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681.
Mohammad Mazloum-Ardakani Mohammad Ali Sheikh-Mohseni Hadi Beitollahi Ali Benvidi Hossein Naeimi 《中国化学快报》2010,21(12):1471-1474
<正>The electrochemical behavior of vitamin C(ascorbic acid or AA) is investigated on the surface of a carbon-paste electrode modified with TiO_2 nanoparticles and 2,2'-(1,2 butanediylbis(nitriloethylidyne))-bis-hydroquinone(BBNBH).The prepared modified electrode showed an efficient catalytic role in the electrochemical oxidation of AA,leading to remarkable decrease in oxidation overpotential and enhancement of the kinetics of the electrode reaction.This modified electrode exhibits well-separated oxidation peaks for AA and uric acid(UA).The modified electrode is successfully applied for the accurate determination of AA in pharmaceutical preparations. 相似文献
682.
Javad Beheshtian Hadi Behzadi Mehdi D. Esrafili Bahram B. Shirvani Nasser L. Hadipour 《Structural chemistry》2010,21(5):903-908
The effect of water molecule adsorption on the surface of (5,0) zigzag boron nitride nanotube was studied by density functional
theory calculations. Geometrical optimizations were carried out at the B3LYP/6-31+G* level of theory. Six different configurations
of water molecule(s) adsorption process including monomer (1WB and 1WN), dimer (2WB, 2WNN, and 2WBN), and trimer (3WB) clusters
were obtained. The strengths of interactions were analyzed by the equilibrium geometries, binding energies, and charge transfer.
The natural bonding analysis was also performed to investigate electronic properties. The results reveal that the adsorption
of water is more favorable as the water cluster size increases. 相似文献
683.
Mehdi Jalali-Heravi Hadi ParastarHeshmatollah Ebrahimi-Najafabadi 《Journal of chromatography. A》2009,1216(33):6088-6097
The volatile components of Iranian saffron were extracted using ultrasonic solvent extraction (USE) technique and then were separated and detected by gas chromatography–mass spectrometry (GC–MS). Variables affecting the extraction procedure were screened by using a 25−1 fractional factorial design and among them; sample amount, solvent volume, solvent ratio and extraction time were optimized by applying a rotatable central composite design (CCD). The optimum values of factors were: 2.38 g sample, 29.04 mL solvent, 69.23% MeOH solvent ratio and 71.8 min for the extraction time. Forty constituents were identified for Iranian saffron by GC–MS representing 90% of the total peak area. The major components were 2,6,6-trimethyl-1,3-cyclohexadiene-1-carboxaldehyde, namely safranal (26.29%), bicyclo[3,2,0]hept-2-ene-,4-ethoxy-,endo (5.69%), linoleic acid (4.77%), 4-hydroxy-2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde, namely HTCC (4.44%), and nonadecanol (3.32%). Some new compounds were identified for the first time in saffron. In addition, the results of this study were compared with those of Greek saffron. 相似文献
684.
Adibi H Rashidi A Khodaei MM Alizadeh A Majnooni MB Pakravan N Abiri R Nematollahi D 《Chemical & pharmaceutical bulletin》2011,59(9):1149-1152
In this research, synthesis, antimicrobial and antioxidant activities of a series of catecholthioethers having benzoxazole and tetrazole moieties are described. Antimicrobial activity was evaluated by minimum inhibitory concentration (MIC) assay. The synthesized compounds were tested in vitro against three Gram-positive bacteria including Staphylococcus aureus (clinical isolated), Staphylococcus aureus ATCC 25922, Enterococcus faecium (clinical isolated), and two Gram-negative bacteria including Klebsiella pneumoniae (clinical isolated) and Pseudomonas aeruginosa 27853 and the yeast Candida albicans in comparison with control drugs. Microbiological results indicated that the synthesized compounds possessed a broad spectrum of activity against the tested microorganisms at MIC values between 4-256 μg/ml. This shows compounds having tetrazole moiety were the most active against Gram-negative strains, whereas compounds having benzoxazole moiety were more active against Gram-positive ones. Also both of them showed significant antifungal activity against Candida albicans and had lower activity than the compared control drugs (Sulfamethoxazole and Fluconazole). The antioxidant activity was assessed using two methods, including, 1,1-biphenyl-2-picrylhydrazyl (DPPH) radical scavenging, and reducing power assays. Some of the catecholthioether derivatives showed antioxidant activity more than Trolox and butylated hydroxyanisole (BHA) as reference antioxidants. 相似文献
685.
Acute toxicity evaluation, antibacterial, antioxidant and immunomodulatory effects of Melastoma malabathricum 总被引:1,自引:0,他引:1
Alnajar ZA Abdulla MA Ali HM Alshawsh MA Hadi AH 《Molecules (Basel, Switzerland)》2012,17(3):3547-3559
Melastoma malabathricum (MM) is a well-known plant in Malaysian traditional medicine, locally known as senduduk. Its ethanol and aqueous extracts have been used in the present investigation to study the immunomodulatory role on human peripheral blood mononuclear cell (PBMC), and the DPPH, ABTS and FRAP free radical scavenging activities were also measured. Total flavonoids and total phenolic contents were assayed and the antibacterial effect was tested against four species of bacteria; two Gram-positive (Staphylococcus aureus and Streptococcus agalactiae) and two Gram-negative (Escherichia coli and Klebsilla pneumonia). The tests were carried out using the disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Moreover, the acute toxicity was evaluated in vivo on the ethanol extract of MM to establish its safety when administered orally. In our results, both extracts of MM showed abilities to scavenge DPPH and ABTS free radicals, IC(50) values: (11.599 ± 0.84, 10.573 ± 0.58 μmol/L) and (62.657 ± 0.78, 63.939 ± 0.48 μmol/L) for ethanol and aqueous extracts respectively. Indeed the ethanol extract evidenced high phenolic content (384.33 ± 0.005 mg/g), flavonoids contents (85.8 ± 0.009 mg/g) and ferric reducing antioxidant power (33,590 ± 0.038 mmol/g), with high activity against S. aureus and S. agalactiae (11 ± 0.3 and 12 ± 0.6 mm inhibition zones). Likewise, the percentage of peripheral blood mononuclear cells (PBMC) viability was increased in response to MM, IC(50) values (1.781 ± 1.2 and 6.545 ± 0.93 μg/mL) for ethanol and aqueous extracts, respectively. In addition, our results showed that the MM extract is safe even at a high dose of 5,000 mg/kg and has no oral toxicity. These findings suggest the excellent medicinal bioactivity of MM and explain the popularity of this plant in the folk medicine as a remedy for different illnesses. 相似文献
686.
Stengel F Baldwin AJ Bush MF Hilton GR Lioe H Basha E Jaya N Vierling E Benesch JL 《Chemistry & biology》2012,19(5):599-607
Small heat-shock proteins (sHSPs) are molecular chaperones that prevent irreversible aggregation through binding nonnative target proteins. Due to their heterogeneity, these sHSP:target complexes remain poorly understood. We present a nanoelectrospray mass spectrometry analysis algorithm for estimating the distribution of stoichiometries comprising a polydisperse ensemble of oligomers. We thus elucidate the organization of complexes formed between sHSPs and different target proteins. We find that binding is mass dependent, with the resultant complexes reflecting the native quaternary architecture of the target, indicating that protection happens early in the denaturation. Our data therefore explain the apparent paradox of how variable complex morphologies result from the generic mechanism of protection afforded by sHSPs. Our approach is applicable to a range of polydisperse proteins and provides a means for the automated and accurate interpretation of mass spectra derived from heterogeneous protein assemblies. 相似文献
687.
A new electrochemical sensor for determination of isoproterenol(IP) is described.The sensor is based on carbon paste electrode (CPE) modified with 5-amino-2’,4’-dimethoxybiphenyl-2-ol(5ADMB) and takes the advantages of carbon nanotubes(CNTs). Under the optimum pH of 7.0,the oxidation of IP occurs at a potential about 210 mV less positive than that of the unmodified CPE. The oxidation currents increased linearly with two concentration intervals of IP,one is 0.09 to 20.0 |xmol/L and,the other is 20.0 to 400.0μmol/L.The detection limit(3σ) obtained by square wave voltammetry(SWV) was 39.0 nmol/L.The practical application of the modified electrode was demonstrated by determining IP in IP ampoule,urine and human blood serum samples. 相似文献
688.
Salmanzadeh A Romero L Shafiee H Gallo-Villanueva RC Stremler MA Cramer SD Davalos RV 《Lab on a chip》2012,12(1):182-189
In this study, the dielectrophoretic response of prostate tumor initiating cells (TICs) was investigated in a microfluidic system utilizing contactless dielectrophoresis (cDEP). The dielectrophoretic response of prostate TICs was observed to be distinctively different than that for non-TICs, enabling them to be sorted using cDEP. Culturing the sorted TICs generated spheroids, indicating that they were indeed initiating cells. This study presents the first marker-free TIC separation from non-TICs utilizing their electrical fingerprints through dielectrophoresis. 相似文献
689.
A novel bisindole alkaloid, bisleucocurine A (1), consisting of two strychnan skeletons with an N-1-C-17′ and a C-12-C-2′ bridges, was isolated from the leaves of Leuconotis griffithii and the structure was elucidated on the basis of spectroscopic data. Bisleucocurine A (1) showed cytotoxicity against various human cancer cell lines. 相似文献
690.
Hadi Beiginejad Ahmad Bagheri Leila Safdari Yekta Z. B. Nojini 《Journal of inclusion phenomena and macrocyclic chemistry》2010,67(3-4):247-252
Thermodynamics on inclusion complexation of β-cyclodextrin (β-CD) with n-alkylpyridinium chlorides (C n PC, n = 12, 14, 16) were measured by conductivity technique to evaluate the effects of chain length of C n PC and temperature. The data obtained indicate that inclusion complexes S(CD) and S(CD)2 had formed between surfactant and β-CD in aqueous solution. Investigation showed that the K 1 (first equilibrium constant) for S(CD) formation is greater than K 2 (second equilibrium constant) for S(CD)2 formation. It has been found that C12PC forms only the 1:1 complex, while C14PC and C16PC form 1:1 and 1:2 complexes. Thermodynamic parameters of the complexation, i.e. ΔG°, ΔH° and ΔS° have been also calculated. The large values of ΔG° indicate that complexation between surfactant and β-CD is very favorable. 相似文献