Chemical composition and antimicrobial activity of essential oils in Xerophytic plant Cotula cinerea Del ( Asteraceae ) during two stages of development : flowering and fruiting

Chouikh Atef , Mayache Boualem , Maazi Mohamed Cherif , Hadef Youcef , Chefrour Azzedine Dept. of Biology, Faculty of Natural Science and Life, University of Echahid Hamma Lakhder-El Oued, BP 789 El-Oued (39000) Algeria. Dept. of Biology, Faculty of Natural Science and life, University of Jijel (18000) Algeria. Faculty of Natural Science and life, University of Mohamed Cherif Messaadia-Souk Ahras (41000) Algeria. Laboratory Development and Control of Hospital Pharmaceutical Preparations. Medical Science Faculty, University of Badji MokhtarAnnaba, LP 205 Ezzafrania, Annaba (23000) Algeria.

The aims of this study highlight the potential fluctuations in yields of essential oils of Cotula cinerea Del and chemical composition, and estimate of Antimicrobial activity of essential oils in two phases of growth: flowering and fruiting.

Plant material
The plant material consists of the aerial part of the plant Cotula cinerea Del; harvested in Oued Souf Sahara (South East of Algeria) during two stages (flowering period in February 2010, and fruiting in April 2010).

Extraction of Essential Oils
The plant material (100g MS) is subjected to extraction by steam distillation in a Clevenger-type apparatus (Clevenger, 1928).The distillation was carried out for four hours in accordance with the recommendations of the European Pharmacopoeia (AFNOR, 2000 ;Lmachraa et al., 2014;Velasco-Negueruela and Perez-Alonso, 1990).The extractions were repeated five times to confirm the return earned by the mode used.The essential oil is stored and maintained optimally at 4 ° C protected from light (Moumni et al., 2013a).
According to (Moumni et al., 2013b) the performance of the essential oil, expressed in ml per 100 g of dry matter of Cotula cinerea Del, and calculated by the following equation: T EO = {V/M S × 100} ± {ΔV/M S × 100}.T EO : Performance of the essential oil.V: volume of essential oil collected (ml).ΔV: Reading error.MS: dry plant mass (g).

Chemical characterization of essential oil by GC/MS
The essential oil of Cotula cinerea Del was analyzed by chromatography phase gas (Trace GC Ultra) coupled to a mass spectrometer (Polaris Q ion trap MS).The database used for the identification of chemical compounds and measurements of peak areas obtained is that of NIST / EPA / NIH MS LIBRARY (NIST 05) and also AMDIS version 2.0 d.

Antimicrobial activity
Antimicrobial activity of C. cinerea essential oils were determined by agar disc diffusion method (Malabadi et al., 2012), Filter paper discs (Whatman N o 3 and 6 mm in diameter) were sterilized by autoclaving (Malabadi et al. 2012).

Organoleptic characteristics of the essential oil extracted:
Essential oils are viscous and persistent odor Pleasant Artémises (Table 1), yellow in flowering and Yellowish Green in fruiting during; the color is strongly influenced by the nature of the complex mixture of oil compounds (Ashnagar et al., 2007).

The yield of essential oils:
The essential oil yield is very low during flowering (0.0801% ± 0.0117%) compared to the fruiting period (0.391% ± 0.0664%) (Fig. 1).It is relatively higher than those obtained by Kether and colleagues (Kether et al., 2012) working on different parts of Cotula coronopifolia L. in Tunisia (0.01134% in leaves; 0.03935% for flowers; 0.00123% in the roots and 0.00405% for the rods).
With respect to n-Valeric acid cis-3-hexenyl ester, the rate remained the same in both periods.

CONCLUSION
The chemical study of essential oil of Cotula cinerea Del, harvested in Oued Souf region (North Eastern Algerian Sahara), revealed that the optimum essential oil yield obtained during the fruiting period (0.391% ± 0.0664%) is characterized by viscous lingering odor and a yellowish green color while in the flowering period it has a yellow color.
According to the results, we can conclude that the yield and chemical composition of essential oils have a relationship with intrinsic (genetic factor, harvest stage, state of the plant) and extrinsic factors (soil, climate, flora procession, insect pests and pollinators, human impact, etc ...).It also appears that the antibacterial essential oil has Cotula cinerea Del The sensitivity of the bacterial strains tested by the method of direct contact with the essential oil of Cotula cinerea Del varies from strain to strain; And E. faecium, E.coli, M. morganii, P. vulgaris, S. aureus and A. baumannii has shown great sensitivity; the strain P. aeruginosa have shown stiff resistance with every concentrations of essential oil.
As we did not notice any differences significant in the diameters of inhibition with all strains in two stages of growth (flowering and fruiting).

Fig. 1 :
Fig. 1: Yield of essential oils from the aerial part of Cotula cinerea Del of Oued Souf region (Algeria).

Fig. 2 :
Fig. 2: Kinetics and variation in the chemical composition of the essential oils of Cotula cinerea Del obtained during the two stages of development.

Table 1 :
organoleptic characteristics of the essential oil of Cotula cinerea Del.

Table 2 :
Chemical composition of essential oils of Cotula cinerea Del collected in during flowering and fruiting.

activity of essential oils of Cotula cinerea Del obtained during the two stages of development
Through the results listed in the table (03) conclude that:  E. faecium showed great sensitivity to all with essential oil concentrations where arrived in (50 mm), which was larger than the diameter discourage antibiotic (Lincomycine: 32 mm).As with strain P. aeruginosa the results were spaced somewhat (12mm).
 Bensizerara et al., (2012)Who experienced different extracts (petroleum ether; ethanol 70%; n-butanol; ethyl acetate) on: E.coli; K. pneumonia and S. aureus gave diameters small inhibitory Compared diameters obtained where you get to Higher diameter inhibition (13 mm E.coli with, 12 mm with S. aureus and 17 mm with K. pneumonia);