Differentiation of <Emphasis Type="BoldItalic">Panax quinquefolius</Emphasis> grown in the USA and China using LC/MS-based chromatographic fingerprinting and chemometric approaches

American ginseng (Panax quinquefolius) is one of the most commonly used herbal medicines in the world. Discriminating between P. quinquefolius grown in different countries is difficult using traditional quantitation methods. In this study, a liquid chromatographic mass spectrometry fingerprint combined with chemometric analysis was established to discriminate between American ginseng grown in the USA and China. Fifteen American ginseng samples grown in Wisconsin and 25 samples grown in China were used. The chromatographic fingerprints, representing the chemical compositions of the samples, made it possible to distinguish samples from the two locations. In addition, it was found that some ginsenosides varied widely from P. quinquefolius cultivated in these two countries. P. quinquefolius grown in the USA is higher in ginsenoside R_c, ginsenoside R_d, quinquenoside III/pseudo-ginsenoside RC₁, malonyl ginsenoside R_b1, and ginsenoside R_b2, but lower in ginsenoside R_b1 compared with P. quinquefolius grown in China. These ginsenosides may be responsible for the class separation seen using fingerprinting and chemometric approaches.     

A flow-injection mass spectrometry fingerprinting method for authentication and quality assessment of Scutellaria lateriflora-based dietary supplements

Scutellaria lateriflora, commonly known as skullcap, is used as an ingredient in numerous herbal products. However, it has been occasionally adulterated/contaminated with Teucrium canadense and/or Teucrium chamaedrys, commonly known as germander, due to the morphological similarities between the two genera. The latter contains hepatotoxic diterpenes. Despite the potential hepatotoxicity introduced by germander contamination, analytical methodologies for the authentication and quality assessment of S. lateriflora-based dietary supplements have not been reported. In this study, a flow-injection/mass spectrometry fingerprinting method in combination with principal component analysis was used to survey S. lateriflora-based dietary supplements sold in the USA.     

Asymptotical stability for memory‐type porous thermoelastic system of type III with constant time delay

In this paper, we consider a one‐dimensional porous thermoelastic system of type III with viscoelastic damping and constant time delay on boundary. Using the energy method, we prove the general stability of the system under suitable assumptions on the relaxation function and the time delay. Copyright © 2016 John Wiley & Sons, Ltd.     

An eigenvalue problem arising from spiky steady states of a minimal chemotaxis model

Asymptotic expansion of singular integrals is presented for the study of the existence and uniqueness of spiky steady states of Keller–Segel's minimal chemotaxis model. A tool is developed to find asymptotic expansion of eigenpairs of a nonlocal singular eigenvalue problem arising from the study of stability of the spiky steady state. New insights are given to simplify significantly the proofs of the main results in [1].     

Characterization of tanshinones in the roots of Salvia miltiorrhiza (Dan-shen) by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry

The qualitative analysis of tanshinones in the roots of Salvia miltiorrhiza (Dan-shen in Chinese) was performed using high-performance liquid chromatography with electrospray ionization tandem mass spectrometry (ESI-MS(n)). Tanshinones are the major bioactive constituents of Dan-shen, which is used in China for the treatment of haematological abnormalities and cardiovascular diseases. The ESI-MS(n) fragmentation behavior of tanshinones was investigated. For tanshinones with the tanshinone I nucleus, the fragmentation was triggered by loss of a molecule of CO except bearing a substituent at C17 or C18, followed by sequential eliminations of CO. If C(15-16) was a saturated bond, the fragmentation was triggered by elimination of a molecule of H2O. For tanshinones with the tanshinone IIA nucleus, the fragmentation was triggered by loss of a molecule of H2O, followed by successive eliminations of CO. Ions corresponding to loss of a molecule of propylene (Delta m = 42) were also observed. Moreover, when C(15-16) was a saturated bond, ions corresponding to losses of CH3, H2O and propylene were more abundant. If no D-ring existed, the presence of isopropyl resulted in an elimination of a molecule of H2O with an adjacent CO or OH. In addition, the extension of the pi-conjugation in the A-ring (especially at C(1-2)) induced the fragmentation by loss of a molecule of CO. These fragmentation rules were applied to the identification of tanshinones in a chloroform/methanol (3:7) extract of Dan-shen, which was separated on a C18 column with gradient elution. A total of 27 tanshinones were identified, including five new constituents. The established method could be used for the sensitive and rapid identification of tanshinones in the Dan-shen drug and its pharmaceutical preparations.     

Comprehensive characterization of C‐glycosyl flavones in wheat (Triticum aestivum L.) germ using UPLC‐PDA‐ESI/HRMSn and mass defect filtering

A comprehensive characterization of C‐glycosyl flavones in wheat germ has been conducted using multi‐stage high resolution mass spectrometry (HRMSⁿ) in combination with a mass defect filtering (MDF) technique. MDF performed the initial search of raw data with defined C‐glycosyl flavone mass windows and mass defect windows to generate the noise‐reduced data focusing on targeted flavonoids. The high specificity of the exact mass measurement permits the unambiguous discrimination of acyl groups (nominal masses of 146, 162 and 176.) from sugar moieties (rhamnose, glucose or galactose and glucuronic acid). A total of 72 flavone C‐glycosyl derivatives, including 2 mono‐C‐glycosides, 34 di‐C‐glycosides, 15 tri‐glycosides, 14 acyl di‐C‐glycosides and 7 acyl tri‐glycosides, were characterized in wheat germ, some of which were considered to be important marker compounds for differentiation of whole grain and refined wheat products. The 7 acylated mono‐O‐glycosyl‐di‐C‐glycosyl flavones and some acylated di‐C‐glycosyl flavones are reported in wheat for the first time. The frequent occurrence of numerous isomers is a remarkable feature of wheat germ flavones. Both UV and mass spectra are needed to maximize the structure information obtained for data interpretation. Copyright © 2016 John Wiley & Sons, Ltd.     

Global existence and blowup of solutions for nonlinear coupled wave equations with viscoelastic terms

In this paper, we study a system of nonlinear coupled wave equations with damping, source, and nonlinear strain terms. We obtain several results concerning local existence, global existence, and finite time blow‐up property with positive initial energy by using Galerkin method and energy method, respectively. Copyright © 2015 John Wiley & Sons, Ltd.