g. amin

Essential oils are very complex mixture of components and their composition may vary in different species or varieties or even within the same variety. Origanum vulgare L. subsp. vulgare is one of the most distributed subspecies within the genus Origanum and has been found to be a poor-oil, categorized in cymyl, bornane or sabinyl chemotypes with higher proportion of sesquiterpenes. In this experiment, the Iranian sample was studied for the chemical composition of the oil and evaluation of its antioxidant activity.

Essential oil was obtained by hydro-distillation and analyzed by GC/MS for determination of components. Antioxidant activity was evaluated by radical scavenging ability (DPPH method) and reducing power (FRAP assay).

The sample belonged to “thymol” chemotype with the main components as thymol (37.13%), gama-terpinene (9.67%), carvacrol (9.57%), carvacrol methyl ether (6.88), cis-alpha-bisabolene (6.80%), eucalyptol (3.82%), p-cymene (3.58%) and elemol (2.04%). The oil of plant showed very strong antioxidant activity (IC50=2.5 µg/mL in DPPH method), which was stronger than the standard antioxidants (Vit E and BHA, p<0.05) and it demonstrated good reducing power (467.25 μmole Eq FeSO4.7H2O/mg of the oil in FRAP assay).

The data suggests the plant as a good potential natural antioxidant preservative.

Laurus nobilis L. (sweet laurel) is one of the volatile oil bearing plants of Lauraceae family. It is cultivated in different parts of Iran and its leaves and fruits have been used in food, cosmetics and pharmaceutical industries. There are a few reports about the effects of some environmental conditions on the quality and quantity of laurel volatiles. The goal of our work was to search the seasonal variations on the L. nobilis leaves volatile composition. The volatiles of four samples of the dried leaves of L. nobilis collected in March, June, September and December 2009 in Isfahan, Iran were prepared by using a Clevenger type apparatus for 3 hours and were analyzed by gas chromatography-mass spectroscopy. Twenty-nine, thirty-one, thirty-three and thirty-four components consisting 96.91%, 97.66%, 97.46% and 95.44% of the total compounds were identified of the volatiles obtained with yields of 1.1%, 1.5%, 1.4% and 0.8% (w/w), subsequently. The main compound was found to be 1,8-cineole (30.80-40.25%). Although twenty-seven out of thirty-six volatile components were similar in different seasons, there were some differences between other compounds of our four samples. While the essential oil composition of the March and June plant samples were characterized by presence of 1,8-cineole, δ-3-carene and camphor, the volatiles of September and December plant samples contained 1,8-cineole, camphene and sabinene. Some compounds like eugenol, methyl eugenol and α-terpenyl acetate were not affected apparently by seasonal changes.

Dracocephalum kotschyi (Lamiaceae), as one of the remarkable aromatic plants, widely grows and also is cultivated in various temperate regions of Iran. There are diverse reports about the composition of the oil of this plant representing limonene derivatives as its major compounds. There is no report on cloning of mono- or sesquiterpene synthases from this plant. In the present study, the aroma profile of D. kotschyi has been extracted and analyzed via Headspace Solid-Phase Microextraction technique coupled with Gas Chromatography- Mass Spectroscopy. In order to determine the sequence of the active terpene synthase in this plant, first mRNA was prepared and cloning was performed by 3’ and 5’-RACEs-PCR method, then cDNA was sequenced and finally aligned with other recognized terpene synthases. The results showed that the plant leaves mainly comprised geranial (37.2%), limonene-10-al (28.5%), limonene (20.1%) and 1,1-dimethoxy decane (14.5%). Sequencing the cDNA cloned from this plant revealed the presence of a monoterpene synthase absolutely similar to limonene synthase, responsible in formation of limonene, terpinolene, camphene and some other cyclic monoterpenes in its young leaves.