Molecular phylogenetic analysis of Phyllanthus species in Thailand and the application of polymerase chain reaction-restriction fragment length polymorphism for Phyllanthus amarus identification.

The genus Phyllanthus (Phyllanthaceae) is distributed in tropical and subtropical regions, and its members are widely used as medicinal plants in many countries. We analyzed the nucleotide sequences of the internal transcribed spacers of ribosomal DNA of 56 plant samples covering 23 Phyllanthus species collected from various habitats in Thailand. Based on the sequence alignment, we constructed phylogenetic trees of all Phyllanthus species distributed in Thailand. Furthermore, a simple protocol to discriminate three important medicinal Phyllanthus species, P. amarus, P. debilis, and P. urinaria, was developed using a Polymerase Chain Reaction-Restriction Fragment Length Polymorphism method and successfully applied to the crude drug samples obtained in Thai markets.