Essential Oils of some Mentha Species and Cultivars, their Chemistry and Bacteriostatic Activity.

The major purpose of this study was to determine the chemical relationships between the essential oils (EO) obtained form 18 mint samples of different species and its cultivrs. GC/MS analysis of all essential oils showed that oxygenated monoterpenoids are the major components of these oils, with the exception of Mentha arvensis 'Banana'. Based on the. chemical composition of the essential oils, the analyzed mints can be divided into five groups. Group I was characterized by the-presence of menthol and menthone, piperitenone oxide is the major constituent of group II, linalool of group III, carvone characterizes group IV, while 3-octanone is the most characteristic compound for group V. A reference strain of biofilm forming Staphylococcus epidermidis ATTC 35984 was tested against the obtained essential oils. Two of them, M suaveolens 'Variegata' and M x piperita 'Almira' exhibited significant bacteriostatic activity. The MIC values of these EOs were 0.25% and 0.5% respectively in comparison with an average MIC of 4% of the other tested mint EOs. Both active EOs are characterized by the presence of piperitenone oxide as the major component.