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Botanical Adulterants Bulletin Highlights the Presence of Synthetic Antimicrobial Compounds in ‘Grapefruit Seed Extract’


The American Botanical Council (ABC)-American Herbal Pharmacopoeia (AHP)-National Center for Natural Products Research (NCNPR) Botanical Adulterants Program (BAP) has published a new Botanical Adulterants Bulletin (BAB) on the adulteration of grapefruit seed extract (GFSE).

GFSE is marketed as a dietary supplement with antimicrobial activity and as a natural preservative for personal care and cosmetic products. The seed of grapefruit (Citrus paradisi, Rutaceae) has no known history of use in traditional herbal medicine.

As early as 1991, the occurrence of undeclared synthetic antimicrobial compounds (i.e., triclosan and methylparaben) was reported in products marketed as GFSE. Thirteen published papers have provided evidence for adulteration of GFSE with these and other synthetic microbicides, such as benzalkonium chloride, benzethonium chloride, cetrimonium bromide, and propylparaben. However, none of these studies found chemical compounds that are characteristic of grapefruit seed in the adulterated products, which suggests that any antimicrobial effects of these products were due to the undeclared microbicides rather than authentic GFSE.

The GFSE bulletin contains information about the production and market importance of GFSE, known adulterants, and analytical approaches to detect adulterants. It was authored by John Cardellina, PhD, chief technical consultant and associate editor of BAP. The bulletin has been peer reviewed by 12 experts from contract analytical laboratories, nonprofit organizations, the US government, and the herb and dietary supplement industry.

The goal of the BABs is to provide accounts of ongoing issues related to botanical identity and adulteration and inform quality control personnel and lab technicians in the herbal medicine, dietary supplement, cosmetic, conventional food, and other industries in which botanical ingredients are used about adulteration problems that may be widespread and/or that may constitute safety problems.

This bulletin marks the second publication on GFSE as part of the BAP’s ongoing efforts to educate industry members and other stakeholders about the adulteration of GFSE. The first publication on GFSE adulteration appeared in issue 94 of ABC’s peer-reviewed journal HerbalGram in 2012.

“The adulteration of ‘grapefruit seed extract’ with undisclosed synthetic disinfectant chemicals is a particularly egregious practice,” noted Mark Blumenthal, founder and executive director of ABC and director of the BAP. “There has been no credible explanation as to why these synthetic compounds have been continually detected by independent laboratories over the past 25 years; the only logical conclusion is that they are being added intentionally. This appears to be adulteration, and, as such, it is fraud. This issue requires investigation by the US Food and Drug Administration and other appropriate agencies internationally.”

Cardellina commented: “Almost five years after publication of the review of the adulteration of GFSE in HerbalGram, analyses continue to show that some so-called GFSE products in the marketplace are adulterated with synthetic microbicides. A recent seminal paper from the research group of Ikhlas Khan, PhD, at the NCNPR at the University of Mississippi provides a critical new tool to address this problem: an analytical method that can simultaneously identify and quantify both the natural constituents of grapefruit seed and also the suite of synthetic disinfectants found for more than 25 years in commercial GFSE products. This new method warranted the issuance of this bulletin.”

ABC Chief Science Officer Stefan Gafner added: “While there are authentic GFSE products available on the market with respect to their containing citrus-related compounds, the sale of synthetic antimicrobial chemicals labeled as GFSE is still ongoing. We hope that our continuing efforts to raise awareness of the issue will ultimately lead to a disappearance of these fraudulent products.”

The GFSE bulletin is the ninth publication in the series of BABs. As with all publications in the program, the bulletins are freely accessible on the program’s website.

About the Botanical Adulterants Program

The ABC-AHP-NCNPR Botanical Adulterants Program is an international consortium of nonprofit professional organizations, analytical laboratories, research centers, industry trade associations, industry members, and other parties with interest in herbs and medicinal plants. The program advises industry, researchers, health professionals, government agencies, the media, and the public about the various challenges related to adulterated botanical ingredients sold in commerce. To date, more than 180 US and international parties have financially supported or otherwise endorsed the program.

In the coming months, the program plans to release additional bulletins on ashwagandha (Withania somnifera, Solanaceae) root, rhodiola (Rhodiola rosea, Crassulaceae) root and rhizome, and tea tree (Melaleuca alternifolia, Myrtaceae) oil.

To date, the BAP has published seven extensively peer-reviewed articles on the history of adulteration, the adulteration of the herbs black cohosh (Actaea racemosa, Ranunculaceae) and skullcap (Scutellaria lateriflora, Lamiaceae), adulteration of bilberry (Vaccinium myrtillus, Ericaceae) fruit extract and pomegranate (Punica granatum, Lythraceae) fruit products, the history of ginseng (Panax spp., Araliaceae) taxonomy, nomenclature, and trade as a basis for understanding ginseng adulteration, and the sale of synthetic antimicrobial compounds labeled to contain GFSE.

In addition, the program has published four Laboratory Guidance Documents (LGDs) that review and evaluate analytical methods to authenticate and detect adulteration of bilberry extract, black cohosh, and skullcap. The fourth LGD, on GFSE, was published in May. The program also publishes a quarterly e-newsletter, the Botanical Adulterants Monitor, that highlights new scientific publications related to botanical authenticity and analysis to detect possible adulteration, recent regulatory actions, and program news. All of the program’s publications are freely available on the ABC website,

—ABC Staff