Yikai Shi

Julphar School of Pharmacy, China, Maine, United States

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Publications (4)4.07 Total impact

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    ABSTRACT: Objective: To determine such molecular characteristic parameters as absolute molecular weight, molecular weight distribution, root-mean-square turning radius (Rg) and polydispersity index (Mw/Mn) of four components contained in Hedysari Radix polysaccharide 3 (HPS-3) and map weight-average molecular weight (Mw) with root-mean-square turning radius (Rg), in order to calculate conformations of the four components at solution state. Method: The gel permeation chromatography-multi angle laser light scatting (GPC-MALLS) was adopted, with 0.1 mol x L(-1) NaNO3 contained 0.02% NaN3 as the mobilephase, Ultrahydrogel 1000 connected in series with Ultrahydrogel500. Result: Among the four components of HPS-3, HPS-3-C showed the highest weight average molecular weight of 1.986 x 10(5) g x mol(-1), followed by HPS-3-B 1.113 x 10(5) g x mol(-1) and HPS-3-D 8.457 x 10(4) g x mol(-1) HPS-3-A showed the lowest weight average molecular weight of 1. 223 x 10(4) g x mol(-1) but the highest square radius of gyration, that is 55.5 nm. HPS-3-D had the widest range of molecular weight distribution in four components, with the polydispersity index (Mw/Mn) of 2.543. In the mobile phase, HPS-3-A was globular structure, HPS-3-C was random coil, HPS-3-B and HPS-3-D were both highly branched structure. Conclusion: The results provided necessary basis for further studies on molecular characteristics of the four components contained in HPS-3 and their relationship with bioactivity.
    No preview · Article · Sep 2012 · Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica
  • Yufeng Ma · Wen Li · Fangdi Hu · Yikai Shi · Yingyan Bi · Shilan Feng
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    ABSTRACT: To determine bergapten's concentration in plasma and observe its pharmacokinetics in rats using a combined LC-MS/MS analytical method. Blood samples were separated on a Hypersil ODS column (4.6 mm x 250 mm, 5 mm) at a temperature of 30 degrees C, and mobile phase consisted of water and methanol (22.5: 77.5) at a flow rate of 0.8 mL x min(-1). The methodological study showed a good linear relationship of 8.12-162.4 g x L(-1) (r = 0.9999). The inner and inter-days relative standard deviations were both less than 10% , indicating legitimate precise and accuracy to the requirement of biological sample analysis. The method is suitable for in vivo quantitative analysis for bergapten due to its accuracy, sensitivity and specificity. The pharmacokinetic process in rats forms a two-compartment model with first-order absorption.
    No preview · Article · Feb 2012 · Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica
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    ABSTRACT: A water-soluble sulfated glucan, SHG, was isolated from Hedysarum polybotrys Hand.-Mazz using anion-exchange and gel-permeation chromatography. Elemental analysis indicated that SHG was a sulfated polysaccharide containing small amount of sulfate groups (1.47 mass%). The molecular weight was estimated to be 1.72 × 105 Da by high-performance gel permeation chromatography (HPGPC) and size exclusion chromatography–multi angle laser light scattering (SEC–MALLS). SHG took random coil compact conformation in 0.1 M NaNO3. Compositional analysis revealed that SHG was composed of glucose only. On the base of partial acid hydrolysis, methylation analysis, gas chromatography–mass spectrometry (GC–MS), Fourier transform infrared (FT-IR) spectra, nuclear magnetic resonance (NMR) spectroscopy of 1H, 13C, β-correlation spectroscopy (β-COSY), total correlation spectroscopy (TOCSY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC), the results showed that SHG was composed of α-d-(1 → 4)-linked glucopyranosyl residues, with branches at C-6 consisting of non-reducing terminal approximately every eight residues. Sulfate groups may attach to the backbone at O-6, occasionally occurring per thirty-eight anhydrous glucose units.
    No preview · Article · Jan 2012 · Carbohydrate Polymers
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    ABSTRACT: To develop a HPLC method for determination of matrine, oxymatrine; ferulic acid, L-shikonin and beta, beta-dimethylacrylshikonin in compound preparatioti of Dangguishuan. The chromatogtaphic separation was performed on a Kromasil ODS C18 column (4.6 mm x 250 mm, 5 microm) maintaining at 30 degrees C during the whole process. The mobile phase consisted of methanol and 0.1% triethylamine aqueous solution (adjusted with phosphoric acid, pH 3) at a flow rate of 1.0 mL x min(-1). The detection wavelength was set at 220 nm for matririne and oxymatrine, 316 nm for ferulic acid, 516 nm for L-shikonin and beta, beta-dimethylacrylshikonin, respectively. All the compounds showed good linearity (r > 0.9996) in the range of the test concentrations, and the average recoveries of the method is betwuen 96.92% and 102.22%, RSD < 3.1%. The method is proved to be credible, sensitive, accurate and repeatable. It can be applied to determine of matrine, oxymatrine, ferulic acid, L-shikonin and beta, beta-dimethylacrylshikonin in compound preparation of Dangguishuan simultaneously, and provide a basal method of quality control to this preparation and other relative preparations.
    No preview · Article · Sep 2010 · Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica