Essential and toxic element concentrations in Hypericum perforatum

Abstract

The herb Hypericum perforatum L. – otherwise known as St John’s Wort – that grows on serpentine and non-serpentine sites is widely used in traditional medicine in Bulgaria. Plant aerial parts (Hiperici herba) as well as methanol/water (1 : 1) and water extracts prepared from eight populations growing on and off serpentine were analysed for essential (Fe, Mn, Cr, Co, Cu, Zn) and toxic (Ni, Cd, Pb) elemental concentration using inductively plasma optical emission spectrometry and electro thermal atomic absorption spectrometry. The results showed that metal concentrations varied across sites. Non-serpentine populations were well separated based on their total metal concentrations. The plant is Ni tolerant, but has the potential to accumulate trace elements at toxic levels. The transfer of elements from the herb material to an extract was solvent and metal dependent. The highest mobility, e.g. percentages of extraction, was found for Cu, Zn and Ni in all extracts. The amount of Cd, Ni and Cr was above the permissible limits in dry plant material and both types of extracts. The element concentrations found in this medicinal plant show that people should be careful when collecting it from serpentine sites and using it for medication.