UHPLC and Chemometrics Tease out Teasel’s Active Compounds

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  • Published: Apr 17, 2017
  • Author: Ryan De Vooght-Johnson
  • Channels: Laboratory Informatics / Chemometrics & Informatics
thumbnail image: UHPLC and Chemometrics Tease out Teasel’s Active Compounds

Current analytical methods for Dipsacus asper need improvement

The rhizomes of Dipsacus asper (Japanese teasel) are used in China to treat osteoporosis and traumatic hematoma, as well as to aid the healing of broken bones. There is also some interest in its possible neuroprotective effects, including its potential use against Alzheimer’s disease. Often the herb is processed with rice wine, which is believed to give greater analgesic and anti-inflammatory properties compared to the raw herb. The herb contains a number of compounds that may account for its properties; however, current analytical methods typically involve only the assay of one major component, asperosaponin VI, while ignoring other potentially active compounds present.

Scientists from Nanjing University of Chinese Medicine devised a new method of examining the active compounds in Dipsacus asper using UHPLC-MS/MS combined with various chemometric methods to clearly outline the differences between the raw and the wine-processed rhizomes.

UHPLC and chemometrics show the effect of wine processing on Dipsacus asper

Wine processing was carried out according to the 2015 Chinese pharmacopeia method. Rhizomes were rinsed for 2 hours with rice wine, then gently boiled in a little water until the latter evaporated. The raw and wine-treated rhizomes were then powdered and extracted with aqueous methanol with sonication. The extraction conditions were optimised: the extraction time was set at 30 minutes, the extraction volume at 50 ml for 0.5 g of powdered material, and the methanol:water ratio at 75:25 v/v. Solids were removed by centrifugation prior to UHPLC. UHPLC was carried out on a Waters Acquity BEH C18 column with a flow rate of 0.3 ml/min. Acetonitrile and 0.1% aqueous formic acid were used as the two mobile phases. A gradient was run using increasing amounts of acetonitrile (5–100%). The conditions were carefully optimised to give acceptable peak separations for the eight compounds of interest. Mass spectrometry was carried out on a Sciex QTRAP 5500 triple quadrupole instrument. Distinctive precursor to product ion transitions were found for the different compounds. The UHPLC-MS/MS method gave good linearity and reproducibility. The limits of detection (LOD) ranged from 3.1 to 4.2 ng/ml, while the limits of quantification ranged from 9.3 to 12.5 ng/ml. Data on the eight compounds were obtained for 20 different batches of the herb, with samples being taken from each batch in both the raw and wine-processed state. Principal component analysis (PCA) was applied using SIMCA-P 11.5 software; the raw and wine-treated samples were separated into two distinct groups. Hierarchical cluster analysis (HCA) with Heml 1.0 software gave similar results, also separating the samples into the two groups of raw and wine-treated samples. Partial least squares discriminant analysis (PLS-DA) was applied, using the SIMCA-P 11.5 package, also showing clear differences between raw and wine-treated samples. The PLS-DA results indicated that four compounds increased on wine-processing: chlorogenic acid (i.e. 3-caffeoylquinic acid), dipsacoside B, asperosaponin VI and loganic acid. The error bars were such that the increase in the latter may be only apparent. The increase in dipsacoside B and asperosaponin VI may be due to the wine treatment making them more available for extraction. It is possible that some chlorogenic acid was formed from the 4-caffeoylquinic acid and 3,5-dicaffeoylquinic acid. Four compounds decreased (maybe due to heat degradation or rearrangement): loganin, sweroside, 4-caffeoylquinic acid and 3,5-dicaffeoylquinic acid.

New chemometric procedure for Dipsacus apser gives more complete analysis

The new procedure enabled a much more complete picture of the different active constituents of the herb to be produced. The chemometric work showed that the wine-treatment protocol caused clear differences in the chemical composition of extracts. It remains to be seen how widely the new analytical method is adopted in future.

Related Links

Journal of Separation Science, 2017, Early View paper. Tao et al. UHPLC–MS/MS quantification combined with chemometrics for the comparative analysis of different batches of raw and wine-processed Dipsacus asper.

Phytotherapy Research, 2011, 25, 1700-1706. Niu et al. Asperosaponin VI, A saponin component from Dipsacus asper Wall, induces osteoblast differentiation through bone morphogenetic protein-2/p38 and extracellular signal-regulated kinase 1/2 pathway.

Life Sciences, 2003, 73, 2443-2454. Zhang et al. The herbal medicine Dipsacus asper Wall extract reduces the cognitive deficits and overexpression of β-amyloid protein induced by aluminum exposure.

Article by Ryan De Vooght-Johnson

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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