Comparative composition of four essential oils of Oregano used in Algerian and Jordanian folk medicine.

The essential oils obtained from Origanum glandulosum Desf., collected from two different localities of north-eastern Algeria, Constantine and Jijel, and from O. syriacum var. syriacum grown at El-Aghwar (northern Jordan) and El-Shubak (southern Jordan), were analyzed by GC-MS. p-Cymene (6.6% and 7.5%) and γ-terpinene (13.4% and 14.5%) were found in O. glandulosum grown at Constantine and Jijel, respectively, in addition to the major components thymol (34.2%, 51.1%) and carvacrol (30.5%, 6.8%). The oil of O. syriacum L. var syriacum (Boiss.) Ietswaart from El-Shubak was mainly represented by thymol (51.8%) and carvacrol (34.4%), while the oil from El-Aghwar was a thymol-chemotype (72.4%), along with γ-terpinene (7.8%) and p-cymene (5.4%). syriacum (Arabic 'Zaatar') are used in Algeria and Jordan, respectively, as folk remedies for bronchitis, pulmonary infection, flu, cough and some gastrointestinal disorders. Compared with the reported essential oils of Algerian O. glandulosum (12-16), the oil composition of our plant material collected at Constantine is similar to that collected at Setif (14), with the following comparative percentages of the major components: p-cymene (6.6%, 7.9%), γ-terpinene (13.4%, 5.1%), thymol (34.2%, 38.8%) and carvacrol (30.5%, 32.9%), respectively. The composition of the oil of the plant collected at Jijel is similar to that grown at Megress-Ain Abassa (Setif) (16), mainly represented by thymol (51.1%, 56.6), carvacrol (6.8%, 7.6%), p-cymene (7.5%, 14.6%) and γ-terpinene (14.5%, 11.7%), respectively (Table 1). The essential oil of the Jordanian plant O. syriacum var. syriacum collected at El-Shubak (southern Jordan) showed it to be a thymol-carvarol chemotype (51.8%