By Gilles Figuérédo, Jean-Claude Chalchat and Bernard Pasquier

Abstract: Abstract: The essential oils of seven species of oregano (Origanum vulgare L. ssp. gracile (Koch), Origanum acutidens (Hand.-Mazz.) Ietswaart, Origanum hypericifolium O. Schwarz et P.H. Davis, Origanum bargyli Mouterde, Origanum saccatum P.H. Davis, Origanum solymicum P.H. Davis, and Origanum leptocladum Boiss.) were studied by GC and GC/MS. Eighty-five constituents were identified. The discriminant components of these oils were p-cymene, γ-terpinene, cis- and trans-sabinene hydrate, borneol, terpinen-4-ol, α-terpineol, thymol, and carvacrol. Some of the species were similar to those described in the literature, and new chemotypes are reported. Key Word Index: Origanum vulgare ssp. gracile, Origanum acutidens, Origanum hypericifolium, Origanum bargyli, Origanum saccatum, Origanum solymicum, Origanum leptocladum, essential oil composition, sabinene, p-cymene, γ-terpinene, cis-sabinene hydrate, trans-sabinene hydrate, borneol, terpinen-4-ol, α-terpineol, thymol, carvacrol, chemotypes.

Introduction
The study concerns seven species of oregano of Mediterranean origin grown at the CNPPMAI facility (Forest of Fontainebleau) from seeds collected in identified populations. They had all been studied before (2-11) and can be grouped in the classification of Ietswaart (1).

The seven species were:

Origanum vulgare ssp.gracile of group C (Origanum section), originating from Munzu Dag (Turkey). This species, obtained from Turkey or conservatory-grown, was studied by Sezik et al. (2), Chalchat and Pasquier (3) and Melegari et al. (4). The oils examined by the first two authors were rich in hydrocarbons such as β-caryophyllene and germacrene D (2) or sabinene, (Z)-β-ocimene and germacrene D (3). The extract analyzed by Melegari et al. (4) was a thymol chemotype.

The six other species belonged to group A:

Origanum hypericifolium (Anatolicon section) harvested near Honaz Dag (Turkey). The oil of this species was studied by Baser et al. (5). It was found to contain mainly γ-terpinene, p-cymene and carvacrol, this last in large amounts (64.3%) before flowering, and in smaller amounts (33.9%) when in full flowering.

Origanum solymicum and Origanum saccatum (Amaracus section) came from Tahtali and Alanya (Turkey). Their oils, analyzed by Tümen et al. (6,7), were composed mainly of p-cymene (53.1% and 83.7%) along with borneol (7.2%) and thymol (9.3%) in O. solymicum.

Origanum leptoclatum, O. acutidens and O. bargyli (Brevifilamentum section) were studied by Baser (8-10). The oils of O. leptoclatum (8) and O. acutidens (9) contained mainly γ-terpinene (4.8-12.9%), p-cymene (48-20.7%), α-terpineol (10.8%) or borneol (9.5%), thymol (14.6%) or carvacrol (14.7%). The oils of O. bargyli contained mainly p-cymene (14%) and carvacrol (66.3%). The taxa that we studied were from Ermenek, Erznacan and Osmaniye (Turkey).