A nucleotide signature for the identification of angelicae sinensis radix (Danggui) and its products

Abstract

It is very difficult to identify Angelicae sinensis radix (Danggui) when it is processed into Chinese patent medicines. The proposed internal transcribed spacer 2 (ITS2) is not sufficient to resolve heavily processed materials. Therefore, a short barcode for the identification of processed materials is urgently needed. In this study, 265 samples of Angelicae sinensis radix and adulterants were collected. The ITS2 region was sequenced, and based on one single nucleotide polymorphism(SNP) site unique to Angelica sinensis, a nucleotide signature consisting of 37-bp (5'-aatccgcgtc atcttagtga gctcaaggac ccttagg-3') was developed. It is highly conserved and specific within Angelica sinensis while divergent among other species. Then, we designed primers (DG01F/DG01R) to amplify the nucleotide signature region from processed materials. 15 samples procured online were analysed. By seeking the signature, we found that 7 of them were counterfeits. 28 batches of Chinese patent medicines containing Danggui were amplified. 19 of them were found to contain the signature, and adulterants such as Ligusticum sinense, Notopterygium incisum, Angelica decursiva and Angelica gigas were detected in other batches. Thus, this nucleotide signature, with only 37-bp, will broaden the application of DNA barcoding to identify the components in decoctions, Chinese patent medicines and other products with degraded DNA.