Practical method for the rapid screening of xanthine oxidase inhibitors in herbal extracts by high-performance liquid chromatography based on on-line precolumn enzymatic reaction.
A high-performance liquid chromatography method with on-line precolumn enzymatic reaction for the screening of xanthine oxidase inhibitors in natural extracts was developed. In this method, the enzymatic reaction occurred at the capillary inlet during a predetermined waiting period, after which the reaction product, uric acid, was separated and detected by liquid chromatography using ultraviolet absorption at 295 nm. Enzyme inhibition can be read out directly from the reduced peak area of uric acid in comparison to a reference chromatogram obtained in the absence of any inhibitor. In the present study, the availability of on-line precolumn enzymatic reaction with ultraviolet detection was firstly evaluated by determining the inhibitory mechanism and IC50 values of allopurinol, a commercially available positive drug. Then, the newly developed method was applied to screening of ten natural extracts from traditional Chinese medicine and as a result, the extract of Epimedium sagittatum (Sieb. et Zucc.) Maxim was found to be most positive for xanthine oxidase inhibition. The results obtained were compared with those obtained by offline enzyme assay and the effectiveness of the present method was confirmed. A rapid, low-cost, and fully automated method for xanthine oxidase inhibitor screening was proposed.
The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei province, China.
Chun-Hua
CH
Zhou
The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei province, China.
De-Qiang
DQ
Li
The Dacheng Country Hospital, Langfang city, Hebei province, China.
Yuan-Yuan
YY
Xiao
The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei province, China.
Xiu-Ling
XL
Yang
The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei province, China.
Zhi-Qing
ZQ
Zhang
Inhibitors screening; Liquid chromatography; Precolumn enzymatic reaction; Xanthine oxidase