Kinetic Insights into the Antioxidant Effect of Isatin-Thiosemicarbazone in Biodiesel Blends.

Biodiesel has several drawbacks, such as being prone to oxidation, having reduced stability, and having limited storage time. Antioxidants compatible with biodiesel are being used to address its drawbacks. Utilizing antioxidants effectively improves the quality of biodiesel. Enhancing the quality of biodiesel for use as a clean energy source benefits both the global economy and ecology. Therefore, we believe that our work will contribute to the advancement of the biodiesel industry worldwide. This study used blends consisting of 20% biodiesel and 80% diesel fuel. Isatin-thiosemicarbazones were tested as additives in blends at a concentration of 3000 parts per million (ppm) using an oxifast device and were compared with the chemical antioxidant Trolox. FT-IR, DSC, and TGA were used to characterize these samples. DSC measured sample crystallization temperatures (Tc). Samples with antioxidants showed decreased values compared to the non-antioxidant diesel sample D100. Several DSC tests were conducted to determine the antioxidant strengths of various samples. The results show that the FT-IR spectrum's antioxidant effect regions grow clearer with antioxidants. The extra antioxidant is effective. Biodiesel's oxidative stability improves with isatin-thiosemicarbazones at varying concentrations. The kinetics of thermal decomposition of isatin-thiosemicarbazones under non-isothermal conditions were determined using the Kissinger, Ozawa, and Boswell techniques. The activation energies of compounds 1 and 2 were calculated as 137-147 kJ mol-1 and 173-183 kJ mol-1, respectively.

Synthesis, Theoretical, in Silico and in Vitro Biological Evaluation Studies of New Thiosemicarbazones as Enzyme Inhibitors.

Eleven new thiosemicarbazone derivatives (1-11) were designed from nine different biologically and pharmacologically important isothiocyanate derivatives containing functional groups such as fluorine, chlorine, methoxy, methyl, and nitro at various positions of the phenyl ring, in addition to the benzyl unit in the molecular skeletal structure. First, their substituted-thiosemicarbazide derivatives were synthesized from the treatment of isothiocyanate with hydrazine to synthesize the designed compounds. Through a one-step easy synthesis and an eco-friendly process, the designed compounds were synthesized with yields of up to 95 % from the treatment of the thiosemicarbazides with aldehyde derivatives having methoxy and hydroxy groups. The structures of the synthesized molecules were elucidated with elemental analysis and FT-IR, 1 H-NMR, and 13 C-NMR spectroscopic methods. The electronic and spectroscopic properties of the compounds were determined by the DFT calculations performed at the B3LYP/6-311++G(2d,2p) level of theory, and the experimental findings were supported. The effects of some global reactivity parameters and nucleophilic-electrophilic attack abilities of the compounds on the enzyme inhibition properties were also investigated. They exhibited a highly potent inhibition effect on acetylcholinesterase (AChE) and carbonic anhydrases (hCAs) (KI values are in the range of 23.54±4.34 to 185.90±26.16 nM, 103.90±23.49 to 325.90±77.99 nM, and 86.15±18.58 to 287.70±43.09 nM for AChE, hCA I, and hCA II, respectively). Furthermore, molecular docking simulations were performed to explain each enzyme-ligand complex's interaction.

Preparation, spectroscopic, X-ray crystallographic, DFT, antimicrobial and ADMET studies of N-[(4-flourophenyl)sulfanyl]phthalimide.

N-[(4-Fluorophenyl)sulfanyl]phthalimide (C14H8FNO2S, FP) was synthesized and characterized using X-ray crystallography. It was then investigated via quantum chemical analysis using the density functional theory (DFT) approach, as well as spectrochemically using FT-IR and 1H and 13C NMR spectroscopy, and elemental analysis. The observed and stimulated spectra are in very good agreement for the DFT method. The in vitro antimicrobial activity of FP against three Gram-positive bacteria, three Gram-negative bacteria and two fungi were determined using the serial dilution method, and FP showed the highest antibacterial activity against E. coli, with a MIC of 128 µg ml-1. Druglikeness, ADME (absorption, distribution, metabolism and excretion) and toxicology studies were carried out to theoretically examine the drug properties of FP.

Kinetic Studies, Antioxidant Activities, Enzyme Inhibition Properties and Molecular Docking of 1,3-Dihydro-1,3-Dioxoisoindole Derivatives.

The acid catalyzed hydrolysis of the N-(p-substitutedphenyl) phthalimides in three different acids was investigated at 50.0±0.1°C. Two different antioxidant activity tests as DPPH• and ABTS•+ scavenging activities, and three various enzyme inhibition activity tests as urease, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibition activities, were applied. Compound 3c (2.03 µg/mL ) has higher antioxidant activity than other compounds and standards according to DPPH test. In AChE assay, compounds 3a and 3b (13.13 and 9.59 µg/mL) has higher enzyme inhibition activity than the standard Galantamine (14.37 µg/mL). In BChE and urease tests, all compounds (6.84-13.60 and 10.49-17.73 µg/mL) have higher enzyme inhibition activity than the standard Galantamine (49.40 µg/mL) and thiourea (26.19 µg/mL), respectively. The molecule interaction for each of the three compounds with the active sites of AChE, BChE, and urease enzymes was examined via molecular docking simulations.

Inhibitory effects of sulfenimides on human and bovine carbonic anhydrase enzymes.

A series of sulfenimide derivatives (1a-i) were investigated as inhibitors of human (hCA-I, hCA-II) and bovine (bCA) carbonic anhydrase enzymes. The compounds were synthesised by the reaction of substituted thiophenols with phthalimide by means of an effective, simple and eco-friendly method and the structures were confirmed by IR, 1H NMR, 13C NMR, MS and elemental analysis. All derivatives except for the methyl derivative (1b) exhibited effective inhibitory action at low micromolar concentrations on human isoforms, but only four derivatives (1e, 1f, 1h, 1i) inhibited the bovine enzyme. The bromo derivative (1f) was found to be strongest inhibitor of all three enzymes with KI values of 0.023, 0.044 and 20.57 µM for hCA-I, hCA-II and bCA, respectively. Results of our study will make valuable contributions to carbonic anhydrase inhibition studies for further investigations since inhibitors of this enzyme are important molecules for medicinal chemistry.

Enzyme inhibition, molecular docking, and density functional theory studies of new thiosemicarbazones incorporating the 4-hydroxy-3,5-dimethoxy benzaldehyde motif.

New Schiff base-bearing thiosemicarbazones (1-13) were obtained from 4-hydroxy-3,5-dimethoxy benzaldehyde and various isocyanates. The structures of the synthesized molecules were elucidated in detail. Density functional theory calculations were also performed to determine the spectroscopic properties of the compounds. Moreover, the enzyme inhibition activities of these compounds were investigated. They showed highly potent inhibition effects on acetylcholinesterase (AChE) and human carbonic anhydrases (hCAs) (KI values are in the range of 51.11 ± 6.01 to 278.10 ± 40.55 nM, 60.32 ± 9.78 to 300.00 ± 77.41 nM, and 64.21 ± 9.99 to 307.70 ± 61.35 nM for AChE, hCA I, and hCA II, respectively). In addition, molecular docking studies were performed, confirmed by binding affinities studies of the most potent derivatives.

Synthesis, X-ray structure, antimicrobial activity, DFT and molecular docking studies of N-(thiophen-2-ylmethyl)thiophene-2-carboxamide.

In the present study, N-(thiophen-2-ylmethyl)thiophene-2-carboxamide, C10H9NOS2, (I), was obtained by the reaction of thiophene-2-carbonyl chloride and thiophen-2-ylmethanamine. Characterization of (I) was carried out using X-ray diffraction, spectroscopic techniques and elemental analyses. The DFT/B3LYP/6-311++G(d,p) theoretical level was successfully applied to calculate the optimized geometry and the local and global chemical activity parameters. The results obtained show good agreement between the experimental and theoretical geometrical parameters. The local and global chemical activity parameters were examined to determine the electrophilic and nucleophilic sites in (I). The natural bond orbital (NBO) analysis of (I) gives an efficient methodology for investigating the inter- and intramolecular bonding, as well as giving a convenient basis for investigating charge transfer or conjugative interactions in molecular systems. Also, the antimicrobial activity of (I) was investigated against eight microorganisms using the microdilution method and it is found to have an effective antibacterial activity. In addition, molecular docking studies were calculated in order to understand the nature of the binding of (I) with a lung cancer protein (PDB entry 1x2j).

Synthesis, Spectroscopic Characterization, Single-Crystal Structure, Hirshfeld Surface Analysis, and Antimicrobial Studies of 3-Acetoxy-2-methylbenzoic Anhydride.

We report a novel anhydride derivative, 3-acetoxy-2-methylbenzoic anhydride (AMA), obtained from the interaction of 3-acetoxy-2-methylbenzoyl chloride with 3-acetoxy-2-methylbenzoic acid. The synthesized compound was characterized by elemental analysis, IR, 1H NMR, and 13C NMR spectroscopic studies and single-crystal X-ray crystallography which revealed the crystallization of AMA as monoclinic with space group P21/c. A Hirshfeld surface analysis was performed to record various intermolecular interactions, indicating the stabilization of the AMA structure by the intermolecular weak C-H···O hydrogen bonds and π···π interactions. The title compound was screened for antibacterial and antifungal activities using a serial dilution technique under aseptic conditions. The results indicate that the title compound has significant antibacterial properties but showed no antifungal behavior.

Synthesis, Structural Investigation, Hirshfeld Surface Analysis, and Biological Evaluation of N-(3-Cyanothiophen-2-yl)-2-(thiophen-2-yl)acetamide.

In this study, a novel heterocyclic amide derivative, N-(3-cyanothiophen-2-yl)-2-(thiophen-2-yl)acetamide (I), was obtained by reacting 2-aminothiophene-3-carbonitrile with activated 2-(thiophen-2-yl)acetic acid in a N-acylation reaction and characterized by elemental analyses, FT-IR, 1H and 13C NMR spectroscopic studies, and single crystal X-ray crystallography. The crystal packing of I is stabilized by C-H···N and N-H···N hydrogen bonds. In addition, I was investigated computationally using the density functional theory (DFT) method with the B3LYP exchange and correlation functions in conjunction with the 6311++G(d,p) basis set in the gas phase. Fukui function (FF) analysis was also carried out. Electrophilicity-based charge transfer (ECT) method and charge transfer (ΔN) were computed to examine the interactions between I and DNA bases (such as guanine, thymine, adenine, and cytosine). The most important contributions to the Hirshfeld surface are H···H (21%), C···H (20%), S···H (19%), N···H (14%), and O···H (12%). An ABTS antioxidant assay was used to evaluate the in vitro antioxidant activity of I. The compound exhibited moderate antioxidant activity. The antimicrobial activity of the title molecule was investigated under aseptic conditions, using the microdilution method, against Gram-positive and Gram-negative bacterial strains, and it also demonstrated significant activity against yeasts (Candida glabrata ATCC 90030, Candida krusei ATCC 34135). The findings revealed that the molecule possesses significant antioxidant and antimicrobial properties.

Experimental and theoretical investigations on a furan-2-carboxamide-bearing thiazole: synthesis, molecular characterization by IR/NMR/XRD, electronic characterization by DFT, Hirshfeld surface analysis and biological activity.

A thiazole-based heterocyclic amide, namely, N-(thiazol-2-yl)furan-2-carboxamide, C8H6N2O2S, was synthesized and investigated for its antimicrobial activity. The structure was characterized by elemental analysis and IR, 1H NMR, and 13C NMR spectroscopy. The molecular and electronic structures were investigated experimentally by single-crystal X-ray diffraction (XRD) and theoretically by density functional theory (DFT) modelling. The compound crystallized in the monoclinic space group P21/n and the asymmetric unit contains two symmetrically independent molecules. Several noncovalent interactions were recorded by XRD and analysed with Hirshfeld surface analysis (HSA) calculations. Natural bond orbital, molecular electrostatic potential, second-order nonlinear optical and thermodynamic property analyses were also carried out using the DFT/B3LYP method. The title compound was evaluated for antimicrobial activity against eight microorganisms consisting of Gram-negative bacteria, Gram-positive bacteria and fungi. The compound showed good antimicrobial activity against the eight tested microorganisms. This suggests that the compound merits further study for potential pharmacological and medical applications.

Potential thiosemicarbazone-based enzyme inhibitors: Assessment of antiproliferative activity, metabolic enzyme inhibition properties, and molecular docking calculations.

A new series of thiosemicarbazone derivatives (1-11) were prepared from various aldehydes and isocyanates with high yields and practical methods. The structures of these compounds were elucidated by Fourier transform infrared, 1 H-nuclear magnetic resonance (NMR), 13 C-NMR spectroscopic methods and elemental analysis. Cytotoxic effects of target compounds were determined by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide assay and compound 1 showed significant cytotoxic activity against both MCF-7 and MDA-MB-231 cells, with half-maximal inhibitory concentration values of 2.97 µM and 6.57 µM, respectively. Moreover, in this study, the anticholinergic and antidiabetic potentials of these compounds were investigated. To this aim, the effect of the newly synthesized thiosemicarbazone derivatives on the activities of acetylcholinesterase (AChE) and αglycosidase (α-Gly) was evaluated spectrophotometrically. The title compounds demonstrated high inhibitory activities compared to standard inhibitors with Ki values in the range of 122.15-333.61 nM for α-Gly (Ki value for standard inhibitor = 75.48 nM), 1.93-12.36 nM for AChE (Ki value for standard inhibitor = 17.45 nM). Antiproliferative activity and enzyme inhibition at the molecular level were performed molecular docking studies for thiosemicarbazone derivatives. 1M17, 5FI2, and 4EY6, 4J5T target proteins with protein data bank identification with (1-11) compounds were docked for anticancer and enzyme inhibition, respectively.

1,2,3-Triazole substituted phthalocyanine metal complexes as potential inhibitors for anticholinesterase and antidiabetic enzymes with molecular docking studies.

In recent years, acetylcholinesterase (AChE) and α-glycosidase (α-gly) inhibition have emerged as a promising and important approach for pharmacological intervention in many diseases such as glaucoma, epilepsy, obesity, cancer, and Alzheimer's. In this manner, the preparation and enzyme inhibition activities of peripherally 1,2,3-triazole group substituted metallophthalocyanine derivatives with strong absorption in the visible region were presented. These novel metallophthalocyanine derivatives (2-6) effectively inhibited AChE, with Ki values in the range of 40.11 ± 5.61 to 78.27 ± 15.42 µM. For α-glycosidase, the most effective Ki values of compounds 1 and 2 were with Ki values of 16.11 ± 3.13 and 18.31 ± 2.42 µM, respectively. Also, theoretical calculations were investigated to compare the chemical and biological activities of the ligand (1) and its metal complexes (2-6). Biological activities of 1 and its complexes against acetylcholinesterase for ID 4M0E (AChE) and α-glycosidase for ID 1R47 (α-gly) are calculated. Theoretical calculations were compatible with the experimental results and these 1,2,3-triazole substituted phthalocyanine metal complexes were found to be efficient inhibitors for anticholinesterase and antidiabetic enzymes.Communicated by Ramaswamy H. Sarma.

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

In recent years, compounds containing thiophene and 1,3,4-thiadiazole skeletons have become important cyclic compounds, especially in medicinal chemistry. In this manner, we synthesized and isolated seven 1,3,4-thiadiazole derivatives with thiophene groups and fully characterized by elemental analysis and general spectroscopic methods such as 1H NMR, 13C NMR, and FT-IR. Antibacterial activities of the title compounds were investigated by using TLC-Dot blot, macro dilution, well diffusion, and growth curve analysis methods. Compounds 1 and 6 showed inhibitory activities against all tested gram-negative and gram-positive bacteria. TLC-DPPH and DPPH assays, on the other hand, were performed to detect the antioxidant activities of the 1,3,4-thiadiazole derivatives and compound 1 exhibited the highest antioxidant activity at all tested concentrations. QTAIM and NCI calculations were performed as well as structural, electronic, and spectral analyzes using density functional theory (DFT). Calculations were carried out at the B3lyp/6-311 + +g(2d,2p) level of theory, and the data were used to examine the antioxidant activity of the compounds.

Synthesis, spectroscopic studies, and antioxidant activities of novel thio/carbohydrazones and bis-isatin derivatives from terephthalaldehyde.

New bis(isatins-thio/carbohydrazones) based on Schiff bases were prepared from terephthalaldehyde biscarbohydrazone and 5-substituted isatins in the presence of a drop of sulfuric acid under reflux in ethanol. Terephthalaldehyde bis(thio/carbohydrazone) was synthesized by the reaction of (thio)/carbohydrazide and terephthalaldehyde in the presence of a few drops of acetic acid under reflux in ethanol. The structures of these synthesized compounds were determined using IR, 1H NMR, and 13C NMR spectroscopy and elemental analysis. The in vitro antioxidant activity of all the compounds was determined by the 1,1-diphenyl-2-picryl hydrazyl (DPPH.) free radical scavenging method. Compound 2 showed the best antioxidant activity.

Preparation, structure elucidation, and antioxidant activity of new bis(thiosemicarbazone) derivatives.

Schiff-base-bearing new bis(thiosemicarbazone) derivatives were prepared from terephthalaldehyde and various thiosemicarbazides. FT-IR, 1H NMR, 13C NMR, and UV-Vis spectroscopic methods and elemental analysis were used to elucidate the identification of the synthesized molecules. The in vitro antioxidant activity of the synthesized compounds was analysed with the 1,1-diphenyl-2-picryl hydrazyl free-radical-trapping process. The synthesized compounds exhibited lower antioxidant activity than the standard ascorbic acid. IC50 values of the synthesized molecules measured from 3.81 ± 0.01 to 29.05 ± 0.11 µM. Among the synthesized compounds, compound 3 had the best antioxidant activity. Moreover, this study explained the structure-activity relationship of the synthesized molecules with different substituents in radical trapping reactions.