ABSTRACT
To effectively identify the Astragalus and its adulterants based on ITS2 sequence and secondary structure, in this study, 32 portions of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Beg.) Hsiao and Astragalus membranaceus (Fisch.) Bge. collected were conducted ITS2 sequence amplification and bidirectional sequencing, whose results were then spliced by CExpress software remove the 5.8S and 28S sequences at both ends to obtain a complete ITS2 sequence. In addition, 3 ITS2 sequences for each of the adulterants of Astragalus, respectively, Oxytropis coerulea, Caragana sinica, Hedysarum polybotrys, Althaea rosea were downloaded from GenBank. The intra-specific and inter-specific genetic distances were calculated by the software MEGA7 to analyze the difference of each sequence; the Neighbor-joining (NJ) method was used to construct the phylogenetic tree based on ITS2 sequence (primary structure) as well as joint ITS2 sequence and its secondary structure. The results showed that the average ITS2 sequence length of both A. mongolicus and A. membranaceus was 216 bp, and their average GC content was 50.00% and 50.46%, respectively. The similarity of ITS2 sequence length and GC content between the two kind of Astragalus and Oxytropis coerulea was the highest, while the ITS2 sequence length and GC content of Althaea rosea showed great differences with those of Astragalus. The inter-specific distance between Astragalus and Oxytropis coerulea was the smallest, while that between the medicinal Astragalus and Hedysarum polybotrys, Caragana sinica as well as Althaea rosea was great. The phylogenetic trees constructed based on the ITS2 sequence (primary structure) and joint ITS2 sequence and its secondary structure showed that the topological relations of the two phylogenetic trees were basically the same, and both could effectively identify the Astragalus and its adulterants. What’s more, the addition of secondary structure information made end branch of the phylogenetic tree become more in its construction, and the distinguish ability and approval rating were also improved, which further reflected the genetic relationship of Astragalus and its adulterants. This provides some scientific basis for classification and accurate identification of Astragalus and its adulterants.
ABSTRACT
Objective: To study the quality differences of medical material, raw decoction pieces, and processed products of Astragalus membranaceus var. mongholicus. Methods: The raw decoction pieces and processed products were obtained from genuine medicinal materials of A. membranaceus var. mongholicus. The reasons for the quality differences were analyzed by comparing the contents of astragaloside IV, calycosin-7-O-β-D-glucopyranoside, formononetin, total polysaccharides, saponins, and flavones. Results: With content analysis, the sequence was found as follows: astragaloside IV (medical material > raw decoction piece > honey-fried piece > alcohol-fried piece > salt-fried piece > fried piece); calycosin-7-O-β-D-glucopyranoside, formononetin, and total polysaccharides (medical material > raw decoction pieces > alcohol-fried piece > salt-fried piece > honey-fried piece > fried piece), total flavones (medical material > alcohol-fried piece > raw decoction pieces > salt-fried piece > honey-fried piece > fried piece), total saponins (medical material > honey-fried piece > raw decoction pieces > alcohol-fried piece > salt-fried piece > fried piece). Conclusion: The temperature and supplementary material may play the main roles for quality differences of A. membranaceus var. mongholicus.