VARIABILITY IN THE COMPOSITION OF THE ESSENTIAL OILS OF MINTOSTACHYS-ANDINA IN CENTRAL BOLIVIA

The essential oils of 129 individuals of the title plant were collecte d from new material harvested in seven sub-regions of central Bolivia. The analyses show a high homogeneity of the composition. Eighty seven per cent of these oils have a high amount of pulegone+menthone (>65%) and these plants formed a 'well-defined pulegone-menthone chemotype'. However, the percentage of small amounts of isomenthone introduce som e variations in this chemotype. Moreover, some samples cannot be linke d to this chemotype: one seems rich in thymol+carvacrol and the corres ponding acetates. The sabinene-para-cymene and the sabinene-1,8-cineol e pairs may form other chemotypes as well their combination with the p ulegone-menthone type. From a geographical point of view it may be inf erred that the higher altitude gives the better pulegone-menthone esse ntial oil providing the sampling zone is out of the transition region between the dry highlands and the more humid and warmer Amazonian regi on.