Investigation of targeted pyrrolizidine alkaloids in traditional Chinese medicines and selected herbal teas sourced in Ireland using LC-ESI-MS/MS

Abstract

Publications linking hepatotoxicity to the use of herbal preparations are escalating. Herbal teas, traditional Chinese medicines (TCMs) and dietary supplements have been shown to contain pyrrolizidine alkaloids (PAs). Acute PA toxicosis of the liver can result in sinusoidal-obstruction syndrome, also known as veno-occlusive disease (VOD). This paper describes a sensitive and robust method for the detection of targeted PAs and their N-oxides (PANOs) in herbal products (selected herbal teas and TCMs) sourced within Ireland. The sample preparation includes a simple acidic extraction with clean-up via solid-phase extraction (SPE). Sample extracts were accurately analysed by using LC-ESI-MS/MS applying for the first time a pentafluorophenyl (PFP) core-shell column to the chromatographic separation of PAs and PANOs. The method was validated for selectivity, taking into consideration matrix effects, specificity, linearity, precision and trueness. Limits of detection (LOD) and limits of quantitation (LOQ) were quantified for all PAs and PANOs ranging from 0.4 to 1.9 µg kg⁻¹ and from 1.3 to 6.3 µg kg⁻¹, respectively. In this study 10 PAs and four PANOs were targeted because they are commercially available as reference standards. Therefore, this study can only report the levels of these PAs and PANOs analysed in the herbal teas and TCMs. The results reported represent the minimum levels of PAs and PANOs present in the samples analysed; commercially available herbal teas (n = 18) and TCMs (n = 54). A total of 50% herbal teas and 78% Chinese medicines tested positive for one or more PAs and/or PANOs included within this study, ranging from 10 to 1733 and from 13 to 3668 µg kg⁻¹, respectively.