Constituents of the Essential Oil of Euphorbia hebecarpa

Abstract

The Euphorbiaceae is a large family of flowering plants including 300 genera and over 5000 species. Euphorbia is the largest genus in this plant family with about 2000 species [1]. The Iranian Flora consists of 70 species of Euphorbia, including 17 endemics, and the popular Persian name of the species is “Farfion” [2]. Euphorbia hebecarpa Boiss., endemic to Iran, is a perennial plant distributed mainly in the Zagros Mountains [3]. Latex of some species of Euphorbia has traditionally been used in the treatment of skin diseases, gonorrhea, migraines, intestinal parasites, and warts [4]. Phytochemical investigation of the genus revealed that many of its components are highly bioactive [5–7]. Diterpenoids are found in the majority of the genus with many different core frameworks such as jatrophanes, lathyranes, tiglianes, ingenanes, and myrsinols [8–13]. In addition, some Euphorbia species are known to possess significant anticancer [14, 15], antitumor [16, 17], antimicrobial [17, 18], and antioxidant [19, 20] activities. To the best of our knowledge, there is no published report on the composition of E. hebecarpa essential oil. However, cytotoxic and antimicrobial activities of the extracts of the plant have been reported [21]. The present work studies the chemical composition of the essential oil from the aerial parts of E. hebecarpa for the first time. The plant material was collected during the flowering stage from Baft, the Kiskan area, Kerman Province, Iran in June 2012. A voucher specimen (No. 1136) has been deposited in the Herbarium of the Department of Microbiology, Kerman Branch, Islamic Azad University, Kerman, Iran. The air-dried aerial parts of the plant (100 g) were crushed and subjected to hydrodistillation for 3 h using a Clevenger-type apparatus. The clear yellowish oil was isolated in a yield of 0.2% (w/w). The constituents of the oil were analyzed by GC and GC-MS. GC analysis of the volatile components was carried out using a Hewlett-Packard 6890 instrument coupled to a flame ionization detector (FID). Compounds were separated on an HP-5 capillary column (30 m 0.25 mm, film thickness 0.25 m). The column temperature was kept at 60 C for 3 min and programmed to 220 C at a rate of 5 C/min. Injector and detector temperatures were 270 C, and the flow rate of helium as carrier gas was 1 mL/min. The percentage composition of the individual components was computed from the GC-FID peak areas without the use of correction factors. GC-MS analysis was performed using an Agilent 5975C mass spectrometer coupled to an Agilent 7890A gas chromatograph equipped with an HP-5MS capillary column (30 m 0.25 mm, film thickness 0.25 m). The carrier gas was helium, and the chromatographic conditions were as above. The spectrometer was scanned over the 40–400 amu range with an ionization voltage of 70 eV and an ionization current of 150 A. Retention indices were determined using the retention times of n-alkanes, injected after the essential oil under the same chromatographic conditions. The chemical compounds, which were identified on the basis of their mass spectral characteristics and retention indices [22], are listed in Table 1. As is shown, 28 components were identified in the essential oil, representing 97.6% of the total oil. The main constituents were -bisabolol (31.2%), cis-cadin-4-en-7-ol (20.1%), trans-piperitol (8.6%), cis-p-menth2-en-1-ol (6.4%), and trans-p-menth-2-en-1-ol (6.2%). Oxygenated sesquiterpenes (59.3%) were the most abundant components in the oil. The essential oil of E. teheranica Boiss., endemic to Iran, was also rich in oxygenated sesquiterpenes, and elemol (57.5%) has been reported as the main constituent of the oil [23].