The application of a DNA-based identification technique to over-the-counter herbal medicines

Reliable methods to identify medicinal plant material are becoming more important in an increasingly regulated market place. DNA-based methods have been recognised as a valuable tool in this area with benefits such as being unaffected by the age of the plant material, growth conditions and harvesting techniques. It is possible that the methods of production used for medicinal plant products will degrade or remove DNA. So how applicable are these techniques to processed medicinal plant products? A simple PCR-based identification technique has been developed for St. John's Wort, Hypericum perforatum L. Thirteen St. John's Wort products were purchased including capsules, tablets and tinctures. DNA was extracted from each product, and the species specific PCR test conducted. DNA was successfully extracted from all thirteen products, using a fast and efficient modified method for extracting DNA from tinctures. Only four products yielded the full length ITS region (850 bp) due to the quality of the DNA. All of the products tested positive for H. perforatum DNA. DNA-based identification methods can complement existing methods of authentication. This paper shows that these methods are applicable to a wide range of processed products, provided that they are designed to account for the possibility of DNA degradation.