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Tablets & Capsules April 2015 32C DNA bar-coding identifies an organism—plant or ani- mal—by detecting short sequences of DNA unique to its genome. When conducted properly on appropriate mate- rials, the test is highly sensitive and specific. "It can iden- tify unexpected adulterants and contaminants," said Danica Reynaud, CEO and Chief Science Officer of AuthenTechnologies, Richmond, CA, which specializes in botanical ingredient authentication using DNA testing. "More importantly, if the methods have been robustly developed and validated, the test can reliably and accu- rately distinguish between closely related species, which may be difficult to discern using alternative methods," Reynaud said. The ability to tell one species from another was crucial to the AG's findings, which, for example, showed that Target's "Up & Up" brand of St. John's wort contained unmistakable genetic traces of rice, garlic, and dracaena (a shrub), but none of the medicinal herb itself. Similarly, Walgreens' "Finest Nature" echinacea was said to contain garlic, rice, and daisies —but no echinacea. Wrong test? The high specificity and scientific cachet of DNA bar- coding, the AG's cease-and-desist letters, and a front page article in The New York Times drawing attention to it all cast the industry in a poor light [3]. But the AG got its share of criticism, too, mainly about the suitability of the testing methodology. "With rare exception, DNA bar- coding is not an appropriate technology for testing the identity of ingredients in [botanical] extracts," said Roy Upton, executive director of the American Herbal Pharmacopoeia. "Extracts are made…by a process that either does not maintain the DNA or significantly dena- tures it." Extracts are then "sometimes subjected to heat- ing or further mechanical filtering, which either removes or further denatures DNA, if present. With most extracts there is no actual plant tissue left," Upton said. "It is clear that adulteration in the herbal products industry, as with all industries, occurs. Unfortunately, [this] testing methodology was not appropriate for deter- mining this" [4]. A week after the story appeared in the Times, The New Yorker published an article titled "How not to test a dietary supplement" [5]. Reynaud, herself a botanist and geneticist as well as founder of a commercial DNA testing laboratory, agrees. "This type of testing is very difficult. Not only is it impor- tant to understand botany, but you need to understand the nature of DNA in finished products, which is very different from DNA in whole plant materials or pressed plant materials. It takes specialized knowledge that I would say most botanists actually don't understand. In a finished product, if there is any DNA left at all, it's not going to be very good quality. So if you don't use the right methods, you are likely to get false-negative results. Also, if you don't have quality control procedures to eliminate confounding cross-contamination, then that will lead to false-positives," Reynaud said. The DNA test- ing done by the laboratory Schneiderman's office con- tracted was led by Professor James Schulte, an evolution- ary biologist at Clarkson University who specializes in reptilian zoology, but is not an expert in botany, pharma- cognosy, or natural product chemistry—key disciplines in the authentication of botantical dietary supplements. Also problematic, DNA bar-coding cannot detect non- biological contaminants such as heavy metals, which do turn up periodically in herbal products. Furthermore, the test provides no quan- titative information about the contami- nants it can detect. And since it identifies only the presence or absence of DNA, it reveals little about the amount of an ingredient in a sample. In December 2014, the US Pharmacopeia (USP) revised General Chapter <563> "Identification of Articles of Botanical Origin" to include DNA bar-coding, but only to complement other chemical-based, chromatographic, macroscopic, and microscopic methods. Furthermore, "No individual monographs in USP-NF currently make explicit references to this general chapter," said Gabriel Giancaspro, vice president of foods, dietary supplements, and herbal medicines at USP. "A general chapter is only applicable if it is explicitly referenced in a monograph" [6]. AG stonewalls calls for transparency Given the limitations of DNA bar-coding in verifying the content of herbal supplements, why did Schnei der man use the test? "The AG has a responsibility to the citizens of the great State of New York to protect them from fraud and "You need to understand the nature of DNA in finished products." –Danica Reynaud, AuthenTechnologies