EVALUATION OF THE CHEMICAL COMPOSITION OF ESSENTIAL OILS FROM LEAVES OF SUDANESE OCIMUM GRATISSIMUM AND OCIMUM BASILICUM

Itmad Awad Elhassan * , Amira Ahmed Hamed-Elneel and Reem Ahmed Adam. Pharmaceutical Industries Research Department, Industrial Research and Consultancy Centre, Khartoum, Sudan, P.O Box 268-Khartoum. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


Essential oils preparation:-
The essential oils were obtained from the leaves of O. basilicum and O. gratissimum by hydro-distillation, using Clevenger apparatus, for four hrs. The yield was expressed in percent of the dry material (v/w). The oil was dried over anhydrous sodium sulfate.

GC-MS analysis of the oil:-
The essential oil was analyzed by gas chromatography coupled with mass spectrometry (GCMS-QP 2010). The sample was dissolved in dichloromethane (1%) and injected at 250 °C (Injector temperature) into the capillary column type HP-1, 30m x 0.25 mm i.d., stationary phase (95 % diethyl-5% diphenylsiloxane, 0.25 μm film thickness), using helium as a carrier gas at a flow rate of 1.2 ml/min. The injected volume was 1 μl and the injection mode used was split (split ration 50:1). The initial oven temperature was 35 o C held for 3min, then raised at a rate of 5 °C/min up to 240 o C, then at a rate of 3 °C/min up to 280 °C, held for 4 min. Detector temperature was 200 o C. The MS was operated in the El mode at 70 eV. The mass and scan range was set at m/z 35-450.
Compounds identification:-Identification of compounds from the essential oils was achieved by matching their mass spectra with reference spectra from the computer library of NIST or Wiley Registry of Mass Spectral Data.

Results and Discussion:-
The yield of the hydro-distilled essential oils obtained from leaves of O. gratissimum and O. basilicum L. were 0.5% and 0.8% (v/w) respectively.
Gas chromatogram of O. gratissimum essential oil revealed detection of twenty four compounds. About 99% of the constituents were identified. The constituents of the essential oil of O. gratissimum, as well as their percentage abundance, are shown in Table (1) according to their retention times. O. gratissimum essential oil consisted mainly of oxygenated monoterpenes (50.63%) and hydrocarbon sesquiterpenes (45.12%) followed by oxygenated sesquiterpenes (4%) and traces of hydrocarbon monoterpenes (Fig.  1).
8 Based on the chemotype classification system proposed by Grayer et al. (1996), which is based on the combination of the essential oil major components rather than the sole dominant compound, O. gratissimum under investigation could be classified as eugenol-caryophellene chemotype.
The GC/MS analysis of the hydro-distilled O. basilicum oil revealed detection and identification of thirty nine compounds ( Table 2).