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  • Author: Ramdani Messaoud x
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Abstract

The allelopathic potential of essential oil extracts from Artemisia herba-alba Asso. was assessed on seed germination of nine weeds and two wheat varieties. The samples were collected from El-Rasfa région (Sétif, Algeria). The essential oil was extracted using hydrodistillation of aerial part and characterized using gaz chromatography coupled with mass spectroscopy. The bioassays with organic solvent (ethanol) were tested using four different concentrations (0.2, 0.4, 0.6 and 0.8 µl/ml of oil/ethanol) on seed and seedling growth of the nine weeds and two wheat varieties. The yield obtained is 1.19%, and 36 compound had been identified. The main components are: camphor (28.58%), cis-thujone (22.03%), eucalyptol (11.65%) and trans-thujone (7.03%). The results of bioassays show that essential oil extracts has a significant effect on seed germination and seedling growth of the major weed tested and two wheat varieties. In conclusion, this study shows that the essential oil tested has an interesting allelopathic potential.

Abstract

The aims of this work are to investigate the chemical composition, the antibacterial activity of the essential oil and the chromosome numbers of two populations of Hertia cheirifolia. The samples were collected in the flowering stage, in eastern Algeria locality. The aerial parts of H. cheirifolia were submitted to a hydro-distillation. GC and GC / MS analysed the chemical compositions of the obtained essential oils. The antibacterial activity of essential oils was evaluated using the disks diffusion method against ten bacterial strains. For karyotypic analysis, the squashing method is used. Fifty-eight compounds representing 98.93% of the total oil were identified in H. cheirifolia. The chemical composition is dominated by the presence of major products, α-pinene (48.49 - 53.85%) and Germacrene-D (2.64 - 12.66%). Two distinct chemical breeds were identified, the α-pinene-spathulenol of Batna population, and the α-pinene-germacrene-D of Setif population. The essential oil of H. cheirifolia has a moderate activity against bacteria tested. In contrast, the strains E. coli ATCC 25922, P. syringae ATCC 53543 and E. fecalis ATCC 49452 are resistant to H. cheirifolia essential oils. The observations of root cells meristematic at metaphase of H. cheirifolia gave a diploid chromosome number 2n = 2x = 20, with a basic chromosome number (x= 10).

Abstract

The objective of the present study was the optimization of the parameters affecting the hydrodistillation of Ruta chalepensis L. essential oil using response surface design type Box-Behnken. After an appropriate choice of three parameters, 15 experiments were performed leading to a mathematical second-degree model relating the response function (yield of essential oil) to parameters and allowing a good control of the extraction process. The realization of the experiments and data analysis was carried out by response surface methodology (RSM). A deduced second-order polynomial expression was used to determine the optimal conditions necessary to obtain a better essential oil yield. These optimized operating conditions were: a granulometry of 2 mm, a condensation-water flow rate of 3.4 mL/min and an extraction time of 204 min. Analysis of variance (ANOVA) indicates that the generated second-order polynomial model was highly significant with R2=0.9589 and P<0.006. The gas chromatography-mass spectrometry analysis of essential oil extracted from the Ruta chalepensis L. aerial parts revealed the presence of 2-undecanone, 2-nonanone and 2-decanone as major components.