DNA sequencing technology has revealed that some traditional Chinese medicines contain potentially toxic plant ingredients, allergens, and traces of endangered animals.
Researchers at Murdoch University, Perth, Australia, discovered that some therapies contained plants of the genus Ephedra and Asarum, which contain chemicals that can be toxic if the wrong dosage is taken.
They also found traces from animals that are classified as vulnerable, endangered, or critically endangered, including the Asiatic black bear and Saiga antelope.
The 15 samples they analysed had been seized by Australian border officials and comprised powders, tablets, capsules, flakes, and herbal teas.
“TCMs [traditional Chinese medicines] have a long cultural history, but today consumers need to be aware of the legal and health safety issues before adopting them as a treatment option,” said Dr Mike Bunce, research leader and Murdoch University Australian Research Council Future Fellow.
“In total we found 68 different plant families in the medicines – they are complex mixtures of species.”
The findings are published in the Public Library of Science journal.
Until now it has been difficult to determine the biological origins of ingredients contained within TCMs because processing into pills and powders makes identification difficult.
PhD student Megan Coghlan said the research demonstrated that second-generation, high throughput sequencing is an efficient and cost-effective way to audit the species composition.
“We found multiple samples that contained DNA from animals listed as trade-restricted according to the Convention on International Trade in Endangered Species Legislation. Put simply, these TCMs are not legal,” Ms Coghlan said.
The researchers also highlighted the mislabelling of TCMs, which meant consumers were unaware of the presence of some ingredients, including animal DNA and potential allergens such as soy or nuts.
“A product labelled as 100 per cent Saiga antelope contained considerable quantities of goat and sheep DNA,” Dr Bunce said. “Another product, Mongnan Tianbao pills, contained deer and cow DNA, the latter of which may violate some religious or cultural strictures.”
He said the new approach to analysing the medicines could bring about new standards of regulation for complementary and alternative medicine.
He said further testing would reveal the extent of the problem and make it easier for customs officials to identify the trade of endangered species. The team also plans to use the DNA tests to evaluate other herbal medicines.
“Auditing TCMs would assist in prosecuting individuals who seek to profit from the illegal trade in animal products,” added Dr Bunce.
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