Molecular analysis of Vitex species using candidate DNA barcoding and PCR-RFLP of the matK gene for authentication of Vitex glabrata

Abstract

Several species of the Vitex genus, family Lamiaceae, are used in folk medicine for a variety of remedies. V. glabrata is unique among Vitex species because its main effect is sexual enhancement. However, crude drugs derived from different Vitex species might not be easily distinguishable, which could lead to their misidentification and misuse. Therefore, the accurate authentication of V. glabrata is critical for its effective medicinal use. In this study, the matK gene and the psbA-trnH intergenic spacer candidate DNA barcodes were sequenced and analyzed to identify five different Vitex species that are medicinally used in Thailand: V. negundo, V. trifolia, V. rotundifolia, V. limonifolia, and V. glabrata. Each region was successfully amplified from the leaves of the five species using a single set of primers, and the sequences determined. The size difference in PCR products of psbA-trnH and PCR restriction fragment length polymorphism (PCR-RFLP) of the matK gene sequences were used to differentiate V. glabrata from other Vitex species. These results indicate both the matK gene and the psbA-trnH intergenic spacer as candidate DNA barcodes of Vitex species and suggest that the difference of psbA-trnH PCR products and PCR-RFLP analysis based on the matK gene are effective for the authentication of V. glabrata.