Studies on synthesis and pharmacological activities of 3,6-disubstituted-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and their dihydro analogues

Elucidating the structural basis for the enhanced antifungal activity of amide derivative against Candida albicans: a comprehensive computational investigation

The continuous search for more effective options against well-known pathogens such as Candida albicans remains the rationale for the search for novel lead compounds from various sources. This study aims to investigate the chemical structure, chemical properties, of 5-(2-((5-(((1S,3R) -3-(5-acetamido-1,3,4-thiadiazolidin-2-yl) cyclopentyl) methyl)-1,3,4-thiadiazolidin-2-yl)amino)-2-oxoethyl)-2-methyl-2,3-dihydro-1H-pyrazol-3-ide designated ATCTP using DFT method ωB97XD/-311 +  + g(2d, 2p) and the biological potential of compound ATCTP against Candida albicans using molecular docking and ADMET studies. Geometry optimization was carried out in DMSO, ethanol. gas and water revealing minute discrepancies in bond length and wider differences in bond angles. Frontier molecular orbital investigations reveal HOMO-LUMO energy gap magnitude in decreasing order of ATCTP_Gas > ATCTP_Water > ATCTP_ethanol > ATCTP_DMSO inferring that water influences chemical stability of the compound the most compared to ethanol and DMSO. Density of state investigations have revealed electron density contributions at corresponding energy peaks. In silico pharmacokinetic predicts ATCTP not to be cytotoxic, hepatotoxic, immunotoxic or mutagenic but probable mutagen. Molecular docking investigation of ATCTP against aspartic proteinase of Candida albicans (ID: 2QZX) in comparison with standard drug Fluconazole. Compound ATCTP had higher binding affinity (- 8.1 kcal/mol) compared to that of the standard drug fluconazole (- 5.6 kcal/mol) which records 4 conventional hydrogen interactions compared to 2 formed in the interaction of ATCTP + 2QZX. ATCTP also reports binding affinity of - 7.2 kcal/mol which reportedly surpassed that of 2QZX interaction with fluconazole (- 5.7 kcal/mol). ATCTP binds with lanosterol14-α-demethylase (5v5z) with binding affinity of - 9.7 kcal/mol binding to active site amino acid residues of the protein compared to fluconazole + 5v5z (- 8.0 kcal/mol). ATCTP is therefore recommended to be a lead compound for the possible design of a new and more effective anti-candida therapeutic compound.

Graphical abstract

[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives as new therapeutic candidates against urease positive microorganisms: design, synthesis, pharmacological evaluations, and in silico studies

Regarding the important role of the urease enzyme as a virulence factor in urease-positive microorganisms in this study, new series of [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives were designed and synthesized. All compounds evaluated against urease enzyme exhibiting IC50 values of 0.87 ± 0.09 to 8.32 ± 1.21 µM as compared with thiourea as the positive control (IC50 = 22.54 ± 2.34 µM). The kinetic evaluations of 6a as the most potent derivative recorded a competitive type of inhibition. Molecular dynamic simulations of the 6a derivative were also conducted, showing that 6a occupied the active site with closed state. Antimicrobial activities of all derivatives were performed, and 6f (R = 3-Cl), 6g (R = 4-Cl), and 6h (R = 3,4-diCl) analogs demonstrated significant antifungal activities with MIC values of 1, 2, and 0.5 µg/mL compared with fluconazole with MIC = 2 µg/mL. Synthesized analogs also exhibited potent urease inhibitory activities against C. neoformans (IC50 = 83.7-118.7 µg/mL) and P. mirabilis (IC50 = 74.5-113.7 µg/mL), confirming their urease inhibitory potential. The results demonstrated that the designed scaffold could be considered a suitable pharmacophore to develop potent urease inhibitors.

Steroid-triazole conjugates: A brief overview of synthesis and their application as anticancer agents

Steroids are biomolecules that play pivotal roles in various physiological and drug discovery processes. Abundant research has been fuelled towards steroid-heterocycles conjugates over the last few decades as potential therapeutic agents against various diseases especially as anticancer agents. In this context various steroid-triazole conjugates have been synthesized and studied for their anticancer potential against various cancer cell lines. A thorough search of the literatures revealed that a concise review pertaining the present topic is not compiled. Therefore, in thus review we summarize the synthesis, anticancer activity against various cancer cell lines and structure activity relationship (SAR) of various steroid-triazole conjugates. This review can lay down the path towards the development of various steroid-heterocycles conjugates with lesser side effects and profound efficacy.

New Semisynthetic Penicillins Obtained by Coupling of the 6-Aminopenicillanic Acid with 5-Mercapto-1,2,4-triazoles-3,4-disubstituted

In a basic medium, 5-Mercapto-1,2,4-triazoles pass into the thiol form, allowing their transformation into sodium salts, which, in reaction with sodium monochloroacetate, lead to sodium 5-thioacetates of 1,2,4-triazoles-3,4-disubstituted. Sulfur derivatives converted to pivalic mixed anhydrides were used as active forms in the acylation of 6-amino penicillanic acid (6-AP) to obtain new semisynthetic penicillins. They contain in the molecule, together with the β-lactam ring, the nucleus 3-[(5-nitroindazol-1'-yl-methyl)]-4-aryl-5-mercapto-1,2,4-triazole, both contributing to an important antibacterial effect. The structure of the new antibiotics was confirmed by the results of elemental and spectral analysis (FT-IR, ¹H- and ¹³C-NMR). The synthetic penicillins were tested for toxicological action and antibacterial activity and the obtained results were close to those for amoxicillin, the reference drug.

Chemistry and Therapeutic Aspect of Triazole: Insight into the Structure-activity Relationship

The triazole ring is a highly significant heterocycle that occurs naturally in many commodities and is a common feature in pharmaceuticals. Recently, heterocyclic compounds and their derivatives have been getting a lot of attention in medicinal chemistry because they have a lot of pharmacological and biological potential. For example, a lot of drugs have nitrogen-containing heterocyclic moieties. The triazole ring is often used as a bio-isostere of the oxadiazole nucleus. The oxygen atom in the oxadiazole nucleus is replaced by nitrogen in the triazole analogue. This article explores the pharmacological properties of the triazole moiety, including but not limited to antibacterial, analgesic, anticonvulsant, anthelmintic, anti-inflammatory, antitubercular, antimalarial, antioxidant, antiviral, and other properties. Additionally, we discuss the diverse multi- target pharmacological activities exhibited by triazole-based compounds. Based on a literature review, it is evident that triazole-based chemicals hold significant potential for various applications.

Monoamine oxidase A and B inhibitory activities of 3,5-diphenyl-1,2,4-triazole substituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives

Monoamine oxidase (EC 1.4.3.4, MAO) is a flavin adenine dinucleotide-containing flavoenzyme located on the outer mitochondrial membrane and catalyzes the oxidative deamination of monoaminergic neurotransmitters and dietary amines. MAO exists in humans as two isoenzymes, hMAO-A and hMAO-B, which are distinguished by their tertiary structures, preferred substrates and inhibitors, and selective inhibition of these isoenzymes are used in the treatment of different diseases such as Alzheimer's, Parkinson's and depression. In the present study, we report the design, synthesis and characterization of 3,5-diphenyl-1,2,4-triazole substituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives as novel and selective inhibitors of hMAO-B. Twenty one compounds (38, 39a-h, 41a-d, 42a-h) were screened for their inhibitory activity against hMAO-A and hMAO-B by using in vitro Amplex Red® reagent based fluorometric method and all compounds were found to be as selective h-MAO-B inhibitors to a different degree. The compound 42e and 42h displayed the highest inhibitory activity against hMAO-B with IC₅₀ values of 2.51 and 2.81 µM, respectively, and more than 25-fold selectivity towards inhibition of hMAO-B. A further kinetic evaluation of the most potent derivative (42e) was also performed and a mixed mode of inhibition of hMAO-B by the compound 42e was determined (K_i = 0,26 µM). According to our findings the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole emerged as a promising scaffold for the development of novel and selective hMAO-B inhibitors.

Triazole analogues as potential pharmacological agents: a brief review

Background

A large number of studies have recently reported that, because of their significant biological and pharmacological properties, heterocyclic compounds and their derivatives have attracted a strong interest in medicinal chemistry. The triazole nucleus is one of the most important heterocycles which has a feature of natural products as well as medicinal agents. Heterocyclic nitrogen is abundantly present in most medicinal compounds. The derivatization of triazole ring is based on the phenomenon of bio-isosteres in which substituted the oxygen atom of oxadiazole nucleus with nitrogen triazole analogue.

Main text

This review focuses on recent synthetic procedure of triazole moiety, which comprises of various pharmacological activities such as antimicrobial, anticonvulsant, anti-inflammatory, analgesic, antitubercular, anthelmintic, antioxidant, antimalarial, antiviral, etc..

Conclusion

This review highlights the current status of triazole compounds as different multi-target pharmacological activities. From the literature survey, triazole is the most widely used compound in different potential activities.

Predictive hybrid paradigm for cytotoxic activity of 1,3,4-thiadiazole derivatives as CDK6 inhibitors against human (MCF-7) breast cancer cell line and its structural modifications: rational for novel cancer therapeutics

The dysregulation of cyclin-CDK6 interactions has been implicated in human breast cancer, providing a rationale for more therapeutic options. Recently, ATP-competitive inhibitors have been employed for managing breast cancer. These molecules, like most natural CDKs inhibitors, potently bind in the ATP-binding site of CDK6 to regulate trans-activation. Nonetheless, only a few numbers of these molecules are approved to mitigate breast cancer, thus, ensuring that the search for more selective inhibitors continues. In this study, we attempted to establish the selective predictive models for identifying potent CDK6 inhibitors against a human breast cancer cell-line using a dataset of fifty-two 1,3,4-thiadiazole derivatives. The significant eight descriptor hybrid QSAR models generated exhibited encouraging statistical attributes including R2> 0.70, Q²_LOO > 0.70, Q²_LMO > 0.60, Qfn2 > 0.6. Furthermore, the study designed new compounds based on the activity and structural basis for selectivity of compounds for CDK6. While demonstrating good potency and modest selectivity, the compound C16, which showed significantly high activity of 5.5607 µM and binding energy value of -9.0 Kcal/mol, was used as template for compounds design to generate 10 novel series of 1,3,4-thiadiazole analogues containing benzisoselenazolone scaffolds, with significant pharmacological activity and better selectivity for CDK6. By our rationale, four of the designed compounds (C16b, C16h, C16i, and C16j) with activity values of 6.2584 µM, 6.7812 µM, 6.4717 µM, and 6.2666 µM respectively, and binding affinities of -10.0 kcal/mol, -9.9 kcal/mol, -9.9 kcal/mol, and -9.9 kcal/mol respectively, may emerge as therapeutic options for breast cancer treatment after extensive in vitro and in vivo studies.Communicated by Ramaswamy H. Sarma.

Synthesis and biological evaluation of novel 1,3,4-thiadiazole derivatives as possible anticancer agents

The synthesis of new N-(5-substituted-1,3,4-thiadiazol-2-yl)-2-[(5-(substituted amino)-1,3,4-thiadiazol-2-yl)thio]acetamide derivatives and investigation of their anticancer activities were the aims of this work. All the new compounds' structures were elucidated by elemental analyses, IR, 1H NMR, 13C NMR and MS spectral data. Anticancer activity studies of the compounds were evaluated against MCF-7 and A549 tumor cell lines. In addition, with the purpose of determining the selectivity of cytotoxic activities, the most active compound was screened against a noncancer NIH3T3 cell line (mouse embryonic fibroblast cells). Among the tested compounds, compound 4y (N-(5-ethyl-1,3,4-thiadiazol-2-yl)-2-((5-(p-tolylamino)-1,3,4-thiadiazol-2-yl)thio)acetamide), showed promising cytotoxic activity against MCF7 cancer cell with an IC 50value of 0.084 ± 0.020 mmol L-1 and against A549 cancer cell with IC 50 value of 0.034 ± 0.008 mmol L-1, compared with cisplatin. The aromatase inhibitory activity was evaluated for compound 4y on MCF-7 cell line showing promising activity with IC50 of 0.062 ± 0.004 mmol L-1.

DFT Study on the Electronic Properties, Spectroscopic Profile, and Biological Activity of 2-Amino-5-trifluoromethyl-1,3,4-thiadiazole with Anticancer Properties

Extensive investigation on the molecular and electronic structure of 2-amino-5-trifluoromethyl-1,3,4-thiadiazole in the ground state and in the first excited state has been performed. The energy barrier corresponding to the conversion between imino and amino tautomers has been calculated, which indicates the existence of amino tautomer in solid state for the title compound. The FT-Raman and FT-IR spectra were recorded and compared with theoretical vibrational wavenumbers, and a good coherence has been observed. The MESP map, dipole moment, polarizability, and hyperpolarizability have been calculated to comprehend the properties of the title molecule. High polarizability value estimation of the title compound may enhance its bioactivity. Natural bonding orbital analysis has been done on monomer and dimer to investigate the charge delocalization and strength of hydrogen bonding, respectively. Strong hydrogen bonding interaction energies of 17.09/17.49 kcal mol^-1 have been calculated at the B3LYP/M06-2X functional. The UV-vis spectrum was recorded and related to the theoretical spectrum. The title compound was biologically examined for anticancer activity by studying the cytotoxic performance against two human cancer cell lines (A549 and HeLa) along with the molecular docking simulation. Both molecular docking and cytotoxic performance against cancer cell lines show positive outcomes, and the title compound appears to be a promising anticancer agent.

Design and Synthesis of Small Molecules as Potent Staphylococcus aureus Sortase A Inhibitors

The widespread and uncontrollable emergence of antibiotic-resistant bacteria, especially methicillin-resistant Staphylococcus aureus, has promoted a wave of efforts to discover a new generation of antibiotics that prevent or treat bacterial infections neither as bactericides nor bacteriostats. Due to its crucial role in virulence and its nonessentiality in bacterial survival, sortase A has been considered as a great target for new antibiotics. Sortase A inhibitors have emerged as promising alternative antivirulence agents against bacteria. Herein, the structural and preparative aspects of some small synthetic organic compounds that block the pathogenic action of sortase A have been described.

Novel 1,2,4-triazole derivatives as apoptotic inducers targeting p53: Synthesis and antiproliferative activity

A series of novel thiazolo[3,2-b][1,2,4]-triazoles 3a-n has been synthesized and evaluated in vitro as potential antiproliferative. Compounds 3b-d exhibited significant antiproliferative activity. Compound 3b was the most potent with Mean GI₅₀ 1.37 µM comparing to doxorubicin (GI₅₀ 1.13 µM). The transcription effects of 3b, 3c and 3d on the p53 were assessed and compared with the reference doxorubicin. The results revealed an increase of 15-27 in p53 level compared to the test cells and that p53 protein level of 3b, 3c and 3d was significantly inductive (1419, 571 and 787 pg/mL, respectively) in relation to doxorubicin (1263 pg/mL). The docking study of the new compounds 3a-n revealed high binding scores for the new compounds toward p53 binding domain in MDM2. The docking analyses revealed the highest affinities for compounds 3b-d which induced p53 activity in MCF-7 cancer cells. Compound 3b which exhibited the highest antiproliferative activity and induced the highest increase in p53 level in MCF-7 cells showed also the highest affinity to MDM2.

Investigation of antioxidant and anti-nociceptive potential of isoxazolone, pyrazolone derivatives, and their molecular docking studies

A series of new isoxazolone (3a-d) and pyrazolone (4a-d) derivatives were synthesized and assessed for their antioxidant and analgesic activity. Among synthesized compounds, 3b and 4b having nitro (NO₂ ) group show high analgesic activity at a dose of 6 mg/kg. Analgesic activity was further proceeded to explore the contribution of opioidergic mechanisms in the mediation of analgesic effects. Animals were administered with naloxone, a nonselective opioid inverse agonist, at the dose of 0.5 mg/kg. The results obtained suggested that the analgesic effects of the synthesized compounds were not reversed by naloxone, specifying that the compounds 3b and 4b do not follow the opioidergic pathway in order to relieve pain in animal models. Further, the binding interactions of compounds 3b and 4b were analyzed by docking them against nonopioid receptors COX-1 (3N8X) and COX-2 (3LN1). The results demonstrate the analgesic potential of isoxazolone and pyrazolone derivatives, especially compounds 3b and 4b can be considered promising lead molecules for further investigation and development into potent analgesic drugs. In addition, the antioxidant potential of compounds was also found to be related to better analgesic activity, thus providing an insight into the role of oxidative stress in the mediation of analgesia.

Design, Synthesis, and Biological Evaluation of 1,2,4-Thiadiazole-1,2,4-Triazole Derivatives Bearing Amide Functionality as Anticancer Agents

A novel library of amide functionality having 1,2,4-thiadiazole-1,2,4-triazole (8a–j) analogs was designed, synthesized, and structures were characterized by ¹H NMR, ¹³C NMR, and mass (ESI–MS) spectral data. Further, all compounds were evaluated for their anticancer activities against four different cancer cell lines including breast cancer (MCF-7, MDA MB-231), lung cancer (A549), and prostate cancer (DU-145) by MTT reduction assay method, and etoposide acts as a standard drug. The results confirmed that majority of the synthesized compounds showed moderate to potent anticancer activities aligned with four cell lines. Among the synthesized compounds, 8b, 8c, 8d, 8e, 8g and 8i displayed more potent activity along with inhibitory concentration values ranging from 0.10 ± 0.084 to 11.5 ± 6.49 µM than the standard IC₅₀ values, which ranges from 1.91 ± 0.84 to 3.08 ± 0.135 µM, respectively.

Design, synthesis and biological evaluation of benzoxazolinone-containing 1,3,4-thiadiazoles as TNF-α inhibitors

A library of nineteen benzoxazolinone-based 1,3,4-thiadiazoles has been synthesized and screened for their anti-inflammatory activity. The compound 1f exhibited a potent anti-inflammatory activity with an inhibition of 65.83% and 32.50% after 3 h and 5 h respectively. It also exhibited a significant in vitro (p < 0.01), TNF- α inhibitory activity with 51.44 % inhibition. The compound 1f showed hydrogen bonding with GLN 61 and interactions with TYR 119, TYR 151 and GLY 121. The histopathology report showed that none of the compounds caused gastric ulceration. The results from the in vivo & in vitro antiinflammatory activity along with In Silico studies exhibit that benzoxazolinone-based 1,3,4-thiadiazoles may be used in the future development of anti-inflammatory drugs.

Design, Synthesis, and Molecular Docking Study of Novel Heterocycles Incorporating 1,3,4-Thiadiazole Moiety as Potential Antimicrobial and Anticancer Agents

A new series of 5-(3,5-dinitrophenyl)-1,3,4-thiadiazole derivatives were prepared and evaluated for their in vitro antimicrobial, antitumor, and DHFR inhibition activity. Compounds 9, 10, 13, and 16 showed strong and broad-spectrum antimicrobial activity comparable to Amoxicillin and Fluconazole as positive antibiotic and antifungal controls, respectively. Compounds 6, 14, and 15 exhibited antitumor activity against four human cancer cell lines, CCRF-CEM leukemia, HCT-15 colon, PC-3 prostate, and UACC-257 melanoma cell lines using Doxorubicin as a reference drug. Compounds 10, 13, 14, and 15 proved to be the most active DHFR inhibitors with an IC₅₀ range of 0.04 ± 0.82–1.00 ± 0.85 µM, in comparison with Methotrexate (IC₅₀ = 0.14 ± 1.38 µM). The highly potent DHFR inhibitors shared a similar molecular docking mode and made a critical hydrogen bond and arene‒arene interactions via Ser59 and Phe31 amino acid residues, respectively.

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.

5-(Thiophen-2-yl)-1,3,4-thiadiazole derivatives: synthesis, molecular docking and in vitro cytotoxicity evaluation as potential anticancer agents

Background

Nowadays, cancer is an important public health problem in all countries. Limitations of current chemotherapy for neoplastic diseases such as severe adverse reactions and tumor resistance to the chemotherapeutic drugs have been led to a temptation for focusing on the discovery and development of new compounds with potential anticancer activity. The importance of thiophene and thiadiazole rings as scaffolds present in a wide range of therapeutic agents has been well reported and has driven the synthesis of a large number of novel antitumor agents.

Methods

A series of new 1,3,4-thiadiazoles were synthesized by heterocyclization of N-(4-nitrophenyl)thiophene-2-carbohydrazonoyl chloride with a variety of hydrazine-carbodithioate derivatives. The mechanisms of these reactions were discussed and the structure of the new products was elucidated via spectral data and elemental analysis. All the new synthesized compounds were investigated for in vitro activities against human hepatocellular carcinoma (HepG-2) and human lung cancer (A-549) cell lines compared with cisplatin standard anticancer drug. Moreover, molecular docking using MOE 2014.09 software was also carried out for the high potent compound 20b with the binding site of dihydrofolate reductase (DHFR, PDB ID (3NU0)).

Results

The results showed that compound 20b has promising activities against HepG-2 and A-549 cell lines (IC50 value of 4.37±0.7 and 8.03±0.5 μM, respectively) and the results of molecular docking supported the biological activity with total binding energy equals −1.6 E (Kcal/mol).

Conclusion

Overall, we synthesized a new series of 1,3,4-thiadiazoles as potential antitumor agents against HepG-2 and A-549 cell lines.

Organoselenium group is critical for antioxidant activity of 7-chloro-4-phenylselenyl-quinoline

The quinolone compounds have been reported for many biological properties, especially as potent antioxidants. This study investigated the antioxidant effect of 7-chloro-4-phenylselenyl-quinoline (PSQ), a quinolone derivative with organoselenium group, against oxidative stress induced by sodium nitroprusside (SNP) in brains of mice. A second objective was to verify the importance of phenylselenyl group presents at position 4 of the quinoline structure to antioxidant effect of compound. So, it was compared the antioxidant effect of PSQ with a quinoline without organoseleniun group (7-chloroquinoline [QN]). Swiss mice were used and received SNP (0.335 μmol/site, intracerebroventricular) 30 min after treatment with PSQ or QN, at the doses of 50 mg/kg (intragastrically). After 1 h, animals were sacrificed and the brains were removed to biochemistry analysis. Thiobarbituric acid reactive species (TBARS), protein carbonyl (PC) and non-protein thiol (NPSH) levels, as well as catalase (CAT), glutathione S transferase (GST) and δ -aminolevulinic acid (δ-ALA-D) activities were determined. SNP increased TBARS and PC levels, and reduced the enzymatic (CAT and GST activity) and non-enzymatic (NPSH levels) antioxidant defenses and inhibited the δ-ALA-D activity. PSQ avoided the increase in the lipid peroxidation and PC levels, as well as the decrease in the NPSH levels, CAT, GST and δ-ALA-D activities QN partially avoided the increase in lipid peroxidation, but it not protected against alterations induced by SNP. In conclusion, phenylselenyl group present in quinoline structure is critical for antioxidant activity of PSQ.

Crystal structure and Hirshfeld surface analysis of ethyl 2-{[4-ethyl-5-(quinolin-8-yloxymeth-yl)-4H-1,2,4-triazol-3-yl]sulfan-yl}acetate

In the title compound, C18H20N4O3S, the 1,2,4-triazole ring is twisted with respect to the mean plane of quinoline moiety at 65.24 (4)°. In the crystal, mol-ecules are linked by weak C-H⋯O and C-H⋯N hydrogen bonds, forming the three-dimensional supra-molecular packing. π-π stacking between the quinoline ring systems of neighbouring mol-ecules is also observed, the centroid-to-centroid distance being 3.6169 (6) Å. Hirshfeld surface (HS) analyses were performed.

One Pot Single Step Synthesis and Biological Evaluation of Some Novel Bis(1,3,4-thiadiazole) Derivatives as Potential Cytotoxic Agents

A novel series of bis(1,3,4-thiadiazole) derivatives were synthesized in one step methodology with good yields by condensation reaction between bis-hydrazonoyl chloride 1 and various reagents. The structures of the prepared compounds were confirmed by spectral data (IR, NMR, and MS), and elemental analysis. The anticancer activity against human breast carcinoma (MCF-7) cancer cell lines was evaluated in MTT assay. The results revealed that the bis-thiadiazole derivatives 5c,d, 7b,c and 9c had higher antitumor activity than the standard drug Imatinib.

Novel Concept of Discrimination of 1,2,4-Triazole-3-thione and 3-Thiol Tautomers

Till now, three major spectroscopic techniques, fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, have been used for determination of thiol-thione tautomeric forms. Therefore, a novel analytical concept of discrimination of 1,2,4-triazole-3-thione and 3-thiol tautomers using two high-resolution mass spectrometers has been proposed. It comprises the high-performance liquid chromatography (HPLC) hyphenated with electrospray ionization (ESI)-time-of-flight mass spectrometry (ESI-TOF-MS, positive ion mode) followed by in-source collision-induced dissociation (CID) and low-energy CID-tandem mass spectrometry (MS/MS) analysis measured with a Quadruple-TOF-MS instrument. The HPLC column was a Zorbax Stable Bond RP-18 and a rapid isocratic elution. Selected 3-thione and 3-thiol tautomers were rapidly separated, within 6 min and detected both by in-source CID ESI(+)-TOF-MS and CID ESI(+)-QTOF-MS with a high mass accuracy and high sensitivity. The method limits of detection were of 2.8-5.6 pg/μl (at S/N 3:1) for ESI-TOF-MS and 0.25-0.55 pg/μl for ESI-QTOF-MS. The tautomeric form could be easily discriminated by both methods and by the different gas-phase fragmentation patterns. Differences and similarities between in-source CID MS and CID MS/MS spectra have also been presented. These findings were also supported by recorded FT-IR spectra in solid state. The developed methodology using both the high-resolution MS systems is considerably the most sensitive among the others.

Synthesis and evaluation of antibacterial and antioxidant activity of novel 2-phenyl-quinoline analogs derivatized at position 4 with aromatically substituted 4H-1,2,4-triazoles

A set of novel quinolone-triazole conjugates (12-31) were synthesized in three steps in good yields starting from 2-phenylquinoline-4-carboxylic acid. All the intermediates, as well as the final 1,2,4-triazolyl quinolines were fully characterized by their detailed spectral analysis utilizing different techniques such as IR, ¹H NMR, ¹³C NMR, and finally mass spectrometry. All the synthesized compounds were evaluated in vitro for their potential antibacterial activity and their preliminary safety profile was assessed through cytotoxicity assay. Additionally, six selected conjugates were evaluated for their antioxidative properties on the basis of density functional theory calculations, using radical scavenging assay (DPPH) and cellular antioxidant assay. The reported results encourage further investigation of selected compounds and are shading light on their potential pharmacological use.