Analysis of Essential Oil from Brazilian Mentha x piperita L. Commercial Samples

The present work aimed to evaluate the content and composition of the essential oil from different Brazilian commercial samples of Mentha x piperita L (peppermint). The essential oil yield of the studied samples ranged from 0.12 to 0.62%. The gas chromatographic analysis of the essential oil showed 28 different compounds, which were obtained by hydrodistillation of the six samples. Samples 1-4 presented menthol as the major compound (49.3-82.0%), and menthone, isomenthone and menthyl acetate as secondary compounds. Samples 5 and 6 presented carvone as the major compound (64.4-65.5%) and pulegone was the second compound in higher proportion (6.1-8.6%). According to the Brazilian Pharmacopoeia, only samples 1-4 are constituted by Mentha x piperita L in agreement with the composition of the essential oils. The results obtained for samples 5 and 6, which conferred essential oil rich in carvone, suggest that these samples are not comprised by Mentha x piperita L but other species of Mentha, which can affect the therapeutic actions expected by people consuming the samples as an herbal medicine.