Simultaneous quantification of eleven bioactive components of male flowers of Eucommia ulmoides oliver by HPLC and their quality evaluation by chemical fingerprint analysis with hierarchical clustering analysis

Eucommia ulmoides Oliv (EU), a dioecious perennial angiosperm, is one of the oldest tonics in Chinese traditional medicine. The tea of male flowers of EU has been become popularities and seen as aspirational health care tea in China. There were no enough marks and effective method to control the quality of male flowers of EU. A simple and efficient HPLC method was developed for the simultaneous determination of 11 bioactive compounds (4 iridoids, 1 phenylpropanoid, 6 flavonoids). HPLC chromatographic fingerprint and hierarchical cluster analysis were used to evaluate and classify the samples of male flowers of EU which came from different locations in China. Samples were separated on a Thermal hypersil gold column (250 mm × 4.6 mm, 5 μm) and detected by an ultraviolet detector. The UV wavelength was set at 206, 236, and 206 nm. Mobile phase consisted of methanol (B) and phosphoric acid-water (0.5%) (C) using a gradient elution. Analytes were performed at 25°C with a flow rate of 1.0 mL/min. In quantitative analysis, the eleven components showed good regression (r(2) > 0.9996) within linear ranges, and their recoveries were in the range of 98.65-102.31%. In the chromatographic fingerprint, 16 peaks were selected as the characteristic peaks to assess the similarities of different samples. Hierarchical cluster analysis (HCA) was also applied to differentiate the samples based on the area of all the common peaks. The samples which had higher similarity in HPLC fingerprint were classified as a cluster. This study will provide methodological reference for the quality control and sample classification of male flowers of E. ulmoides.