# Chemical Composition and Biological Activities of Oregon and Lavender Essential Oils
## 4 Discussion  
The results of this work show that both _L. dentata_ and _O. glandulosum_ are valid sources of essential oils with useful biological activities, and oregano essential oil in particular proved to be most active for the tested activities. For _L. dentata_, our essential oil yields are in agreement with the literature data: 1.44% [43], 0.89% [18], and 1.1% [44]. Higher yields than ours were found by [PERSON] et al. [28], [PERSON] et al. [27], and [PERSON] et al. [45]: 2.9%, 2.6%, and 1.76% respectively. Conversely, [PERSON] et al. [46] and [PERSON] et al. [47] reported yield results lower than ours: 0.79% and 0.53% respectively. As for _O. glandulosum_, our essential oil yields are comparable to those obtained with the same species by [PERSON] et al. [23], while [PERSON] et al. [22] and [PERSON] et al. [21] found yields higher than ours. These differences in the yields of essential oils are not surprising and may be related to different conditions and factors, namely the species, genotype, environment, harvest period, place of drying, and geographical origin of the plant [27; 28]. Among the identified 23 components, analysis of _O. glandulosum_ essential oil revealed that the main compounds were thymol (33.2%), \(\gamma\)-terpinene (25.4%), p-cymene (16.1%), and carvacrol (13.0%) (Table 1). As for the chemical composition, the percentage of 1,8-cineole (6.1%) in the oil of _L. dentata_ revealed a dissimilarity with those described in the literature. [PERSON] et al. [46] reported that the main constituents of the oil were 1,8-cineole (38.4%), _cis_-verbenol (4.3%), _p_-cymen-8-oil (3.8%), and fenchone (2.3%). [PERSON] et al. [44] found that the two monoterpens \(\beta\)-pinene (25.82%) and 1,8-cineole (10.82%) were the main essential oil compounds of _L. dentata_. [PERSON] et al. [45] showed that the main component was 1,8-cineole. [PERSON] et al. [47] identified 16 components, with oxygenated monoterpens (80.71%) as main constituents followed by monoterpens (16.19%); within these chemical classes, the main constituents were 1,8-cineole (68.59%) and \(\beta\)-pinene (11.53%), respectively. As for the chemical composition of _O. glandulosum_ essential oil, the results of this work are comparable to some literature data on the same species [21; 25; 32], but different results have also been obtained by [PERSON] et al. [23], who found that the major compounds in _O. glandulosum_ were carvacrol (47.0%), \(\gamma\)-terpinene (13.4%), _p_-Cymene (11.2%), and thymol (6.6%). [PERSON] et al. [48] also found that the main compounds were \(\gamma\)-terpinene (29.4%) and carvacrol (12.9%). [PERSON] et al. [2] found that the 4 main components detected in plants  
Figure 4: Effect of essential oil extracts (_O. glandulosum_ 5.2 and 10.4 mg/mL and _L. dentata_ 40.6 and 81.2 mg/mL) on ROS production in polymorphonuclear neutrophils (PMN). Data were presented as mean and standard error and were analyzed with a paired _t_-test. Bars not accompanied by the same letter were significantly different at \(p\) < 0.05.  
from different Algeria regions were thymol (15.1-56.3%), carvacrol (2.8-59.6%), \(\gamma\)-terpinene (9.8-21.8%), and \(p\)-cymene (8.5-13.9%). Considering the availability of \(O\). _glandolosum_ in Algeria and their richness in essential oil as well as the homogeneity and the stability of the chemical composition of its essential oil, this plant is likely to have an industrial interest and can also be recommended as a potential source of thymol [22]. The previously reported differences in the chemical composition, in particular in the quantity of the main components of the essential oils, may be due to variations in many factors such as climate, thermal range, duration of sunshine, collection period, type of soil, and the considered organs of the plant [2, 18, 27]. These chemical differences may also affect their biological activities [27, 49]. Hence, the composition of the essential oils has been the subject of several studies, from which it can be concluded that the plants exhibit chemical variability.