B. Pasquier, Gilles Figuérédo and Jean-Claude Chalchat*

Abstract: Seedlings obtained from seeds of three populations of oregano (Origanum ehrenbergii) harvested in Lebanon and sown at a research station in France were planted in three replicates in a Fischer block design. Oils produced by water distillation were subjected to analysis by GC and GC/MS. The oils of one of the populations were uniform and carvacrol-rich. The other population displayed a variable chemical composition, including thymol, thymol-carvacrol and p-cymene/γ-terpinene chemotypes.

Origanum ehrenbergii belongs to the Prolaticorolla section of Group C in the classifi cation of Ietswaart (1). Although many species belonging to the genus Origanum have been studied by Baser and Duman (2-6), Arnold et al. (7), Valentini et al. (8), Skoula et al. (9) and Melegari et al. (10), no work has been done on the chemical composition of O. ehrenbergii. However, O. compactum Benth. and O. laevigatum Boiss. from the same group have been studied by Charai et al. (11), Baser et al. (12) and Tucker and Maciarello (13), respectively. Origanum compactum was found to contain carvacrol (56%), γ-terpinene (15%) and p-cymene (9%), while O. laevigatum was found to be rich in sesquiterpenes, principally bicyclogermacrene (25-38%), germacrene D (20-21%) and β-caryophyllene (17-14%). Origanum ehrenbergii is endemic in Lebanon where it grows at an altitude of up to 1500 m. It occurs on dry limestonebased stony scrubland and in open pinewood understories in acid soils. It is used as a condiment, although the less strongly fl avored O. syriacum L. is preferred.