Identification of Epilobium species and willow-herbs (Onagraceae) by HPLC analysis of flavonoids as chemotaxonomic markers

The aim of this work was to compare macro- and micromorphological characteristics and flavonoid composition of some Epilobium species and commercial willow-herbs for their authentication and quality control. In order to determine the flavonoid composition of extracts, the flavonol-glycosides were also hydrolised quantitatively to their aglycones. Before and after hydrolysis flavonoid fingerprints were studied by high-performance liquid chromatography using two different gradient mobile phase systems. Flavonoid composition was found to be suitable for the authentication of Epilobium species and commercial willow-herbs as an alternative to the current phytochemical study and time-consuming microscopic procedures [1]. The combined HPLC analysis of free flavonoid-aglycones and glycosides, developed in our laboratory can be used for the quality control of willow-herb samples and various commercial preparations.