Essential Oils Leaf of Cinnamomum glaucescens and Cinnamomum verum from Vietnam

In this paper, compounds identified in the essential oils obtained by hydrodistillation of the leaves of Cinnamomum glaucescens (Nees) Hand.-Mazz and Cinnamomum verum J.S. Presl (Lauraceae family) of Vietnam origin are reported. The chemical analyses were performed using gas chromatography-flame ionisation detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). The significant compounds of C. glaucescens were geraniol (36.2%) and terpinen-4-ol (19.7%). On the other hand, C. verum comprised of linalool (22.0%) and bicyclogermacrene (11.2%). The present results may represent new chemotypes of the essential oils of C. verum and C. glaucescens.

Cinnamomum verum J.S. Presl is an evergreen tree that grows up to 18 m tall.
In the present paper, the results of our studied on the phytochemicals in the essential oils of Vietnamese species of C. verum and C. glaucescens were reported.Previously, the phytochemical constituents of some other plants have been characterized and reported [41].

Plant Samples
The leaf samples of C. glaucescens and C. verum were collected from Bến En National park, Thanh Hóa Province, Vietnam, in August 2013.Voucher specimens HVC 377 and HVC 04 respectively were deposited at the HN, Vietnam.
The drying of the plant samples was accomplished by exposure to air under laboratorys shade for two weeks.

Hydrodistillation of Essential Oils
Aliquots of 500 g air-dried and pulverized samples individually subjected to hydrodistillation process which was carried out in an all glass Clevenger-type distillation unit designed according to the established specification [43].The distillation American Journal of Plant Sciences time was 3 h and conducted at normal pressure.The volatile oils distilled over water and were collected in the receiver arm of the apparatus into clean and previously weighed sample bottles.The oils were kept under refrigeration (4˚C) until the moment of analyses as previously described [41].

Gas Chromatography (GC) Analysis
The GC analysis was carried out on HP 6890 Plus Gas chromatograph (Agilent

Gas Chromatography/Mass Spectrometry (GC/MS) Analysis
The GC/MS experiment was performed on Mass spectrometer (HP 5973 MSD) combined with HP 6890N Plus GC.The system was fitted with HP-5 MS capillary column of 30 m × 0.25 mm having film thickness of 0.25 µm.All operating conditions were similar to that of GC except that He (1 mL/min) was the carrier gas.The Mass Spectrometer was operated on the following conditions: ionization voltage (70 eV), emission current (40 mA) and acquisitions scan (mass range of 35 -350 amu).The sampling rate was 1.0 scan/s as previously described [41].

Identification of Constituents of Essential Oils
The compounds present in the oil samples were identified by comparing the individual relative retention indices with standards obtained from pure compounds.In addition, comparison was made with values from literature under the similar experimental conditions [44] and as previously described [41].

Results and Discussion
The percentage yields of essentials oils obtained from the extraction processes were 0.42% (v/w, C. glaucescens) and 0.45% (v/w, C. verum).The colours of the essential oils were determined as light yellow.The compounds that were identified in the samples could be seen in Table 1 with detailed analysis of their reten- (36.2%) and terpinen-4-ol (19.7%).α-Pinene (6.0%), sabinene (6.0%) and limonene (5.2%).Sesquiterpne compounds were present in amount < 1%.Except for α-terpineol, all other known compounds such as 1,8-cineole and methyl cinnamate [3] [5], α-terpineol [3], (E)-cinnamate [4] and elemicin [6] that were previously identified in the essential oil of C. glaucescens were not present in the present oil sample.On the other hand, the present oil sample contained large quantities of geraniol and terpinen-4-ol which were not identified in previously studied oil samples of C. glaucescens.
In [25] [26] [27] [28] [30] and cinnamyl acetate [31] that were described previously as main compounds of C. veum oil, were not obtained in the oil sample.However, the amount of linalool in the present C. veum oil was in agreement with previously investigated oil sample [31].A noteworthy observation is that bicyclogermacrene, a main compound in the present C. veum oil was not described to be a significant compound in previously investigated samples of C. verum oils.
Several reports describing the chemical compositions of essential oils from some Vietnamese species of Cinnamomum have been published.In summary, each of the essential oils possessed compounds that were different from the other oil samples.The main compounds in the essential oil of C. sericans [41] were spathulenol (14.5%) and caryophyllene oxide (9.3%), while ρ-cymene (15.6%), limonene (13.9%) and α-phellandrene (9.2%) were found C. durifolium [41].
From the chemotaxonomy point of view, C. verum in the present study contained linalool which was also found to be the dominant compound of essential oils of C. damhaensis and C. cambodianum from Vietnam [42].However, the essential oils of most Cinnamomum species from Vietnam possessed low content of (E)-cinnamaldehyde [41] [42] when compared with other samples analyzed from other parts of the world.

Conclusion
The paper reported the compounds identified in the essential oils of C. verum and C. glaucescens grown in Vietnam.The significant compounds of C. glaucescens were geraniol and terpinen-4-ol whil, C. verum comprised of linalool and bicyclogermacrene.In addition, a comparative analysis of the composition of the essential oils was performed with results from other species reported from Vietnam as well as Cinnamomum plants grown in other parts of the world.
More studied will be required in order to be able to delineate the various chemotypes of essential oils of Cinnamomum plants in various parts of the world.

2 (
Technologies) equipped with a flame ionization detector (FID).The column used was HP-5MS column with the dimension 30 m × 0.25 mm (film thickness 0.25 µm).Temperature programming parameters: column oven-40˚C, injection pot-250˚C, detector-300˚C.Time programming: 40˚C for 2 min, temperature raised to 220˚C (10 min hold) at 4˚C/min.Carrier gas used was H flow rate of 1 mL/min), split ratio 10:1, volume injected-1.0 µL.Inlet pressure was 6.1 kPa.Retention indices (RI) value of each component was determined relative to the retention times of a homologous n-alkane series (C 4 -C 32 ) with linear interpolation on the HP-5MS column.Relative percentage amounts were computed from GC peak areas without FID response factor correction as previously described[41].

Table 1 .
Volatile compounds present in the essential oils of C. galucescens and C. verum.
tion indices and percentage compositions.Monoterpene hydrocarbons (25.9%) and oxygenated monoterpenes (64.3%) were determined as the dominant class of compounds of C. glaucescens oil. the main constituents of the oil were geraniol H. V. Chinh et al.DOI: 10.4236/ajps.2017.8111822715 American Journal of Plant Sciences a Compounds order of elution from HP-5MS column; RI (cal.)Calculated retention indices of each compounds on HP-5MS column; RI (Lit.)Literature retention indices; -not identified.