Adulterants and Contaminants in Psychotropic Herbal Medicines Detected with Mass Spectrometry and Next-Generation DNA Sequencing

Existing status and future advancements of adulteration detection techniques in herbal products

BACKGROUND

Herbal products have been commonly used all over the world for centuries. Its products have gained remarkable acceptance as therapeutic agents for a variety of disorders. However, following recent research disclosing discrepancies between labeling and actual components of herbal products, there is growing concern about the efficacy, quality and safety of the products. The admixture and adulteration of herbal medicinal products pose a risk of serious health compromise and the well-being of the consumers. To prevent adulteration in raw ingredients and final herbal products, it is necessary to use approaches to assess both genomes as well as metabolomics of the products; this offers quality assurance in terms of product identification and purity. The combinations of molecular and analytical methods are inevitable for thorough verification and quality control of herbal medicine.

METHODS AND RESULTS

This review discusses the combination of DNA barcoding, DNA metabarcoding, mass spectroscopy as well as HPLC for the authentication of herbal medicine and determination of the level of adulteration. It also discusses the roles of PCR and real-time PCR techniques in validating and ensuring the quality, purity and identity of the herbal products.

CONCLUSIONS

In conclusion, each technique has its own pros and cons, but the cumulative of both the chemical and molecular methods is proven to be the best strategy for adulteration detection. Moreover, CRISPR diagnosis tools equipped with multiplexing techniques may be implemented for screening adulteration from herbal drugs, this will play a crucial role in herbal product authentication in the future.

Intestinal epithelial damage due to herbal compounds - an in vitro study

Intestinal epithelial injury from herbal products has rarely been reported, despite the gut being the first point of contact for oral preparations. These products often consist of multiple herbs, thereby potentially exposing consumers to higher levels of reactive phytochemicals than predicted due to pharmacokinetic interactions. The phytochemical coumarin, found in many herbal products, may be taken in combination with herbal medicines containing astragalosides and atractylenolides, purported cytochrome P450 (CYP) modulators. As herbal use increases, the need to predict interactions in multiple at-risk organ systems is becoming critical. Hence, to determine whether certain herbal preparations containing coumarin may cause damage to the intestinal epithelium, Caco2 cells were exposed to common phytochemicals. Coumarin, astragaloside IV (AST-IV) or atractylenolide I (ATR-I) solutions were exposed to Caco2 cultures in increasing concentrations, individually or combined. Coumarin produced a significant concentration-dependant fall in cell viability that was potentiated when CYP enzymes were induced with rifampicin and incubated with CYP3A4 inhibitor econazole, suggesting a role for other CYP enzymes generating toxic metabolites. ATR-I alone produced no toxicity in uninduced cells but showed significant toxicity in rifampicin-induced cells. ATR-I had no effect on coumarin-induced toxicity. AST-IV was nontoxic alone but produced significant toxicity when combined with nontoxic concentrations of coumarin. The combination of coumarin, ATR-I and AST-IV was significantly toxic, but no synergistic interaction was seen. This investigation was conducted to determine the likelihood for intestinal-based interactions, with the results demonstrating coumarin is potentially toxic to intestinal epithelium, and combinations with other phytochemicals can potentiate this toxicity.

Chemical Authentication of Botanical Ingredients: A Review of Commercial Herbal Products

Chemical methods are the most important and widely used traditional plant identification techniques recommended by national and international pharmacopoeias. We have reviewed the successful use of different chemical methods for the botanical authentication of 2,386 commercial herbal products, sold in 37 countries spread over six continents. The majority of the analyzed products were reported to be authentic (73%) but more than a quarter proved to be adulterated (27%). At a national level, the number of products and the adulteration proportions varied very widely. Yet, the adulteration reported for the four countries, from which more than 100 commercial products were purchased and their botanical ingredients chemically authenticated, was 37% (United Kingdom), 31% (Italy), 27% (United States), and 21% (China). Simple or hyphenated chemical analytical techniques have identified the total absence of labeled botanical ingredients, substitution with closely related or unrelated species, the use of biological filler material, and the hidden presence of regulated, forbidden or allergenic species. Additionally, affecting the safety and efficacy of the commercial herbal products, other low quality aspects were reported: considerable variability of the labeled metabolic profile and/or phytochemical content, significant product-to-product variation of botanical ingredients or even between batches by the same manufacturer, and misleading quality and quantity label claims. Choosing an appropriate chemical technique can be the only possibility for assessing the botanical authenticity of samples which have lost their diagnostic microscopic characteristics or were processed so that DNA cannot be adequately recovered.

An Analysis for Adulteration and Contamination of Over-the-Counter Weight-Loss Products

Six Australian and five overseas complementary medicines (CM) and meal replacement shake products were analysed for potential adulteration with two common active pharmaceutical ingredients, caffeine and sibutramine, using thin-layer chromatography and mass spectrometry. The declared amount of caffeine in each product was also reviewed. Finally, the products were examined for heavy metal contamination using inductively coupled plasma-mass spectrometry. The results showed that there was no detected adulteration of either caffeine (for those products that did not list caffeine as an ingredient) or sibutramine in the 11 products; however, based on the product labels, one Australian and one overseas (two in total) CM product contained more than the maximum daily safety limit (400 mg) of caffeine. Potentially excessive lead and/or chromium was detected in six products, including four Australian products and two products purchased online. One Australian CM product appeared to contain these heavy metals at concentrations at, or exceeding, the safety limits specified in the United States Pharmacopeia or set by the World Health Organization. The overconsumption of caffeine and heavy metals has the potential of causing significant health effects in consumers.

Combined Liquid Chromatography-mass Spectrometry and Next-generation DNA Sequencing Detection of Adulterants and Contaminants in Analgesic and Anti-inflammatory Herbal Medicines

INTRODUCTION

Methods for assessing the quality of herbal medicine preparations have advanced significantly in recent years in conjunction with increases in herbal medicine use and reports of adulteration and contamination.

OBJECTIVE

This study examined the quality of analgesic and anti-inflammatory herbal medicine preparations available on the Australian market by detecting the presence of listed ingredients, adulterants and contaminants.

METHODS

Forty-nine analgesic and anti-inflammatory herbal medicine preparations were randomly sourced from Australian capital cities. They were audited using a dual approach of liquid chromatography-mass spectrometry (LC-MS) combined with next-generation DNA sequencing. Once screened, a comparison of listed ingredients with verified ingredients was conducted to determine the accuracy of labelling, and the extent of adulteration and contamination.

RESULTS

Twenty-six of 49 (53%) herbal medicines were adulterated or contaminated with undeclared ingredients. LC-MS revealed the presence of pharmaceutical adulterants including atropine and ephedrine. DNA sequencing uncovered concerning levels of herbal substitution, adulteration and contamination, including the use of fillers (alfalfa, wheat and soy), as well as pharmacologically relevant species (Centella asiatica, Panax ginseng, Bupleurum and Passiflora). Pig/boar and bird DNA was found in some preparations, inferring substandard manufacturing practices. Of the 26 contaminated samples, 19 (73%) were manufactured in Australia, and 7 (27%) were imported from other countries (6 from China, 1 from New Zealand). In 23 of 49 (47%) herbal medicine samples, no biological ingredients were detected at all. These were predominantly pain and anti-inflammatory preparations such as glucosamine and eicosapentaenoic and docosahexaenoic acids found in krill and fish oils, so DNA would not be expected to survive the manufacturing process.

CONCLUSION

The high level of contamination and substitution of herbal medicine preparations sourced from Australian dispensaries supports the need for more stringent pharmacovigilance measures in Australia and abroad.

Applied Barcoding: The Practicalities of DNA Testing for Herbals

DNA barcoding is a widely accepted technique for the identification of plant materials, and its application to the authentication of commercial medicinal plants has attracted significant attention. The incorporation of DNA-based technologies into the quality testing protocols of international pharmacopoeias represents a step-change in status, requiring the establishment of standardized, reliable and reproducible methods. The process by which this can be achieved for any herbal medicine is described, using Hypericum perforatum L. (St John's Wort) and potential adulterant Hypericum species as a case study. A range of practical issues are considered including quality control of DNA sequences from public repositories and the construction of individual curated databases, choice of DNA barcode region(s) and the identification of informative polymorphic nucleotide sequences. A decision tree informs the structure of the manuscript and provides a template to guide the development of future DNA barcode tests for herbals.

Analysis of spontaneous adverse drug reactions to echinacea, valerian, black cohosh and ginkgo in Australia from 2000 to 2015

OBJECTIVE

Assessing adverse drug reactions (ADRs) is a proven method to estimate the safety of medicines. The ADRs to herbal medicines in Australia (and by inference, the safety of herbal medicines in Australia) remain unknown. This study examines spontaneous ADR cases to four of the most popular herbs in Australia from 2000 to 2015: echinacea (Echinacea purpurea), valerian (Valeriana officinalis), black cohosh (Actaea racemosa) and ginkgo (Ginkgo biloba).

METHODS

ADRs of echinacea, valerian, black cohosh and ginkgo reported to the Australian Therapeutic Goods Administration (TGA) between 2000 and 2015 were obtained from the TGA database. Data were collated and analysed according to age, sex, severity, type of ADR and body system affected. Statistics were calculated using GraphPad Prism software.

RESULTS

Most ADRs were mild or moderate. However, every herbal medicine was associated with life-threatening ADRs. In each life-threatening case, the herbal medicine was taken concomitantly with prescription medications. Black cohosh was associated with a significant number of severe ADRs (30.3% of the total), with 39.4% of these ADRs being associated with abnormal hepatic function, hepatitis or hepatotoxicity.

CONCLUSION

This study highlights the lack of public awareness with regard to herb-drug interactions, since most of the severe ADRs involved a herb-drug interaction.