Introduction of seven new chemotypes of Thymus eriocalyx (Ronniger) Jalas in Iran based upon the variation of essential oil composition in different populations

Thymus eriocalyx (Ronniger) Jalas belongs to the family Lamiaceae. Among different species of Thymus, distributed in the world, 18 species are growing in Iran, of which four species are endemic. To study the variation of essential oils among population individuals of this species in Iran D.S.S. (Determination of special station) method was used. In this study, the aerial parts of 5 individuals of Thymus eriocalyx were collected from 10 special stations, at full flowering stage for chemical investigation and were dried at room temperature. The essential oil was extracted by hydrodistilation method using a Clevenger-type apparatus. The chemical composition of essential oils was analyzed by GC-FID and GC-MS. Results showed that the highest average yield of essential oil in three replications based on dry weight belonged to the first individual of Te2 population (4.09%), while the lowest was recorded for the second individual of Te10 population (0.21%). Totally, thirty one compounds were identified in the essential oil of 10 studied population individuals. In this study, it is noteworthy that the individuals of a population showed variation among themselves in terms of chemical compositions. Among existing chemical compounds in the essential oil of 50 individuals, the following compounds revealed the variation widely: p-cymene (0.1-20.1%), 1,8-cineole (0.4-29.4%), γ-terpinene (0.1-8.7%), linalool (0.1-82.3%), camphor (0.1-15%), borneol (1.6-22.7%), geraniol (0.1-74.6%), thymol (0.1-57.7%), geranyl acetate (0.1-49.6%), caryophyllene oxide (0.2-9.1%), limonene (0.2-24%) and α-terpineol (0.1-36.2%). The results of the analysis of chemical data using MVSP Software by UPGMA and PCO methods led to the identification of 9 chemotypes as follows of which 7 chemotypes were introduced as new chemotypes: 1-geraniol/geranyl acetate, 2-geraniol, 3- linalool/geraniol/geranyl acetate, 4-linalool,5-α-terpineol/1,8-cineole, 6-geranyl acetate, 7-geraniol/thymol/borneol/1,8-cineole,8-thymol/limonene and 9-thymol/p-cymene/borneol.