A molecular approach for the discrimination of medicinal Astragali radix used in TCM

The genus Astragalus L. (Fabaceae) is represented in the Flora of China with approximately 360 species, many of them occurring as local endemics [1]. Regarding the morphological variability within the genus, species delimitation is a general problem [2]. Although the main source of the popular chinese drug huangqi (radix Astragali) is derived from Astragalus mongholicus BUNGE var. dahurica (DC.) PODLECH (Syn.: A. membranaceus (FISCH.) BUNGE) and A. mongholicus BUNGE var. mongholicus (Syn.: A. membranaceus (FISCH.) BUNGE var. mongholicus (BUNGE) P.K.HSIAO) other taxa such as A. hoantchy, A. lehmannianus, A. tongolensis, A. chrysopterus, A. aksuensis, A. tribulifolius, A. floridulus, A. dshimensis, A. tribulifolius, A. lepsensis, A. ernestii, A. laxmanniii or A. penduliflorus are commonly used as adulterants [2,3]. Thus the correct identification of huangqi is indispensible for phytochemical investigations and therapeutical application in TCM. Benefiting from molecular techniques, DNA markers have become popular for identification and authentication of plant species. The use of DNA sequencing (nuclear ITS and 5S- rDNA; plastidal trnL-F) combined with PCR-RFLP have shown that this approach is suitable for the identification at the species level. The utility of DNA-based markers has been applied successfully for authentication of selected Chinese medicinal plants cultivated in Bavaria, a project conducted by the Bavarian State Research Center for Agriculture (LfL) in Freising-Weihenstephan. Concerning phytochemistry, HPLC analyses of many samples from Astragalus mongholicus revealed no significant differences in the content of the main active component astragaloside IV (AGS-IV).

References: [1] Xu, Lang-Ran & D. Podlech (2005) Astragalus. In: Flora of China. Vol. 10 (Fabaceae – in preparation). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis (www.eFloras.org) [2] Valant-Vetschera and C. Zyka (2005) Proc. WOCMAP III, Vol. 1: 41–48. [3] Pui Yin Yip and Hoi Shan Kwan (2006) J. Ethnopharmacol. 106: 222–229. [4] Ma, X. Q., Shi Q., Duan, J.A,. Dong. T. X and K.W. Tsi (2002) J. Agric. Food Chem. 50: 4861–4866