Background: Certain frequently used Chinese herbal medicines commonly used for weight control, may contain toxic Aristolochia species, which have been associated with severe nephropathy and urothelial cancer in humans and animals. The toxic entities in Aristolochia species are aristolochic acid-I (AA-I) and aristolochic acid-II (AA-II). There is a lack of systematic information about the aristolochic acid content of Aristolochia species and related genera, including those in Chinese materia medica that are used in the treatment of overweight individuals.
Objectives: To determine the content of AA-I and AA-II of commonly used Chinese herbal medicines (raw herbs and manufactured products) including species of Aristolochia and related genera.
Methods: Twenty-one raw herbs and seven manufactured herbal products were purchased from herbal wholesalers and traditional Chinese medicinal herb retailers in Melbourne, Australia in September 2003, after the supply of known aristolochic acid-containing herbs and products had been banned in Australia. Six additional raw herbs were sourced from a herbal teaching museum. These were purchased in 2001, before the prohibition. The contents of aristolochic acids of each was determined by high pressure liquid chromatography (HPLC), and confirmed by liquid chromatography-mass spectrometry (LC-MS).
Results: Of the samples tested, four of the raw herbs purchased before the ban and two manufactured products purchased after the ban, were found to contain aristolochic acids (16-1002 ppm).
Conclusions: Several Chinese raw herbs and some commercially available manufactured herbal products contain aristolochic acids. The confusion in Chinese nomenclature for related raw herbs, and imprecise labelling of manufactured products may contribute to the inadvertent use of toxic herbal species in Chinese medicine practice. Additional measures are needed to ensure the safety of consumers of Chinese herbal medicines.