Synthesis,characterization, and antioxidant activity of a new Gd(III) complex

A new gadolinium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in molar ratio of 1:3 to ligand. The structure of the complex was determined by elemental analysis, FT-IR, and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Gd(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygens. The newly synthesized gadolinium(III) complex of 5-aminoorotic acid (GdAOA) showed antioxidant properties. The antioxidant activity of both HAOA and GdAOA was related with their electron donor properties.     

Synthesis,characterization, and antioxidant activity of heterocyclic Schiff bases

Schiff base derivatives have gained great importance due to revealing a great number of biological properties. Schiff bases were synthesized by treatment of 4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one ( 1 ) with various aldehydes in methanol at reflux. In addition, diamine was reacted with an aldehyde to yield the corresponding Schiff bases. The structures of synthesized Schiff bases were elucidated by spectroscopic methods such as microanalysis, ¹H-NMR, ¹³C-NMR, and FTIR. Antioxidant activities of synthesized Schiff bases were carried out using different antioxidant assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH^•) scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power activity. (E)-4-((1H-indol-3-yl)methyleneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one ( 3 ), (E)-1,5-dimethyl-4-((2-methyl-1H-indol-3-yl)methyleneamino)-2-phenyl-1H-pyrazol-3(2H)-one ( 5 ), (E)-1,5-dimethyl-2-phenyl-4-(thiophen-2-ylmethyleneamino)-1H-pyrazol-3(2H)-one ( 7 ), (E)-1,5-dimethyl-2-phenyl-4-(quinolin-2-ylmethyleneamino)-1H-pyrazol-3(2H)-one ( 9 ), (1S,2S,N1,N2)-N1,N2-bis((1H-indol-3-yl)methylene)cyclohexane-1,2-diamine ( 11 ), and (1S,2S,N1,N2)-N1,N2-bis((2-methyl-1H-indol-3-yl)methylene)cyclohexane-1,2-diamine ( 12 ) were synthesized in high yields. Compound 5 displayed a good ABTS^•+ activity. Compound 3 revealed the outstanding activity in all assays. Compound 7 has the best-reducing power ability in comparison to other synthesized compounds. Although compounds 5, 11, 12 are new, compounds 3, 7, 9 are known. Due to revealing a good antioxidant activity, the synthesized compounds ( 3, 5, 7 ) have the potential to be used as synthetic antioxidant agents.     

Synthesis, characterization, and antioxidant activity of some ebselen analogues

Simple synthetic routes for several analogues of the anti-inflammatory organoselenium drug, ebselen, are described. The compounds are characterized by (1)H, (13)C, and (77)Se NMR spectroscopy and mass spectral techniques and, in some cases, by single-crystal X-ray diffraction studies. The glutathione peroxidase (GPx)-like antioxidant activity has been studied by using H(2)O(2), tBuOOH, and Cum-OOH as substrates, and thiophenol (PhSH, 4-Me-C(6)H(4)SH) and glutathione (GSH) as cosubstrates. Density functional theory (DFT) calculations have been performed on these systems to understand the effects of various substituents on the (77)Se NMR chemical shifts; these results have been compared with the experimental data. The experimental and theoretical results suggest that the presence of a phenyl substituent on the nitrogen atom is important for the antioxidant activity of ebselen. While ebselen and its analogues are poor catalysts in aromatic thiol assays, these compounds exhibit high GPx activity when GSH is used as the cosubstrate. The poor catalytic activity of ebselen analogues in the presence of aromatic thiols such as PhSH and 4-Me-C(6)H(4)SH can be ascribed to the undesired thiol exchange reaction that takes place at the selenium center due to SeO nonbonding interactions. To understand the effects of different peroxides on the catalytic activities, we have determined the initial rates at various concentrations of GSH and peroxides. These data suggest that the nature of peroxide has little effect on the catalytic efficiencies, although the initial reaction rates observed with hydrogen peroxide were found to be higher than that with tBuOOH and Cum-OOH. In contrast to the effect of peroxides, the nature of thiols appears to have a dramatic effect on the catalytic activity of ebselen and its related derivatives.     

Synthesis, characterization and antioxidant activity of angiotensin converting enzyme inhibitors

Angiotensin converting enzyme (ACE) catalyzes the conversion of angiotensin I (Ang I) to angiotensin II (Ang II). ACE also cleaves the terminal dipeptide of vasodilating hormone bradykinin (a nonapeptide) to inactivate this hormone. Therefore, inhibition of ACE is generally used as one of the methods for the treatment of hypertension. 'Oxidative stress' is another disease state caused by an imbalance in the production of oxidants and antioxidants. A number of studies suggest that hypertension and oxidative stress are interdependent. Therefore, ACE inhibitors having antioxidant property are considered beneficial for the treatment of hypertension. As selenium compounds are known to exhibit better antioxidant behavior than their sulfur analogues, we have synthesized a number of selenium analogues of captopril, an ACE inhibitor used as an antihypertensive drug. The selenium analogues of captopril not only inhibit ACE activity but also effectively scavenge peroxynitrite, a strong oxidant found in vivo.     

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.     

肉苁蓉多糖锌的制备、表征及抗氧化活性

采用超声酶法辅助提取肉苁蓉粗多糖,并用季铵盐沉淀法对肉苁蓉粗多糖进行精制,获得肉苁蓉精制多糖(UCEP1);以UCEP1和硫酸锌为原料,制备了肉苁蓉多糖锌配合物(UCEP1-Zn),对其结构进行了表征,并研究其抗氧化活性.结果表明,肉苁蓉粗多糖收率及含量分别为22.31%和48.50%,UCEP1中多糖含量为70.13%;UCEP1-Zn中-OH和-COO~-和Zn~(2+)发生了配位,其中锌含量为7.57%,且多糖链构象及多糖分子表面形貌发生变化;UCEP1-Zn的抗氧化能力显著高于UCEP1,且对ABTS~+自由基清除活性最好.该研究可为肉苁蓉多糖、新型锌营养素补充剂以及锌功能配合物的研究和利用提供参考.     

Synthesis, characterization and antioxidant capacity of naringenin-oxime

The recognition of the benefits of polyphenolic antioxidants is eliciting increasing interest in the search for new polyphenolic derivatives with improved antioxidant activity. Since naringenin (4',5,7-trihydroxyflavanone) (NG) is one of the most abundant citrus and grapefruit polyphenolics and flavanone oximes were used in the synthesis of anticancer and radioprotector compounds having antiradical activity, the corresponding oxime of NG, naringenin oxime (NG-Ox), was synthesized and investigated. The structure of NG-Ox was characterized by FT-IR, (1)H NMR, elemental analysis, and the synthesized compound was screened for its antioxidant capacity by using the cupric reducing antioxidant capacity (CUPRAC) method. Trolox equivalent antioxidant capacity (TEAC) of NG-Ox was measured to be higher than that of the parent compound, NG. Other parameters of antioxidant activity (scavenging effects on *OH, O(2)*-, and H(2)O(2)) of NG-Ox were also determined.     

Synthesis,characterization, crystal structure,and biological activity of the copper complex

This work reports the synthesis and biological activity of the copper complex with 2–thenoyltrif-luoroacetone (HTTA). The complex was characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analysis. The crystal structure was determined by single-crystal X-ray diffraction. The complex exists as a parallelogram with four coordination sites occupied by the carbonyl oxygen atoms from HTTA. The antibacterial activity test shows that the complex exhibits better antibacterial ability against Escherichia coli and Staphylociccus aureus (MIC were about 180, 150 μg/ml, respectively) and can be considered as broad-spectral antimicrobial. The antitumor activity of the copper(II) complex is tested by methyl thiazolyl tetrazolium assays against human Leukemia cells K562. The copper(II) complex exhibits potent antitumor effects against K562 cell lines. The IC₅₀ value of the complex is about 0.01 μg/ml. The research shows that the complex can inhibit K562 tumor cell growth and generation and induce apoptosis. The inhibition ratio is accele by increasing the dosage and has a significant positive correlation with medication dosage.     

Synthesis,characterization and antioxidant activity of bis (arylsulfonylmethyl/arylaminosulfonylmethylazolyl) pyridines

A new class of bis(arylsulfonylmethylazolyl)pyridines and bis(arylaminosulfonylmethyl-azolyl)pyridines were synthesized from the synthetic intermediates methyl arylsulfonylacetic acid hydrazide and methyl arylaminosulfonylacetic acid hydrazide adopting a green methodology-ultrasonication. All the synthesized compounds were resulted in higher yield and in shorter reaction times. The spectral parameters such as IR, ¹H NMR, ¹³C NMR, mass and microanalyzes were used to determine the structures of all the synthesized compounds and were assayed for antioxidant activity. The bis(arylaminosulfonylmethylazolyl)pyridines showed higher radical scavenging activity than the bis(arylsulfonylmethylazolyl)pyridines. Besides, unsubstituted, and methyl substituted compounds exhibited greater activity. Among all the tested compounds 8b and 11b were identified as potential antioxidants.     

Synthesis,characterization, and biological activity of a Schiff-base Zn(II) complex

Preparation and crystal structure of {4-chloro-2-[(2-morpholinoethylimino)methyl]phenolato} methanolchlorozinc(II) are reported. The X-ray structure reveals highly distorted square pyramidal geometry around zinc, binding to one phenolate O and two imine N atoms of the Schiff base, one methanol and one chloride. The complex and its ligand were tested in vitro for antibacterial and cytotoxic activity with a wide range of bactericidal activity and significant cytotoxic activity.     

Synthesis,structure and antioxidant activity of sulfur-containing tetrakisphenol

3-[2-(3,5-Di-tert-butyl-4-hydroxyphenylsulfanyl)acetoxy]2,2-bis[2-(3,5-di-tert-butyl-4-hydroxyphenylsulfanyl) acetoxymethyl]propyl 3,5-di-tert-butyl-4-hydroxyphenylsulfanylacetate was synthesized. Its structure was determined by means of ¹H and ¹³C NMR spectroscopy and X-ray-diffraction analysis. This compound was found to possess high antioxidant activity in the conditions of auto-oxidation of low-pressure polyethylene.     

Synthesis,characterization, antioxidant and anti‐diabetic activities of a novel protein–vanadium complex

The protein–vanadium complex was successfully synthesized and systematically characterized using electron paramagnetic resonance, Fourier transform‐infrared spectroscopy and thermogravimetric analysis. The antioxidant activity analysis indicated that it had better radical scavenging activity on 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), 2,2′‐azinobis (3‐ethylbenzothiazoline)‐6‐sulfonic acid (ABTS) and O₂^? compared with the free protein and vanadate. Additionally, the complex exhibited high anti‐diabetic activity against Saccharomyces cerevisiae α‐glucosidase and rat intestinal maltase with IC₅₀ values of 258.53 and 72.41 μg/ml, respectively. Kinetics study showed that the complex was a mixed inhibition type against S. cerevisiae α‐glucosidase and uncompetitive inhibition type against rat intestinal maltase. These indicated that the complex with antioxidant and anti‐diabetic potential could be used for lowering blood glucose that might be caused by insufficient secretion of insulin in the body or excess fat storage. Our findings provide a new protein–vanadium complex for further use in diabetes mellitus or obesity.     

Synthesis,characterization, and antibacterial activity of a manganese(II) complex of triaryltriazole

A manganese(II) complex of 4-(4-methylphenyl)-3,5-bis(2-pyridyl)-4H-1,2,4-triazole (MBPT) was synthesized and characterized by X-ray crystallography. [Mn(MBPT)₂(H₂O)₂](ClO₄)₂?·?4H₂O is a divalent mononuclear manganese(II) complex with manganese coordinated to four nitrogens from two triazole ligands and two oxygens from two water molecules in a slightly distorted octahedral geometry. The complex and ligand were tested in vitro for their antibacterial activities. The title complex showed a wide range of bactericidal activities.     

Synthesis,characterization, and antioxidant and anticholinesterase activities of pyrazolo derivatives

Twenty-four pyrazolo derivatives (1–4)(a-f) were synthesized and characterized by FTIR, ¹H, and ¹³C NMR (Nuclear Magnetic Resonance), and elemental analysis. The synthesized compounds were also investigated for their antioxidant and anticholinesterase activities. The compounds (3–4)(a-f) carrying morpholine ring were more active than the piperidinyl containing compounds (1–2)(a-f) in both activities. The compound 4f showed higher activity in both assays as compared with the others. Additionally, the anticholinesterase activity test provided higher values than the galantamine in the BChE assay. Therefore, compound 4f can be used as anticholinesterase agent and/or anticholinesterase assay standard.     

CCC-N-heterocyclic carbene pincer complexes: Synthesis, characterization and hydroamination activity of a hafnium complex

Our methodology for the stoichiometric preparation of CCC-NHC pincer complexes of Zr has been extended to Hf. The CCC^Bu-NHC pincer Hf complex has been characterized by X-ray crystal structure analysis. Catalytic activity in the intramolecular hydroamination/cyclization of unactivated alkenes is reported and compared to the recently reported Zr analog. An improved, scaled-up CuO-catalyzed aryl amination of 1,3-dibromobenzene and an improved salt formation methodology for preparation of bis(butyl-imidazolium)benzene are reported also.