Rational synthesis of 1,3,4-thiadiazole based ESIPT-fluorescent probe for detection of Cu2+ and H2S in herbs, wine and fruits

Here, 1,3,4-thiadiazole unit was employed as novel excited state intramolecular proton transfer (ESIPT) structure to prepare favorable fluorescent probe. High selectivity and rapid response to Cu2+ was obtained and the settling reaction was also used to recover ESIPT characteristics of probe to achieve sequential detection of H2S. Remarkable color change of solution from colorless to bright yellow and fluorescence emission from green to dark realized the visual detection of Cu2+ by naked eyes and transition of probe into portable fluorescent test strips. As expected, L-E could be utilized to quantitatively sense Cu2+ and H2S in different actual water and food samples including herbs, wine and fruits. The limits of detection for Cu2+ and H2S were as low as 34.5 nM and 38.6 nM. Also, probe L-E achieved real-time, portable, on-site quantitative detection of Cu2+ via a colorimeter and a smartphone platform with limit of detection to 90.3 nM.

Towards Covid-19 TMPRSS2 enzyme inhibitors and antimicrobial agents: Synthesis, antimicrobial potency, molecular docking, and drug-likeness prediction of thiadiazole-triazole hybrids

1,3,4-Thiadiazole analogues 3 and 4 were synthesised via the reaction of 1-(5-methyl-1-(5-(methylthio)-1,3,4-thiadiazol-2-yl)-1H-1,2,3-triazol-4-yl)ethan-1one 2 with vanillin or thiophene-2-carboxaldhyde, respectively through chalcone reaction. Compounds 3 and 4 were submitted to react with thiosemicarbazide affording 5-(4‑hydroxy-3-methoxyphenyl)-3-(5-methyl-1-(5-(methylthio)-1,3,4-thiadiazol-2-yl)-1H-1,2,3-triazol-4-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide (5) give 3-(5-methyl-1-(5-(methylthio)-1,3,4-thiadiazol-2-yl)-1H-1,2,3-triazol-4-yl)-5-(thiophen-2-yl)-4,5 dihydro-1H-pyrazole-1-carbothioamide (6), respectively. The letters were reacted with N-(4-chlorophenyl)-2-oxopropanehydrazonoyl chloride to give compounds 7 and 8. The chemical compositions of the novel compounds were affirmed by spectral and microanalytical data. Meanwhile, all the newly synthesized compounds have been screened for their ability to prevent the proliferation of different pathogens named Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, and Candida albicans in vitro. Additionally, the potency of the newly synthesized compounds to be anti-COVID-19 candidates was studied through a molecular docking study. The newly prepared molecules 2-8 were studied in silico against transmembrane serine protease 2 (TMPRSS2) to identify their potential therapeutic activity against Coronavirus. Moreover, the drug-likeness of the compounds was tested theoretically by ADMET studies. Compound 8 exhibited a better binding affinity (-9.1 kcal/mol) against the target enzyme TMPRSS2. Additionally, it respects Lipinski's rule of five and has acceptable ADMET properties, indicating that compound 8 could be interesting for the treatment of Covid-19.

Further Develop 1,3,4-Thiadiazole Based Probe to Effectively Detect 2,4,6-Trinitrophenol with the Help of DFT Calculations

Four fluorimetric probes had been developed to rapidly detect 2,4,6-trinitrophenol (TNP). They were designed and synthesized on the basis of 1,3,4-thiadiazole framework combining calculation with experiment. Among them, SK-1 displayed strong blue emission with fluorescence quantum yield as high as 63.6% in solution. Further evaluation demonstrated that SK-1 displays good selectivity and high sensitivity for rapid and visual detection of TNP. It brought significant changes in both colour and fluorescence emission spectrum. The detection limit was as low as 38 nM. Quenching mechanism was confirmed as photo-induced electron transfer (PET) by nuclear magnetic titration and DFT calculations. What's more, application in real water samples and solid phase paper tests illustrated the practical significance of detection of TNP in both vapor and solution.

Accurately selected 1,3,4-thiadiazole and coumarin unit to construct fluorescent probes that effectively detect 2,4,6-trinitrophenol

Two remarkablely fluorimetric probes were developed to rapidly detect 2,4,6-trinitrophenol (TNP). With the help of density functional theory (DFT) calculations, we confirmed that using 1,3,4-thiadiazole skeleton as recognition group and coumarin unit as fluorophore would show excellent application prospects in terms of TNP detection. The probes LK-1 and LK-2 displayed green and orange emission with fluorescence quenching yield as high as 83.7% and 75.1% in solution. Further evaluation demonstrated that they display outstanding selectivity and sensitivity for rapid and visual detection of TNP. Both fluorescent color and fluorescence emission spectrum had significant changes and these phenomena could easily observe via naked-eye and analytical instrument. The detection limits of them were 97 nM and 71 nM. What's more, application in real water samples and solid phase paper tests illustrated the practical significance of detection of TNP.

Synthesis and biological evaluation of isatin derivatives containing 1,3,4-thiadiazole as potent a-glucosidase inhibitors

A series of (Z)-3-(2-(1,3,4-thiadiazol-2-yl)hydrazono)-1-substituted indolin-2-ones derivatives (3a-3m) were designed and synthesized. All newly synthesized compounds were evaluated for their a-glucosidase inhibitory activity with resveratrol as positive control in vitro. Except for 3i and 3j, all of the compounds showed a potent inhibitory activity against a-glucosidase with IC₅₀ values in the range of 3.12 ± 1.25 to 45.95 ± 1.26 μM and the purity of these compounds was greater than 95%. The IC₅₀ values were being compared to the standard resveratrol (IC₅₀ = 22.00 ± 1.15 μM) and it was found that compounds 3b, 3d-3h were found to be more active than resveratrol. Specifically, (Z)-3-(2-(1,3,4-thiadiazol-2-yl)hydrazono)-1-(4-chlorobenzyl)indolin-2-one (3d) exhibited the most potent a-glucosidase inhibitory activity with IC₅₀ value of 3.12 ± 1.25 μM. The kinetic analysis revealed that compound (3d) is noncompetitive inhibitor. Structure activity relationship has been established for all compounds. Furthermore, the binding interactions of compound 3d with the active site of a-glucosidase were confirmed through molecular docking. This study has identified a new class of potent a-glucosidase inhibitors for further investigation.

Insight into dual fluorescence effects induced by molecular aggregation occurring in membrane model systems containing 1,3,4-thiadiazole derivatives

This work reports on biophysical insights into the excited state intramolecular proton transfer (ESIPT) processes taking place in three 1,3,4-thiadiazole derivatives that served as model compounds, on which electronic absorption, fluorescence, Fourier-transform infrared spectroscopy (FTIR), surface plasmon resonance (SPR) and electrochemical impedance spectroscopy (EIS) studies were performed. The fluorescence spectra recorded in various solvents revealed an interesting dual fluorescence effect. In molecules in their monomeric form, the effect is associated with the ESIPT phenomenon, and may be further enhanced by aggregation-related effects, such as aggregation-induced emissions. Other spectroscopic studies on the selected molecules in a liposomal medium as a model revealed that, in a biomimetic environment, they can exist in both monomeric and aggregated forms. In both cases, however, the effects observed are closely related to the lipid's main phase transition temperature and the structure of the molecule. Introduction of specific substituents to the phenyl moiety either allows or prevents proton transfer from occurring in the excited state. The hydrophobicity changes in a lipid environment may result in an emergence of specific molecular forms and therefore either facilitate or hinder ESIPT processes. SPR and EIS confirmed the significant hydrophobicity changes in the model lipid systems, while FTIR measurements revealed a notable influence of 1,3,4-thiadiazoles on the fluidity of liposomal membranes. The results obtained clearly show that the thiadiazole derivatives are very good model molecules for studying hydrophobic-hydrophilic environments, and particularly with polymers or liposomes used as drug delivery systems.

Multicomponent reaction for the synthesis of new 1,3,4-thiadiazole-thiazolidine-4-one molecular hybrids as promising antidiabetic agents through α-glucosidase and α-amylase inhibition

A simple and efficient protocol was developed to synthesize a new library of thiazolidine-4-one molecular hybrids (4a-n) via a one-pot multicomponent reaction involving 5-substituted phenyl-1,3,4-thiadiazol-2-amines, substituted benzaldehydes and 2-mercaptoacetic acid. The synthesized compounds were evaluated in vitro for their antidiabetic activities through α-glucosidase and α-amylase inhibition as well as their antioxidant and antimicrobial potentials. Compound 4e exhibited the most promising α-glucosidase and α-amylase inhibition with an IC₅₀ value of 2.59 μM, which is ~1.5- and 14-fold superior as compared to the standard inhibitor acarbose. Structure-activity relationship (SAR) analysis revealed that the nature and position of substituents on the phenyl rings had a significant effect on the inhibitory potency.

Design, microwave assisted synthesis, and molecular modeling study of some new 1,3,4-thiadiazole derivatives as potent anticancer agents and potential VEGFR-2 inhibitors

A green and efficient method was developed for the synthesis of 1,3,4-thiadiazole based compounds under microwave (MW) activation. The nucleophile N-(5-amino-1,3,4-thiadiazol-2-yl)thiophene-2-carboxamide (3) was synthesized and reacted with different carbon electrophilic reagents to afford thiadiazolo-pyrimidine or imidazolo-thiadiazoline derivatives (4-6 and 8), respectively. Furthermore, a one-pot reaction of 3 with p-chlorobenzaldehyde and different carbon electrophile/ or nucleophiles under microwave irradiation yields the cyclic thiadiazolo-pyrimidine derivatives 10-15. Additionally, nucleophilic substitution of aromatic amines and/or potassium salts of some heterocyclic compounds with chloroacetamido-thiadiazole 6 yields derivatives 16-20. All the new derivatives were synthesized by both conventional and MW irradiation methods. All the new 1,3,4-thiadiazole derivatives were evaluated against four cancer cell lines, HepG-2, MCF-7, HCT-116, and PC-3. The anti-proliferative activity of most of the synthesized compounds exhibited excellent broad-spectrum cytotoxic activity against the cancer cell lines with IC₅₀ values ranging from 3.97 to 9.62 μM. Moreover, the enzymatic assessment of five derivatives (2,4b, 6, 8, 9a) against VEGFR-2 tyrosine kinase showed significant inhibitory activities with IC₅₀ of 11.5, 8.2, 10.3, 10.5 and 9.4 nM respectively. Further studies revealed the ability of compound 9a to have a strong DNA-binding affinity of 36.06 μM via DNA/methyl green assay. Moreover, molecular docking study was carried out to reveal the binding interactions of compounds in the binding site of VEGFR-2 enzyme explaining the significant inhibitory activity of these derivatives. Finally, ADME/Tox studies was performed to predict the pharmacokinetics of the synthesized compounds.

2,5-Disubstituted furan derivatives containing 1,3,4-thiadiazole moiety as potent α-glucosidase and E. coli β-glucuronidase inhibitors

In this paper, the 2,5-disubstituted furan derivatives containing 1,3,4-thiadiazole were synthesized and screened for their inhibitory activity against α-glucosidase and β-glucuronidases to obtain potent α-glucosidase inhibitor 9 (IC₅₀ = 0.186 μM) and E. coli β-glucuronidase inhibitor 26 (IC₅₀ = 0.082 μM), respectively. The mechanisms of the compounds were studied. The kinetic study revealed that compound 9 is a competitive inhibitor against α-glucosidase (Ki = 0.05 ± 0.003 μM) and molecular docking simulation showed several key interactions between 9 and the target including hydrogen bond and p-π stacking interaction. Derivative 26 (Ki = 0.06 ± 0.005 μM) displayed uncompetitive inhibition behavior against EcGUS. Furthermore, the result of docking revealed the furan ring of 26 may be a key moiety in obstructing the active domain of EcGUS. In addition, compound 15 exhibited significant inhibitory activity against these two enzymes, with potential therapeutic effects against diabetes and against CPT-11-induced diarrhea. At the same time, their low toxicity against normal liver tissue LO2 cells lays the foundation for in vivo studies and the development of bifunctional drug.

Biological evaluation and molecular docking of novel 1,3,4-thiadiazole-resorcinol conjugates as multifunctional cholinesterases inhibitors

Two series of novel 1,3,4-thiadiazole-resorcinol conjugates were efficiently synthesized and evaluated as cholinesterases inhibitors. N-Butyl- and N-chlorophenyl-5-amino-1,3,4-thiadiazol-2-yl)benzene-1,3-diols were identified as the most promising compounds of low nanomolar activity against AChE (IC₅₀ = 29-76 nM) and moderate activity against BuChE. The inhibition mechanism studies proved that the compounds are mixed type inhibitors. The docking simulations showed great affinity of the compounds for both enzymes. The modelled amine derivatives exhibited a similar arrangement in the catalytic anionic site of AChE similar to that of tacrine. The thiadiazole ring interacted with Trp84 and the phenyl groups created π-π stacking interactions with the residue - Phe330. The compounds showed better inhibition of the in vitro self-induced Aβ (1-42) aggregation than that compared with curcumin as well as antioxidant properties similar to those of quercetin. They exhibited metal ion chelating properties, acceptable cytotoxicity in vitro and favourable ADMET profile determined in silico.

Synthesis and biological assessment of ciprofloxacin-derived 1,3,4-thiadiazoles as anticancer agents

The quinolone-3-carboxylic acid scaffold is essential structure for antibacterial activity of fluoroquinolones such as ciprofloxacin. Modification of 3-carboxylic functionality in this structure can be used for switching its activity from antibacterial to anticancer. Accordingly, a series of C-3 modified ciprofloxacin derivatives containing N-(5-(benzylthio)-1,3,4-thiadiazol-2-yl)-carboxamide moiety was synthesized as novel anticancer agents. Most of compounds showed significant activity against MCF-7, A549 and SKOV-3 cancer cells in the MTT assay. In particular, compounds 13a-e and 13g were found to be as potent as standard drug doxorubicin against MCF-7 cell line (IC₅₀s = 3.26-3.90 µM). Furthermore, the 4-fluorobenzyl derivatives 13h and 14b with IC₅₀ values of 3.58 and 2.79 µM exhibited the highest activity against SKOV-3 and A549 cells, being as potent as doxorubicin. Two promising compounds 13e and 13g were further tested for their apoptosis inducing activity and cell cycle arrest. Both compounds could significantly induce apoptosis in MCF-7 cells, while compound 13e was more potent apoptosis inducer resulting in an 18-fold increase in the proportion of apoptotic cells at the IC₅₀ concentration in MCF-7 cells. The cell cycle analysis revealed that compounds 13e and 13g could increase cell portions in the sub-G1 phase, inducing oligonucleosomal DNA fragmentation and apoptosis confirmed by comet assay.

Design, synthesis and evaluation of novel thienopyrimidine-based agents bearing diaryl urea functionality as potential inhibitors of angiogenesis

Inhibition of angiogenesis is a promising strategy for the treatment of cancer. Herein, we describe the design and synthesis of thieno[2,3-d]pyrimidine-1,3,4-thiadiazole-aryl urea derivatives 11a-m to evaluate their efficacy in the chick chorioallantoic membrane (CAM) assay. Among target agents, 11i had a considerable activity against prostate cancer cell line, PC3 (IC₅₀ = 3.6 μM). Moreover, induction of apoptosis, good inhibitory activity against the growth of capillary blood vessels, and inhibition of VEGFR-2 phosphorylation were noticeable parameters which convinced us that 11i could be considered as a promising candidate for the discovery of novel drugs to treat tumors, particularly prostate cancer.

Novel vanillin derivatives containing a 1,3,4-thiadiazole moiety as potential antibacterial agents

In this study, thirty-four novel vanillin derivatives containing a 1,3,4-thiadiazole structure were obtained and their antibacterial activities were evaluated. The results indicate that most of the title compounds displayed inhibitory effects on Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc). Among them, compound 29 exhibited excellent antibacterial activities against Xoo and Xoc in vitro, with the EC₅₀ values of 3.14 and 8.83 μg/mL, respectively, much superior to thiodiazole copper (87.03 and 108.99 μg/mL) and bismerthiazol (67.64 and 79.26 μg/mL). Under greenhouse condition, the protective efficiency of compound 29 against rice bacterial leaf blight was 49.34%, and curative efficiency was 40.96%. In addition, compound 29 can reduce the exopolysaccharides production of Xoo, increase the permeability of cell membrane and damage cell membrane.

Design, synthesis and antimicrobial activities of novel 1,3,5-thiadiazine-2-thione derivatives containing a 1,3,4-thiadiazole group

A series of novel 1,3,5-thiadiazine-2-thione derivatives containing a 1,3,4-thiadiazole group was designed and synthesized. The structures of all the compounds were well characterized using ¹H NMR, ¹³C NMR and high-resolution mass spectrometer, and further confirmed by the X-ray diffraction analysis of 8d. The antimicrobial activities of all the target compounds against Xanthomonas oryzae pv. oryzicola, X. oryzae pv. oryzae, Rhizoctonia solani and Fusarium graminearum were evaluated. The in vitro antimicrobial bioassays indicated that some title compounds exhibited noteworthy antimicrobial effects against the above strains. Notably, the compound N-(5-(ethylthio)-1,3,4-thiadiazol-2-yl)-2-(5-methyl-6-thioxo-1,3,5-thiadiazinan-3-yl)acetamide (8a) displayed obvious antibacterial effects against X. oryzae pv. oryzicola and X. oryzae pv. oryzae at 100 μg/mL with the inhibition rates of 30% and 56%, respectively, which was better than the commercial bactericide thiodiazole-copper. In addition, the anti-R. solani EC₅₀ value of 8a was 33.70 μg/mL, which was more effective than that of the commercial fungicide hymexazol (67.10 μg/mL). It was found that the substitutes in the 1,3,5-thiadiazine-2-thione and the 1,3,4-thiadiazole rings played a vital role in the antimicrobial activities of the title compounds. More active title compounds against phytopathogenic microorganisms might be obtained via further structural modification.

Discovery of Novel 2-Amino-5-(Substituted)-1,3,4-Thiadiazole Derivatives: New Utilities for Colon Cancer Treatment

BACKGROUND

Colon cancer is one of the most widespread disease, the mortality rate is high due to cancer metastasis and the development of drug resistance. In this regards, new chemotherapeutic agents with specific mechanisms of action and significant effect on patient's survival are the new era for the colon cancer drug development.

OBJECTIVE

The main objective of present study was to design, synthesize of a novel series of 1,3,4-thiadiazole derivatives (VR1 to VR35) and screen them against HT-29 human colon cancer cell line.

METHOD

Newly 1,3,4-thiadiazole scaffold were designed, synthesized and further, characterized by FTIR, NMR (1H and 13C), MS and elemental analyses. Before the synthesis, molecular dynamic simulation and ADME studies were performed to find out the most potent lead compounds. Later, SRB assay using HT-29 cells and ELISA assays were performed to explore activity and molecular targets of VR24 and VR27 and find out whether in silico data had a similar pattern in the molecular level.

RESULTS

The results of docking study revealed that both VR24 and VR27 had interaction energy >-5 kcal/mol with various assigned molecular targets and the ligand-protein complexes were found to be stable with IL-6. The computational analysis of molecules showed good ADMET profiling. Later, the in vitro anticancer study was conducted where VR24 and VR27 were found to be active against HT-29 cells (GI50<10 µM). Finally, ELISA assays revealed that both the compounds had higher inhibition properties to various biomarker of colon cancer like IL-6 and COX-2.

CONCLUSION

Collectively, these result suggested that VR24 and VR27 inhibited the assigned molecular targets, imparting their ameliorative effects against colon cancer. Due to these encouraging results, we concluded that both VR24 and VR27 may be effective against colon cancer therapy in future.

Novel amide derivatives containing 1,3,4-thiadiazole moiety: Design, synthesis, nematocidal and antibacterial activities

A series of novel amide derivatives containing 1,3,4-thiadiazole moiety were synthesized and their bioactivities were evaluated. The compound 34 exhibited good nematocidal activities against Meloidogyne incognita in vitro and in vivo, the LC₅₀ value and control effect were 6.5 mg/L and 83.3%, respectively. Meanwhile, it exhibited exciting antibacterial activities against Xanthomonas oryzae pv. oryzae, Xanthomonas campestris pv. citri, and Ralstonia solanacearum, the EC₅₀ values were 0.4, 6.7 and 5.1 mg/L, respectively, which were better than positive controls. The curative and protection activities under the greenhouse conditions of compound 34 against rice bacterial blight were 47.9 and 55.8%, respectively. The structure-activity relationship were analyzed in detail.

Synthesis and Docking Study of Novel 4-Thiazolidinone Derivatives as Anti-Gram-positive and Anti-H. pylori Agents

BACKGROUND

Bacterial resistance to the available antibiotics is a life threatening issue and researchers are trying to find new drugs to overcome this problem. Amongst the different structural classes, thiazolidinone-4-one, as a new effective pharmacophore against various bacteria, has been introduced.

OBJECTIVE

A new series of 2-(5-(5-nitrothiophene-2-yl)-1,3,4-thiadiazole-2-ylimino)-5-arylidenethiazolidin- 4-one derivatives were designed and synthesized as new antibacterial agents.

METHOD

Target compounds were synthesized during 5 steps and their in vitro antibacterial and anti-H. pylori activities were evaluated. The interaction of the most active derivatives with the probable targets was assessed by Auto Dock 4.2 Program.

RESULTS

The results showed that the most potent compounds, 18, 22 and 23, displayed antibacterial activity versus S.aureus, S.epidermidis, B.cereus and B.subtilis (MIC, 1.56-12.5 µg/mL) and none of the derivatives were active on tested Gram-negative bacteria. Compound 12 in all considered doses and compounds 10, and 27 had strong anti-H. pylori activity (inhibition zone >20 mm) in 25 μg disc. Docking studies determined suitable interactions and affinity of potent compounds with bacterial MUR B and H. pylori urease enzymes.

CONCLUSION

According to the results most of the derivatives are effective anti-bacterial agents and docking evaluation confirmed their possible mechanisms of actions as MURB and Urease inhibitors.

Pyridine and nitro-phenyl linked 1,3,4-thiadiazoles as MDR-TB inhibitors

In the present study, a series of substituted 1,3,4-thiadiazole derivatives 4(a-o), 5(a-m) and 6(a-j) were synthesized and characterized by IR, ¹H NMR, ¹³C NMR and mass spectroscopic technique. The synthesized compounds were evaluated for their in vitro anti-mycobacterial activity against the Mycobacterium tuberculosis H37Rv and resistance MDR-TB strain. Among the compounds tested N-(5-(4-nitrophenyl)-1,3,4-thiadiazol-2-yl)furan-2-carboxamide (4h) showed significant inhibitory activity with MIC of 9.87 μM (H37Rv strain) and 9.87 μM (MDR-TB strain) compared to isoniazide [MIC of 3.64 μM (H37Rv) and >200 μM (MDR-TB strain)] and rifampin [MIC of 0.152 μM (H37Rv) and 128 μM (MDR-TB strain)]. In addition, these compounds have also been assessed for their cyto-toxicity to a mammalian Vero cell line using the MTT assay. The result shows that these compounds exhibit anti-tubercular activity at non-cytototoxic concentrations.

Spectroscopic and Theoretical Studies of Fluorescence Effects in 2-Methylamino-5-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole Induced by Molecular Aggregation

The article presents the results of fluorescence analyses of 2-methylamino-5-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole (MDFT) in an aqueous environment. MDFT dissolved in aqueous solutions with a pH value in the range from 1 to 4.5 yielded an interesting effect of two clearly separated fluorescence emissions. In turn, a single fluorescence was observed in MDFT dissolved in water solutions with a pH value from 4.5 to 12. As it was suggested in the previous investigations of other 1,3,4-thiadiazole compounds, these effects may be associated with conformational changes in the structure of the analysed molecule accompanied by aggregation effects. Crystallographic data showed that the effect of the two separated fluorescence emissions occurred in a conformation with the –OH group in the resorcyl ring bound on the side of the sulphur atom from the 1,3,4-thiadiazole ring. The hypothesis of aggregation as the mechanism involved in the change in the spectral properties at low pH is supported by the results of (Time-Dependent) Density Functional Theory calculations. The possibility of rapid analysis of conformational changes with the fluorescence spectroscopy technique may be rather important outcome obtained from the spectroscopic studies presented in this article. Additionally, the presented results seem to be highly important as they can be easily observed in solutions and biologically important samples.

Synthesis and biological activities of novel 1,3,4-thiadiazole-containing pyrazole oxime derivatives

A new library of 1,3,4-thiadiazole-containing pyrazole oximes was designed and synthesized. Their acaricidal and insecticidal activities were evaluated. Bioassay results indicated that some target compounds exhibited good acaricidal and insecticidal properties. Especially, compound 8m had 80% acaricidal activity against Tetranychus cinnabarinus at the concentration of 50μg/mL, compound 8f displayed 100% insecticidal activities against Aphis craccivora at the concentration of 50μg/mL, compounds 8r and 8w showed 100% insecticidal activities against Plutella xylostella at the concentration of 50μg/mL. Furthermore, compounds 8r (LC50=19.61μg/mL) and 8w (LC50=9.78μg/mL) possessed comparable or even better insecticidal activities than the control Pyridalyl (LC50=17.40μg/mL) against P. xylostella.

Synthesis and multi-spectroscopic DNA binding study of 1,3,4-oxadiazole and 1,3,4-thiadiazole derivatives of fatty acid

A facile and convenient synthesis of a series of fatty acid derivatives of 1,3,4-oxadiazole and 1,3,4-thiadiazole has been described. The key step of this protocol is the cyclization of acyl thiosemicarbazides via iodobenzene diacetate and methanesulfonic acid under mild conditions. The newly synthesized compounds were characterized by FT-IR, (1)HNMR, (13)CNMR and mass spectral study. The binding affinity of 5-(pentadecyl)-N-propenyl-1,3,4-oxadiazol-2-amine (3a) and 5-(heptadecyl)-2-amino-1,3,4-thiadiazole (6a) with CT-DNA has been evaluated by UV, fluorescence, Circular Dichroism (CD) and thermal denaturation studies. It has been found that these small and planer heteroaromatic compounds are capable of binding to the minor groove region of DNA.

Design of new phenothiazine-thiadiazole hybrids via molecular hybridization approach for the development of potent antitubercular agents

A new library of phenothiazine and 1,3,4-thiadiazole hybrid derivatives (5a-u) was designed based on the molecular hybridization approach and the molecules were synthesized in excellent yields using a facile single-step chloro-amine coupling reaction between 2-chloro-1-(10H-phenothiazin-10-yl)ethanones and 2-amino-5-subsituted-1,3,4-thiadiazoles. The compounds were evaluated for their in vitro inhibition activity against Mycobacterium tuberculosis H37Rv (MTB). Compounds 5 g and 5 n were emerged as the most active compounds of the series with MIC of 0.8 μg/mL (∼ 1.9 μM). Also, compounds 5a, 5b, 5c, 5e, 5l and 5m (MIC = 1.6 μg/mL), and compounds 5j, 5k and 5o (MIC = 3.125 μg/mL) showed significant inhibition activity. The structure-activity relationship demonstrated that an alkyl (methyl/n-propyl) or substituted (4-methyl/4-Cl/4-F) phenyl groups on the 1,3,4-thiadiazole ring enhance the inhibition activity of the compounds. The cytotoxicity study revealed that none of the active molecules are toxic to a normal Vero cell line thus proving the lack of general cellular toxicity. Further, the active molecules were subjected to molecular docking studies with target enzymes InhA and CYP121.

Synthesis and antiviral activity of some new bis-1,3-thiazole derivatives

Treatment of 3-phenyl-1,3-thiazolidin-4-one derivative 1 with phenylisothiocyanate in DMF, in the presence of potassium hydroxide, at room temperature gave the non-isolable potassium salt 2. The in-situ reaction of 2 with differently substituted N-aryl hydrazonoyl chlorides 3, 7a-d and 14a-d afforded the corresponding 2-(pyrazolyl)thiazolylimino-5-(thiadiazolylidene)thiazolidin-4-one derivatives 6, 10a-d and 17a-d, respectively. Reaction of 2 with further α-haloketones yielded the 4-(pyrazolyl)thiazolylimino-bis-thiazolidine derivatives 22, 25 and 26. Single crystal X-ray analysis was used in structure elucidation of the products. The in-vitro antiviral screening against four viruses (Poliovirus, Influenza A (H1N1) virus, Hepatitis B virus and Hepatitis C virus) for the obtained compounds was examined. Structure activity relationship (SAR) was also studied. The goal of the work was achieved in discovering a very active compound 10a as anti HCV agent (EC50 0.56 μM).

Efficient access to novel androsteno-17-(1',3',4')-oxadiazoles and 17β-(1',3',4')-thiadiazoles via N-substituted hydrazone and N,N'-disubstituted hydrazine intermediates, and their pharmacological evaluation in vitro

A series of novel 17-exo-oxadiazoles and -thiadiazoles in the Δ(5) androstene series were efficiently synthesized from pregnenolone acetate and pregnadienolone acetate via multistep pathways. 17β-(1',3',4')-Oxadiazoles were obtained in high yields by the phenyliodonium diacetate-induced oxidative ring closure of semicarbazone and N-acylhydrazones derived from 3β-acetoxy- and 3β-hydroxyandrost-5-ene-17β-carbaldehydes. For the synthesis of analogous Δ(16)-17-oxadiazolyl derivatives, N,N'-disubstituted hydrazine intermediates were prepared from 3β-acetoxyandrosta-5,16-diene-17-carboxylic acid, which then underwent cyclodehydration in the presence of POCl3. The cyclization of steroidal N,N'-diacylhydrazines containing a saturated ring D with the Lawesson reagent afforded 17β-(1',3',4')-thiadiazoles in good yields. Most of the products were subjected to deacetylation in basic media in order to enlarge the compound library available for pharmacological studies. All of these derivatives were screened in vitro for their antiproliferative effects against four malignant human adherent cell lines (HeLa, A2780, MCF7 and A431) by means of the MTT assay. The 3β-hydroxy derivatives of the newly-synthesized 17-exo-heterocycles were tested in vitro to investigate their inhibitory effects on rat testicular C17,20-lyase. One of the 1,3,4-oxadiazolyl derivatives proved to exert noteworthy enzyme-inhibitory action, with an IC50 (0.065 μM) of the same order of magnitude as that of abiraterone.

Synthesis and evaluation of benzosuberone embedded with 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole moieties as new potential anti proliferative agents

As an aspect of our ongoing research in search of new anti proliferative agents, a series of novel analogs of benzosuberone embedded with 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole moieties were synthesized in excellent yields (82-93%). All the newly synthesized compounds were characterized by (1)H NMR, (13)C NMR, ESI/LC-MS, HRMS and evaluated for their in vitro anti proliferative activity against four human cancer cell lines (cervical, breast, pancreatic and alveolar). Among the synthesized compounds, 4b, 6a, 7d and 7l showed potent anti proliferative activity with GI50 values range of 0.079-0.957μM against four human cancer cell lines. However, it was revealed that the compound 7d have shown very close GI50 value 0.079μM as compared with positive control of colchicine against cervical cancer cell line.

Improved antiproliferative activity of 1,3,4-thiadiazole-containing histone deacetylase (HDAC) inhibitors by introduction of the heteroaromatic surface recognition motif

A series of 1,3,4-thiadiazole-containing hydroxamic acids, in accord with the common pharmacophore of histone deacetylase (HDAC) inhibitors (a Zn(2+) binding moiety-a linker-a surface recognition motif), was identified as submicromolar HDAC inhibitors by our group. In this study, we continued our efforts to develop 1,3,4-thiadiazole bearing hydroxamate analogues by modifying the surface recognition motif. We found that 1,3,4-thiadiazoles having a heteroaromatic substituent showed better HDAC inhibitory activity in enzymatic assay and higher antiproliferative potency in cellular assay compared to SAHA.

Synthesis of 5-arylidine amino-1,3,4-thiadiazol-2-[(N-substituted benzyol)]sulphonamides endowed with potent antioxidants and anticancer activity induces growth inhibition in HEK293, BT474 and NCI-H226 cells

Abstract

A series of imines 5-amino-1,3,4-thiadiazol-2-[(N-substituted benzyol)]sulphonamide derivatives were synthesized from various aromatic aldehydes and substituted with benzoyl acetazolamides under different reaction conditions and were evaluated for their antioxidant and free radical scavenging, antimitotic activity by Allium cepa meristem root model and cytotoxicity activity against HEK 293 (human epidermal kidney cell line), BT474 (breast cancer cell line) and NCI-H226 (lung cancer cell line) by MTT assay. Some of the synthesized compounds showed moderately potent cytotoxicity compared to indisulam.

Graphical abstract

A series of imines 5-amino-1,3,4-thiadiazol-2-[(N-substituted benzyol)]sulphonamide derivatives (9a–j); 5-amino-1,3,4-thiadiazol-2-[N-(substituted benzoyl)]sulphonamide (4a–g); 5-(4-acetamido phenyl sulphonamido)-1,3,4-thiadiazol-2-[N-(substituted benzoyl)]sulphonamide (6a–g); and 5-(4-amino phenyl sulphonamido)-1,3,4-thiadiazol-2-[N-(substituted benzoyl)]sulphonamide (7a–g) were synthesized from acetazolamide and were investigated for the in vitro anticancer by MTT assay, free radical scavenging and antimitotic activity by Allium cepa root meristem model. Experimental observations indicate that synthesized compounds were moderately potent anticancer agents.

Synthesis of some new pyrazole-based 1,3-thiazoles and 1,3,4-thiadiazoles as anticancer agents

N-(4-(Pyrazol-4-yl)thiazol-2-yl)-N'-phenylthiourea derivative 2 was synthesized and then treated with variety of hydrazonoyl chlorides under basic condition at reflux to afford the corresponding 2-(4-(pyrazol-4-yl)thiazol-2-ylimino)-1,3,4-thiadiazole derivatives 6, 10a-e and 17a-e. Reaction of 2 with ethyl chloroacetate and with 3-chloro-2,4-pentanedione gave the thiazolidin-4-one 22 and 1,3-thiazole 25 derivatives, respectively. Condensation of thiazolidin-4-one 22 with aldehydes gave their 5-arylidene derivatives 23a-f. Most of the synthesized compounds were tested for anticancer activity against human hepatocelluar carcinoma HepG2, human breast cancer MCF-7 and human lung cancer A549. Their SAR was studied and variously affected by the electronic factor of electron donating and withdrawing groups. Many of the tested compounds showed moderate to high anticancer activity.

Synthesis and In-vitro Cytotoxicity Assessment of N-(5-(Benzylthio)-1,3,4- thiadiazol-2-yl)-2-(4-(trifluoromethyl)phenyl)acetamide with Potential Anticancer Activity

Cancer is the second leading cause of death in the world. Despite advances in the diagnosis and treatment, overall survival of patients still remains poor. Hence, there is an urgent need for development of new anticancer agents. Considering promising biological activity of 1,3,4-thiadiazole derivatives, in the present study, synthesis and cytotoxicity assessment of new derivatives of this ring was done. All synthesized compounds were characterized by NMR, IR and MS spectroscopic methods. Obtained data from MTT assay showed that all compounds 3a- 3l had better anticancer activity against MDA(breast cancer) compared to PC3(prostate cancer) and U87(Glioblastoma). Compound 3 g with m-OCH3 moiety on the phenyl ring was the most potent one in this series with IC50 = 9 μM against MDA breast cell line in comparison with imatinib (IC50 = 20 μM) as reference drug.