Molecular biology techniques as new alternatives for medicinal plant identification

Abstract

Mexico bears witness to a long-standing tradition in the use of plants for medicinal purposes; nevertheless, standardized methodological approaches for the proper identification of these are still needed. The problem is especially noticeable during the validation of ingredients in herbal preparations, as so many of them are sold as powders. It is for these reasons that the present study aims to compare the results of classic taxonomical assessments with those obtained using more modern molecular techniques (e.g. PCR-amplified 18S ribosomal RNA gene analysis) in one ethnobotanical case-study carried out in the “Desierto de los Leones” National Park in Mexico City, Mexico. Molecular identification resulting from the comparison of PCR-amplified 18S rRNA genes from 7 different plant species to those deposited in the GenBank database was performed. Genuslevel identification by molecular techniques and database searches coincided with results obtained using classic taxonomical approaches in 6 of the 7-species analyzed. Only one (Eupatorium) could not be identified in the GenBank database and has therefore been described in this study. In a further phytochemical analysis, the plant commonly known as “Avena del campo” presented the highest content of total flavonoids, while the plants “Sienecilla”, “Jarilla amarilla” and “Jarameo” showed abundant levels of alkaloids. Our results support the idea of using molecular biology techniques such as 18S rRNA gene comparisons for plant identification at the genus-level. However, if this is to become a viable alternative for the large-scale assessment of herbal medicines, the need to expand current 18S rRNA gene databases is made patently obvious.