Studies of interaction of emodin and DNA in the presence of ethidium bromide by spectroscopic method

Emodin interacting with deoxyribonucleic acid (DNA) has been studied by different spectroscopic techniques, such as fluorescence, ultraviolet and visible (UV-vis), and fourier transform infared (FT-IR) spectroscopies, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of emodin shows that the fluorescence quenching of DNA-EB complex by emodin occurs. The binding constants of emodin with DNA in the presence of EB are 6.02x10(4), 9.20x10(4) and 1.17x10(5)Lmol(-1) at 20, 35 and 50 degrees C, respectively. FT-IR spectrum further suggests that both the phosphate groups and the bases of DNA react with emodin. The reaction of DNA with emodin in the presence of EB is affected by ionic strength and temperature. The values of melting temperature (T(m)) of DNA-EB complex and emodin-DNA-EB complexes were determined, respectively. From the experiment evidences, the major binding mode of emodin with DNA should be the groove binding.     

Characterization of aroma active compounds in fruit juice and peel oil of Jinchen sweet orange fruit (Citrus sinensis (L.) Osbeck) by GC-MS and GC-O

Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to determine the aromatic composition and aroma active compounds of fruit juice and peel oil of Jinchen sweet orange fruit. Totals of 49 and 32 compounds were identified in fruit juice and peel oil, respectively. GC-O was performed to study the aromatic profile of Jinchen fruit juice and peel oil. A total of 41 components appeared to contribute to the aroma of fruit juice and peel oil. Twelve components were the odorants perceived in both samples. The aromatic compositions of fruit juice were more complex than that of peel oil. Ethyl butanoate, beta-myrcene, octanal, linalool, alpha-pinene, and decanal were found to be responsible for the aromatic notes in fruit juice and peel oil. Nineteen components have been perceived only in the juice and ten compounds were described as aromatic components of only the peel oil by the panelists. These differences lead to the different overall aroma between fruit juice and peel oil.     

Ferric hydroxide supported gold subnano clusters or quantum dots: enhanced catalytic performance in chemoselective hydrogenation

An attempt to prepare ferric hydroxide supported Au subnano clusters via modified co-precipitation without any calcination was made. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been employed to study the structure and chemical states of these catalysts. No Au species could be observed in the HRTEM image nor from the XRD pattern, suggesting that the sizes of the Au species in and on the ferric hydroxide support were less than or around 1 nm. Chemoselective hydrogenation of aromatic nitro compounds and alpha,beta-unsaturated aldehydes was selected as a probe reaction to examine the catalytic properties of this catalyst. Under the same reaction conditions, such as 100 degrees C and 1 MPa H2 in the hydrogenation of aromatic nitro compounds, a 96-99% conversion (except for 4-nitrobenzonitrile) with 99% selectivity was obtained over the ferric hydroxide supported Au catalyst, and the TOF values were 2-6 times higher than that of the corresponding ferric oxide supported catalyst with 3-5 nm size Au particles. For further evaluation of this Au catalyst in the hydrogenation of citral and cinnamaldehyde, selectivity towards unsaturated alcohols was 2-20 times higher than that of the corresponding ferric oxide Au catalyst.     

Improved high-performance liquid chromatographic method for simultaneous determination of 12 cytotoxic caged xanthones in gamboges, a potential anticancer resin from Garcinia hanburyi

The potential anti-tumor activity of gamboges, a herbal medicine derived from Garcinia hanburyi, has increasingly gained the interest of scientist worldwide. The major components of gamboges are cytotoxic caged xanthones. In the present study, an improved HPLC method was developed to simultaneously quantify 12 caged xanthones, including three pairs of epimers and four pairs of trans-cis isomers, i.e. forbesione, isomorellic acid, morellic acid, R-30-hydroxygambogic acid, S-30-hydroxygambogic acid, isogambogenic acid, gambogenic acid, gambogellic acid, R-isogambogic acid, S-isogambogic acid, R-gambogic acid and S-gambogic acid. This method was validated to be sensitive, precise and accurate with limits of detection of 0.03-0.08 microg/mL, overall intra-day and inter-day variations less than 7.9% and overall recovery over 93.2%. The correlation coefficients (r(2)) of the calibration curves were higher than 0.995 for all analytes. The newly established method was successfully applied to reveal the difference in the chemical profiles and contents of these analytes in gamboges from different origins. It can be concluded that this method was not only an effective quality control method to ensure the safety and efficacy consistency of gamboges, but also a useful tool for screening and determining more potent cytotoxic xanthones with potential anticancer activity.     

Determination of danshensu in rat plasma and tissues by high-performance liquid chromatography

A systematic study on pharmacokinetics and tissue distribution of danshensu (one of the major active components from Salvia miltiorrhizae) is conducted using a rapid and sensitive high-performance liquid chromatographic (HPLC) method. Before HPLC analysis, biological samples are pretreated with a liquid-liquid extraction. Separation of danshensu and internal standard is achieved on an Agilent Zorbax C18 column with a mobile phase made up of acetonitrile and 0.05% trifluoracetic acid at a flow rate of 0.8 mL/min. The calibration curves in plasma and tissues are linear in the given concentration ranges, with r2 no less than 0.99. The intra-day and inter-day relative standard deviations in the measurement of quality control samples are less than 15%, and the accuracies are in the range of 86-115%. The recoveries of danshensu in plasma and tissues are among 80% to 118%. Meanwhile, the multi-peaks in pharmacokinetic profiles are observed. The method is successfully applied to the pharmacokinetics and tissue distribution study of danshensu after a single oral administration of 50.0 mg/kg sodium danshensu to rats.     

Copper-catalyzed synthesis of primary arylamines via cascade reactions of aryl halides with amidine hydrochlorides

We have developed an efficient method for the synthesis of primary arylamines from aryl halides using amidine hydrochlorides as the ammonia surrogates. The protocol uses 10 mol % CuI as the catalyst, 20 mol % L-proline as the ligand, Cs2CO3 as the base, and DMF as the solvent and proceeds the sequential coupling of aryl halides with amidine hydrochlorides and hydrolysis of intermediates to give the target products. This is a convenient, inexpensive, and practical approach to primary arylamines.     

A new bibenzyl derivative from Pleione bulbocodioides

A new bibenzyl derivative 1, named 2-（4＇＇-hydroxybenzy1）-3-（3＇-hydroxyphenethy1）-5-methoxy-cyclohexa-2,5-diene-1,4- dione, and two known stilbenoids （2, 3） were isolated from the tubers of Pleione bulbocodioides （Franch.） Rolfe. Their structures were elucidated by spectroscopic methods.     

Anisotropic wetting behavior arising from superhydrophobic surfaces: parallel grooved structure

It has been found experimentally that superhydrophobic surfaces exhibit strong anisotropic wetting behavior. This study reports a simple but robust thermodynamic methodology to investigate the anisotropic superhydrophobic behavior for parallel grooved surfaces. Free energy and its barrier and the corresponding contact angle and its hysteresis for various orientations of the groove structure are calculated based on the proposed thermodynamic model. It is revealed that the strong anisotropy of equilibrium contact angle (ECA) and contact angle hysteresis (CAH) is shown in the noncomposite state but almost isotropic wetting properties are exhibited in the composite state. Furthermore, for the noncomposite state, decreasing groove width and spacing or increasing groove depth can amplify the anisotropy for ECA. Meanwhile, decreasing groove width and increasing depth can amplify the anisotropy for CAH, while varying groove spacing can barely influence CAH. For the composite state, however, the surface geometry hardly leads to the anisotropic behavior. In addition, using a fitting approximation, a simple quantitative correlation between wettability and orientation can be established well, which is consistent with the numerical calculations.     

Rapid determination of polyprenylated xanthones in gamboge resin of Garcinia hanburyi by HPLC

A rapid ion-pair HPLC method was developed and validated for the determination of eight polyprenylated xanthones including three pairs of epimers, namely morellic acid (MA), 30-hydroxygambogic acid (HGA), 30-hydroxyepigambogic acid (HEGA), isogambogic acid (IGA), epiisogambogic acid (EIGA), gambogenic acid (GNA), gambogic acid (GA), and epigambogic acid (EGA), in gamboge resin of Garcinia hanburyi. The separation was performed on a narrow bore C8 column with isocratic elution using a mixture of methanol-ACN-40 mM KH2PO4 buffer (37.5:37.5:25 v/v/v, containing 0.1% tetradecyltrimethylammonium bromide). The newly developed method was used to determine the contents of the eight compounds present in the gamboge. Results showed that GA and EGA are the dominant components of gamboge. The content ratio of each epimer pair remained constant, indicating that the content ratio of epimers can be used as a specific characteristic for the quality control of gamboge.