Characterising the active ingredients and toxins in Chinese medicinal herbs

Improving the quality and safety of Chinese medicinal herbs

Researchers have developed a simple, rapid and useful new technique for characterising the active ingredients and toxins in Chinese medicinal herbs – creating new opportunities for improved quality control and safer medicinal use.

Embedded for centuries in traditional medical practice in many Eastern countries, the use of herbal remedies is increasing in popularity in Western cultures. In the UK alone, it is estimated that up to one in five of the population use herbal products at some point in their lives.

Extracts from members of the Aconitum plant species are widely used in traditional Chinese medicine for their purported anti-rheumatic, anti-inflammatory and analgesic effects. But these plants also contain toxic alkaloids that can cause heart and respiratory problems – historically, they were even used as a poison on arrows. If thorough soaking and boiling processes are not carried out properly by a trained person, residual toxins could have dangerous consequences for the patient.

The root of Panax ginseng is another popular and important herb in traditional Chinese medicine. Its major active ingredients are ginsenosides, which are claimed to provide anti-fatigue, anti-inflammatory and anti-cancer properties – along with other benefits such as boosting the immune system.

Protecting consumers from harm

In the West, evidence-based use of medicines demands rigorous clinical trials to prove the effectiveness and safety of treatment before they are approved for wider use. But, as herbal medicine is based upon traditional practice rather than science, this creates ongoing challenges around how the industry should be regulated to protect consumers from potential harm. 

One huge challenge is ensuring the purity of Chinese herbal medicines, with some products reportedly not containing the ingredients claimed on the packaging or being contaminated with other substances. And counterfeit herbs can enter the marketplace which is difficult to distinguish from authentic products by visual examination.
Although chromatographic separation followed by mass spectrometry can identify phytochemical compounds with high sensitivity and specificity, this approach is not easily scalable due to the time-consuming sample preparation processes needed. Improved analytical techniques that can accurately characterise the ingredients within herbal products are urgently needed to improve quality control and consumer safety.

Developing a new method suitable for high-throughput quality control analyses

In a new study, researchers in Taiwan develop a simple new technique that combines thin layer chromatography with electrospray ionization mass spectrometry (TLC-ESI/MS) – for characterising herbal compounds in a rapid analysis.¹ To reduce the risk of introducing contaminants that could harm the integrity of the results of their sensitive analytical analyses, the team relied on ultrapure water produced from an ELGA PURELAB® Pulse laboratory water purification system.

Toxic compounds identified in a medicinal product

The team successfully demonstrated the use of their new analytical technique by characterising the phytochemical compounds in two root extracts purchased from a local pharmacy for traditional Chinese medicines.
Of concern, they detected 16 highly toxic alkaloid compounds including aconitine, mesaconitine, and hypaconitine as well as sugars in their A. carmichaelii Debx root extract. They also identified six major ginsenosides within their P. ginseng extract, reflecting its detailed chemical composition.

This new study demonstrates that their modified TLC-ESI/MS is a simple, rapid and useful technique for characterising both toxins and active ingredients within herbal extracts and could offer an improved method for quality control assessments as well as distinguishing authentic from counterfeit products – helping to protect patients from harm.

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Reference:
Cheng, S et al. Thin layer chromatography combined with electrospray ionization mass spectrometry for characterising herbal compounds. International Journal of Mass Spectrometry (2018): 434; 264-271.