Discriminating Astragali Radix from Hedysarum Radix in Chinese Medicine Preparations Using Nested PCR and DNA Sequencing Methods

摘要

Astragali Radix are originated from Astragalus membranaceus and A. membranaceus var. mongholicus. However, Hedysarum Radix, the dried root of Hedysarum polybotrys, is often used as a substitute in Taiwan. In Chinese medicinal preparations, authenticity of Astragali Radix is difficult to be certified. The nested PCR and DNA sequencing method was used to identify Astragali Radix and Hedysarum Radix in preparation samples. Primer sets were designed for detecting Astragali Radix and Hedysarum Radix. The total DNA of all samples was extracted. Internal transcribed spacer (ITS) regions of the DNA samples were amplified by nested PCR and the sequences received from an auto-sequencer. We compared ITS sequences of the preparation samples with the standard to check whether Astragali Radix or Hedysarum Radix was in the preparation samples. Results indicated that 20 out of 30 samples contained a mixture of Astragali Radix and Hedysarum Radix, five Hedysarum Radix as substitute and five Astragali Radix. The combination of nested PCR and restriction fragment lengths polymorphism (RFLP) was employed to rapidly differentiate Astragalus membranaceus, A membranaceus var. mongholicus and hybrid. The nested PCR and DNA sequencing method successfully identified Astragali Radix and Hedysarum Radix in Chinese medicine preparations.