GC/MS Analysis of the Volatile Constituents from Arum Cyreniacum Flowers

Arum cyreniacum (family Araceae) is a Libyan plant have many medicinal uses. The volatile constituents of the flowers of the plant were extracted separately with two different solvents (n-hexane and chloroform). The two volatiles were analyzed using GC/MS. It was found that the volatile constituents of the flowers extracted with nhexane consists of 32 compounds in which, the oxygenated monoterpenes is the most abundant class (51.43%) with 1,8-cineole as a major compound (43.32%), while the chloroform extract substantiated the presence of esters hydrocarbons and sterols as main groups (44.95%, 30.38% and 16.05% respectively).


INTRODUCTION
The genus Arum is an important genus in the family Araceae.This genus is composed of 28 species, largely distributed in Europe, North Africa, Middle East and Central Asia.This genus is represented in Libya by only one endemic species known as Arum cyreniacum [6,7].
By reviewing the literature about the chemical constituents and biological activity of Arum genus, it was found that, the plants of this genus have many biological activity as treatment of rheumatic pain, diaphoretic, diuretic, expectorant, strongly purgative and vermifuge, affect on the cells of the immune system, antioxidant activity, anticancer activity (against hepato carcinoma, breast carcinoma cells and lymphoplasticleukemia) and have antimicrobial activity [11,12,13].The phytochemicals like volatile oil, terpenes, flavonoids, lectins and alkaloids were studied in Arum genus.Kite et al. [8][9][10] studied the odours of many Arum species and they identified 36 compounds, in which butanoïc acid esters, 1-decene, terpenes (citronellene and its derivatives), p-cresol, methyl salicylate, indole and 2-heptanone are common compounds.Some species appear clearly different like A. creticum or A. palaestinum, whose rotten fruit odour is due to benzyl alcohol and ethyl acetate.Arum rupicola var.rupicola is also different because of a mixture of various sesquiterpenes even if p-cresol is abundant [14].
Skatole (3-methyl indole) methyl amine and ammonia have been detected in the condensates produced from cuts of A. italicum and A. dioscoridisi.Fifty-six compounds were identified from the odour of A. maculatum.The major components being: 2-heptanone, indole, p.cresol, Also, several ketones and esters were detected and the majority of the compounds were terpenoids [8].By reviewing the available literature, it was found nothing about the chemical constituents of the volatiles from the flowers of Arum cyrenicum so the aim of this study is the isolation and identification of volatile constituents from the Arum cyrenicum flowers using solvent extraction.

MATERIALS AND METHODS
Plant material: Arum cyrinaicum was collected from Aljabal AlAkhder region -Libya during the flowering stage.The plant was kindly identified and authenticated by Dr. Naser Elshekhi, lecturer of taxonomy at Botany Dept, Faculty of Science, Binghazi University.A voucher speciemin was deposited at the herbarium of faculty of science, Sirt University.The flowers of the plant were separated from the aerial parts, air dried and grinded to a fine powder for extraction.

Extraction of volatiles using two different solvents:
Two batches of about 50 g each of powdered dry flowers, one of it was macerated in 250 ml n-hexane and the other was macerated in chloroform for 24 hr.two times.The solvents were evaporated in vacuo at about 30 °C, the pale yellow extract and dark extract (0.5 g and 1.1 g respectively) were subjected to GC/MC analysis using the following conditions:

RESULTS AND DISCUSSION
The data in Table 1 proved that, the volatile constituents of the flowers extracted with n-hexane consists of 35 compounds (32 of them were identified and representing about 98.53% while the other three compounds were unidentified which constituted 1.47%) belonging to many classes as follow: the oxygenated monoterpenes is the most abundant class (51.43%) with 1,8-cineole as a major compound (43.32%), the second class is oxygenated sesquiterpenes (18.54%) in which Spathulenol is the highest one (12.12%)followed by the esters group where it constitute about 11.86% with the principle compound viz.Linalyl acetate.The nonoxygenated monoterpenes, aromatics and nitrogenous components were found to form 10.33%, 2.30% and 1.83% respectively.
If we compare the chemical constituents of volatile in both solvents, it is concluded that, the oxygenated monoterpenes and oxygenated sesquiterpenes are main in case of hexane while these compounds are not present in case of chloroform.Also, the steroidal compounds are absent in case of n-hexane extraction while in case of chloroform extraction is consider as a main group where it represented about 14.05%.It is noted that, these data were disagree with that reported by Kite et al.in 1995 where they analyzed the odour of A. maculatum by noninvasive headspace and they identified the major components as: 2-heptanone, indole (each comprising 8-23% of the volatiles among the inflorescences studied) and bicyclogermacrene (10-14%), p.crsol was also a notable odouors.Component (0.2-6%) as were several ketones and ester, but simple aliphatic amines were not detected; the majority of the compounds were terpenoids [9].Also, Diaz & Kite, in 2002, were found that, the odor composition of A. italicum differs from A. maculatum.The main compounds were: 1 -decene, methyl butyrate, and ß -citronellene [11].These differences may be due to the method of extraction of the volatile constituents, where the headspace is more efficient for the aroma compound while the solvent extraction may resulted in less volatile components.In conclusion this is the first report about the study of the chemical constituents of volatiles extracted from the flowers of Arum cyreniacum.

Table 1 .
GC/MS data of the volatiles of n-hexane extract of A. cyrenaicum flowers Rt = Retention time, M = Molecular ion peak, B.P. = Base peak.

Table 2 .
GC/MS data of the volatile of A. cyrenaicum flowers extracted with chloroform Rt = Retention time, M = Molecular ion peak, B.P. = Base peak.