Screening and characterization of potential anti-gout components from Polygonum cuspidatum by integration off-line two-dimensional liquid chromatography-mass spectrometry with affinity ultrafiltration and on-line HPLC-ABTS.

Polygonum cuspidatum (P. cuspidatum) is a traditional herbal medicine with a long history and proven efficacy in treating gout. However, due to the complexity of composition and extensive content distribution, the substance basis of its anti-gout effectiveness is still unclear. A strategy was proposed via integrating off-line two-dimensional liquid chromatography (2D-LC) and targeted rapid screening technology based on ultrafiltration-liquid chromatography-mass spectrometry (UF-LC/MS) and on-line high-performance liquid chromatography-2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (HPLC-ABTS) to accomplish high coverage and high throughput screening of anti-gout components from P. cuspidatum. As a result, twenty components were screened from P. cuspidatum extract with both xanthine oxidase (XOD) inhibitory activity and free radical scavenging activity, then were preliminarily identified by high-resolution electrospray ionization-quadrupole-time-of-flight mass spectrometer (ESI-Q-TOF/MS). The screened results were verified by the in vitro assays. Meanwhile, molecular docking further elucidated that the screened bioactive ingredients had favourable binding capabilities with XOD. The performance of this study can achieve high efficiency and high coverage screening of the anti-gout components from P. cuspidatum, which provides methodology and strategy support for the rapid screening of bioactive ingredients from complex medicinal plants.

Determination of oleanolic and ursolic acid in Chinese herbs using HPLC and γ-CD as mobile phase modifier.

To separate and determine oleanolic acid and ursolic acid, a rapid and accurate HPLC using γ-CD as the mobile phase additive was developed. The effect of CD nature and concentration, and the acidity of the mobile phase on the chromatographic behavior of two bioactive triterpenes were systematically studied. Two bioactive triterpenes were completely separated (R = 3.11) on a Kromasil(®) C(18) column (150×4.6 mm id, 5 µm) with the mobile phase consisting of acetonitrile/0.1% phosphoric acid with 2 mM γ-CD as the mobile phase modifier (60:40, v/v). The flow rate was set at 1.0 mL/min and the eluent was detected at 210 nm for two bioactive triterpenes. The linearity of the method was excellent (r=0.9999) over the studied range of 6-300 µg/mL for oleanolic acid, and 12-600 µg/mL for ursolic acid. The LOD and LOQ were 1.5 and 5.0, 1.0 and 3.0 µg/mL for oleanolic acid and ursolic acid, respectively. The optimized method was successfully applied to separate and determine two bioactive triterpenes in five Chinese herbs. It is concluded that this method could be used for rapid and accurate qualitative and quantitative analysis of the two bioactive triterpenes in Chinese herbs.