Content and composition of essential oil of four Origanum vulgare L. accessions under reduced and normal light intensity conditions

Abstract

The variation in the chemical composition and content of the essential oil was examined in four Origanum vulgare accessions (Ov): 1- Origanum vulgare L. ssp. vulgare (=Ovu), 2- Origanum vulgare L. ssp. hirtum (Link) letswaart (=Ohi), 3- Origanum vulgare L. ssp. viride (Boiss.) Hayek (=Ovi) and 4- Origanum vulgare L. ssp. viride (Boiss.) Hayek × O. majorana L. (=Oxm), growing under reduced (26%) and normal light intensity. Altogether, 64 compounds representing 98.95% of the total oil were identified. Reduced light had a minor effect on the composition of essential oil. It decreased the content of p-cymene in Ohi and increased the sabinene content in Oxm herb samples. The essential oil of Ovu in both samples was mainly composed of trans-sabinene hydrate, ß-caryophellene and germacrene D. The major components of essential oil of Ohi were thymol and carvacrol followed by gamma-terpinene and p-cymene. Herb samples had a considerably higher amount of essential oil than leaf samples. In herb extracts of Ovi, cymyl compounds such as p-cymene, thymol and gamma-terpinene were dominant. Oxm was characterized by several monoterpenes with low concentrations including gamma-terpinene, sabinene cis-b-ocimene and carvacrol methyl ether. The results of the current study suggest a chemical toleration of the evaluated accessions to the applied light reduction. Furthermore, a full investigation of essential oil profiles of Origanum vulgare accessions is presented.