TLC-GC/MS Method for identifying and selecting valuable essential Oil Chemotypes from Wild Populations of Mentha longifolia L.

Abstract

Wild populations of aromatic plants can be considered resources of natural biodiversity for selecting valuable genotypes in order to obtain well-characterized cultivars with defined essential oil (EO) profiles suitable for different purposes due to their biological activity. Often, their high intrapopulational variability requires preliminary screenings based on a significant number of individuals and, therefore, simple and fast methods to identify EO profiles are required. For this purpose, a TLC-GC/MS method has been proposed in order to identify chemotypes occurring in a selected wild population. Stolons of 50 individuals of Mentha longifolia L were planted and bred in greenhouse conditions before growing in experimental plots. Individual sampling and extraction of leaves were performed to determinate TLC individual profiles. They were validated by preparative TLC and GC/MS analysis of discriminant spots. Fresh material belonging to each defined TLC profile was collected in full flowering stage and subjected to SDE extraction and GC/MS analysis. Five chemotypes were characterized: A (piperitone and piperitenone oxides); B (piperitone oxide + pulegone); C (α- terpineol acetate + carvone acetate); D ((E) – dihydrocarvone) and E (pulegone + isomenthone + menthol). This TLC method was applied to individuals coming from another population. All of them could be clearly identified as belonging to chemotype E, which was afterwards confirmed by GC/MS analysis.