Browsing by Author "Hazzit, M."
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- Chemical composition and biological activities of Algerian Thymus oilsPublication . Hazzit, M.; Baaliouamer, A.; Verissimo, A. R.; Faleiro, Leonor; Miguel, Maria GraçaThe compositions of essential oils isolated from nine samples of three Thymus species (Thymus algeriensis, Thymus pallescens and Thymus dreatensis) were analysed by GC and GC-MS, and a total of 114 components were identified. T. pallescens collected from various regions showed a great similarity in their compositions and were characterised by carvacrol (44.4-57.7%), p-cymene (10.3-17.3%) and gamma-terpinene (10.8-14.2%) as the major components for four samples; only one sample was thymol-rich (49.3t) with a small amount of carvacrol (9.0%). On the other hand, T. algeriensis showed a chemical polymorphism, even for samples from the same location, and two new chemotypes for this species were proposed. Oxygen-containing monoterpenes were the predominant class (76.3%) in T. dreatensis oil, with linalool (30.4%), thymol (20.2%) and geraniol (19.6%) as the principal constituents. The oils were screened for their possible antioxidant activities by four complementary assays, namely DPPH free radical scavenging, hydroxyl radical scavenging, inhibition of lipid peroxidation and reducing power. The two new chemotypes of T algeriensis exhibited strong hydroxyl radical scavenging (IC(50) = 2.2-3.3 mu g/ml), but were not or only slightly active against the other radicals and exhibited a weak reducing power. Despite their chemical similarity, T. pallescens oils sometimes produced significant differences in their antioxidant activities. The essential oils were also screened for their antimicrobial activity against five bacteria (three Gram-positive and two Gram-negative) and one yeast (Candida albicans). The tested essential oils showed antimicrobial activity against the microorganisms used, in particular against two important pathogens, C. albicans and Helicobacter pylori. (C) 2009 Elsevier Ltd. All rights reserved.
- Composition of the essential oils of Thymus and Origanum species from Algeria and their antioxidant and antimicrobial activitiesPublication . Hazzit, M.; Baaliouamer, A.; Faleiro, Leonor; Miguel, Maria GraçaThe composition of the essential oils of Origanum and Thymus species restricted to Algeria and the North Africa region was determined. Antioxidant and antibacterial activities of the isolated essential oils were also determined. The oils of oregano plants were strongly characterized by p-cymene (16.8-24.9%), gamma-terpinene (16.8-24.9%), thymol (8.4-36.0%), and carvacrol (1.1-29.7%), a thymol chemotype for Origanum floribundum and a R-terpineol chemotype for Thymus numidicus being described for the first time. The strains of Listeria monocytogenes tested were relatively resistant to the action of essential oils of either Origanum or Thymus species. All essential oils possessed antioxidant activity, but this was dependent on the specific chemical composition and the method employed to determine such activity.