the human lung cancer cell. In cases of BJ, SH-SY5Y, and CACO-2 cells the anticancer usage of such compounds is limited due to effect visible only at 50 and 100 µM.

The Chemical Recycling of Polyesters for a Circular Plastics Economy: Challenges and Emerging Opportunities

Whilst plastics have played an instrumental role in human development, growing environmental concerns have led to increasing public scrutiny and demands for outright bans. This has stimulated considerable research into renewable alternatives, and more recently, the development of alternative waste management strategies. Herein, the aim was to highlight recent developments in the catalytic chemical recycling of two commercial polyesters, namely poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET). The concept of chemical recycling is first introduced, and associated opportunities/challenges are discussed within the context of the governing depolymerisation thermodynamics. Chemical recycling methods for PLA and PET are then discussed, with a particular focus on upcycling and the use of metal-based catalysts. Finally, the attention shifts to the emergence of new materials with the potential to modernise the plastics economy. Emerging opportunities and challenges are discussed within the context of industrial feasibility.

Catalytic methods for chemical recycling or upcycling of commercial polymers

Polymers (plastics) have transformed our lives by providing access to inexpensive and versatile materials with a variety of useful properties. While polymers have improved our lives in many ways, their longevity has created some unintended consequences. The extreme stability and durability of most commercial polymers, combined with the lack of equivalent degradable alternatives and ineffective collection and recycling policies, have led to an accumulation of polymers in landfills and oceans. This problem is reaching a critical threat to the environment, creating a demand for immediate action. Chemical recycling and upcycling involve the conversion of polymer materials into their original monomers, fuels or chemical precursors for value-added products. These approaches are the most promising for value-recovery of post-consumer polymer products; however, they are often cost-prohibitive in comparison to current recycling and disposal methods. Catalysts can be used to accelerate and improve product selectivity for chemical recycling and upcycling of polymers. This review aims to not only highlight and describe the tremendous efforts towards the development of improved catalysts for well-known chemical recycling processes, but also identify new promising methods for catalytic recycling or upcycling of the most abundant commercial polymers.

Antitubercular properties of thiazolidin-4-ones - A review

Thiazolidin-4-one scaffold has great potential for medicinal chemistry and is of interest to scientists in view of wide spectrum of biological activity. This scaffold is often used for designing of small molecules with various biological activity including antituberculosis activity. The presented review is an attempt to gather, analyze and systemize data about antitubercular properties of thiazolidine-4-ones from two last decades. Some of them have promising antitubercular activity which is significantly higher than that of the reference drugs. Among them compounds 82c, 82d and 84 that were active against M. tuberculosis H37Rv strain with MICs in the range of 0.05-0.2 μg/mL and compound 108 exhibited activity with MIC = 0.36 μM. Compounds 115a-115c and 116a-116c were very effective against M. tuberculosis H37Ra with MIC values in the range of 0.031-0.125 μg/mL. Acidomycin was showed activity against seven MDR M. tuberculosis strains with MICs in the range of 0.6-0.62 μM and against two XDR M. tuberculosis strains with MICs 0.096 and 1.2 μM. The structure-activity relationship (SAR) of some groups of compounds, as well as some potential molecular targets were also discussed.

Design, Synthesis, and Biological Evaluation of Novel Thiazolidinone-Containing Quinoxaline-1,4-di-N-oxides as Antimycobacterial and Antifungal Agents

Tuberculosis and fungal infections can pose serious threats to human health. In order to find novel antimicrobial agents, 26 novel quinoxaline-1,4-di-N-oxides containing a thiazolidinone moiety were designed and synthesized, and their antimycobacterial activities were evaluated. Among them, compounds 2t, 2u, 2y, and 2z displayed the most potent antimycobacterial activity against Mycobacterium tuberculosis strain H37Rv (minimal inhibitory concentration [MIC] = 1.56 μg/mL). The antifungal activity of all the compounds was also evaluated against Candida albicans, Candida tropicalis, Aspergillus fumigatus, and Cryptococcus neoformans. Compounds 2t, 2u, 2y, and 2z exhibited potential antifungal activities, with an MIC between 2 and 4 μg/mL. Comparative molecular field analysis (CoMFA: q² = 0.914, r² = 0.967) and comparative molecular similarity index analysis (CoMSIA: q² = 0.918, r² = 0.968) models were established to investigate the structure and antimycobacterial activity relationship. The results of contour maps revealed that electronegative and sterically bulky substituents play an important role in the antimycobacterial activity. Electronegative and sterically bulky substituents are preferred at the C7 position of the quinoxaline ring and the C4 position of the phenyl group to increase the antimycobacterial activity. Additionally, more hydrogen bond donor substituents should be considered at the C2 side chain of the quinoxaline ring to improve the activity.

Molecular docking studies, biological evaluation and synthesis of novel 3-mercapto-1,2,4-triazole derivatives

Synthesis of bioactive heterocyclic compounds having effective biological activity is an essential research area for wide-ranging applications. In this study, a conventional methodology has been developed for the synthesis of a series of new 3-mercapto-1,2,4-triazole derivatives 4a-f. The purity and structure of the synthesized molecules were confirmed by ¹H NMR, ¹³C NMR and elemental analysis. In addition, the prepared compounds were screened for their anti-proliferative activity against three human cancer cell lines including A549 (lung cancer), MCF7 (breast cancer) and SKOV3 (ovarian cancer) using MTT reduction assay. All the tested compounds demonstrated remarkable cytotoxic activity with IC₅₀ values ranging from 3.02 to 15.37 µM. The heterocyclic compound bearing 3,4,5-trimethoxy moiety was found to be the most effective among the series displaying an IC₅₀ of 3.02 µM specifically against the ovarian carcinoma cancer cell line (SKOV3). Moreover, Annexin V-FITC/propidium iodide staining assay indicated that this compound can induce apoptosis in SKOV3 cells. Furthermore, cell cycle assay showed a significant cell cycle arrest at the G2/M phase in a dose-dependent manner for this compound. The molecular docking results was showed binding modes of potent compound 4d perfectly corroborated the suggestion of binding to the colchicine site. The entire results conclude that 3-mercapto-1,2,4-triazole derivatives can be synthesized by a green method for biological and pharmacological applications. New analogs of 3-mercapto-1,2,4-triazole potential derivatives for anti-proliferative activity were synthesized. Cytotoxic activity of all synthesized compounds was evaluated against tree human cancer cell lines: lung (A549), breast (MCF7) and ovarian (SKOV3).

Design, synthesis and validation of anti-microbial coumarin derivatives: An efficient green approach

An ecofriendly itinerary for the synthesis of newly substituted chromene-3-carboxamide derivatives was undertaken to avoid impurities, usage of toxic solvents, toxic catalyst, and having improved quantitative yields. The green synthesis involves the condensation of substituted salicylaldehyde with N-(substituted)phenyl malonic acid in the presence of a base catalyst, piperidine. All reported compounds were assessed for their antimicrobial activities which clearly suggested their therapeutic implications to address antimicrobial pathogenesis. The synthesized coumarin compounds were examined for their antimicrobial activity against 7 fungal strains and 2 bacterial strains at concentration 125–1000 μg/mL. In particular, the compounds 4 and 5 showed lower minimum inhibitory concentration value (125 μg/mL) against maximum microbial strains. Further, docking of all the synthesized compounds was performed with the enzymes lanosterol 14α-demethylase and glucosamine-6-phosphate synthase and a significant binding affinity was observed which supports in vivo antimicrobial study. In addition, the thermal analysis revealed good thermal stability of compounds up to 250 °C. The compounds showed abroad absorption spectrum between 280-550 nm establishing them to be good UV absorbers.

Synthesis and characterization of isophorondiamine-based oligoamides: catalytic effect of amides during the curing of epoxy resins

The aminolysis products of PET could be applied in several fields. The purpose of this study was to explore their use as a dual-purpose component as cross-linkers and catalysts in epoxy curing. PET aminolysis was carried out with 1:1.5 and 1:2 PET/amine ratios to produce amides with different molecular weights. The reaction products were characterized with functional group analysis, NMR, FTIR, MALDI-TOF, and solution viscosimetry. The terephthalamides were dissolved in isophorondiamine and used as cross-linkers. Reaction kinetics studies with DSC, viscosimetry, and quantum chemical computational methods were used to characterize their accelerative effects. Our studies have shown that terephthalamides are active catalyst and their efficiency can be tuned with their molecular weight. The quantum chemical simulations suggested that the terephthalamides are in the same order of magnitude in effectiveness as phenolic accelerators. Consequently, terephthalamides are valued materials that can serve as double-purpose components in epoxy curing.

Structure-based rational design, synthesis, crystal structure, DFT and molecular docking of 1,4-benzene dicarboxamide isomers with application as hardeners

Molecular structures of two isomers have been investigated by SXRD analysis and DFT calculations and the isomers are assessed for their antimicrobial properties and as curing agents for epoxy resins.

Cytotoxic, DNA Cleavage and Pharmacokinetic Parameter Study of Substituted Novel Furan C-2 Quinoline Coupled 1, 2, 4-Triazole and Its Analogs

BACKGROUND

Furan, quinoline and triazoles are known for their wide spectrum biologically active molecules. A series of novel furan C-2 quinoline and 1, 2, 4-triazole (FQT) coupled hybrids were designed and synthesized to evaluate for their DNA cleavage and cytotoxic studies.

OBJECTIVES

In this work we describe the synthesis and biological evaluation of furan C-2 quinoline coupled triazoles exposed for cytotoxic and DNA cleavage study.

METHODS

The electrophoretic DNA cleavage studies on λ-DNA (Eco-RI/Hinda-III double digest) using agarose gelelectrophoresis and the cytotoxic activity were carried out by MTT assay method.

RESULTS

The results revealed that, the molecules 7(a-o) did cleave the DNA completely with no trace of fragments at 100 µg concentration, on the other hand, cytotoxic assay was achieved by two different human cancer cell lines (melanoma cell line-A375 and breast cancer cell line MDA-MB 231). Among the synthesized compounds 7a, 7b, 7c and 7k exhibited potent cytotoxic activity with IC50 values ranging from 2.9, 4.0, 7.8 and 5.1 µg/ml against A375 and 6.2, 9.5, 11.3 and 7.3 µg/ml against, MDA-MB 231, respectively.

CONCLUSION

In synthesized compounds 7(a-o) exhibited complete DNA cleavage at 100 µg/ml and the compounds 7a, 7b, 7c and 7k showed very less cytotoxic in nature. The structure activity relationship revealed that, the presence of halogen group/atoms at para position of phenyl ring remarkably enhanced the DNA cleavage and cytotoxic activities among the synthesized compounds.

Catalyst-free and environment friendly synthesis of 2-aryl-3-substituted-4-thiazolidinones in water

A simple, efficient, eco-friendly, and cost-effective method has been developed for the three component one pot synthesis of 2-aryl-3-substituted-4-thiazolidinones is described.