Commercial herbal medicines vary widely in quality – new research

In their paper entitled ‘Validation of a HPLC method for flavonoid biomarkers in skullcap(Scutellaria) and its use to illustrate wide variability in the quality of commercial tinctures’ the authors Jiayu Gao, Alberto Sanchez-Medina, Barbara A. Pendry, Michael J. Hughes, Geoffrey P. Webb and Olivia Corcoran, all from the Medicines Research Group at UEL’s School of Health and Bioscience in Stratford, concluded that the wide variability between undermines the practice of scientific herbal medicine and makes accurate scientific assessment difficult.

Skullcap is a powerful medicinal herb. The genus Scutellaria consists of over 350 species worldwide and has been used by many cultures to treat a variety of medical conditions, including anxiety, nervous disorders, liver disease and cancers.

The UEL team conducted a number of tests to compare the flavonoid biomarker content of eleven commercial tinctures derived from the two most commonly-used species, S. lateriflora (American skullcap) and S. baicalensis (Chinese skullcap).

They found that commercial tinctures of both Scutellaria species vary widely in the drug-to-extract ratio (ranging from 1:1 to 1:5) and alcohol concentration (25 to 70%), depending on the manufacturer. Thus, for the herbalist there is no guarantee or measure of either quality or efficacy from the products currently available.

They suggested this variation could help to explain the variable efficacy of herbal medicines used in clinical practice and also the variation in the reported activity of herbal medicines and dietary supplements in clinical trials and in assays of pharmacological activity.

Dr Olivia Corcoran, lead researcher and head of Forensic Science at UEL, said: “Wide variability in the biomarker content of herbal preparations undermines the practice of herbal medicine itself. There is an urgent need for products to be labelled with accurate assessment of the content of agreed biomarkers.

“Without such labelling, it is extremely difficult to assess the effects of herbal medicines, many of which are known to be useless in low doses and dangerous in high concentrations.”