Composition and extraction of essential oil from Rumex chalepensis using hydrodistillation

Abstract

The aim of our study was to evaluate the chemical composition of Rumex chalepensis essential oil. From the aerial parts of Rumex chalepensis at the flowering stage, a yellowish oil was obtained at a yield of 0.03% (w/w). Thirty-three components were identified, accounting for 66.3% of the total oil. p-Menth-2-en-ol (18.8%) was determined as the major constituent in the extract. The other major components in the oil of Rumex chalepensis were identified as dibutyl phthalate (6.5%), fleximel (4.3%), and dodecane (3.4%). It was also confirmed that the oxygenated and non-oxygenated terpenes made up 20.5% and 1.2% of the extract, respectively. The percentage composition of the various oil components is listed in Table 1. Plant Material. Arial parts of Rumex chalepensis were collected at the flowering stage from Southern Khorasan, Birjand, Iran, in June 2010, and identified at the Research Center for Plant Sciences, Ferdowsi University of Mashhad, Iran. A voucher specimen has been deposited in the Herbarium of Research Center for Plant Sciences. Isolation of the Essential Oil. Arial parts of Rumex chalepensis were air-dried for 5 days before isolation of essential oil. The plant material (100 g) was cut into small pieces and the essential oil obtained by hydrodistillation with a Clevenger-type apparatus until there was no significant increase in the volume of the oil collected (6 h). The yield of the yellow oil was 0.03% (w/w) based on the dry weight of the plant. GC and GC-MS Analysis. GC analysis of the oil from the aerial parts of the plant was performed using a Shimadzu GC-MS-QP (2010) gas chromatograph equipped with flame ionization detector (FID) and an RTx-5MS column (95% diphenyl– 5% dimethylpolysiloxane, 15 m 0.25 mm.i.d., film thickness 0.25 m). The oven temperature was programmed to 35–280C at a rate of 5C/min; the carrier gas was helium with a flow rate of 1 mL/min, and the sample was injected using the split sampling technique 1:10. The percentage composition of the oil was calculated automatically from peak areas without any correction. Retention indices (RI) were determined by comparing with the retention times of a series of n-alkanes with linear interpolation. Identification of each component was confirmed by comparison of its retention index either with those of authentic compounds or with data in the literature [8–10].