Natural Products Insider

SEP-OCT 2017

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88 INSIDER September/October 2017 The technology has other limitations. For example, Mark Blumenthal, ABC's executive director and founder, referenced DNA's inability to determine specifi c plant parts present in a sample. DNA tests also can pick up minute amounts of organic material, which could lead to the misimpression that a product is adulterated or misbranded. Schneiderman's DNA investigation revealed such undeclared matter in herbal supplements as rice, wheat and houseplant. DNA barcoding, Murch explained, is subject to a process in which fragments of DNA are "amplifi ed" or "copied" so there is suffi cient DNA to measure. Murch said DNA barcoding won't disclose such things as the amount of rice in a product, for example, and whether the sequencing standards applicable to rice are even appropriate. Commenting on the amplifi cation step previously mentioned, Brown said DNA barcoding can identify a single molecule of DNA. "But at these limits, whatever is reported has nothing to do with the plant materials used," she asserted. What's more, it's not surprising to herbal professionals that minute quantities of undeclared substances could be found in a botanical product using DNA barcoding. "As we know, plants are products of nature … and when you collect products of nature, you tend to get some other minor … ingredients," said Sharaf of AHPA. In a paper published in 2016 by AHPA, botany professor Steven Newmaster, Ph.D., of the University of Guelph in Canada and his two co-authors pointed out, "DNA is everywhere," and DNA from humans, pets and plants may be scattered around a person. "'Incidental DNA fragments' should also be assumed to be present in various combinations and amounts in samples of herbal ingredients," the authors wrote. "In fact, pharmacopoeial botanical monographs specifi cally allow some small amount— usually 2 to 5 percent—of 'foreign organic matter,' which may reasonably include other plant parts of the target species or inadvertent but minimal presence of other species that may be comingled in a harvested crop." Complicating matters further, in the quest to verify the identity of herbs, DNA testing isn't 100 percent accurate. Murch pegged the certainty of a DNA barcode test at between 53 and 85 percent, depending on the species used in different studies. "We don't really know," she acknowledged. "The main point … is that a DNA result is not an absolute answer." Brown said a company must understand the material being studied and the testing method's limitations to place confi dence in the testing method and subsequent results. "Without a doubt, DNA can be a useful tool for assigning identity to plant materials when the classic diagnostic features have been lost, but only if the DNA in that format is intact," she observed. Cautioned Brown: "Getting a 'negative' for a DNA test does not mean the product is not authentic and within its specifi cations." The bottom line, experts suggest, is that DNA barcoding is not a panacea for the herbal supplements industry. Nonetheless, the technology is evolving and becoming more useful for industry as a growing number of supplement companies express interest in it, and new businesses emerge in the DNA testing fi eld. Gafner found noteworthy, for example, the introduction of next-generation sequencing instruments, which he said enable a researcher to retrieve thousands of sequences from a sample and consequently obtain "a more accurate representation of the materials present." Perhaps the most important lesson from Schneiderman's 2015 herbal supplements investigation is a simple one rooted in modern science. As Newmaster and his co-authors noted, a company testing plant species and ingredients should abide by certain criteria—regardless of the testing method used. That includes, among other things, using a testing method fi t for purpose and scientifi cally valid. AHPA's Sharaf described DNA technology as an "alternative" or "complementary" technique—that while potentially benefi cial, shouldn't be exclusively relied on. "I personally would not rely on DNA as the only identifi cation tool" for a botanical, he said. "I need other techniques to confi rm the reality of the material I'm testing." Supply Chain Regulations DNA Barcoding: The Basics Where did it come from? According to the International Barcode of Life Project (iBOL), an international consortium and research alliance, DNA barcoding fi rst drew the scientifi c community's attention when a research group at the University of Guelph in Canada published a paper proposing "a new system of species identifi cation and discovery using a short section of DNA from a standardized region of the genome." What is the concept behind the technology? "The theory of DNA barcoding is the identifi cation of a specifi c short fragment of the DNA that is characteristic of the species," explained Susan Murch, Ph.D., professor of chemistry at the University of British Columbia. How does DNA barcoding work? According to iBOL, DNA barcoding begins with obtaining specimens, like plants, from a variety of sources. Some are collected in nature, while others originate from natural history museums, zoos and other places. In the laboratory, technicians use a small piece of tissue from the specimen to extract its DNA. "The barcode region is isolated, replicated using a process called PCR amplifi cation and then sequenced," iBOL noted on its website. All DNA is comprised of four chemicals associated with the letters A,G, C and T, observed Murch, who described the sequence as "a list of these letters in the order that the chemicals appear in the DNA strand."

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