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.     

Ultrasonic Assisted Synthesis of Naphthalene Substituted Schiff Base Derivatives and Their Antioxidant Activity Studies

New Schiff base derivatives, 2,2′‐[naphthalene‐2,7‐diylbis(oxy)]bis[N′‐substituted acetohydrazide] ( 4a‐m ) were synthesized by the acid catalyzed condensation of aryl/hetero aromatic aldehydes with 2,2′‐ [naphthalene‐2,7‐diylbis(oxy)]diacetohydrazide ( 3 ) under reflux temperature and ultrasonic irradiation. These Schiff base derivatives were confirmed through spectral characterization using IR, ¹H NMR, ¹³C NMR and mass spectra. All the synthesized compounds were screened for their antioxidant activity using DPPH free radical scavenging method.     

Design,synthesis, characterization,computational study and in-vitro antioxidant and anti-inflammatory activities of few novel 6-aryl substituted pyrimidine azo dyes

A series of 6-aryl substituted pyrimidine azodyes were synthesized by coupling of phenyl pyrimidine 2-amine with different aromatic amines. The synthetic compounds were screened for their in-vitro antioxidant and anti-inflammatory activities. The characterization of the synthesized compounds was carried out by IR, ¹H NMR, ¹³C NMR and Mass spectrophotometry. Computational study of designed compounds was done by OCHEM, Molinspiration cheminformatics, Datawarrior, and Swiss ADME. DPPH assay was used to determine the antioxidant activity and heat hemolysis method for anti-inflammatory 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.     

Synthesis,characterization, DNA binding,antibacterial, and antioxidant activity of new bis-phthalimides

New bis-phthalimides were synthesized by 2: 1 condensation of phthalic anhydride and tetrachlorophthalic anhydride with 1,2,4-triazole-3,5-diamine, pyridine-2,6-diamine, and 4-hydroxypyrimidine- 2,6-diamine. The synthesized compounds were characterized by elemental analyses and IR, ¹H NMR, and mass spectra. Their interaction with calf thymus DNA (ct-DNA) was studied by UV-Vis spectrophotometry, cyclic voltammetry, and viscosity measurements, which revealed intercalative mode of binding to ct-DNA. Antibacterial activity of the synthesized compounds against Escherichia coli and Streptococcus mutans was assessed in vitro by the agar well diffusion method. The antioxidant activity of these compounds was estimated by DPPH assay.     

Cytotoxicity, antioxidant, and antimicrobial activities of novel 2-quinolone derivatives derived from coumarin

Coumarins are important and useful compounds with diverse pharmacological properties. New coumarin derivatives namely N-aminoquinoline-2-one 1, 1-((4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)methyleneamino)quinolin-2(1H)-one 2 and 1,1′-(1E,1′E)-(1,4-phenylenebis(methan-1-yl-1-ylidene))bis(azan-1-yl-1-ylidene)diquinolin-2(1H)-one 3, were synthesized and characterized by UV–Vis, FT-IR, and NMR spectra in addition of elemental analysis. The synthesized compounds (2 and 3) show considerable anticancer activity against HEp-2 cell line. Synthesized compounds (2 and 3) were tested against selected types of microbial organisms and showed significant activities. The free-radical scavenging activity of synthesized compounds (2 and 3) have been determined by their interaction with the stable free-radical 1,1-diphenyl-2-picrilhydrazyl (DPPH) and all the compounds have shown encouraging antioxidant activities.     

Synthesis,antioxidant activity,and α-glucosidase enzyme inhibition of α-aminophosphonate derivatives bearing piperazine-1,2,3-triazole moiety

A novel series of piperazine-1,2,3-triazole bearing dimethyl(((2-(4-((1H-1,2,3-triazole-4-yl)methyl)piperazin-1-yl)ethylamino)(2-hydroxyaryl)methyl)phosphonate derivatives have been prepared via copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) (Click Reaction) and Schiff base reactions. The synthesized compounds were confirmed by spectral characterization (¹H, ¹³C and ³¹P NMR, and mass). The title compounds were evaluated for in vitro alpha glucosidase enzyme inhibition and in vitro antioxidant activity using DPPH and H₂O₂ methods.     

8-羟基喹啉共轭连接芳香杂环化合物的合成、荧光性质及生物活性的研究

设计合成了4个8-羟基喹啉共轭联接芳香杂环化合物来研究它们在有机发光材料和荧光探针的潜在应用。用IR, 1H NMR, 13C NMR, MS, UV确认了这些新化合物的结构。测定了化合物1-4的荧光性质,发光衰变时间和量子产率,并用密度泛函方法研究了4个化合物的几何结构和荧光发射波长的关系。在调控骨髓间充质干细胞增殖以及清除DPPH自由基的活性测试结果表明,这些化合物具有促进小鼠骨髓间充质干细胞的增殖的活性及良好的抗氧化性。     

Experimental and theoretical investigations of the antioxidant activity of 2,2′‐methylenebis(4,6‐dialkylphenol) compounds

The antioxidant activity of two primary antioxidants, 2,2′‐methylenebis(4‐methyl‐6‐tert ‐butylphenol) (MMBPH2) and 2,2′‐methylenebis(4,6‐di‐tert ‐butylphenol) (MDBPH2), has been studied using the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) method. The synthesized compounds have been successfully characterized systematically using elemental analyses, infrared, ¹H NMR and ¹³C NMR spectra and GC–MS. Importantly, it has been found that the compound MMBPH2 in particular is more active in DPPH radical scavenging. In addition, density functional theory calculations (B3LYP) have been used to predict the antioxidant activity and predict structural geometries of the compounds in the gas phase.     

Synthesis and antioxidant properties of organosulfur and organoselenium compounds derived from 5-substituted-1,3,4-oxadiazole/thiadiazole-2-thiols

Organosulfur and organoselenium compounds were synthesized in good yields through reaction with 5-aryl-1,3,4-oxadiazole/thiadiazole-2-thiols and α-chloromethyl arylselenides or 4-(chloromethyl)-2-methylthiazole/2-(chloromethyl)-5-phenyl-1,3,4-oxadiazole. The obtained compounds were characterized by NMR and mass spectroscopy and screened for in vitro antioxidant activity as reflected by free radical scavenging against 2,2-diphenyl-2-picrylhydrazyl (DPPH) and reduction of molybdenum (VI) to molybdenum (V). The compounds have significant antioxidant properties in both applied methodologies.     

Synthesis,antimicrobial and antioxidant activity of bis sulfonamide/carbamate derivatives of bis-(4-aminophenyl) methane

A series of new bis sulfonamide/carbamate derivatives of bis-(4-aminophenyl)methane 3 ( a–d )/ 5 ( a–f ) were synthesized from bis-(4-aminophenyl)methane ( 1 ) using various pharmacologically active sulfonyl chlorides 2 ( a–d ) and carbonochloridates 4 ( a–f ) in high yields. The structures of all the newly synthesized compounds were characterized by the Infrared spectroscopy, NMR (¹H and ¹³C), mass, and elemental analyses. Further, all the synthesized compounds were tested for the antioxidant activity by using 2, 2-diphenyl-1-picrylhydrazyl, NO, and H₂O₂ scavenging methods and antimicrobial activity. Most of the compounds exhibited good antioxidant and antimicrobial activities.     

Bis benzothiophene Schiff bases: synthesis and in silico-guided biological activity studies

Since benzo [ b ] thiophene scaffold is one of the privileged structures in drug discovery as this core exhibitsactivities for different biological problems, in this study bis (benzo[ b ]thiophene-2-yl) alkyl methanimine derivatives (1-9) were synthesized by reacting benzo[ b ]thiophene-2-carbaldehyde with diamines. All newly compounds were characterized by IR, ¹H NMR and ¹³C NMR spectroscopic methods. Synthesized compounds were investigated using binary QSARbased models on therapeutic activity prediction of synthesized compounds and they showed high predicted activities in following diseases: bacterial, angina, allergy, depression and obesity. Thus, they were then tested for their antimicrobial and antileishmanial activities as a result of this theoretical study. Compound 1(N, N’- (propane-1,3-diyl) bis (1-(benzo [ b ] thiophene-2-yl)) methanimine) was found the most active compound in both diseases. Thus, its molecular docking studies were also carried out.     

Novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazine derivatives embedded with benzimidazole moiety as potent antioxidants

Fourteen novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazine derivatives bearing benzimidazole moiety ( 7a-n ) have been synthesized using the one-pot nitro reductive cyclization method. All the synthesized compounds were confirmed by ¹H nuclear magnetic resonance (¹H NMR), ¹³C NMR, fourier-transform infrared (FT-IR), mass spectrum, and elemental analyses. All the title compounds were subjected to in vitro antioxidant activity. The free radical scavenging activity of the compounds was examined using DPPH, nitric oxide, and superoxide radical scavenging methods. The results demonstrated that compound 3-(2-(3,4-dimethoxyphenyl)-1-propyl-1H-benzo[d]imidazol-5-yl)-6-4-tolyl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine ( 7c ) was potent in scavenging both DPPH and nitric oxide radical with IC₅₀ values of 13.57 and 18.55 μg/ml when compared to the standard with IC₅₀ values of 23.75 and 23.14 μg/ml, respectively, which was due to the presence of electron-donating groups. The activity was found to decline when electron-donating groups were replaced by electron-withdrawing groups. Moderate scavenging activity was observed for the superoxide radical. Structure activity relationship and physiochemical properties were studied for all the derivatives.     

Synthesis and antioxidant activities of novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters and ketimines

Novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters 2a–g ( 3a–g ) and N‐aryl (and N‐alkyl) ketimines 2h–j ( 3h–j ) were synthesized in high yields (80–99%) from their corresponding γ‐ and δ‐keto esters and ketones in this study. The structures of the synthesized compounds were clarified by Fourier transform infrared (FT‐IR), NMR (¹H and ¹³C), mass spectrometry, and elemental analyses. Isomerizations [E/Z] were also determined by their ¹H NMR spectra. The free‐radical scavenging activity of imines was evaluated using the 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) method. The relationships between the structure and antioxidant activity of these compounds are discussed. Among these compounds, 2a–c (at the concentration 1000 μg/mL) exhibit high antioxidant activity similar to those of the standards (butylated hydroxyanisole [ BHA], butylated hydroxytoluene [ BHT], and ascorbic acid).     

Design of Novel Binuclear Phthalocyanines formed by Dioxyphenyl Bridges: Synthesis and Investigation of Thermal and Antioxidant Properties

4, 4′‐(1, 4‐Phenylenebis(oxy)diphthalonitrile was synthesized by reaction of hydroquinone with 4‐nitrophthalonitrile. Binuclear metallophthalocyanines 2–4 were obtained by the reaction between 4, 4′‐(1, 4‐phenylenebis(oxy)diphthalonitrile and 4‐(benzo [d] 1 , 3 dioxol‐5‐ylmethoxy)phthalonitrile in the presence of metal salts. These new compounds were characterized by using elemental analysis, FTIR, ¹H‐NMR and UV/Vis spectroscopic data. Thermal properties of phthalocyanines 2‐4 were investigated by TG and DTA. In addition, antioxidant properties of compounds II , 3 and 4 were investigated. Their radical‐scavenging capacity and chelating effects was fully studied. The maximum 1, 1‐diphenyl‐2‐picrylhydrazyl radicals (DPPH) were obtained from compound 3 . Chelating effects on ferrous ions were 91.6 % at concentration of 100 mg L^–1 with compound II .     

Study of reaction of gossypol and its imino derivatives with 2,2-diphenyl-1-picrylhydrazyl

Structures and state in solutions of natural polyphenol gossypol and four its imino derivatives, three of which were synthesized for the first time, were studied by IR and NMR spectroscopy, and by quantum chemistry. The reaction of these compounds with 2,2-diphenyl-1-picrylhydrazyl (DPPH) in ethanol was examined. The antioxidant activity of the studied compounds in the reaction with DPPH was evaluated using the values of the stoichiometric coefficients of reaction, EC₅₀, T ₁^2/DPPH and AE parameters. Gossypol hydrazones were shown to be 5–10 times more efficient, while Schiff base to be less efficient as antioxidants in comparison with gossypol itself. The influence of metal cations on the antioxidant activity of gossypol derivatives was studied.     

Synthesis, ab initio calculations, thermal, thermodynamic and antioxidant properties of some oxovanadium(IV) complexes containing N2O2 set of donor atoms

The formation constants of some oxovanadium(IV) binary complexes containing Schiff bases resulting from condensation of salicylaldehyde with aniline and with its derivatives were determined spectophotometrically. The synthesized compounds were characterized by analytical and different physico-chemical techniques like ¹H NMR, IR, elemental analysis, mass and UV-Vis spectral studies. The IR spectra affirm that coordination takes place through azomethine nitrogen and phenolate oxygen. Three of the VO(IV) Schiff base complexes i.e. bis(salicylideneaniline)oxovanadium(IV), [VO(L¹)₂], bis(salicylidene-4-methoxyaniline) oxovanadium (IV), [VO(L²)₂] and bis(salicylidene-4-cyanoaniline)oxovanadium(IV), [VO(L¹⁰)₂], were studied by thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathways. The number of steps and, in particular, the starting temperature of decomposition of these complexes depends on the equatorial ligand. The complexes screened for antioxidant activity and the ab initio calculations were carried out to determine the structural and the geometrical properties of a typical vanadyl salicylideneaniline complex, [VO(L¹)₂].     

One-pot multicomponent synthesis of indol-3-yl-hydrazinyl thiazoles as antimicrobial agents

A series of novel mono- and bis(indol-3-yl)hydrazinyl thiazole derivatives were efficiently synthesized via one-pot cyclocondensation of mono- or bis(indole-3-carbaldehyde), thiosemicarbazide, and phenacyl bromides. The structure of the products was confirmed by Fourier-transform infrared (FT-IR), ¹H nuclear magnetic resonance (NMR), and ¹³C NMR spectra. All synthesized compounds were evaluated for in vitro antibacterial activity against Gram-positive (Bacillus subtilis and Micrococcus luteus) and Gram-negative bacteria (Pseudomonas aeruginosa and Salmonella enteritis). Among the compounds screened, a few were found to be highly effective antibacterial agents. The bis-compounds with OCH₃ donating group exhibited good activity against the Gram-positive bacteria.     

Synthesis,antibacterial, and antioxidant activities of naphthyl-linked disubstituted 1,2,3-triazoles

Here, click synthesis of 15 naphthyl-linked disubstituted 1,2,3-triazoles has been carried out by the reaction between 1-(prop-2-yn-1-yloxy)naphthalene and aromatic azides. The structure elucidation of the synthesized compounds was carried out by FTIR, ¹H NMR, ¹³C NMR, and HRMS techniques. Further, the compound 7f was confirmed by X-ray crystallography (CCDC 1876891). The synthesized compounds were explored for antibacterial activity against Bacillus cereus, Escherichia coli, and Staphylococcus aureus. Biological evaluation of synthesized 1,2,3-triazoles revealed moderate to good antibacterial activity against the tested strains. The antioxidative behavior of synthesized compounds manifested the remarkable free radical scavenging activity using DPPH assay.     

Metallo Phthalocyanines bearing 2‐Isopropyl‐6‐methylpyrimidin‐4‐yloxy Substituents: Synthesis,Characterization, Aggregation Behavior,Antioxidant and Antibacterial Activity,and Electronic Properties

A novel phthalonitrile derivative bearing 2‐isopropyl‐6‐methylpyrimidin‐4‐yloxy substituents at peripheral positions was synthesized by a nucleophilic substitution reaction. Metallophthalocyanines were obtained from the reaction of the novel phthalonitrile with metal Zn, Cu, Co, and Ni salts. The characterization of the compounds was performed using elemental analysis as well as UV/Vis, FT‐IR, and ¹H‐NMR spectroscopy. The aggregation behaviors of phthalocyanine complexes were also investigated. These metallophthalocyanines do not show any aggregation behavior between 10^–4–10^–6 M concentration range in THF. The antioxidant activities of the synthesized compounds were evaluated using three different tests: 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, metal chelating activity, and reducing power assays. All the compounds exhibited various antioxidant activities. In addition, antimicrobial activity of the compounds was tested over four gram positive and two gram negative bacteria. Moreover, the ground‐state geometries of the complexes were optimized using density functional theory (DFT) methods at B3LYP/6‐31G(d, p) level in order to obtain information about the 3D arrangements and electronic structure.