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No more cheating? Vibrational spectroscopy allows the differentiation between real Devil’s claw and its replacement species

Harpagophytum procumbens (“Devil’s claw”) is an important medicinal plant from Southern Africa. The European Pharmacopoeia allows the use of a closely related species, Harpagophytum zeyheri, in root preparations applied for the treatment of inflammation-related disorders. Although the two plant species are botanically and chemically similar, H. zeyheri contains lower levels of harpagoside, and the two species have not been proven to exhibit equipotent pharmacological activity. T

he distinction between the two species is difficult once the roots are cut to slices and dried. Effective quality control measures are urgently needed, as H. zeyheri is usually considered an inferior quality of Devil’s claw. In the ideal case a non-destructive method could provide an instant result already on site.

Such a method has been tested and shown applicable by the working group of Professor Viljoen from the university of Pretoria (Republic of South Africa). Using the method of “short wave infrared hyperspectral imaging” in combination with mid-infrared spectroscopy – designated as “vibrational spectroscopy” – provides a rapid and reliable method for the distinction between the two species (Mncwangi et al. 2014).

Viljoen and his co-workers could prove the method of vibrational spectroscopy well suited for reliable, rapid and non-destructive quality control. As the method is robust, it could be used on site at collection points of Devil’s claw for an immediate assessment of quality and identification of species.

Practical examples had been given by Alvaro Viljoen in a presentation on the 3rd International Symposium on Medicinal plants (Viljoen and Vermaak 2012). Clearly this method could become a break-through for an improvement of medicinal plant quality, especially for plants gathered by wild crafting.

Mncwangi N, Vermaak I & Viljoen AM. 2014. Mid-infrared spectroscopy and short-wave infrared hyperspectral imaging - A novel approach in the qualitative assessment of Harpagophytum procumbens and H. zeyheri (Devil's Claw) Phytochem. Lett. 7, 143-149.

Viljoen AM & Vermaak I 2012. Standardisation and quality control of herbal medicinal products. The 3rd International Symposium on Medicinal Plants, their Cultivation and Aspects of Uses: Petra (Jordan), 21-23 November 2012. Shoubak (Jordan): Al'Balqa'a Applied University.