Optimization of DNA extraction for Chinese patent medicine and its application on molecular identification of ginseng preparations by MAS-PCR / 中草药

ABSTRACT

Objective: To establish an optimized method for extracting DNA from Chinese patent medicine (CPM) and health-care products and assuring the quality of DNA for successful molecular identification in ginseng preparations. Methods: Commonly-used pharmaceutical excipients, such as starch, sucrose, and glucose in CPM and health-care products were employed to discover the potential cause of low quality of DNA extraction in classic CTAB method. Methanol was used to precipitate and purify the DNA extracted with the classic CTAB method in order to improve the quality and quantity of DNA thus extracted. Finally, thus extracted DNA was employed to conduct the molecular identification of CPM and health-care products with ginseng herbs and validate the optimized method. Results: Starch in CPM and health-care products may react with CTAB and thus form a high polar complex that is insoluble in 70% ethanol but can strongly dissolve DNA, resulting a very low DNA extraction rate in classic CTAB method. Methanol is able to dissolve the high polar complex and thus the application of 70% methanol and NaAc solution guaranteed the successful extraction of DNA with high quality and quantity from CPM and health-care products. With the optimized CTAB method, the DNA samples of 11 kinds of CPM and health-care products containing ginseng or American ginseng were extracted and applied for molecular identification with MAS-PCR method. The results showed that the identified herb complied with the label description in eight samples, but did not in three samples, in which one would be adulteration and two would be counterfeits. Conclusion: Application of 70% methanol as a purification and precipitation reagent in classic CTAB method effectively overcome the negative influence of starch contained in Chinese herbal preparations to DNA extraction and can make the DNA molecular identification of Chinese herbal preparations successful.