Essential oil of some seasonal flowering plants grown in Saudi Arabia

2.1 Plant material

The plant samples were collected from the central region of Saudi Arabia over the period of January to March 2001 and was identified at the Herbarium of the Department of Botany, King Saud University, Riyadh, Saudi Arabia. Aerial parts of fresh plants (50 gm each) were ground and subjected to hydrodistillation for 4 h using essential oil distillation apparatus.

2.2 Essential oils analysis

The essential oils were analyzed on Shimadzu GC/MS-QP 5050 system. The column used was DB-1 glass column (30 m × 0.25 nm). The carrier gas was helium with a flaw rate of 41.8 ml/min, the injector temperature was 250 °C with column temperature ranging from 50–290 °C. The MS was operated with 0.1 L split 100:1 using El Mode. Each compound was identified by comparison with the literature reports and by computer matching with standard spectra in NIST and Wiley libraries (Stenhagen et al., 1975; Formacek, 1982).

3.1 Rumex vesicarius

Essential oils of six plant samples collected from different places of central Saudi Arabia were obtained by steam distillation. The samples were given the following codes according to the place of collections: Sudier (200 km north of Riyadh) (RV-1), Dawadmi (300 km west of Riyadh) (RV-2), Kharj (100 km south of Riyadh) (RV-3), Riyadh Airport (50 km north of Riyadh) (RV-4), Aljenadriah (80 km east of Riyadh) (RV-5), and Riyadh city (RV-6). Yields of essential oils obtained from these samples on fresh weight basis are given in Table 1.

Steam distillation of these samples gave light brownish color oil with no smell which turned to a waxy like material after being left for few minutes at room temperature. Gas chromatography–mass spectrometry (GC–MS) analysis of the oil samples resulted in the identification of fifteen constituents of the oils in total. The relative concentrations of the volatile components identified are presented in Table 2. The major constituents of Sudier (RV-1) oil were nonacosane (27.7%), pentatriacontane (16.7%), palmitic acid (12.9%), 3,8-dimethylundecane (6.4%), and 2-ethyl-2-methyl-l-decanol (5.8%). The major constituents of Dawadmi (RV-2) oil were 9,12-octadecadienoic acid (41.4%), palmitic acid (39.4%) and phytol (7.7%). The major constituents of Kharj (RV-3) oil were palmitic acid (30.7%) and phytol (17.4%). The major constituents of Riyadh Airport (RV-4) oil were 9,12,15-octadecatrienoic acid (46.7%) and palmitic acid (26.0%). The major constituents of Aljenadriah (RV-5) were palmitic acid (37.2%) and 9,12,15-octadecatrienoic acid (29.5%) while the major constituents of Riyadh city (RV-6) oil were 9,12-octadecadienoic acid (29.1%) and palmitic acid (20.3%).

From Table 2 it is evident that essential oils composition of R. vesicarius collected from six places of central Saudi Arabia were drastically varies quantitatively as well as qualitatively. Palmitic acid was the only compound which was present as major constituents (ranging from 12.9–39.4%) in all oil samples of R. vesicarius, thus presence of palmitic acid could be considered as a characteristic parameter for R. vesicarius essential oils.

3.2 Erucaria hispanica

Steam distillation of E. hispanica aerial parts gave oil in 0.04% yield (v/w) on fresh weight basis. Gas chromatography–mass spectrometry (GC–MS) analysis of the oil resulted in the identification of total 13 constituents representing 85.1% of the oil. The relative concentrations of the volatile components identified are presented in Table 3. The main constituents of the oil were palmitic acid (36.7%), cyclohexanol dodecyl (11.2%), 1,14,17-Eicosatrienoic acid methyl ester (9.1%), Linolenic acid (7.5%) and phytol (5.6%).

3.3 Schimpera arabica

Fresh aerial parts of S. arabica was steam distilled to gave oil in 0.18% yield (v/w) on fresh weight basis. The oil was analyzed by Gas chromatography–massspectrometry (GC–MS) which resulted in the identification of 13 constituents representing 97.4% of the oil. The relative concentrations of the identified compounds are presented in Table 4. The major constituents of the oil were palmitic acid (42.6%), linolenic acid (16.7%), tetradecanoic acid (14.3%) and undecanoic acid (5.6%).

3.4 Savignya parviflora

Aerial parts of this plant gave yellow color oil in 0.13% yield (v/w) on a fresh weight basis by steam distillation. Gas chromatography–mass spectrometry (GC/MS) analysis of the oil resulted in the identification of 14 components representing 89.8% of the oil. The relative concentrations of the identified constituents are presented in Table 5. The major constituents of the oil were palmitic acid (40.9%), Phytol (8.5%), eicosane (6.4%) and tetratetracontane (5.9%).

3.5 Horwoodia dicksoniae

Aerial parts of H. dicksoniae yielded 0.07% oil (v/w) on fresh weight basis by steam distillation. The volatile oil has a yellow color. Fifteen component representing 98.8% of the oil were identified through Gas chromatography–mass spectrometry (GC/MS) analysis. The relative concentrations of the identified constituents are presented in Table 6. The principle components of this oil were heaxtriacontane (55.0%), pentacosane (19.4%), palmitic acid (6.2%) and tricosane (4.9%).

3.6 Sisymbrium irio

Steam distillation of S. irio Aerial parts gave yellow color oil in 0.08% yield (v/w) on fresh weight basis. Gas chromatography–mass spectrometry (GC–MS) analysis of the oil resulted in the identification of total 13 constituents representing 67.1% of the oil. The relative concentrations of the volatile components identified are presented in Table 7. The main constituents of the oil were palmitic acid (10.4%), menthol (6.7%), Pentacosane (6.5%) and n-heptadecanol (5.2%).

3.7 Plantago amplexicaulis

Fresh aerial parts of P. amplexicaulis yielded 0.07% oil (v/w) on fresh weight basis by steam distillation. The volatile oil turned to a waxy like material after being left for few minutes at room temperature. Eight constituents representing 49.7% of the oil were identified through Gas chromatography–mass spectrometry (GC/MS) analysis. The relative concentrations of the identified constituents are presented in Table 8. The principle components of this oil were palmitic acid (19.8%), 3-mathylundecane (10.5%) and l-ethyl-2-methylcyclohexanol (7.8%).

3.8 Plantago boissieri

Steam distillation of P. boissieri aerial parts gave oil in good yield i.e. 0.2% (v/w) on fresh weight basis. Gas chromatography–mass spectrometry (GC–MS) analysis of the oil resulted in the identification of total seven constituents representing 67.89% of the oil. The relative concentrations of the volatile components identified are presented in Table 9. The main constituents of the oil were Bicyclo-2,2,1-heptane,2-(2-propenyl) (17.86%), l-dodecane-3-ol (12.36%), phenol, 3-ethyl (9.8%) phenol, 4-methyl (7.96%), nonacosane (7.64%), 2,3,6-trimethyl hepta-6-en-l-ol (6.41%) and benzoic acid (5.86%).

3.9 Arnebia. linearifolia

Aerial parts of A. linearifolia gave oil in 0.01% yield (v/w) on fresh weight basis by steam distillation. The volatile oil turned to a waxy like material after being left for few minutes at room temperature. Twelve constituents representing 90.6% of the oil were identified through Gas chromatography–mass spectrometry (GC/MS) analysis. The relative concentrations of the identified constituents are presented in Table 10. The major components of this oil were phytol (19.0%), pentalene, octahydro-l-(2-octyldecyl) (18.8%), docosane (11.8%), tetratetracontane (9.2%), heptadecane (7.9%) and palmitic acid (7.3%).

3.10 Foeniculum vulgare

Detailed literature survey revealed that several studies on essential oil of F. vulgare growing in different parts of world (Ronsted et al., 2001; El-sayed et al., 2001; Ravid et al., 1983; Arsalan et al., 1989; Singh et al., 1990; Venskutonis and Dapkevicius, 1996; Baser and Ozek, 1997; Muckenstrum et al., 1997) have been done. However, no literatures on chemical investigation of F. vulgare grown in Saudi Arabia were found. This prompted us carry out this study. Steam distillation of F. vulgare aerial parts gave a yellow oil in 0.1 yield (v/w) on fresh weight basis. Gas chromatography–mass spectrometry (GC–MS) analysis of the oil resulted in the identification of total nine constituents representing 99.6% of the oil. The relative concentrations of the volatile components identified are presented in Table 11. The principle constituents of the oil were anethole (76.4%) and apiol (16.3%).

3.11 Trigonella hamosa

Fresh aerial parts of T. hamosa on steam distillation gave yellow color oil in yield 0.04% (v/w) on fresh weight basis. Twelve constituents representing 91.1% of the oil were identified through Gas chromatography–mass spectrometry (GC/MS) analysis. The relative concentrations of the identified components are presented in Table 12. The major components of this oil were palmitic acid (38.4%), tetradecanoic acid (15.9%), linolenic acid methyl ester (11.3%), phytol (7.6%) and decanoic acid (7.3%).

3.12 Lotus halophilus

Steam distillation of L. halophilus aerial parts gave yellow color oil in yield 0.07% (v/w) on fresh weight basis, interestingly, only three components contributing 99.3% of the oil were identified. The relative concentrations of these three identified components i.e. phytol (49.8%), Heptadecane (33.0%) and 2,9-Dimethyldecane (6.3%) are presented in Table 13.

3.13 Reseda muricata

Steam distillation of R. muricata aerial parts gave yellow oil in 0.13% yield (v/w) on fresh weight basis. Gas chromatography–mass spectrometry (GC–MS) analysis of the oil resulted in the identification of total 12 constituents representing 63.2% of the oil. The relative concentrations of the volatile components identified are presented in Table 14. The main constituents of the oil were hexatricontane (17.2%), palmitic acid (10.0%), nonadecane (8.9%), phytol (6.8%) and 2,2-dimethyl-3-(E)-beta-(2-methylallyl)-cyclopropane carboxylic acid (6.5%).

3.14 Cenchrus ciliaris

Fresh aerial parts of C. ciliaris was steam distilled to gave oil in 0.08% yield (v/w) on fresh weight basis. The oil was analyzed by Gas chromatography–mass spectrometry (GC–MS) which resulted in the identification of 13 constituents representing 86.4% of the oil. The relative concentrations of the identified compounds are presented in Table 15. The major constituents of the oil were palmitic acid (42.9%), phytol (9.9%), tridecanol, 2-ethyl-2-methyl (6.7%) and 3,9-dimethylundecane (5.8%).