Partial least squares multicomponent fluorimetric determination of fluoroquinolones in human urine samples

Ternary mixtures of fluoroquinolones, with a 7-piperazinyl substituted group have been simultaneously determined in human urine samples by application of a multivariate calibration partial least squares (PLS) model. The calibration set was designed with 15 urine samples containing different concentrations of the three fluoroquinolones and 16 blank urine samples. The concentration range for the fluoroquinolones were up to 25 ng ml⁻¹ for norfloxacin (NOR), 80 ng ml⁻¹ for ofloxacin (OFLO) and 300 ng ml⁻¹ for enoxacin (ENO). The method is based on the native fluorescence emission of these compounds in sodium dodecyl sulfate (SDS) medium, at pH 4.0, when exciting at 277 nm. A selection of the emission wavelength range used for the analysis was made for each component. Intraday and interday precision values were determined. Figures of merit as selectivity, sensitivity, limit of detection (LOD) and analytical sensitivity were also calculated. Using the standard addition methodology, five urine samples from five different persons, fortified with three concentration levels of the fluoroquinolones, were analyzed. The limits of detection in urine were 10.0, 0.5 and 0.8 ng ml⁻¹ for ENO, NOR and OFLO, respectively.     

Medium optimization for polysaccharide production of Cordyceps sinensis

As a potential anticarcinogenic agent, polysaccharides from Cordyceps sinensis have been demonstrated to possess strong antioxidation activity. The aim of the present research was to study the optimal medium to produce polysaccharides of C. sinensis by using response surface methodology (RSM). The composition of optimized medium for polysaccharide production calculated from the regression model of RSM was 6.17% sucrose, 0.53% corn steep powder, 0.5% (NH₄)₂HPO₄, and 0.15% KH₂PO₄ at pH 4.44, with a predicted maximum polysaccharide production of 3.17 g/L. When applying this optimal medium, the maximum polysaccharide production was 3.05 and 3.21 g/L in a shake flask and a 5-L jar fermentor, respectively. When the pH was controlled at a higher level such as pH 5.0, both cell growth and polysaccharide production were inhibited. A low pH of 2.85 was required for maximum production of polysaccharides.     

以单分散树脂为基质的中强阳离子交换色谱填料的合成及应用

将粒径为8.0μm多孔单分散交联氯甲基苯乙烯-二乙烯苯树脂的表面经化学方法改性,得到了一种亲水性良好的中强阳离子交换色谱填料,详细考察了该改性后树脂的表面亲水性、对标准蛋白的分离性能、盐种类及盐浓度对蛋白保留行为的影响。实验结果表明,当流动相流速为3 mL/min时,四种标准蛋白可在3min内基线快速分离,蛋白质的保留符合阳离子交换色谱规律。该填料应用于鸡蛋清中溶菌酶快速分离纯化,取得较好效果。     

在星际媒介中合成H2NCH2CN分子的理论研究

在早期地球原始化学生命起源过程中, 氨基酸是重要的必需的生物化合物, 生成肽和蛋白. 为了探究一个可能的新的氨基酸起源, 采用密度泛函理论(B3LYP)在6-311++G(d, p) 基组水平上研究了在星际媒介条件下在气相中和在模拟的冰颗粒表面上的化学反应: CH2NH分子和两个异构体分子HNC/HCN通过Strecker合成生成H2NCH2CN(氨基乙氰, 一个重要的苷氨基酸前置分子). 在研究体系中, CH2NH、HCN、HNC 和H2O分子存在于星际密集分子云中, 且早于地球广泛存在. 研究证明, 这些分子之间在星际媒介条件下和在冰颗粒表面上通过Strecker合成路线很容易生成H2NCH2CN. 所以, H2NCH2CN分子在宇宙的星际密集分子云中是广泛存在的. 还讨论了H2NCH2CN分子在新的氨基酸起源中所起的作用, 以及在通过“原始汤”生命起源理论解析早期地球生命起源中可能所起的作用.     

Astragalin identification in graviola pericarp indicates a possible participation in the anticancer activity of pericarp crude extracts: In vitro and in silico approaches

Graviola, soursop, or guanabana (Annona muricata L.), is an ethnomedical fruit consumed to alleviate headache, diarrhea, diabetes, and cancer. Pericarp is the inedible part of graviola least studied in comparison to seeds and leaves, even thought, it contains the highest concentration of graviola total polyphenols. Anticancer effect of graviola pericarp has been demonstrated in crude extracts attributing the effect to acetogenins, however, crude extracts contain several active molecules. Thus, the present work aimed to fractionate and purify an ethanolic crude extract from graviola pericarp. Purified graviola pericarp fraction (PGPF) was evaluated on cancerous and non-cancerous cell lines, and then was identified by NMR, TOF-MS, and HPLC. Finally, an in silico analysis was performed to predict targets cancer-related of the molecule detected. Our results revealed IC₅₀ values for cervix adenocarcinoma (HeLa), hepatocellular carcinoma (HepG2), triple-negative breast cancer (MDA-MB-231), and non-cancerous cell line (HaCaT) of 92.85 ± 1.23, 81.70 ± 1.09, 84.28 ± 1.08, and 170.2 ± 1.12 µg PGPF/mL, respectively. In vitro therapeutic indexes estimated as quantitative relationship between safety and efficacy of PGPF were 1.83, 2.08, and 2.02 for HeLa, HepG2, and MDA-MB-231, respectively. The NMR analysis revealed astragalin (kaempferol-3-O-glucoside) in PGPF, a flavonoid not reported in graviola pericarp until now. Astragalin identity was confirmed by TOF-MS and HPLC. In silico results support previous reports about astragalin modulating proteins such as Bcl-2, CDK2, CDK4, MAPK and RAF1. Also, results suggest that astragalin may interact with other cancer-related proteins not associated previously with astragalin. In conclusion, astragalin may be contributing to the anticancer effect observed in graviola pericarp extracts.     

Standard Gibbs energies of transfer of rubidium tetraphenylborate from water to straight-chain n-alkanols

Solubilities of ribidium tetraphenylborate in water,methanol,ethanol,1-propanol,1-butanol,l-pentanol,1-hexanol and 1-octanol at 288.15,298.15,308.15,318.15,328.15 K have been determined by spectrophotometry.The standard Gibbs energy of transfer of ribidium tetraphenylborate from water to straight-chain n-alkanols and the primary medium effect of rubidium tetraphenylborate from 288.15 to 328.15 K have been calculated.Furthermore,the contribution of microscopic interactions to the standard Gibbs energy of transfer of rubidium tetraphenylborate is calculated and discussed.     

非线性化学反应在低维介质中的动力学行为

通过数值模拟对３分子自催化反应Ａ＋２Ｘ＝３Ｘ在一维和二维介质中的动力学行为进行了研究。发现在一维和二维情形下，如果施以不同的微观反应规则，该反应的渐近行为既可能偏经典化学反应动力学（平均场理论）所预言的平衡极限行为，也可能与之一致。     

Integrating approach to discover novel bergenin derivatives and phenolics with antioxidant and anti-inflammatory activities from bio-active fraction of Syzygium brachythyrsum

Syzygium brachythyrsum is an important folk medicinal and edible plant in Yunnan ethnic minority community of China, however, little is known about the chemical and bio-active properties. The present study is aimed to identify the bioactive constituents with antioxidant and anti-inflammatory properties by an integrating approach. First, two new bergenin derivatives, brachythol A (1) and brachythol B (2), together with eleven known phenolic compounds (3–13) were isolated from bioactive fractions by phytochemical method. Among these isolated chemicals, five bergenin derivatives, along with 3 phenolics were found in Syzygium genus for the first time. Then, a further chemical investigation based on ultra-high-performance liquid chromatography-Q Exactive Orbitrap mass spectrometry resulted in a total of 107 compounds characterized in the bio-active fractions, including 50 bergenin derivatives, among which 14 bergenin derivatives and 14 phenolics were potential new natural chemicals. Most of the isolated compounds showed obvious antioxidant activities, while compounds 11, 12, and 13 had favorable performance. Eight compounds (2–5, 7, and 9–11) showed good inhibitory activity on nitric oxide (NO) production in macrophage RAW 264.7 cells. The structure–activity correlation analysis indicated that the antioxidation and anti-inflammatory activities enhanced when bergenin was esterified with gallic acid, caffeic acid or ferulic acid. This is the first report of bergenins in Syzygium genus and the richness in new bio-active bergenins and gallic acid derivatives indicated that Syzygium brachythyrsum is a promising functional and medicinal resource.     

Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

Capillary electrophoresis ( CE ) has rapidly gained great interests among researchers in many different fields. One of these areas is the separation of small ions such as inorganic cations, anions, and low Mr organic molecules However, as the separation of ions     

Solving the random diffusion model in an infinite medium: A mean square approach

This paper deals with the construction of an analytic-numerical mean square solution of the random diffusion model in an infinite medium. The well-known Fourier transform method, which is used to solve this problem in the deterministic case, is extended to the random framework. Mean square operational rules to the Fourier transform of a stochastic process are developed and stated. The main statistical moments of the stochastic process solution are also computed. Finally, some illustrative numerical examples are included.