Variation in the composition of the essential oils, phenolic compounds and mineral elements of Hypericum perforatum L. growing in Estonia

Abstract

A comprehensive investigation of the chemical composition of the aerial parts of Hypericum perforatum L. collected in three habitations in Estonia was carried out. An analysis by gas chromatography–mass spectrometry and gas chromatography–flame ionisation detection established the main components of the essential oils. The phenolic compounds both in ethanol and water extracts of the plant were analysed using liquid chromatography–mass spectrometry (LC–MS) and capillary zone electrophoresis. In addition to the earlier published polyphenols, several new phenolic acids and flavonoids, such as quercetin hexoside malonates and an A-type catechin–epicatechin trimer were identified in this Hypericum for the first time. The contents of the pharmaceutically important antidepressants hyperforin and hypericin were also estimated by LC–MS and compared with the data in the literature. The composition of the mineral elements was determined by atomic absorption spectroscopy. The results of the study demonstrate a rather high variability in the content of different substance groups in H. perforatum L. and, hence, the need for a survey of the raw material in the course of selection of raw materials for pharmaceutical preparations.

Keywords:

• St. John's wort
• chromatography
• capillary electrophoresis
• essential oils
• polyphenols

Acknowledgements

The authors greatly acknowledge Tiiu Kailas and Dr Mati Müürisepp for their help in the analysis of GC–MS.