The Affinity of Carboplatin to B-Vitamins and Nucleobases

Platinum compounds have found wide application in the treatment of various types of cancer and carboplatin is one of the main platinum-based drugs used as antitumor agents. The anticancer activity of carboplatin arises from interacting with DNA and inducing programmed cell death. However, such interactions may occur with other chemical compounds, such as vitamins containing aromatic rings with lone-pair orbitals, which reduces the anti-cancer effect of carboplatin. The most important aspect of the conducted research was related to the evaluation of carboplatin affinity to vitamins from the B group and the potential impact of such interactions on the reduction of therapeutic capabilities of carboplatin in anticancer therapy. Realized computations, including estimation of Gibbs Free Energies, allowed for the identification of the most reactive molecule, namely vitamin B6 (pyridoxal phosphate). In this case, the computational estimations indicating carboplatin reactivity were confirmed by spectrophotometric measurements.     

布洛芬-烟酰胺共晶制备及其溶解度测定

采用乙醇-水混合溶剂,对布洛芬-烟酰胺共晶的溶液结晶法制备过程进行了研究,制备样品的PXRD和DSC表征结果证明了通过溶液结晶法大规模制备布洛芬 烟酰胺共晶的可行性。制备过程研究结果表明,当混合溶剂中乙醇与水的体积配比为1.82～7.11时,可以制备出布洛芬-烟酰胺共晶;而且随着乙醇与水体积配比的增大,共晶收率呈现先增大再减小的趋势,当体积配比为2.76时,共晶收率达到最大值(76.31%)。还在不同温度下测定了布洛芬-烟酰胺共晶在不同体积配比乙醇-水混合溶剂中的溶解度,结果表明随着温度和乙醇体积比例的升高,布洛芬-烟酰胺共晶的溶解度增大,最后用 Apelblat方程对溶解度数据进行拟合。     

Mediatorless Carbohydrate/Oxygen Biofuel Cells with Improved Cellobiose Dehydrogenase Based Bioanode

Direct electron transfer (DET) between cellobiose dehydrogenase from Humicola insolens ascomycete (HiCDH) and gold nanoparticles (AuNPs) was achieved by modifying AuNPs with a novel, positively charged thiol N‐(6‐mercapto)hexylpyridinium (MHP). The DET enabled the use of the HiCDH enzyme as an anodic biocatalyst in the design of a mediatorless carbohydrate/oxygen enzymatic fuel cell (EFC). A biocathode of the EFC was based on bilirubin oxidase from Myrothecium verrucaria (MvBOx) directly immobilised on the surface of AuNPs. The following parameters of the EFC based on Au/AuNP/MHP/HiCDH bioanode and Au/AuNP/MvBOx biocathode were obtained in quiescent air saturated PBS, pH 7.4, containing: (i) 5 mM glucose‐open‐circuit voltage (OCV) of 0.65 ± 0.011 V and the maximal power density of 4.77 ± 1.34 μW cm⁻² at operating voltage of 0.50 V; or (ii) 10 mM lactose‐OCV of 0.67 ± 0.006 V and the maximal power density of 8.64 ± 1.91 μW cm⁻² at operating voltage of 0.50 V. The half‐life operation times of the EFC were estimated to be at least 13 and 44 h in air saturated PBS containing 5 mM glucose and 10 mM lactose, respectively. Among advantages of HiCDH/MvBOx FCs are (i) simplified construction, (ii) relatively high power output with glucose as biofuel, and (iii) the absence of the inhibition of the HiCDH based bioanode by lactose, when compared with the best previously reported CDH based bioanode.     

XRD and optical microscopic studies of Co(III) complexes containing 5-cyano-6-(4-pyridyl)-2-thiouracil, thymine and adenine bases

Multifunctional ligand 5-cyano-6-(-4-pyridyl)-2-thiouracil (L) was prepared and allowed to react withtrans [Co(en)₂Cl₂]⁺Cl^‡ resulting into [Co(en)₂LCl]²⁺.2Cl^- which upon further reaction with equimolar ratio of ligand [L] gave the complex [Co(en)₂L₂]³⁺.3Cl⁻. These metal complexes were then separately reacted with thymine and adenine bases. Complexes thus prepared after characterization by their elemental analysis, FAB mass and spectral (IR,¹ HNMR, UV-visible) data were studied for their powder X-ray diffraction and optical microscopic characteristics.     

Poultry marketing controls – Inter-laboratory validation of a method to detect previously frozen chicken breasts by determination of HADH activity

EU poultry marketing legislation requires that poultry be marketed either as fresh (chilled) poultry or as frozen (or quick-frozen) poultry. It is not permitted to market poultry which has been previously frozen as if it were fresh. A robust analytical method that is capable of distinguishing between fresh and previously frozen poultry is therefore required for the enforcement of the legislation. A method to detect whether poultry and other meats have been previously frozen was developed and validated by an earlier collaborative study in 1997. The method is based on measuring the HADH activity of intracellular juice pressed from the test samples. The ratio of the HADH activity of sub-samples tested before and after laboratory freezing is compared to a reference cut-off limit, to determine whether the sample has previously been frozen. In a subsequent study in 2010, improvements were made to the analytical procedure and a revised cut-off limit for chicken of 0.5 was determined. The aim of the current study was to validate the improved analytical procedure and the revised cut-off value for chicken via a collaborative trial with 12 European NRLs and 12 UK OCLs. Each laboratory was asked to analyse 24 chicken breast samples and to use the results to determine their thermal history (chilled or previously frozen) according to the SOP provided. All samples were supplied as chilled blind samples. The results of the study showed inter-laboratory variation between the results obtained for chilled and for previously frozen chicken breasts, however despite this, almost all of the samples were correctly identified and reported in terms of their thermal history. Although some reduction in the analytical variability of the method would be beneficial, the results confirmed the suitability of the method and the revised cut-off limit of 0.5 for the official control of marketing of chicken breasts within the EU.     

The Catalysis of NAD^＋ on Methanol Anode Oxidation Electrode for Direct Methanol Fuel Cell

A tentative idea of developing a liquid-catalytic system on methanol anode oxidation was proposed by analyzing the characteristics of methanol anode oxidation in direct methanol fuel cell. The kinetics of methanol oxidation at a glassy carbon electrode in the presence of nicotinamide adenine dinucleotide ( NAD^ ) was investigated. It is found that the current density of methanol oxidation increases greatly and the electrochemical reaction impedance reduces obviously in the presence of NAD^ compared with those in the adsenee of NAD^ . The catalytic activity of NAD^ is sensitive to temperature. When the temperature preponderates over 45℃, NAD^ is out of fuuction of catalysis for methanol oxidation, which is probably due to the denaturation of NAD^ at a relatively high temperature.     

Direct electrochemical regeneration of enzymatic cofactor 1,4‐NADH on a cathode composed of multi‐walled carbon nanotubes decorated with nickel nanoparticles

Multi‐walled carbon nanotubes (MWCNTs) were grown on a stainless steel mesh and decorated with nickel nanoparticles (Ni NPs). The developed Ni NP‐MWCNT material was then used as a cathode in an electrochemical batch reactor to electrocatalytically convert NAD⁺ to enzymatically‐active 1,4‐NADH. The regeneration of 1,4‐NADH was studied at various electrode potentials. At electrode potential of ?1.6 V, a very high recovery (relative amount of 1,4‐NADH in the product mixture) was obtained, 98 ± 1 %. In comparison, to achieve the same recovery on a non‐decorated MWCNT cathode, a much higher cathodic potential was needed (?2.3 V), establishing the importance of Ni NPs on the electrocatalytic activity in reducing NAD⁺ to 1,4‐NADH. It was postulated that hydrogen adsorbs on Ni NPs immobilized on MWCNTs to form Ni‐H_ads, and this activated hydrogen rapidly reacts with neighbouring NAD‐radicals, preventing the dimerization of the latter species, ultimately yielding 1,4‐NADH.     

鸟嘌呤和腺嘌呤吸附和电氧化行为的电化学石英晶体微天平研究

基于压电电化学石英晶体微天平(EQCM)技术,研究了腺嘌呤(A)和鸟嘌呤(G)在裸金电极和多壁碳纳米管(MWCNTs)修饰金电极上的吸附和电氧化行为。结果表明,在金电极上,A的吸附量和氧化电流均比G大,而在MWCNTs/Au电极上,A和G可类似地吸附,但其氧化峰电位负移且氧化峰电流增大,表明MWCNTs对A和G的氧化具有催化作用。实验发现,A和G在裸金电极上氧化的电子转移数分别为5.4(RSD=±2.3%)和1.9(RSD=±1.3%),而在MWCNTs/Au电极上的氧化电子转移数分别为5.1(RSD=±1.8%)和1.5(RSD=±1.6%)。     

Molecularly imprinted polymer for solid phase extraction of nicotinamide in pork liver samples

Aromatic polyamides and polythioamides with pendent chlorobenzylidine rings were synthesized through direct polycondenzation of 2‐(p‐chlorobenzalimino) terephthalic acid with the diamines 4,4′‐oxidianiline (1a), 4,4′‐methylenediamide (1b), 4,4′‐diaminodiphenyl sulfone (1c), and thioamines 4,4′‐(bisthiourea) diphenyl ether (3a), 4,4′‐(bisthiourea) diphenyl methane (3b), 4,4′‐(bisthiourea) diphenyl sulfone (3c), respectively, in DMF using P(OPh)₃/pyridine. The polymers were precipitated using water as nonsolvent. FTIR and ¹H‐NMR spectroscopic analysis was used to characterize the monomers and polymers. Representative polyamides and polythioamides were used for the removal of heavy metal ions such as Pb(II), Cd(II), Cu(II), and Cr(III) from aqueous solutions. The effects of pH, contact time, and initial concentration on the uptake of metal ions have been investigated. The adsorption capacities under competitive conditions were in the order Pb (II) > Cu (II) > Cr (III) > Cd (II). The adsorbed ions were eluted by treatment with 2N HCl, and the activities of the polymers are retained after fourth regeneration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

一种由乙酰基次黄嘌呤直接制备6-氯嘌呤的新方法

以乙酰基次黄嘌呤为原料,经三氯氧磷氯代直接制得6-氯嘌呤。该方法避免了老工艺先将乙酰基次黄嘌呤脱乙酰基制成次黄嘌呤,然后再氯代制得6-氯嘌呤的过程。考察了三氯氧磷的用量、缚酸剂的选择与用量、温度、时间对反应的影响,确定了较优的工艺条件:n(乙酰基次黄嘌呤)∶n(三氯氧磷)∶n(三乙胺)=1∶8∶1,105℃反应5 h,后处理中氨水过量10%。新方法步骤少、操作简单、三废污染少,改进后的工艺收率达95.0%,纯度为99%,适合工业化生产。