Authentication of Shan-Dou-Gen Based on DNA Analysis
Shan-Dou-Gen (山豆根) is a crude drug mainly derived from the roots of Leguminosae plants, and it has antipyretic, antidotal, anti-inflammatory, and analgesic effects. In Japan, the root of Euchresta japonica has been used as a material of Shan-Dou-Gen. However, E. japonica is not used for medicinal purposes today, and commercial Shan-Dou-Gen products are imported from China. In China, several plant species have been used as Shan-Dou-Gen materials, but a crude drug derived from the root of Sophora tonkinensis is now officially used as Shan-Dou-Gen. However, it is difficult to morphologically identify the species used in Shan-Dou-Gen. In the present study, we showed that the Shan-Dou-Gen products commercially available in Japan are derived from S. tonkinensis using phylogenetic and sequencing analyses of the chloroplast trnH–psbA region. Furthermore, we performed species-specific polymerase chain reaction using conserved sequences of S. tonkinensis. Amplification was observed with Shan-Dou-Gen, whereas no amplification occurred with other crude drugs derived from the roots of S. flavescens and S. japonica. These results indicated that the genetic approach can be useful to authenticate Shan-Dou-Gen.