Enzymatic preparation of ginsenosides Rg2, Rh1, and F1

During investigation of the hydrolysis of a protopanaxatriol-type saponin mixture by various glycoside hydrolases, crude preparations of beta-galactosidase from Aspergillus oryzae and lactase from Penicillium sp. were found to produce two minor saponins, ginsenoside Rg(2) [6-O-(alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl)-20(S)-protopanaxatriol] and ginsenoside Rh(1) (6-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol), respectively, in high yields. Moreover, a naringinase preparation from Penicillium decumbens readily gave an intestinal bacterial metabolite, ginsenoside F(1) (20-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol), as the main product, with a small amount of 20(S)-protopanaxatriol from a protopanaxatriol-type saponin mixture. Also, a hesperidinase from Penicillium sp. selectively hydrolyzed ginsenoside Re into ginsenoside Rg(1). This is the first report on the enzymatic preparation of minor saponins, ginsenosides Rg(2) and Rh(1), and of an intestinal bacterial metabolite, ginsenoside F(1), with high efficiency from a protopanaxatriol-type saponin mixture.     

Development and validation of a reversed-phase HPLC method for quantitative determination of ginsenosides Rb1, Rd, F2, and compound K during the process of biotransformation of ginsenoside Rb1

A simple and rapid gradient RP-HPLC method for simultaneous separation and determination of related ginsenosides during the process of biotransformation of ginsenoside Rb1 has been developed. As many as four process ginsenosides have been separated and identified on an Eclipse XDB C(18) column (4.6 mm x 150 mm, 5 mum) with gradient elution using water and ACN as a mobile phase. The column was maintained at 30 degrees C and the eluents were monitored with diode array detection at 203 nm. The method was validated in terms of linearity, sensitivity, precision, and accuracy. The correlation coefficients (r) for calibration curves of ginsenosides were in the range of 0.9996-1.0000. The proposed RP-HPLC method was successfully applied to the analysis of fermentation broth and the recoveries of ginsenosides were in the range of 94.4-103.1% with RSD <2.87%. The method could be of use for rapid and routine evaluation of the quantity of ginsenosides during the biotransformation process of ginsenoside Rb1.     

Tartaric acid induced conversion of protopanaxadiol to ginsenosides Rg3 and Rg5 and their in situ recoveries by integrated expanded bed adsorption chromatography

Panax ginseng has been applied in traditional Chinese medicine for over 2000 years. It is still one of the most popular herbs in recent decades. The prescribed ginseng‐containing medicines consist of protopanaxadiol and protopanaxatriol ginsenosides, which are the major constituents of the herb. Minor ginsenosides at low levels in the herb, such as Rg₃ and Rg₅, have attracted more rising attention than the major ones. The existing approaches to prepare Rg₃ and Rg₅ usually rely on either steamed red ginseng as the source or chemical/enzymatic conversion of protopanaxadiol to the targets. It is still highly desirable to effectively achieve such minor components. In this paper, a method integrated extraction of protopanaxadiol and conversion of it to Rg₃ and Rg₅ has been proposed. Protopanaxadiol was extracted and simultaneously converted to Rg₃ and Rg₅ by d ,l ‐tartaric acid. The targets were absorbed by resins on expanded bed adsorption chromatography and were then separated from other ginsenosides in different stages. Compared with conventional methods, the developed process has advantages in shortening time consumption and improving the conversion ratio of protopanaxadiol, which is promising in directly achieving Rg₃ and Rg₅ from P. ginseng.     

胶束电动毛细管色谱法同时测定西洋参中人参皂苷Rg1、Re和Rb1

建立了西洋参中人参皂苷Rg1、Re及Rb1同时分离测定的胶束电动毛细管色谱新方法,以解决西洋参样品中难溶于水的3种人参皂苷的准确定量问题。以40.2 cm(有效长度30 cm)×50 μm的熔融石英毛细管柱为分离柱,分离缓冲液的组成为V(15 mmol/L Na2B4O7+30 mmol/L H3BO3 (pH 9.0)+100 mmol/L十二烷基硫酸钠(SDS)+30 g/L聚乙二醇35000):V(甲醇):V(异丙醇)=2:1:1,于214 nm下检测。详细研究了影响分离的因素。Rg1、Re及Rb1检出限(信噪比(S/N)为3)分别为30、40及30 mg/L,定量限(S/N=9)分别为90、120及90 mg/L,加标回收率为87.4%～95.2%。用该法测定了西洋参标准物质,并与高效液相色谱法的检测结果进行了比对,结果吻合。应用该方法分别测定了中国、加拿大及美国的西洋参,获得满意的结果。     

Spectroscopy of K+ x Rg and transport coefficients of K+ in Rg (Rg=He-Rn)

Ab initio calculations employing the coupled-cluster method, with single and double substitutions and accounting for triple excitations noniteratively [CCSD(T)], are used to obtain accurate potential energy curves for the K(+)He, K(+)Ne, K(+)Ar, K(+)Kr, K(+)Xe, and K(+)Rn cationic complexes. From these potentials, rovibrational energy levels and spectroscopic parameters are calculated. In addition, mobilities and diffusion coefficients for K(+) cations moving through the six rare gases are calculated, under conditions that match previous experimental determinations. A detailed statistical comparison of the present and previous potentials is made with available experimental data, and critical conclusions are drawn as to the reliability of each set of data. It is concluded that the present ab initio potentials match the accuracy of the best model potentials and the most reliable experimental data.     

Stereoselective determination of ginsenosides Rg3 and Rh2 epimers in rat plasma by LC‐MS/MS: Application to a pharmacokinetic study

We developed and validated an accurate and sensitive LC–MS/MS method for the simultaneous quantitation of ginsenoside Rg3 and Rh2 epimers (R‐Rg3, S‐Rg3, R‐Rh2, and S‐Rh2) in rat plasma. Analytes were extracted from 0.1 mL aliquots of rat plasma by liquid–liquid extraction, using 2 mL of ethyl acetate. In this assay, dioscin (500 ng/mL) was used as an internal standard. Chromatographic separation was conducted using an Acclaim RSLC C₁₈ column (150 × 2.1 mm, 2.2 μm) at 40°C, with a gradient mobile phase consisting of 0.1% formic acid in distilled water and in acetonitrile, a flow rate of 0.35 mL/min, and a total run time of 20 min. Detection and quantification were performed using a mass spectrometer in selected reaction‐monitoring mode with negative electrospray ionization at m/z 783.4 → 161.1 for R‐Rg3 and S‐Rg3, m/z 621.3 → 161.1 for R‐Rh2 and S‐Rh2, and m/z 867.2 → 761.5 for the internal standard. For R‐Rg3 and S‐Rg3, the lower limit of quantification was 5 ng/mL, with a linear range up to 500 ng/mL; for R‐Rh2 and S‐Rh2, the lower limit of quantification was 150 ng/mL, with a linear range up to 6000 ng/mL. The coefficient of variation for assay precision was less than 10.5%, with an accuracy of 86.4–112%. No relevant cross‐talk or matrix effect was observed. The method was successfully applied to a pharmacokinetic study after oral administration of 400 mg/kg and 2000 mg/kg of BST204, a fermented ginseng extract, to rats. We found that the S epimers exhibited significantly higher plasma concentrations and area under curve values for both Rg3 and Rh2. This is the first report on the separation and simultaneous quantification of R‐Rg3, S‐Rg3, R‐Rh2, and S‐Rh2 in rat plasma by LC‐MS/MS. The method should be useful in the clinical use of ginseng or its derivatives.     

Preparation and characterization of microsized K2Ta2O3F6 with ellipsoidal morphology by anodization

Ellipsoidal K₂Ta₂O₃F₆ particles with an average length of 2.79 μm and a diameter of 0.63 μm were synthesized by anodization in saturated solutions of potassium chloride containing 5 wt% HF. Microstructure and composition analysis were conducted by scanning electron microscopy, X-ray diffractometry and energy dispersive spectroscopy. Formation mechanism of this special morphology was given based on the experimental results.     

Dirubidium fluoro­trioxophosphate,Rb2PO3F,at 290 and 130 K,and dicaesium fluoro­trioxophosphate,Cs2PO3F,at 240 and 100 K

The structure of Rb₂PO₃F was determined at 290 and 130 K, while that of Cs₂PO₃F was determined at 240 and 100 K. Both compounds belong to the β‐K₂SO₄ family. The structure analysis did not reveal signs of a phase transition in either compound. Crystal chemical considerations do not favour the presence of a phase transition in either Rb₂PO₃F or Cs₂PO₃F. However, glass‐like phase transitions were observed by differential scanning calorimetry in slightly humid samples at 175 and 177 K for Rb₂PO₃F and Cs₂PO₃F, respectively, but were not observed in well dried samples. The bond distances are normal and Cs₂PO₃F is twinned.     

Polymerization of aniline derivatives by K2Cr2O7 and production of Cr2O3 nanoparticles

Oxidative polymerization of aniline, anthranilic acid, and aniline‐co‐anthranilic acid by potassium dichromate Cr(VI) as an oxidant in acidic medium was investigated. In this study, the polymerization process of aniline, o‐anthranilic acid as well as aniline/o‐anthranlic acid using K₂Cr₂O₇ produced, coordinated Cr(III)/polyaniline (PANI), Cr(III)/polyanthranilic acid (PAA) and Cr(III)/poly aniline‐co‐anthranilic acid (PANAA). The mechanism of polymerization reaction in the presence of dichromate was hypothesized. The precursor chromium doped polymers were characterized by TGA, FT‐IR, UV‐visible, XRD analyses. Cr₂O₃ nanoparticles size were determined using TEM analysis. The calcinations process of synthesized chromium doped PANI, PAA and PANAA yields Cr₂O₃ nanoparticles 26%, 31%, and 34% wt. respectively. Rhombohedral phase of Cr₂O₃ particles in the range from 33 to 61 nm was produced from chromium/polyanthranilic acid (PAA) and chromium/poly(aniline‐co‐anthranilic acid) PANAA. UV‐ visible analysis showed that optical band gaps (E_g) of doped poly aniline and its derivatives are in the range from1.55 to 1.80 using Tacu's law. The band gap values reveal that the doped chromium emeraldine base can be used as semiconductor materials. Copyright © 2016 John Wiley & Sons, Ltd.     

Peroxofluorokomplexe der Übergangsmetalle. VII. Peroxofluorokryolithe A3Ti(O2)F5 (A = K,Na) und K2NaTi(O2)F5 Kristallstruktur von K3Ti(O2)F5

Transition Metal Peroxofluoro Complexes. VII. Peroxofluorokryolithes A₃Ti(O₂)F₅ (A = K, Na) and K₂NaTi(O₂)F₅. Crystal Structure of K₃Ti(O₂)F₅ Peroxofluorokryolithes A₃Ti(O₂)F₅ (A = K, Na) and K₂NaTi(O₂)F₅ were prepared at pH 4.5–6 by adding H₂O₂ and AOH/AF to solutions of TiO₂ in hydrofluoric acid or aqueous solutions of TiF₄. In the range of pH 3–4.5 exist phases of peroxofluoro-kryolithes with variations in stoichiometrie. A single crystall X-ray structure analysis of K₃Ti(O₂)F₅ (Fm3m, a = 883.6(1) pm) yielded a disordered kryolithstructure (R = 0.020, R_W = 0.017). Na₃Ti(O₂)F₅ was found to crystallize in two monoclinic low-temperature – and one cubic high-temperature modifications. K₂NaTi(O₂)F₅ crystallizes cubic (Fm3m) with a = 847.8(1) pm. Vibrational spectra have been measured and thermal behavior was studied by DTA/DTG and high-temperature guinier. At pH 9.5 K₃Ti(O₂)₂F₃ has been synthesized     

Rates of reaction of atomic oxygen with C2H3F,C2H3Cl,C2H3Br, 1,1-C2H2F2, and 1,2-C2H2F2

Rate constants for the reactions of atomic oxygen (O³P) with C₂H₃F, C₂H₃Cl, C₂H₃Br, 1,1-C₂H₂F₂, and 1,2-C₂H₂F₂ have been measured at 307°K using a discharge-flow system coupled to a mass spectrometer. The rate constants for these reactions are (in units of 10¹¹ cm³ mole^?1 s^?1) 2.63 ± 0.38, 5.22 ± 0.24, 4.90 ± 0.34, 2.19 ± 0.18, and 2.70 ± 0.34, respectively. For some of these reactions, the product carbonyl halides were identified.     

The dark reactions F2 + CF3I,C2F5I,and n-C3F7I

The reactions between F₂ and the lowest members of the homologous series of perfluoroalkyl iodides (CF₃I, C₂F₅I, and n-C₃F₇I) have been studied. For these compounds, an exponential decrease in the alkyl iodide concentration over time following an induction period is observed for certain experimental conditions. Other conditions lead to chaotic-like kinetic behavior where the rate of alkyl iodide consumption continually changes. Kinetic rate data with CF₃I show that the disappearance rate depends upon both the type of surface and surface preparation. For all three compounds, Arrhenius plots reveal activation energies on the order of 10 kcal/mol, consistent with effective initiation steps of F₂ + RI → RIF + F, where R represents the CF₃, C₂F₅, or n-C₃F₇ radical respectively. The end products of the F₂ + RI reactions are RF, R₂, and IF₅, suggesting that the R radicals play an important kinetic role. Introducing O₂ into the F₂ + RI reaction systems results in successive oxidation of R by O₂, leading to the formation of CF₂O as an additional end product. IF(B → X) emission is observed from the RI-rich F₂ + RI reactions, confirming the existence of IF as an intermediate. © 1996 John Wiley & Sons, Inc.     

A method for the analysis of ginsenosides, malonyl ginsenosides, and hydrolyzed ginsenosides using high-performance liquid chromatography with ultraviolet and positive mode electrospray ionization mass spectrometric detection

A high-performance liquid chromatographic separation coupled to diode array absorbance and positive mode electrospray mass spectrometric detection has been developed for the analysis of ginsenosides, malonyl ginsenosides, and hydrolyzed ginsenosides in extracts of Asian ginseng (Panax ginseng) and American ginseng (P. quinquefolius). The method is capable of separating, identifying, and quantifying the predominant ginsenosides found in heated alcoholic extracts of Asian and American ginseng roots routinely sold as nutraceuticals. It also separates and identifies the malonyl ginsenosides often found in cold alcoholic extracts of ginseng root and has the potential to quantify these compounds if pure standards are available. Furthermore, it can separate and identify ginsenoside hydrolysis products such as those readily produced in situations mimicking gastric situations, including those used for dissolution studies (i.e., 0.1 N HCl, 37 degrees C).     

A kinetic study of the reaction of fluorine atoms with CH3F,CH3Cl,CH3Br,CF2H2, CO,CF3H,CF3CHCl2, CF3CH2F,CHF2CHF2, CF2ClCH3, CHF2CH3, and CF3CF2H at 295 ± 2 K

A variety of relative and absolute techniques have been used to measure the reactivity of fluorine atoms with a series of halogenated organic compounds and CO. The following rate constants were derived, in units of cm³ molecule^?1 s^?1: CH₃F, (3.7 ± 0.8) × 10^?11, CH₃Cl, (3.3 ± 0.7) × 10^?11; CH₃Br, (3.0 ± 0.7) × 10^?11; CF₂H₂, (4.3 ± 0.9) × 10^?12; CO, (5.5 ± 1.0) × 10^?13 (in 700 torr total pressure of N₂ diluent); CF₃H, (1.4 ± 0.4) × 10^?13; CF₃CCl₂H (HCFC-123), (1.2 ± 0.4) × 10^?12; CF₃CFH₂ (HFC-134a), (1.3 ± 0.3) × 10^?12, CHF₂CHF₂ (HFC-134), (1.0 ± 0.3) × 10^?12; CF₂ClCH₃ (HCFC-42b), (3.9 ± 0.9) × 10^?12, CF₂HCH₃ (HFC-152a), (1.7 ± 0.4) × 10^?11; and CF₃CF₂H (HFC-125), (3.5 ± 0.8) × 10^?13. Quoted errors are statistical uncertainties (2σ). For rate constants derived using relative rate techniques, an additional uncertainty has been added to account for potential systematic errors in the reference rate constants used. Experiments were performed at 295 ± 2 K. Results are discussed with respect to the previous literature data and to the interpretation of laboratory studies of the atmospheric chemistry of HCFCs and HFCs. © 1993 John Wiley & Sons, Inc.     

Spectrophotometric determination of ethanol by an enzymatic method with 2, 2'-azino-di(3-ethylbenzthiazo- line-6-sulfonate)

The method is based on the oxidation of ethanol in the presence of alcohol oxidase, followed by oxidation of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonate) in the presence of peroxidase.     

Steric effect in the energy transfer reaction of N2 + Rg (3P2) (Rg = Kr, Ar)

Steric effect for the formation of N 2 (B, (3)Pi u ) in the energy transfer reaction of Kr ( (3)P 2) + N 2 has been measured using an oriented Kr ( (3)P 2, M J = 2) beam at a collision energy of 0.07 eV. The N 2 (B, (3)Pi u ) emission intensity was measured as a function of the magnetic orientation field direction in the collision frame. A significant atomic alignment effect on the energy transfer probability was observed. This result was compared with that for the formation of N 2 (C, (3)Pi g ) in the Ar ( (3)P 2) + N 2 reaction. Despite the large difference on the energy transfer cross-section, the atomic alignment dependence for Kr ( (3)P 2) + N 2 is found to be analogous to that for Ar ( (3)P 2) + N 2. It is revealed that the configuration of inner 4p (3p) orbital in the collision frame gives an important role for the stereoselectivity on electron transfer process via the curve-crossing mechanism.     

Ba2F2Fe2+ 0.5Fe3+ S3: a two-dimensional inhomogeneous mixed valence iron compound

The structure of the new mixed valence compound Ba2F2Fe1.5S3 was solved by means of single crystal X-ray analysis. It crystallizes in an orthorhombic cell, in the Pnma space group with the cell parameters a = 12.528(3) A, b = 18.852(4) A, and c = 6.0896(12) A. The structure is formed by the alternated stacking of fluorite type [Ba2F2]2+ blocks and the newly discovered [Fe1.5S3]2- blocks. This [Fe1.5S3]2- block exhibits a mixed valence of iron with Fe(+II) located in octahedrons and Fe(+III) in tetrahedrons. Preliminary susceptibility measurements suggest a low dimensional antiferromagnetic behavior.