Variation in essential oil composition within and among Tunisian Thymus algeriensis Boiss et Reut.(Lamiaceae)populations: Effect of ecological factors and incidence on antiacetylcholinesterase and antioxidant activities

The variation of the essential oil composition of fourteen Tunisian Thymus algeriensis populations and their antioxidant and antiacetylcholinesterase activities were assessed. At the species level, ?-pinene, 1,8-cineole, camphor, caryophyllene oxide and carvacrol were the main compounds. Significant variation in the essential oil composition was observed between populations according to ecological factors. Six chemotypes were revealed (1,8-cineole-?-panasinsene/1,8-cineole/caryophyllene oxide/1,8-cineole-camphor-caryophyllene oxide/1,8-cineole-camphor-caryophyllene oxide-terpenyl acetate/carvacrol)with the distinction of upper arid populations (Ta 13 and Ta 14)with the dominance of carvacrol chemotype. The occurrence of the carvacrol was positively correlated to the evapotranspiration, summer drought stress and the temperature of the warmest months of the year. High chemical intrapopulation variability was also observed, revealing the presence of seven chemotypes (carvacrol/terpenyl acetate/caryophyllene oxide/linalool-linalyl acetate/1,8-cineole-?-panasinsene/1,8-cineole/1,8-cineole-camphor). The level of antioxidant and anti-acetylcholinesterase activity was linked to their chemical composition difference. The best activities were revealed for populations Ta 13 and Ta 14 from the most arid zones, characterized by their carvacrol richness.