MediHerb research shows limitations of DNA barcoding in authenticating botanical extracts

May 16, 2016—Herbal supplement manufacturer MediHerb recently led a research study that identified major shortcomings in the use of DNA barcoding to authenticate botanical materials in finished products. Standard Process Inc., the exclusive distributor of MediHerb herbal supplements in the United States, commends MediHerb for its role in the research study.

The new research, conducted by an Australian research consortium, and instigated by Australian natural health company Integria Healthcare/MediHerb, was presented during the 16th Annual Oxford International Conference on the Science of Botanicals, held at the University of Mississippi, in Oxford, Mississippi, April 11 to 14, 2016.

Hans Wohlmuth, PhD, research and development manager for Integria Healthcare and MediHerb presented the results at the international conference.

“With this work we have clearly demonstrated that DNA barcoding is not always appropriate for botanical extracts and finished products containing extracts,” said Wohlmuth.

The study examined four widely used universal DNA barcodes in 61 samples. The samples, which were also the subject of phytochemical analysis, included 17 dried botanical raw materials, 17 MediHerb liquid extracts made from the same batches of raw materials, and six MediHerb tablets containing some of the dried liquid extracts. The results showed that while the phytochemical composition (assessed by chemical profile and the presence of active compounds) was preserved in both extracts and tablets, the DNA barcodes were not. DNA barcoding also performed poorly with respect to the dried raw materials, with only just over half correctly identified by at least one of the four barcodes used.

The researchers concluded that the most likely explanation for this is that DNA strands start to break up when plant material is dried and extracted, making it difficult to successfully amplify and sequence the universal barcode regions.

“Further, we have shown that the absence of DNA barcodes does not indicate the absence of phytochemicals and active compounds,” said Wohlmuth. “Based on these results, we do not believe DNA barcoding using universal barcodes would make a valuable addition to our existing routine quality control program, which is extensive and based on specific morphological and chemical tests prescribed by pharmacopoeial monographs.”

Questions about the veracity of DNA barcoding have been in the news since early 2015, when the New York Attorney General forced several major retailers to stop selling a variety of dietary supplements containing botanicals. The enforcement was initiated on the basis that DNA barcoding had failed to identify the presence of the labeled botanical species or had identified the presence of unlabeled plant species.

“It is also important to realize that no DNA technique can provide information about which plant part was used or which phytochemicals are present,” he said. “When it comes to assessing the quality of botanicals, the imperative questions are, ‘Is the product derived from the correct species?’ and ‘Was the correct plant part used?’, and ’Does it contain the active compounds in meaningful amounts?’ No DNA based method is able answer the last two, very important questions.

“I have no doubt that various DNA techniques have the potential to make valuable contributions to the quality assurance of botanicals, but our study highlights what most experts agree on, namely that no single method can provide all the answers when it comes to the complex task of authenticating botanicals. Clearly, morphological and chemical tests, as prescribed by pharmacopoeial monographs, continue to form the basis for rigorous quality assurance of botanicals,” he said.

Soon after the regulatory events in New York State, Integria instigated the study to determine the validity and utility of DNA barcoding as a tool for use in routine quality control. The study involved the Australian Genome Research Facility, the Medicinal Plant Herbarium at Southern Cross University and the University of Queensland.

In 2001, whole food nutrient solutions leader Standard Process began its partnership with MediHerb to provide health care professionals in the United States with quality herbal solutions. Standard Process remains the exclusive distributor of MediHerb products in the U.S.

Source: Standard Process Inc.