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The composition of the fatty acids of the roots and aerial parts of Aritolochia longa (Aristolacheae) and Bryonia dioica (Cucurbutaceae) was analyzed by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The oils extracted from the aerial parts of both species were rich in polyunsaturated fatty acids with the essential linolenic and linoleic acids being the most prominent compounds. Oleic and linoleic acids were the majors fatty acids in the roots of both species. Whatever the plant part analyzed and the species, the saturated fatty acids were predominantly composed of palmitic and stearic acids. The antibacterial activity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the lipid extracts were determined against a panel of five bacterial strains. The results showed that the sensitivity to the lipid extracts was different for the test bacterial strains, and the susceptibility of gram positive bacteria was found to be greater than gram negative bacteria. The antibacterial activity of the root lipid extracts was particularly important against Enterococcus feacium (CMI value of 125 µg/mL; CMB values > 250 µg/mL) and Streptococcus agalactiae (CMI value of 125 µg/mL; CMB values 250 µg/mL for A. longa roots). These results indicate that A. longa and B. dioica could be considered as good sources of essential fatty acids which can act as natural antibacterial agents.

International audience; The main goal of the present study is to evaluate the effects of enzymatic pre-treatment on the yields, chemical composition and antimicrobial activities of the essential oils of Thymus capitatus and Rosmarinus officinalis leaves. In T. capitatus, application of cellulase, hemicellulase and combination of both enzymes induced 63.55, 23.72 and 109% increase in the essential oil yields. It also induced increment by 2.7, 31 and 38% in the amount of its main component carvacrol. In R. officinalis, enzymatic treatment resulted in enhanced oil yields by 5, 50 and 20% for cellulase, hemicellulase and the combination of both enzymes, respectively. In contrast to T. capitatus, the amount of the main component 1,8-cineole dropped by 17.73, 36.92 and 15.46% in oils extracted from cellulase, hemicellulase and cellulose/hemicellulase treated samples of R. officinalis. At the same time, the essential oils (at 1/32 and 1/4 dilution for T. capitatus and R. officinalis, respectively) were evaluated for their antimicrobial activities against 6 food-borne pathogens (Escherichia coli, Salmonella typhimurium, Streptococcus agalactiae, Staphylococcus aureus, Enterococcus feacium and Candida albicans). All investigated oils exhibited antimicrobial activity with those issued from hemicellulase treated samples being the most effective. Enzymatic pre-treatment could be useful for enhancing yield and antimicrobial activity of the essential oils, and hold a good potential for use in food and pharmaceutical industries