Effect of the Altitude Geographic and Species Type on the Volatile Compounds of the Genus Origanum from Southern Perú

Genus Origanum is an aromatic plant used in folk medicine and as a culinary herb, whose composition of volatile compounds is influenced by the type of species and geographical locations. This research evaluates the effect of altitude on the composition of volatile compounds and the contents of carvacrol and thymol of Origanum x majoricum Cambess and Origanum majorana L. fifty samples of both species were recollected from different altitudes (2500 - 3500 MASL) of the Southern Perú and analyzed by solid-phase microextraction integrated to gas chromatography-mass spectrometry. The principal component analysis was used to differentiate the plants rich in thymol and carvacrol. Peruvian oregano presented 30 different volatile compounds between some monoterpenes (>30%) and some sesquiterpenes (>5%).  The thymol and carvacrol contents of O. majorana and O. majoricum varied between 0.38 and 16.47% and 0.44 and 11.16%, respectively. Interestingly an inverse correlation of the concentration of thymol and carvacrol with their precursors (p-cymene and ɣ-terpinene) was also observed. Altitudes between 3000 and 3200 MASL favors the high proportions of volatile compounds. The data obtained contribute to planning programs for the selection of species and agricultural conditions that allow obtaining a better quality of oregano essential oil.