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Traditional Chinese medicines under scrutiny

DNA analysis can identify illegal or unsafe ingredients in traditional Chinese medicines, according to new research.

An Australian-led group of scientists found traces of endangered species, as well as potential toxins and allergens in traditional Chinese medicines that were confiscated from overseas travellers.

"We can use the latest DNA technology to investigate what's in these medicines and do a comprehensive genetic audit," says Dr Mike Bunce, molecular biologist at Murdoch University, Western Australia, and team leader of the study published today PLoS Genetics.

Traditional Chinese medicine has been practised in China for more than 3000 years and has become increasing popular in Australia in recent decades.

In this study, scientists assessed 15 samples of traditional Chinese medicines seized by Australian customs. They extracted DNA from the tablets, powders and herbal teas. Then they used a technique called 'second generation DNA sequencing' to identify the plant and animal species they contained.

Their study identified the presence of vulnerable and endangered species such as the Asiatic black bear and the saiga antelope. The trade of these species is illegal under the Convention on International Trade in Endangered Species.

Missing information

The analysis also revealed issues with misleading and poor labelling. For example, one product contained a plant called Ephedra - considered toxic if taken in too high a dosage - which did not list a recommended dosage on the label. Potential allergens such as nuts were also identified, but not listed in the ingredients.

Bunce says it's possible these products also contained beneficial therapeutic agents. But, he thinks there should be higher manufacturing and labelling standards, and the use of new molecular approaches can help to regulate the industry.

"Second generation DNA sequencing is a cost-effective method to investigate honesty in food labelling and combat illegal trade in animals and plants," he says.

Professor Chun Guang Li, a pharmacologist in the Discipline for Chinese Medicine at RMIT University, Melbourne, agrees that it's important to monitor the quality of these health products.

But, he thinks there is some uncertainty associated with the DNA sequencing used in this study, and further tests may be required to correctly identify ingredients at a species level.

"A combination of genetic and chemical profiles may be a future direction for analysis of these products," he says.

These technologies may help to enforce laws that ensure the safety of alternative therapies and protect vulnerable species.