# Chemical Composition and Biological Activities of Oregon and Lavender Essential Oils
###### Abstract  
Folk medicine uses wild herbs, especially from the Lamiaceae family, such as oregano and lavelorier, in the treatment of many diseases. In the present study, we investigated the antibacterial activity of the essential oils of _Origanum glandulosum_ Desf. and _Lavandula dentata_ L. Against multidrug-resistant _Klebsiella pneumoniae_ strains. The chemical composition of essential oils and their effect on the ultrastructure of the tested bacteria and on the release of cellular components that absorb at 260 nm were studied. Furthermore, the cytotoxicity and the production of reactive oxygen species in human lymphocytes treated with essential oils were evaluated. Thymol (33.2%) was the major constituent in _O. glandulosum_, and \(\beta\)-pinene (17.3%) was the major constituent in _L. dentata_. We observed ultrastructural damage in bacteria and increased release of cellular material. Furthermore, ROS production in human lymphocytes treated with essential oils was lower than in untreated lymphocytes and no cytotoxicity was observed. Therefore, the essential oils of lavelor and oregano could be used as a source of natural antibacterial and antioxidant agents with potential pharmacological applications. Origanum glandulosum; Lavandula dentata; Klebsiella pneumoniae; antibacterial activity; transmission electron microscopy TEM; cell viability; ROS +
Footnote †: journal: Medical Imaging and Vision  
_Klebsiella pneumoniae_, belonging to the Enterobacteriaceaeaee family, is a common opportunistic hospital-associated pathogen, accounting for about one-third of all Gram infections overall. It is involved in extra-intestinal infections including urinary tract infections, cystitistis, pneumoniae, surgical wound infections, and life-threatening infections such as endocarditis and septicmia. Along with its high prevalence, _K. pneumoniae_ is a major source of antibiotic resistance. Data retrieved from the European Antimicrobial Resistance Surveillance Network ([[http://atlas.eddc.europa.eu/public/index.aspx?Instance=GeneralAtlas](http://atlas.eddc.europa.eu/public/index.aspx?Instance=GeneralAtlas)]([http://atlas.eddc.europa.eu/public/index.aspx?Instance=GeneralAtlas](http://atlas.eddc.europa.eu/public/index.aspx?Instance=GeneralAtlas)) accessed on 1 May 2021) for the years 2005-2015 show non-susceptible rates for _K. pneumoniae_ and _Escherichia coli_ against the four major antibiotic classes, namely the third-generation cephalosporporins, aminoglycosos, fluoroquinoles, and carbapenemems. It is therefore urgent to make available new molecules with antibacterial effects and which can act against multidrug-resistant strains. Natural substances are promising sources of alternatives drugs [13]. Essential oils have numerous activities, ranging from antibacterial and antiradical [14], insecticide, acaricide, antifungal, cytotoxic, antiviral, antiprotozoan, anthelmmitic, antiseptic, and antiinflammatory [15; 16], antitumoral, antioxidant, antiallergic, anticonvulsant, antidepressant, contraceptive, antimutagen, analgesic, and diuretic [17], and anticancer activity as well as activity in preventing the development of cardiovascular and degenerative diseases [18]. Folk medicine uses wild herbs, especially from the Lamiaceae family, such as oregano and lavender, in the treatment of many illnesses [19]. _Origanum glandulosum_ Desf. is an endemic plant in the African-Mediterranean countries, namely Algeria, Tunisia, and Morocco [2; 20]. This plant is used by local populations in traditional medicine to treat numerous diseases and is also commonly used as a skin powder in traditional bathrooms [2; 20; 21; 22; 23]. _O. glandulosum_ is also used in culinary preparations, as a food additive, in the breeding of bees, as a powerful disinfectant, and as an ingredient in perfumes [22; 24]. _O. glandulosum_ is rich in essential oils that have antibacterial, antifungal, insecticidal, antioxidant, antithrombin, antimutagenic, angiogenic, antiparasitic, and antihyperglycemic properties [20; 24; 25].