Aristolochic Acids (AA)
- Aristolochic acid (AA) is an herbal compound found in many traditional medicines and can cause liver cancers
- AA containing herbs have been restricted or banned in some countries like Europe, Singapore, Taiwan and China
- There is a great need for creating awareness and educating the public to avoid exposure to these AA-containing herbs and remedies
are natural products of some plants that are used in herbal remedies. AA was found to be linked to liver cancers, reveals a research team from Singapore and Taiwan.
The research team used mutational signature analysis and found that liver tumors were exposed to AA and mutation took place in many genes that cause cancer.
‘Plants and remedies that contain aristolochic acid (AA) are still widely available. Therefore, there is a need to create awareness and educate the public to avoid exposure.’
The research team was led by Professor Steven Rozen from Duke-NUS Medical School (Duke-NUS); Professor Alex Chang from Johns Hopkins Medicine Singapore; Professor Teh Bin Tean from the National Cancer Centre Singapore (NCCS), and Professor Hsieh Sen-Yung from Chang Gung Memorial Hospital in Taiwan and have first sequenced the DNA of 98 liver cancers from Taiwan.
Link between AA and Liver Cancers
In about three-quarters of liver cancers, large numbers of AA-related mutations have been found. The research team used mutational signature analysis and examined these cancers.
are the pattern of changes that occur in the DNA is caused by mutagens, which are compounds that cause cancer.
Professor Hsieh said, "Although we knew that there was exposure to AA in Taiwan, we were very surprised to find such a high proportion of liver cancer sufferers had exposure to AA."
Later, the research team went through publicly available data on mutations from 1,400 liver cancers from all around the world.
AA is mainly found in plants and is used in traditional medicine worldwide. However, a high prevalence of exposure was also found in other parts of East and Southeast Asia.
"This also was an unexpected finding. We did not suspect that exposure to AA was so prevalent in so many different areas," said Professor Rozen. AA is a known mutagen. In Taiwan, AA was previously implicated in kidney and urinary tract cancers.
In this study, it is confirmed that AA mutations were involved in causing liver cancer,
which was a surprising finding of this study, noted Professor Rozen.
Banning of AA compounds
Professor Teh from NCCS that this study is a follow-up of their 2013 paper, where a breakthrough was made in knowing the action of AA in causing cancer in the urinary tract. He also said that this new study reveals that AA causes liver cancer as well.
AA, a natural compound found in Aristolochia and Asarum plants are used in traditional herbal remedies. It is commonly used for many purposes like in weight loss and slimming.
AA was banned officially in Europe since 2001 and in Singapore since 2004. Use of some herbs that contain AA has been restricted in traditional medicine in Taiwan and China since 2003.
The U.S. Food and Drug Administration (FDA) issued warnings about AA-containing herbs, and their sale is not restricted if they are labeled correctly, and no health claims are made.
However, it might take years for the bans to come into effect and it could be years before rates of cancer that were caused by AA fall. Also, herbs containing AA are readily available online.
Need for Education and Awareness Programs
Herbs are often sold as formulations and are bundled rather than being sold individually, and some even contain AA, which could complicate matters even more.
To worsen matters, sometimes herbs that contain AA are labeled improperly, which makes it difficult for suppliers and consumers to be sure of the constituents of multi-herb formulations.
Plants that contain AA included Asarum plants (xì xīn) and powered xì xīn products that are manufactured in Taiwan and China were recalled in Singapore in 2014, as they contained AA.
Plants and remedies that contain AA are still widely available. Therefore, there is an urgent need to create awareness and educate the public to avoid any exposure, explained Professor Alex Chang.
This study was published in Science Translational Medicine,
, which is a publication with a high scientific impact that focuses mainly on practical medical advances.
The study was supported by the Singapore Medical Research Council (NMRC/CIRG/1422/2015), the Singapore Ministry of Health through the Duke-NUS Signature Research Programmes, and the Chang Gung Medical Foundation in Taiwan.
- Alvin W. T. Ng, Song Ling Poon, Mi Ni Huang, et al. Aristolochic acids and their derivatives are widely implicated in liver cancers in Taiwan and throughout Asia. Science Translational Medicine (2017). DOI:10.1126/scitranslmed.aan6446