Discrimination of Lonicera japonica THUNB. from different geographical origins using restriction fragment length polymorphism analysis.

Lonicera japonica THUNB. is a commonly used anti-inflammatory herbal medicine. The therapeutic effectiveness of L. japonica depends significantly on its geographical origin. However, it is difficult to define criteria for confirming geographical authenticity using microscopic and chemical characteristics. In the present study, the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA loci of L. japonica from different origins and related species was sequenced. The mutation site found in the ITS region from geo-authentic L. japonica can be recognized by the restriction endonuclease EcoN I. Since PCR products from geo-authentic L. japonica cannot be digested completely, a quantitative restriction fragment length polymorphism analysis method was developed. The cleavage rate of PCR products by EcoN I was determined to be more than 70% in all geo-authentic L. japonica and less than 20% in non-geo-authentic L. japonica and other species from genus Lonicera. The rate correlated remarkably with the geographical origin of L. japonica. Therefore, this method can be used to classify geo-authentic L. japonica.