Exploring of antioxidant and antibacterial properties of novel 1,3,4-thiadiazole derivatives: Facile synthesis, structural elucidation and DFT approach to antioxidant characteristics

Advancing drug discovery: Thiadiazole derivatives as multifaceted agents in medicinal chemistry and pharmacology

In this dispensation of rapid scientific and technological advancements, significant efforts are being made to curb health-related diseases. Research discoveries have highlighted the value of heterocyclic compounds, particularly thiadiazole derivatives, due to their diverse pharmacological activities. These compounds play a crucial role in therapeutic medicine and the development of effective drugs. Thiadiazoles are five-membered heterocyclic compounds consisting of one sulfur and two nitrogen atoms. This review explores advanced synthesis techniques, including the use of heterogeneous catalysts, microwave-assisted methods, ultrasound-assisted synthesis, solvent-free processes, multicomponent reactions, copper-catalyzed aerobic oxidative annulation, intramolecular cyclization, click-chemistry supported synthesis, and alkali-promoted, transition-metal-free mediated synthesis. These methods enhance the diversity and potential applications of thiadiazole compounds. Furthermore, this study provides up-to-date information on the key pharmacological activities of thiadiazole derivatives, highlighting their potential in therapeutic medicine for drug development. The structure-activity relationship (SAR) is also discussed to better understand their interactions and safety in biological systems. This work aims to expand on the reported chemistry and pharmacological potential of the thiadiazole moiety to validate their efficacy as promising pharmacophores in drug design and development.

Redox homeostasis in human renal cells that had been treated with amphotericin B in combination with selected 1,3,4-thiadiazole derivatives

BACKGROUND

The use of amphotericin B (AmB) in the therapy of systemic mycosis is associated with strong side effects, including nephrotoxicity, and hepatotoxicity. Therefore, agents that can reduce the toxic effects of AmB while acting synergistically as antifungal agents are currently being sought. 1,3,4-thiadiazole derivatives are promising compounds that have an antifungal activity and act synergically with AmB. Such combinations might allow the dose of AmB, which is essential for preventing patients from having serious side effects, to be decreased. This might result from the antioxidant properties of 1,3,4-thiadiazoles. Thus, the aim of the study was to investigate redox homeostasis in human renal proximal tubule epithelial cells (RPTEC) after they had been treated with AmB in combination with 1,3,4-thiadiazole derivatives.

METHODS

Cellular redox homeostasis was assessed by investigating the total antioxidant capacity (TAC) of cells, the malondialdehyde (MDA) concentration, and the activity of antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT). TAC was measured using an ABTS method. The MDA concentration, and the activity of SOD, GPX, and CAT were determined spectrophotometrically using commercially available assays. Additionally, the antioxidant defense system-related gene expression profile was determined using oligonucleotide microarrays (HG-U133A 2.0). Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to confirm the microarray results.

RESULTS

Amphotericin B and selected 1,3,4-thiadiazole derivatives had a significant effect on the total antioxidant capacity of the RPTEC cells, and the activity of the antioxidant enzymes. We also revealed that the effect of thiadiazoles on the SOD and CAT activities is dependent on the treatment of RPTEC cells with AmB. At the transcriptional level, the expression of several genes was affected by the studied compounds and their combinations.

CONCLUSIONS

The results confirmed that thiadiazoles can stimulate the RPTEC cells to defend against the oxidative stress that is generated by AmB. In addition, together with the previously demonstrated synergistic antifungal activity, and low nephrotoxicity, these compounds have the potential to be used in new therapeutic strategies in the treatment of fungal infections.

New 1,3,4-Thiadiazole Derivatives as α-Glucosidase Inhibitors: Design, Synthesis, DFT, ADME, and In Vitro Enzymatic Studies

Diabetes is an emerging disorder in the world and is caused due to the imbalance of insulin production as well as serious effects on the body. In search of a better treatment for diabetes, we designed a novel class of 1,3,4-thiadiazole-bearing Schiff base analogues and assessed them for the α-glucosidase enzyme. In the series (1-12), compounds are synthesized and 3 analogues showed excellent inhibitory activity against α-glucosidase enzymes in the range of IC50 values of 18.10 ± 0.20 to 1.10 ± 0.10 μM. In this series, analogues 4, 8, and 9 show remarkable inhibition profile IC50 2.20 ± 0.10, 1.10 ± 0.10, and 1.30 ± 0.10 μM by using acarbose as a standard, whose IC50 is 11.50 ± 0.30 μM. The structure of the synthesized compounds was confirmed through various spectroscopic techniques, such as NMR and HREI-MS. Additionally, molecular docking, pharmacokinetics, cytotoxic evaluation, and density functional theory study were performed to investigate their behavior.

Synthesis, DFT investigations, antioxidant, antibacterial activity and SAR-study of novel thiophene-2-carboxamide derivatives

Synthetic strategy for the synthesis of thiophene 2-carboxamide derivatives substituted with hydroxyl, methyl and amino groups at position-3 was proposed. The strategy includes the cyclization of the precursor ethyl 2-arylazo-3-mercapto-3-(phenylamino)acrylate derivatives, 2-acetyl-2-arylazo-thioacetanilide derivatives and N-aryl-2-cyano-3-mercapto-3-(phenylamino)acrylamide derivatives with N-(4-acetylphenyl)-2-chloroacetamide in alcoholic sodium ethoxide. IR, ¹H NMR, and mass spectroscopic analyses were used to characterize the synthesized derivatives. In addition, molecular, electronic properties of the synthesized products were studied by the density functional theory (DFT) where they exhibited close HOMO-LUMO energy gap (ΔE_H-L) in which the amino derivatives 7a-c have the highest while the methyl derivatives 5a-c were the lowest. Using the ABTS method, the antioxidant properties of the produced compounds were evaluated, where amino thiophene-2-carboxamide 7a exhibit significant inhibition activity 62.0% compared to ascorbic acid The antibacterial activity against two pathogenic Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two of pathogenic Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) revealed that 7b records the highest activity index compared to ampicillin 83.3, 82.6, 64.0, 86.9%, respectively. Furthermore, the thiophene-2-carboxamide derivatives were docked with five different proteins with the use molecular docking tools and the results explained interactions between amino acid residue of enzyme and compounds. Compounds 3b and 3c showed the highest binding score with 2AS1 protein.

Effect of Antibiotic Amphotericin B Combinations with Selected 1,3,4-Thiadiazole Derivatives on RPTECs in an In Vitro Model

4-(5-methyl-1,3,4-thiadiazole-2-yl) benzene-1,3-diol (C1) and 4-[5-(naphthalen-1-ylmethyl)-1,3,4-thiadiazol-2-yl] benzene1,3-diol (NTBD) are representative derivatives of the thiadiazole group, with a high antimycotic potential and minimal toxicity against normal human fibroblast cells. The present study has proved its ability to synergize with the antifungal activity of AmB. The aim of this work was to evaluate the cytotoxic effects of C1 or NTBD, alone or in combination with AmB, on human renal proximal tubule epithelial cells (RPTECs) in vitro. Cell viability was assessed with the MTT assay. Flow cytometry and spectrofluorimetric techniques were used to assess the type of cell death and production of reactive oxygen species (ROS), respectively. The ELISA assay was performed to measure the caspase-2, -3, and -9 activity. ATR-FTIR spectroscopy was used to evaluate biomolecular changes in RPTECs induced by the tested formulas. The combinations of C1/NTBD and AmB did not exert a strong inhibitory effect on the viability/growth of kidney cells, as evidenced by the negligible changes in the apoptotic/necrotic rate and caspase activity, compared to the control cells. Both NTBD and C1 displayed stronger anti-oxidant activity when combined with AmB. The relatively low nephrotoxicity of the thiadiazole derivative combinations and the protective activity against AmB-induced oxidative stress may indicate their potential use in the therapy of fungal infections.

Synthesis, crystal structure, DFT and molecular docking studies of N-acetyl-2,4-[diaryl-3-azabicyclo[3.3.1]nonan-9-yl]-9-spiro-4'-acetyl-2'-(acetylamino)-4',9-dihydro-[1',3',4']-thiadiazoles: A potential SARS-nCoV-2 Mpro (COVID-19) inhibitor

In this paper, we describe the synthesis and crystal structure analysis of N-acetyl-2,4-[diphenyl-3-azabicyclo[3.3.1]nonan-9-yl]-9-spiro-4′-acetyl-2′-(acetylamino)-4′,9-dihydro-[1′,3′,4′]-thiadiazole (3a) and N-acetyl- 2,4-[bis(p-methoxyphenyl)-3-azabicyclo[3.3.1]nonan-9-yl]-9-spiro-4′-acetyl-2′-(acetylamino)-4′,9-dihydro-[1′,3′,4′]-thiadiazole (3b). The title compounds 3a and 3b are characterized by 1D NMR and single crystal x-ray diffraction analysis. Non-covalent interactions in a molecule were identified by Hirshfeld surface (d_norm contacts and 2D fingerprint plot) analysis. In addition, the existence of chalcogen bond (S•••O bond) in the molecular structures (3a and 3b) are described by NCI-RDG and QTAIM analysis. NBO analysis is employed to describe the orbital interactions and electron transfer between sulfur and oxygen atoms. Molecular docking is carried out for compounds 3a and 3b with COVID-19 viral protein SARS-nCoV-2 M^pro (PDB ID: 6LU7).

Design, Synthesis, Antibacterial Evaluations and In Silico Studies of Novel Thiosemicarbazides and 1,3,4-Thiadiazoles

The emergence of drug-resistant bacterial strains continues to be one of the major challenges of medicine. For this reason, the importance of searching for novel structures of antibacterial drugs chemically different from the currently known antibiotics is still of great importance. In this study, we synthesized the thiosemicarbazide and 1,3,4-thiadiazole derivatives and tested them for antibacterial activity. In in vitro tests, we examined the activity of the synthesized substances against Gram-positive and Gram-negative bacteria strains. While all 1,3,4-thiadiazoles tested lacked significant activity, the antimicrobial response of the thiosemicarbazides was moderate and it was also dependent on the type and position of the substituent on the phenyl ring. The highest activity towards all Gram-positive bacteria strains was shown by all three linear compounds containing the trifluoromethylphenyl group in the structure. The MIC (minimum inhibitory concentration) values were in the range of 3.9–250 µg/mL. Additionally, we try to explain the mechanism of the antibacterial activity of the tested compounds using the molecular docking to DNA gyrase and topoisomerase IV, following previous reports on the molecular basis of the activity of thiosemicarbazides. Docking simulations allow the purposing dual mechanism of the antibacterial activity of the synthesized compounds through inhibition of topoisomerase IV DNA gyrase with the moderate prevalence of the topoisomerase pathway.