By Gilles Figuérédo, Patrick Cabassu, Jean-Claude Chalchat and Bernard Pasquier

Abstract: Abstract: Six species of oregano were studied: Origanum compactum Benth., O. dictamnus L., O. dubium Boiss., O. minutiflorum Schwarz et Davis, O. onites L. and O. vulgare ssp. hirtum Ietswaart. Collected at their natural sites, sown, planted and oils isolated at the CNPPMAI. The oils were analyzed by GC and GC/MS; 118 constituents were identified. All species presented a carvacrol chemotype (60 - 90%) accompanied by various chemical forms, such as a thymol-rich type, as in O. dictamnus, O. dubium and O. vulgare ssp. hirtum, in which its levels ranged widely (20 - 90%), or linalool-rich (27 - 90%), as in O. onites and O. dubium. Key Word Index: Origanum compactum, Origanum dictamnus, Origanum dubium, Origanum minutiflorum, Origanum onites and Origanum vulgare ssp. hirtum, essential oil composition, carvacrol, thymol, γ-terpinene, p-cymene, linalool.

Introduction
The chemical compositions of all have been described (1). Origanum compactum (2,3), Origanum dubium (4), synonym of Origanum majorana L. (5) and Origanum minutiflorum (6) were found to be carvacrol-rich (≈ 80%). Origanum onites was mostly carvacrol-rich, whether it came from Greece (80%) (4,6), Turkey (66 - 80%) (7) or Sicily (62%) (8). However, a Turkish linalool chemotype has also been found (80%) (7). Whereas O. dictamnus (9) was found to contain mainly p-cymene (26%) and thymoquinone (23%), O. vulgare ssp. hirtum (10 - 13) includes a carvacrol type (55 - 78%) and thymol types (40 - 70%) from Greece and Italy, which also contain γ-terpinene and p-cymene in ranging amounts (7 - 50%).

The species studied grow in specific locations, generally on limestone soils: O. compactum, from Morocco, on dry stony soils up to altitude 700 m; and O. dictamnus on shady rocky cliff-sides at altitudes between 300 and 1500 m. It is cultivated in the region of Embaros in eastern central Crete. O. vulgare ssp. hirtum, Greek or Turkish, is known as O. heracleoticum and is a subspecies of the ordinary oregano or perennial marjoram (O. vulgare ssp. vulgare) found in France. It grows naturally in shady rocky-stony soils up to altitude 1500 m. The O. dubium ‘Rigani’ (oregano) of Cyprus grows in scrubland on stony-rocky soils (eruptive rock) at altitudes between 600 and 1200 m. Origanum minutiflorum, a rare species, grows only at altitudes above 1500 m on rocky soils in two or three mountain massifs in southern Turkey. Origanum onites grows naturally in Greece and Turkey on stony-rocky soils at altitudes between 0 m and 1400 m.

Here we report the oil composition results obtained from plants grown at the CNPPMAI obtained from seeds collected on natural sites.