Evaluation of capillary electrophoresis for the analysis of nicotine and selected minor alkaloids from tobacco

Summary Difficulties encountered in the gas or liquid chromatographic analysis of nicotine and other alkaloids in tobacco are largely due to the ionic character of these compounds. The potential of using capillary electrophoresis (CE) as an alternative analytical tool to eliminate these problems was evaluated. Parameters including electroosmotic flow, ionic forms of the analytes, buffer composition and applied voltage were studied using nicotine as a model compound. Ionic forms and electrophoretic mobility, as well as UV absorbance, of nicotine were controlled by varying the pH of an aqueous buffer solution. Thus the separation was optimized based on the characters of alkaloids and the nature of capillary electrophoresis. For tobacco samples in which nicotine accounts for more than 98% of the total alkaloid content, a quick method for the determination of nicotine in an aqueous tobacco extract within 100 seconds can be achieved.     

Influence of dielectric microcavity on the spontaneous emission rate of atom: a perspective on the closed-orbit theory of photons

The formulas of the quantum electrodynamics have been applied to calculate the spontaneous emission rate of excited atom in dielectric microcavity.The results exhibit damping oscillating Patterns which depend sensitively on the scaling parameter and geometrical structure.Compared with the case that the emitting atom is immersed in dielectric,the spontaneous emission rate is depressed obviously and the center or the mean value of the oscillations is intimately related to the real refractive index of the local position where the atom is.In order to explain this phenomenon,we utilize the closed-orbit theory to deal with the classical trajectories of the emitted photon.and extract the corresponding frequencies of the oscillations by Fourier transform.It is found that the oscillations can be represented in terms of the closed-orbits of the photon motion constrained in dielectric microcavity,thus providing another perspective on the spontaneous emission of atom sandwiched by dielectric slabs.     

用清除有机自由基DPPH法评价竹叶提取物抗氧化能力

通过对1,1-二苯基苦基苯肼(DPPH)溶液吸收光谱、DPPH溶液反应体系的研究,得出以下结论,分光光度法测定DPPH溶液反应体系的测定波长为518.4 nm,反应体系为4.00 mL 257.7 mg·L-1的DPPH溶液中加1 mL不同浓度的抗氧化剂,反应体系加入抗氧化剂后反应时间为40 min;用上述方法研究评价合成抗氧化剂叔丁基对苯二酚(TBHQ)和2,6-二叔丁基对甲酚(BHT)对DPPH自由基清除率和浓度的关系,以IC₅₀值(清除率为50%时,抗氧化剂的浓度值)作为评价指标,测得合成抗氧化剂和效果最好竹叶提取物样品IC₅₀值分别为,TBHQ(21.14 mg·L-1),BHT(42.09 mg·L-1),M40(108.40 mg·L-1),M40等竹叶提取物可以作为天然抗氧化剂进行开发。     

Effect of yeast extract on growth kinetics of Monascus purpureus

Growth kinetics and red pigment production of Monascus purpureus CCT 3802 was studied. A reproducible inoculum with extremely dispersed hyphae for bioreactor runs was obtained through a two-step cultivation in a shaker. First, the spores were cultivated in a complex medium rendering a suspension of vegetative cells. In the second step these cells were grown in a semisynthetic medium. Two types of media were employed in the bioreactor runs: a semisynthetic (glucose, salts, and yeast extract), and a synthetic, without yeast extract. The inclusion of yeast extract, caused an increase in cell yield on glucose (Y_s/s) as high as 40%. Also, yeast extract probably yielded a higher proportion of red pigment associated with the cell, relative to the synthetic medium. On the other hand, cells grown on the synthetic medium were slightly higher producers of red soluble pigments.     

Tissue distribution comparison between healthy and fatty liver rats after oral administration of hawthorn leaf extract

Hawthorn leaves, a well‐known traditional Chinese medicine, have been widely used for treating cardiovascular and fatty liver diseases. The present study aimed to investigate the therapeutic basis treating fatty liver disease by comparing the tissue distribution of six compounds of hawthorn leaf extract (HLE) in fatty liver rats and healthy rats after oral administration at first day, half month and one month, separately. Therefore, a sensitive and specific HPLC method with internal standard was developed and validated to determine chlorogenic acid, vitexin‐4′′‐O‐glucoside, vitexin‐2′′‐O‐rhamnoside, vitexin, rutin and hyperoside in the tissues including heart, liver, spleen, kidney, stomach and intestine. The results indicated that the six compounds in HLE presented some bioactivity in treating rat fatty liver as the concentrations of the six compounds varied significantly in inter‐ and intragroup comparisons (healthy and/or fatty liver group). Copyright © 2013 John Wiley & Sons, Ltd.     

Biocatalytic reduction of prochiral aromatic ketones to optically pure alcohols by a coupled enzyme system for cofactor regeneration

A simple, highly efficient, and economical biphasic cell-free system was developed for biocatalytic reduction of prochiral aromatic ketones to furnish enantiopure alcohols. This system is characterized by using endogenous enzymes of the cell-free extract to form enzyme-coupled NADPH recycling system. Besides, it offered much higher productivity than whole cells and greatly simplified the preparation process of biocatalysts in comparison with isolated enzymes. Various prochiral aromatic ketones, especially α-substituted acetophenone derivatives, were reduced to chiral alcohols with excellent enantiomeric excess (ee) and moderate to good yield by this cell-free system.     

Chemical characterization and evaluation of antimicrobial and cutaneous wound healing potentials of gold nanoparticles using Allium saralicum R.M. Fritsch

The use of herbal medicines dates back a long way in history. Herbal medicines have been widely used all over the world since ancient times and have been recognized by physicians and patients for their good therapeutic value as they have fewer adverse effects than modern medicines. Recently, researchers have used gold nanoparticles synthesized by plants in the prevention, control, and treatment of infectious disorders and cutaneous wounds. The aims of this study were to synthesize gold nanoparticles from aqueous extract of Allium saralicum R.M. Fritsch (AuNPs) and assess their therapeutic capacities. The nanoparticles were characterized by UV–visible spectroscopy (UV–Vis), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FT-IR results offered polysaccharides and protein in A. saralicum were the sources of reducing power, reducing gold ions to AuNPs. According to XRD analysis, the crystal size of the nanoparticles was 41.6 nm. TEM and FE-SEM images exhibited average diameters of 45 nm for the biosynthesized nanoparticles. The synthesized AuNPs had great cell viability on HUVECs line and showed this method was nontoxic. The 2,2-diphenyl-1-picrylhydrazyl free radical scavenging test indicated similar antioxidant potentials for A. saralicum, AuNPs, and butylated hydroxytoluene. To determine the antifungal and antibacterial properties of HAuCl₄, A. saralicum, and AuNPs, agar diffusion tests were used. The aim of the application both HAuCl₄ and A. saralicum in microbial tests was to investigate the synergism effects between them. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were specified by macro-broth dilution assay. AuNPs exhibited higher antifungal and antibacterial effects than all standard antibiotics (p ≤ 0.01). The MIC and MBC of AuNPs against all bacteria were in the ranges 1–4 mg/ml and 2–8 mg/ml, respectively. The MIC and MFC of AuNPs against all fungi were in the ranges 1–4 mg/ml and 2–4 mg/ml, respectively. In vivo part, AuNPs ointment group raised significantly (p ≤ 0.01) the wound contracture, vessel, hydroxyl proline, hexuronic acid, fibrocyte, fibroblast, and fibrocytes/fibroblast rate and decreased significantly (p ≤ 0.01) the wound area, total cells, and lymphocyte compared to other groups in rats. The results of FT-IR, UV–Vis, XRD, TEM, and FE-SEM analyses confirm that the aqueous extract of A. saralicum leaves can be used to yield gold nanoparticles with a notable amount of remedial effects without any cytotoxicity against HUVECs.     

Effect of the γ-radiation on phenol fractions obtained from the leaves of Echinodorus macrophyllus Mich.

Echinodorus macrophyllus Mich. (Chapéu-de-couro) is popularly used as diuretic, anti-arrhythmic, anti-inflammatory, and anti-rheumatic agents. Leaves of this species are largely commercialized and show high level of microbiological contamination (bacteria and fungi). This work describes the effect of the ⁶⁰Co γ-radiation on the phenol fractions obtained from the leaves of E. macrophyllus. trans-Ferulic acid, (E)-caffeoyltartronic acid, 6-C-(1-hexitol)-apigenin, and 6-C-(1-hexitol)-luteolin were isolated by preparative HPLC. HPLC chromatograms showed concentration changes of some phenolic constituents, suggesting the formation of radiolytic products. The phenol fractions were active against Bacillus subitilis and Staphylococcus aureus and showed high antioxidant activity. However, the antibacterial and antioxidant activities reduced when the absorbed dose was increased.