The Signature of Toxic Herbs

Dutchmans pipe compound called aristolochic acid has molecular signature that signals exposure

(RxWiki News) Chinese herbal medicines have been used for centuries to treat everything from asthma and allergies to yellow fever. Recently, an ingredient widely used in these treatments has been shown to be dangerous.

A group of plants known as “Dutchman’s pipe” contain a compound that has been used in a variety of traditional Chinese remedies.

This compound — aristolochic acid — is now known to cause kidney damage and has been linked to bladder cancer.

Scientists in two new studies have uncovered a “molecular signature” that signals exposure to this compound — exposure the individual may never have been aware of.

This signature could be used to develop a test for aristolochic acid exposure so that individuals could be more closely monitored for potential serious health issues.

"Research the ingredients of any supplements you take."

Song Ling Poon, PhD, a researcher at the National Cancer Centre Singapore, Margaret L. Hoang, PhD, of Johns Hopkins University, and colleagues conducted these studies.

According to these researchers, aristolochic acid has been used in traditional health preparations as supplements and remedies for various conditions including weight loss, menstrual symptoms and rheumatism (diseases like rheumatoid arthritis).

Starting in the 1990s, studies found the compound to be associated with kidney disease and bladder cancer, specifically urothelial carcinoma.

Women given the compound at a weight loss clinic in Belgium in the late 1990s developed kidney damage.

The FDA listed several botanical products of concern in 2001, and urged consumers to stop taking a total of 16 products containing aristolochic acid.

Import of aristolochic acid has been banned in the US since 2002, but millions of people, particularly in Asia, have been exposed to this compound.

The researchers wrote, “Despite public health warnings regarding the safety of botanical products and dietary supplements containing aristolochic acid and bans on the use of such products in several countries, almost 20 years later potential sources of aristolochic acid remain available.” They noted that the products are “...easily available worldwide over the Internet.”

The two studies examined tumors of people who had known exposure to aristolochic acid. The scientists developed what they called a "molecular signature" which showed DNA damage likely caused by exposure to aristolochic acid. DNA damage can lead to cancer and other diseases.

These studies found that aristolochic acid was more likely to have caused the damage in some of the tumors than other carcinogens (cancer causing agents) such as tobacco.

Aristolochic acid apparently caused more mutations than other carcinogens do, the researchers found.

This signature may lead to the development of cancer biomarkers (molecules that indicate the presence of cancer) that could be used to test for aristolochic acid exposure.

“The technology gives us the recognizable mutational signature to say with certainty that a specific toxin is responsible for causing a specific cancer. Our hope is that using the more targeted whole-exome-sequencing process will provide the necessary data to guide public health decisions related to cancer prevention,” Kenneth Kinzler, PhD, professor of oncology in the Johns Hopkins Kimmel Cancer Center’s Ludwig Center for Cancer Genetics and Therapeutics, said in a prepared statement.

Meanwhile, individuals with this signature could be more closely monitored for kidney damage and bladder cancer.

Findings from these studies were published August 6 in the journal Science Translational Medicine.

This work was supported in part by funding from the Singapore National Medical Research Council, the Singapore Millennium Foundation, the Lee Foundation, the Singapore National Cancer Centre Research Fund, The Verdant Foundation, the Duke-NUS Graduate Medical School, the Cancer Science Institute, Singapore, the Chang Gung Memorial Hospital, the Taiwan National Science Council and Wellcome Trust.

No conflicts of interest were reported.

Review Date: 
August 7, 2013