Discrimination of Zi Cao species based on genomic analysis, TLC and HPLC

Plants used in traditional Chinese medicine (TCM) represent a great source of novel lead compounds due to its long history and tradition. However, the exact identification of the plant material sometimes remains a problem because of trivial and local names or wrong identification. Since plants differ in their chemical composition this mix-up can lead to serious health problems when applied. Roots of the genera Onosma, Arnebia and Lithospermum are traditionally known as Zicao. On markets they are sometimes distinguished by prefixes such as Ruan Zi Cao (Arnebia euchroma), Dian Zi Cao (Onosma paniculata) or Ying Zi Cao (Lithospermum erythrorhizon). But even this distinction does not protect from mistakes. The main active principles in Zicao species are shikonin and alkannin derivatives. The exact content and composition varies within the different species. In this study, we investigated 16 samples from various places and identified them using genomic analysis. Moreover, we tried to find a TLC and/or HPLC method to identify them phytochemically. 13 of the samples were sold as Arnebia euchroma and three as Lithospermum erythrorhizon. After genomic analysis, we identified 5 samples as Arnebia euchroma, one as Onosma paniculata and one as Lithospermum erythrorhizon. The rest of samples could not be identified by DNA analysis. Moreover, we did not succeed to distinguish the different species unambiguously by using HPLC. However, we were able to develop a method to distinguish the species by TLC on the basis of several blue fluorescent zones.

Acknowledgements: This work was supported by the Austrian Science Fund (P 27505).