herbs, wood, fruits and root) and therefore extracted from these parts, where they are stored in secretory cells, cavities, canals, epidermic cells or glandular trichomes (8, 9). Essential oils only represent a small fraction of a plant’s composition; nevertheless they confer the characteristics by which aromatic plants are used in the food, cosmetic and pharmaceutical industries (10).
Mediterranean countries are the biggest producers of native aromatic plants (11) due to the favorable climatic conditions, oil composition, and geographical morphology. Algeria is also one country which produces hundreds of species of aromatic plants which are native (12). Among them oregano.
The genus Origanum (oregano) is one of over 200 genera in the Lamiaceae family and includes annual and perennial herbs growing on stony slopes at a wide range of altitudes (13, 14). It comprises about 38 species, six subspecies and 17 hybrids, most of them indigenous to the Mediterranean region (15, 16).
The origanum composition depends on the climate, altitude, time of recollection and the stage of growth (14). O. vulgare growing in a Mediterranean climate contains a higher amount of phenols (15) or terpenic alcohols, respectively. In general, essential oil yields peak under hot summer conditions with species producing oil containing 60–75% phenols, mostly carvacrol (16). This compound, together with thymol, p-cymene and c-terpinene are commonly reported as the main components of origanum Eos (17, 18, 19).
The structure of thymol is similar to that of carvacrol; however, they differ as to the location of the hydroxyl group in the phenolic ring. Both substances seem to make the membrane permeable (20). Their structure disintegrates the external membrane of the Gram-negative bacteria, releasing lipopolysaccharides (LPS) and increasing the permeability of the cytoplasmic membrane to ATP (21).
Our results of research on the antibacterial activity of oregano essential oil
Our results suggest the possible exploitation of oregano in the management of the infectious diseases. Further purification of the extract may yield a novel antibacterial drug. The plant can also be used as a natural source of antioxidants to prevent oxidative degradation of foods and to minimize oxidative damage to living cells.
The bacterial strains tested were found to be sensitive to essential oil studied and showed a very effective bactericidal activity with maximal inhibition zones in the range of 21.3–32.6 mm.
Assistant Professor Nora Mahfouf works in the Department of Pharmacy at Badji Mokhtar University (Algeria). She received her Diploma of Higher Studies in Microbiology, University of Badji Mokhtar, working with Professor Boutefnouchet Nafissa on topics in nosocomial infections and the resistance to antibiotics of the species Pseudomonas aeruginosa. She then moved to Chadli Ben Djedid University where she received a Biology Master’s diploma in Ecotoxicology. She worked on the antibacterial activity of rosemary essential oil on strains of Gram-positive and Gram-negative antibiotic-resistant bacteria. At present, she is preparing a PhD thesis on the study of the Origanum vulgare species. She works with Prof. Hichem Nasri and Prof. Bennadja Salima on the bactericidal activity of the essential oil of oregano.
1. Cosge B, Turker A, Ipek I et al. Chemical compositions and antibacterial activities of the essential oils from aerial parts and corollas of Origanum acutidens (Hand.-Mazz.) Ietswaart, an endemic species to Turkey. Molecules 2009;14:1702-1712
2. Goze I, Cetin A, Goze A. Investigation of effects of essential oils of Origanum minutiflorum O Schwarz PH Davis and Cyclotrichium niveum (Labiatae) plants on angiogenesis in shell-less Chick embryo culture. African Journal of Biotechnology. 2010; 9(14): 2156-2160
3. Hammer KA, Carson CF, Ri1ley TV. In-vitro activity of essential oils in particular Melaleuca allemifolia (tea tree) oil and tea tree oil products, against Candida spp. Journal of Antimicrobial Chemotherapy 1998;42: 591-595.
4. Burt S. Essential oils: their antibacterial 