Browsing by Author "Yakan H."

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1,2,3-Triazole substituted phthalocyanine metal complexes as potential inhibitors for anticholinesterase and antidiabetic enzymes with molecular docking studies
(2022-01-01) Koçyiğit Ü.M.; Taslimi P.; Tüzün B.; Yakan H.; Muğlu H.; Güzel E.
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.
A novel series of thiosemicarbazone hybrid scaffolds: Design, synthesis, DFT studies, metabolic enzyme inhibition properties, and molecular docking calculations
(2023-05-15) Yakan H.; Muğlu H.; Türkeş C.; Demir Y.; Erdoğan M.; Çavuş M.S.; Beydemir Ş.
The fourteen new thiosemicarbazone derivatives of Schiff base were synthesized from the condensation reactions of two different aldehydes (3‑hydroxy-4-methoxhybenzaldehyde and 3-ethoxhy-4-hydroxybenzaldehyde) with various substituted-thiosemicarbazides. Structures of the compounds (1-14) were characterized by using FT-IR, 1H NMR, and 13C NMR spectroscopic techniques, and elemental analysis. Furthermore, the enzyme inhibitory effect of the obtained hybrid scaffolds was studied. They exhibited highly potent inhibition effect on acetylcholinesterase (AChE) and carbonic anhydrases (hCAs) (KI values are in the range of 111.00 ± 12.12 to 381.60 ± 38.10 nM, 120.60 ± 20.45 to 338.90 ± 42.18 nM, and 100.60 ± 11.31 to 285.30 ± 45.27 nM for AChE, hCA I, and hCA II, respectively). DFT analyzes were performed to demonstrate the usability of some electronic parameters and nucleophilic-electrophilic attack abilities of the compounds in predicting enzyme inhibition properties. A correlation was seen between the HOMO energy eigenvalues of the compounds and the inhibition reactivity, and revealing that QTAIM calculations could also be used to predict the probability of electrophilic and nucleophilic attacks. Findings supporting that hCA I and AChE enzyme inhibition reactions primarily proceed through electrophilic attack, while hCA II reactions tend to occur via nucleophilic attack have been obtained. Also, molecular docking studies were conducted to confirm the outcomes of studies on binding affinities and the most powerful derivatives. The obtained results showed that the novel thiosemicarbazone derivatives may lead to the development of novel types of pharmacological agents in the treatment of patients with Alzheimer's disease, idiopathic intracranial hypertension, glaucoma, and related conditions.
Determination of biological studies and molecular docking calculations of isatin-thiosemicarbazone hybrid compounds
(2022-09-15) Koçyiğit Ü.M.; Doğan M.; Muğlu H.; Taslimi P.; Tüzün B.; Yakan H.; Bal H.; Güzel E.; Gülçin İ.
Design, synthesis, structural elucidation, and investigation of cytotoxic and antimicrobial activity, butyrylcholinesterase (BChE), and acetylcholinesterase (AChE) enzyme inhibition effects of isatin-thiosemicarbazone hybrid compounds (1–15) are reported in this study. Hybrid compounds (14 and 15) were synthesized, isolated, and characterized for the first time. FT-IR, 1H NMR, and 13C NMR spectroscopic methods and elemental analysis were used to characterize the structures of the compounds. In the enzymatic evaluation, hybrid compound 13 was observed as the most potent inhibitor of AChE with a Kİ value of 0.94 ± 0.13 µM (all compound Kİ values between 0.94 ± 0.13 and 4.47 ± 0.92), also this compound was observed as the most potent inhibitor of BChE with a Kİ value of 0.82 ± 0.11 µM (all compounds had Kİ values between of 0.82 ± 0.11 and 3.48 ± 0.92). Almost all compounds were shown better inhibition profile than standard compound. In the theoretical calculations, the comparison of the biological activities of isatin-thiosemicarbazone hybrid derivatives against enzymes was studied. The enzymes studied in docking calculations are AChE and BChE. Then, ADME/T analysis was conducted to examine the drug properties of these derivatives. Besides, the antimicrobial activity of these molecules was investigated by the microdilution method according to Clinical Laboratory Standards Institute (CLSI) criteria in the study. Cytotoxic activity of isatin-thiosemicarbazone hybrids was determined by the XTT cell viability assay on human breast cancer cell lines MCF-7 and MDA-MB-231. Among the hybrid compounds, compound 8 exhibited the most potent cytotoxic activity with IC50 values of 23.42 ± 0.21 µg/mL and 19.68 ± 0.23 µg/mL on MCF-7 and MDA-MB-231 cell lines, respectively. Overall, the hybridization of isatin and thiosemicarbazone skeleton has played an essential role in the inhibition of enzymes and cytotoxic activity.
Enzyme inhibition, molecular docking, and density functional theory studies of new thiosemicarbazones incorporating the 4-hydroxy-3,5-dimethoxy benzaldehyde motif
(2022-01-01) Demir Y.; Türkeş C.; Çavuş M.S.; Erdoğan M.; Muğlu H.; Yakan H.; Beydemir Ş.
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.
Exploring of antioxidant and antibacterial properties of novel 1,3,4-thiadiazole derivatives: Facile synthesis, structural elucidation and DFT approach to antioxidant characteristics
(2022-02-01) Muğlu H.; Akın M.; Çavuş M.S.; Yakan H.; Şaki N.; Güzel E.
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.
ISATIN/THIOSEMICARBAZONE HYBRIDS: FACILE SYNTHESIS, AND THEIR EVALUATION AS ANTI-PROLIFERATIVE AGENTS AND METABOLIC ENZYME INHIBITORS
(2023-01-01) Yakan H.; Azam M.; Kansiz S.; Muǧlu H.; Ergül M.; Taslimi P.; Koçyiǧit Ü.M.; Karaman M.; Al-Resayes S.I.; Min K.
New 1,3,4-thiadiazoles based on thiophene-2-carboxylic acid: Synthesis, characterization, and antimicrobial activities
(2020-03-05) Muğlu H.; Yakan H.; Shouaib H.
Novel 1,3,4-thiadiazole derivatives were prepared by cyclization reaction of thiophene-2-carboxylic acid with N-arylthiosemicarbazides and POCl3. The antibacterial activities of the synthesized compounds were tested against Gram-negative bacteria (Salmonella enteritidis, Salmonella typhimurium, Enterobacter aerogenes, Salmonella infantis, Salmonella kentucky, and Escherichia coli), Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, and Enterococcus durans), and the fungus Candida albicans using the disk diffusion method. Selected 1,3,4-thiadiazole derivatives exhibited effective antimicrobial activity against S. aureus, C. albicans, S. typhimurium, E. aerogenes, and S. kentucky. Therefore, 1,3,4-thiadiazole derivatives can be considered as bioactive agents for pharmacological and medicinal applications. The synthesized compounds were characterized by using IR, 1H NMR, and 13C NMR spectroscopies and elemental analysis.
New 5-methylisatin including thiocarbohydrazones: preparation, structure elucidation and antimicrobial activity
(2022-10-01) Yakan H.; Çakmak Ş.; Buruk O.; Veyisoğlu A.; Muğlu H.; Türköz Karakullukçu N.
New 5-methylisatin including thiocarbohydrazones (1–5) have been synthesized. The chemical structure of synthesized compounds was elucidated with IR, 1H NMR, 13C NMR spectroscopic methods, and elemental analysis. Moreover, the synthesized compounds have been screened for antimicrobial activity. Their antibacterial activities were tested against Gram-positive (Bacillus subtilis ATCC 6623, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212), Gram-negative (Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 70060, Pseudomonas aeruginosa ATCC 27853), and fungal (Candida albicans ATCC 10231, Aspergillus niger ATCC 16404) microbial strains using the microdilution method. In the isatin series, particularly the compound 2 showed the best antimicrobial activity against E. faecalis strain with MIC values of 64 μg/mL compared to other compounds. This high activity of compound 2 is due to the presence of two electron-donating methoxy groups in its structure. The remaining substituted compounds have shown good and moderate antimicrobial activity compared to standard drugs. The results may provide insights into the target compounds' structure–activity relationships, which may facilitate the development of pharmacological and biological applications for the target compounds. Graphical abstract: New isatins bearing thiocarbohydrazone were synthesized. Structures of all compounds were elucidated with spectroscopic approaches. The antimicrobial activities of the tested compounds presented promising antimicrobial activity against the eight tested microorganisms. [Figure not available: see fulltext.]
New Bis-1,3,4-Thiadiazoles Based on Fumaric Acid: Preparation, Structure Elucidation, Antibacterial Activities, and Quantum-Chemical Studies
(2023-01-01) Muğlu H.; Yakan H.; Elefkhakry G.A.I.; Altuner E.M.; Serdar Çavuş M.
New N,N'-bis(thioamido)thiocarbohydrazones and carbohydrazones: synthesis, structure characterization, antioxidant activity, corrosion inhibitors and DFT studies
(2022-04-01) Çavuş M.S.; Yakan H.; Özorak C.; Muğlu H.; Bakır T.K.
New symmetric N,N'-bis(thioamido)thio/carbohydrazones (1–4) were prepared from thio/carbohydrazide and various isothiocyanates with high yields and characterized the structures of the compounds. The compounds were evaluated as new corrosion inhibitors for corrosion of mild steel in 0.1 M HCl solutions using polarization and electrochemical impedance spectroscopy (EIS) techniques, and all compounds showed effective inhibitory properties. Antioxidant activity values determined using the DPPH method for all compounds showed higher antioxidant activity than the standard Trolox (5.89 µM). The IC50 values of the compounds were obtained between 3.45 and 4.25 µM, and also showed a ranking of 4 > 2 > 3 > 1 > Trolox , with antioxidant activities better than Trolox. Compound 4 (1,5-bis((3-fluorophenyl)carbamothioyl)carbonohydrazide) exhibited the highest activity in terms of both antioxidant and anti-corrosion properties. DFT calculations were also performed to determine the spectroscopic properties of the compounds and to analyze the structure–activity relationship for their antioxidant characteristics. It was investigated how DPPH reactions are affected by the dependence of delocalization indices and charge densities of N–H bonds on intramolecular interactions. As well as the calculations of intramolecular interactions and some QTAIM parameters, Laplacian bond order and bond polarity index (BPI) analysis were also performed to examine the electronic properties of reactive N–H bonds. Graphical abstract: New symmetric N,N'-bis(thioamido)thio/carbohydrazones were obtained. Structures of all compounds were elucidated using spectroscopic approaches. Antioxidant activities of the compounds were determined by DPPH method. QTAIM analyses were used to examine the relationship between the electronic properties and antioxidant activity. The compounds were evaluated as new corrosion inhibitors for corrosion of mild steel in 0.1 M HCl.[Figure not available: see fulltext.].
New Schiff bases based on isatin and (thio)/carbohydrazone: preparation, experimental–theoretical spectroscopic characterization, and DFT approach to antioxidant characteristics
(2023-04-01) Muğlu H.; Sönmez F.; Çavuş M.S.; Kurt B.Z.; Yakan H.
In this study, synthesis, spectroscopic elucidation, and investigation of antioxidant properties of new Schiff bases based on isatin and (thio)/carbohydrazone derivatives have been reported for the first time. The structures of the synthesized compounds were elucidated by FT-IR, 1H-NMR, and 13C-NMR spectroscopic methods and elemental analysis. Their DPPH, ABTS, and CUPRAC activities were evaluated as antioxidant properties. Electronic and spectral data of the compounds were obtained by DFT calculations at the B3LYP/6–311+ +G(2d,2p) level of theory. Intramolecular interactions and charge densities on the bonds were analyzed by QTAIM and IRI calculations. In addition to parameters such as frontier molecular orbital energy eigenvalues, electronegativity, nucleophilicity index, and electrodonating power, the changes in the enthalpy of the compounds for the reactions realized through the SET mechanism were calculated to elucidate the antioxidant reactions of the compounds. Most of synthesized compounds exhibited antioxidant activities with the IC50 values ranging from 27.13 to 43.35 µM for DPPH, from 6.47 to 24.96 µM for ABTS and with the A0.50 values ranging from 9.04 to 47.52 µM for CUPRAC. Among them, compound 3, containing two hydroxyl groups, showed the strongest antioxidant activity for each assay (IC50 = 27.13 µM for DPPH, 6.47 µM for ABTS, and A0.50 = 9.04 µM for CUPRAC). The antioxidant activities of compound 3 were almost two or threefold weaker than that of BHA (IC50 = 9.55 µM for DPPH, 3.42 µM for ABTS, and A0.50 = 2.24 µM for CUPRAC), used as a standard. In addition, thiocarbohydrazone compounds exhibited higher antioxidant activity than carbohydrazones. Electron donating ability and single electron transfer enthalpy calculations predicted that thiocarbohydrazone compounds can perform SET reactions more easily than carbohydrazones.
New β-isatin aldehyde-N,N′-thiocarbohydrazones: preparation, spectroscopic studies and DFT approach to antioxidant characteristics
(2020-12-01) Yakan H.; Bakır T.K.; Çavuş M.S.; Muğlu H.
Abstract: Five new Schiff bases of isatin and its derivatives were prepared from monothiocarbohydrazides and 5-chloro isatin. The chemical structures of the synthesized compounds were performed by 1H NMR, 13C NMR, and FT-IR spectroscopic techniques and elemental analysis. The in vitro antioxidant activities of all the products were determined by 1,1-Diphenyl-2-Picryl Hydrazyl free radical scavenging method. It also examined the antioxidant properties of the compounds based on quantum chemical calculations as well as supporting experimental spectroscopic data. Theoretical calculations carried out at B3LYP correlation functional with 6-311++g(2d,2p) basis set. Some chemical reactivity descriptors obtained from AIM, NCI, and ELF analysis were used to reveal the relationship between the electronic and antioxidant properties of the compounds. Furthermore, the bond lengths, charge densities, potential energy densities, inter-atomic dipole moments, and delocalization indices of the active phenolic hydrogen bonds of the compounds were shown to be parameters that can be used to determine the antioxidant properties of compounds. Graphic Abstract: New β-isatin aldehyde-N,N′-thiocarbohydrazones were synthesized. Structures of synthesized molecules were clarified using spectroscopic methods. Antioxidant activities of the compounds were tested by the DPPH method. AIM, NCI, and ELF analysis were performed to investigate the relationship between the electronic properties and antioxidant activity.[Figure not available: see fulltext.]
Novel asymmetric biscarbothioamides as Alzheimer's disease associated cholinesterase inhibitors: synthesis, biological activity, and molecular docking studies
(2024-06-03) Muğlu H.; Yakan H.; Erdoğan M.; Topal F.; Topal M.; Türkeş C.; Beydemir Ş.
Novel carbohydrazones including 5-substituted isatin: Synthesis, characterization, and quantum-chemical studies on the relationship between electronic and antioxidant properties
(2020-05-01) Çavuş M.S.; Yakan H.; Muğlu H.; Bakır T.
1-(5-Chloro-2-oxoindolin-3-ylidene)carbohydrazone (1), 1-(5-fluoro-2-oxoindolin-3-ylidene)carbohydrazone (2), 1-(5-methoxy-2-oxoindolin-3-ylidene)thiocarbohydrazone (3), and 1-(5-methoxy-2-oxoindolin-3-ylidene)carbohydrazone (4) were synthesized from 5-substituted isatins and thiocarbohydrazide/carbohydrazide under reflux in absolute ethanol. Fourier transform-IR, 1H NMR, and 13C NMR spectroscopy and elemental analysis were used to characterize the structures of the compounds. Experimental spectroscopic data were supported by theoretical data obtained with the Becke three-parameter Lee–Yang–Parr (B3LYP) correlation functional with cc-pvtz and 6–311++g(2d,2p) basis sets. The antioxidant properties of the compounds were examined on the basis of the quantum-chemical calculations. Analysis by quantum theory of atoms in molecules (QTAIM), density of states analysis (DOS), frontier molecular orbital eigenvalues (FMO), and other chemical reactivity descriptors were used to elucidate the relationship between electronic and antioxidant characteristics of the compounds. The in vitro antioxidant activity of all the compounds were evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging method. Antioxidant activity was in the following order: 3 > 4 > butylated hydroxytoluene (BHT) > 2 > 1. Theoretical investigations of the structural and antioxidant properties were performed.
Phthalocyanines including 2-mercaptobenzimidazole analogs: Synthesis, spectroscopic characteristics, quantum-chemical studies on the relationship between electronic and antioxidant properties
(2020-02-15) Yakan H.; Çavuş M.; Güzel E.; Arslan B.; Bakır T.; Muğlu H.
In this study, peripherally tetra 2-mercaptobenzimidazole group substituted cobalt and indium phthalocyanine complexes (2 and 3) were prepared from 4-(benzo[d]imidazole-2-ylthio)phthalonitrile (1) for the first time. Antioxidant behaviors and theoretical calculations of benzimidazole-substituted metallophthalocyanines are presented. The structures of these compounds were determined by the spectroscopic methods (IR, 1H NMR, UV–Vis and mass spectroscopies) and elemental analysis. Antioxidant activities of the compounds (1–3) were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Antioxidant activity was followed by 1 > 3 > 2 > Trolox. In addition, density functional theory (DFT) calculations were carried out to determine the stable electronic structure, charge density distributions, FMO energy eigenvalues, and electronegativity of the ligand (1) and complexes (2 and 3). NBO and QTAIM analysis were performed to investigate the relationship between the electronic properties and antioxidant activity of the compounds.
Potential thiosemicarbazone-based enzyme inhibitors: Assessment of antiproliferative activity, metabolic enzyme inhibition properties, and molecular docking calculations
(2022-05-01) Yakan H.; Koçyiğit Ü.M.; Muğlu H.; Ergul M.; Erkan S.; Güzel E.; Taslimi P.; Gülçin İ.
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, 1H-nuclear magnetic resonance (NMR), 13C-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.
Preparation, antioxidant activity, and theoretical studies on the relationship between antioxidant and electronic properties of bis(thio/carbohydrazone) derivatives
(2022-05-01) Muğlu H.; Kurt B.Z.; Sönmez F.; Güzel E.; Çavuş M.S.; Yakan H.
A series of novel bis(thio/carbohydrazone) compounds has been prepared from (thio)/carbohydrazide and various aldehyde derivatives. FTIR, 1H and 13C NMR spectroscopy, and elemental analysis have been used to elucidate the structures of synthesized compounds. Their antioxidant properties have been assessed using the DPPH, ABTS, and CUPRAC methods. Most of the synthesized compounds exhibited antioxidant activity in each assay. The effects of the electronic and structural properties of urea/thiourea groups on the antioxidant properties of the compounds have been investigated, and it was observed that thiourea-based compounds showed better antioxidant activity than structurally similar urea-based compounds. Among them, N′,N‴-1,4-phenylene-bis(methaneylylidene)-bis(N′-2-hydroxybenzylidene)methane-bis(thiohydrazide) (9) and N′,N‴-(1,4-phenylene-bis(methaneylylidene)-bis(N′-2,4-dihydroxybenzylidene)methane-bis(thiohydrazide) (11) showed higher ABTS activity (IC50 = 2.69 μM and 3.24 μM, respectively) than the reference butylated hydroxyanisole (BHA, IC50 = 3.42 μM). Moreover, compound 11 showed the strongest DPPH activity with an IC50 value of 5.77 μM, almost twofold higher than that of BHA (IC50 = 9.55 μM). Structural, spectral, and electronic analyses of the compounds have also been performed by DFT calculations at the B3LYP/6–311++g(2d,2p) level of theory. EDR, NCI, DOS, and QTAIM calculations have been carried out to analyze the bond properties of electronegative atoms and to investigate intramolecular interactions. DFT simulations have also been carried out in order to study the relationship between electronic characteristics and antioxidant activity.
Synthesis of new bis(thiosemicarbazone) derivatives and DFT analysis of antioxidant characteristics in relation to HAT and SET reactions
(2022-12-01) Muğlu H.; Çavuş M.S.; Bakır T.K.; Yakan H.
A series of new bis(thiosemicarbazones) have been synthesized from terephthalaldehyde and various thiosemicarbazides. IR, 1H NMR, 13C NMR spectroscopic methods, and elemental analysis were used to characterize the identification of the synthesized compounds. The in vitro antioxidant activity determinations were made using the 1,1-Diphenyl-2-Picryl Hydrazil (DPPH) method. The compounds exhibited very different inhibition activities with the change of groups attached to the bis(thiosemicarbazone) structure. The spectral and electronic properties of the compounds were investigated by DFT calculation. Intramolecular interactions were analyzed by QTAIM and IRI calculations. Intrinsic bond strength index values of the N–H bonds, Fukui indices and the local electron affinities of the compounds were calculated, and the relationships between the compounds and their antioxidant activity properties were investigated. The SET and HAT mechanisms in the reactions of the compounds with DPPH were affected by the concentration of the compounds, and the possible effects of the parameters supporting the dominant characteristics in these reactions were examined using theoretical data.
Synthesis, characterization, quantum chemical calculations and antioxidant activity of new bis-isatin carbohydrazone and thiocarbohydrazone derivatives
(2019-11-15) Muğlu H.; Çavuş M.; Bakır T.; Yakan H.
1,5-Bis(5-chloro-2-oxoindolin-3-ylidene)thiocarbohydrazone (3), 1,5-Bis(5-metoxy-2-oxoindolin-3-ylidene)thiocarbohydrazone (4), 1,5-Bis(5-metoxy-2-oxoindolin-3-ylidene)carbohydrazone (5) were obtained from isatins and thio/carbohydrazides under reflux in absolute ethanol. The structures of these synthesized compounds were determined using FT-IR, 1H NMR, 13C NMR spectroscopy, and elemental analysis. Quantum chemical calculations were also performed at B3LYP/6-311++G(2d,2p) level in order to obtain information about the molecular geometries and electronic data, such as HOMO-LUMO energy eigenvalues and density of states (DOSs). In addition, structural and antioxidant properties of the compounds were studied theoretically. QTAIM analysis was performed to investigate the relationship between intramolecular interactions, electronic data and antioxidant activity. The in vitro antioxidant activity of all the compounds was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method. Antioxidant activity was followed by Ascorbic acid > 3 > 4 > 5.
Synthesis, spectroscopic studies, and antioxidant activities of novel thio/carbohydrazones and bis-isatin derivatives from terephthalaldehyde
(2020-01-01) Muǧlu H.; Yakan H.; Bakir T.K.
New bis(isatins-thio/carbohydrazones) based on Schiff bases were prepared from terephthalaldehyde bis-carbohydrazone 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.