RESUMO
<p><b>OBJECTIVE</b>To analyze the nuclear ribosome DNA (nrDNA) internal transcribed spacer (ITS) sequences of 4 Leonurus species, and the possibility of using them for molecular authentication of the crude drugs from the genus.</p><p><b>METHODS</b>The nrDNA ITS sequence (including ITS1, 5.8S rDNA, ITS2, and partial 18S rDNA and 26S rDNA) of L. japonicus and its 3 adulterant species were amplified and sequenced, and CLUSTRAL X and MEGA software was employed for analysis.</p><p><b>RESULTS</b>The variation of ITS1 and ITS2 between L. japonicus and its adulterant species ranged between 7.2% and 18.8% and between 14.2% and 27%, respectively. The phylogenic tree derived from the dendrograms based on the ITS sequence data contained some discrepancy from the traditional classification.</p><p><b>CONCLUSION</b>The nrDNA ITS sequences can be used potentially as efficient markers for identification of L. japonicus and its adulterants, and further study is needed for studying the phylogeny of Leonurus.</p>