Essential-oil diversity of three Calamintha species from Greece.

The aim of the present study was to contribute to the knowledge of the essential-oil composition of the Calamintha officinalis-nepeta complex in Greece and to clarify the main patterns of its variation. The oils obtained from 22 wild-growing populations of C. glandulosa, C. nepeta, and C. menthifolia were studied. They could be classified into two different chemotypes, which correspond to the main biosynthetic routes of the C(3)-oxygenated p-menthane compounds. Chemotype I includes oils rich in trans-piperitone oxide, cis-piperitone oxide, and piperitenone oxide, while Chemotype II comprises oils rich in pulegone and menthone or menthone and isomenthone. Within both chemotypes, quantitative fluctuations of the main components were observed. Comparison with published data showed that the presence of Chemotype II has not been observed before in C. menthifolia, while Chemotype I has been reported in C. nepeta plants from Greece for the first time.