mixture of animals.
A product made using saiga critically endangered also contained goat and sheep DNA.
M. L. Coghlan et al. PLoS Genetics 8 (April 2012)
Traditional Chinese medicine (TCM) is enjoying increasing popularity throughout the world. But two molecular genetic studies published this week show that fashionable treatments can be harmful as well. The documents draw attention to the fact that not all the ingredients are listed, or even legal, and some can cause cancer.
"These two studies clearly show the danger of TCM products can be," says Fritz Sörgel, the head of the Biomedical and Pharmaceutical Research Institute in Nuremberg, Germany, who was not involved the work. "The public needs to be better informed about these dangers."
Hundreds of millions of dollars are spent on TCM products every year an increasing share of it on the Internet and some scientists are looking for these preparations in the hope of discovering new pharmacological substances. Many would like to emulate the success of Tu Youyou, the Chinese scientist who isolated artemisinin, now drug against malaria the most important in the world from an ancient Chinese medicine. You won a Lasker Award last year and is rumored to be a Nobel candidate.
But critics have long warned that certain mixtures may also contain naturally occurring toxins, contaminants such as heavy metals, added substances such as steroids that make them seem more effective, and traces of animals that are endangered and restricted trading.
Now, researchers at Murdoch University in Australia studied the problem using modern sequencing technology. The team, based at the Australian Wildlife university Forensic Services and Ancient DNA Laboratory in Perth, has analyzed 15 samples of traditional Chinese medicine seized by Australian authorities of the border.
"We took these traditional preparations, in pieces, and the powder extracted DNA," says molecular geneticist Michael Bunce. The scientists then caught two copies of specific genes trnL , a common chloroplast gene to all plants, and 16S rRNA , conserved among plants and animals, and multiplied and sequences. in comparing the sequences of those databases genetic they could identify animals and plants used to make the drug. "Sometimes we really had trouble assigning a particular DNA to a particular species," says Bunce. But as genetic databases grow, it should become easier.
Some products contained material from animals classified as vulnerable or critically endangered, as Asiatic black bears and saiga, as the producers claimed. But often ingredients, the drug has also not feed on the packaging, the team announced today online in PLoS Genetics . "For instance, a product labeled 100 percent Saiga antelope contained considerable quantities of goat and sheep DNA," Bunce wrote.
"Using DNA to identify the species and thus prove the illegal trade is very elegant," says Dietmar Lieckfeldt, working in molecular forensics at the Leibniz Institute for Zoo and Research wildlife in Berlin, Germany. Identification of animals by their DNA has been possible for some time, he said, but the new generation sequencing technology to nail species in a mixture very quickly.
In preparations herbal, Bunce and his colleagues found members of 68 families of different plants, including the plants of the genera Ephedra and Asarum . Both can contain toxic chemicals such as aristolochic acid, a compound banned in many countries because it causes kidney disease and cancer of the upper urinary tract (UUC). Upon detection of DNA of a species does not mean a toxin produced by this plant is present, the chemical analysis of one of the four samples containing Asarum DNA was rotated until to aristolochic acid.
The threat aristolochic acid is also highlighted in an article in the Proceedings of the National Academy of Sciences on Monday. The researchers, led by pharmacologist Arthur Grollman of Stony Brook University, focused on Taiwan, the country with the highest rate of UUC in the world. Previous analysis showed that nearly a third of the Taiwanese population consumed herbs may contain aristolochic acid.
Scientists have sequenced the tumors of 151 patients with UUC. Among patients with characteristic mutations in the tumor suppressor gene important TP53 -which make people more vulnerable to cancer of 84% also showed a molecular signature of known exposure to aristolochic acid, they found. The study provides compelling evidence that aristolochic acid is a main cause of UUC in Taiwan, the authors state.
Bunce and his colleagues also found the DNA of known plant families contain important medicinal species that could pose risks when used in combination with other drugs and DNA soy and plants of the family of cashew nuts, which may contain allergens. . "It just shows that the ingredients in these preparations are not reported accurately," says Bunce Indeed, said Sörgel, studies show that participating in traditional Chinese medicine herbal is a gamble: "We do not know enough."
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