Chemical Composition of Essential Oils from Aerial Parts of Sisymbrium Irio from Jordan

The volatile compounds obtained from Sisymbrium irio growing in Jordan has been analyzed by GC-MS. The major constituents are dioctyladipate (25.44%), N-(n-proyl) acetamide (14.77%), isopropyl isothiocyanate (11.55%), isobutyl isothiocyanate (6.75%), 3,7,11,15-tetramethyl-2-hexadecen-1-ol (6.52%), cis-8,11,14-eicosatrienoic acid (6.30%), heptacosane (3.89%), palmitic acid (3.45%), n-butyl isothiocyanate (2.85 %) and dimethoxyacetophenone (2.54 %).


Introduction
The cruciferae family is a large plant family that includes important food crops, herbs, ornamentals and weeds 1 .Forty six genera of this family are distributed in Jordan, including the genus Sisymbrium.There are seven species belonging to this genus in Jordan 2 .One of the most important species of this genus is Sisymbrium irio, which is grown in many parts of the world.The plant is a rich source of flavoinoids 3,4 and glucosinolates 5,6 .It has a sharp flavor and can be used in salads.The plant is used in folk medicine as a febrifuge, a stimulating poultice, treating asthma and for infections of the throat and chest 7 .In this paper we report on the isolation and analysis of the volatile compounds from the aerial parts of Sisymbrium irio collected from the north of Jordan.

Experimental
Aerial parts of Sisymbrium irio ("al-hwarineh or al-shalwa" in Arabic) were collected at the onset of flowering, from Irbid area (north of Jordan).Identification of the plant species was done by professor D. Al-Esawi (Department of Biological Sciences, Faculty of Science, University of Jordan).

Isolation of the volatile components
The fresh aerial parts of Sisymbrium irio (30.0 g) were hydrodistilled using a Clevenger-type apparatus to recover the essential oils for 4 h.The oils distillate was separate from trace of water by extraction three times with 3 mL of Ether and dried overnight over 3.0 g of anhydrous sodium sulfate.

GC-MS analysis
Gas chromatography -mass spectrometry (GC-MS) analyses were performed using Agillent 6890 series II-5973 mass spectrometer interfaced with a HP chemstation.The chromatographic conditions were as follow: column oven programe, 40 ºC (10 min, isothermal) to 240 ºC (10 min, isothermal) at 2 ºC/min; the injector and detector temperatures were 270 and 280 ºC, respectively.Helium was the carrier gas (flow rate 0.70 mL/min).A HP-5 MS capillary column (30×0.25 mm i.d., 0.25 µm film thicknesses) was utilized.The actual temperatures in MS source reached approximately 180 ºC.The ionization voltage was 70 eV.The volatile compounds were identified by comparing their MS patterns and retention times with those of known compounds published in the literature 8 .

Conclusion
Many crucifers such as Sisymbrium irio contain glucosinolates which are precursors of many volatile compounds, in particular nitriles and isothiocyanates.Isothiocyanates, which are strongly odorous and pungent compounds, are formed by the action of the enzyme thioglucoside glucohydrolase (myrosinase) on the glucosinolate when the plant tissue is disrupted 9,10 .In our case, intact plant material was subjected to an isolation procedure so that myrosinase action was restrained; hydrodistillation gave predominantly Isothiocyanates degradation products as observed in the chemical composition of the oil.

Table 1 .
Composition and percentage of the essential oil from Sisymbrium irio.

Table 2 .
Classification of the constituents of the Sisymbrium irio.