## 3 Discussion
albicans_ was 5.731 mg/mL (0.625% (\(v/v\))), but predominant values were 0.734 mg/mL (0.08% (\(v/v\))) or less than 0.046 mg/mL (0.005% (\(v/v\))). These results are in agreement with those obtained by other investigators. High anticandidal activity of thyme oil (_Thymus capitatus_) was reported by [PERSON] and coworkers (MIC 0.125 or 0.25% (\(v/v\))) [24]. The effectiveness of _Thymus vulgaris_ EO toward _C. albicans_ was also confirmed by [PERSON] [25]. Antimicrobial activity (mainly toward bacteria) of _Thymus vulgaris_ (thymol chemotype), _Thymus zygis_ subsp. _gracilis_ (thymol and two linalool chemotypes), and _Thymus hyemalis_ Lange (thymol, thymol/linalool and carvacrol chemotypes) essential oils extracted from seven plants cultivated in Murcia (Spain) was reported by [PERSON] and coworkers [26]. [PERSON] tested the anticandidal activity of seven _Thymus_ species: _Thymus broussonetti, T. ciliates, T. leptoborrys, T. marocanus, T. pallidus, T. satureioides_, and _T. serpyllum_ collected from different natural regions in southern and southwestern Morocco. He reported high antifungal activity toward four _Candida_ species (_C. albicans_, _C. Krusei, C. glabrata_, and _C. parapsilosis_) for EOs rich in thymol or carvacrol (MIC 0.43-0.9 mg/mL). _T. serpyllum_ EO, in which the predominant compound detected was linalyl acetate (52.2%), had the lowest anticandidal activity (MIC in the range 3.52-7.05 mg/mL) [27]. The investigated in our studies thyme oil contained carvacrol and thymol at concentrations comparable to the product investigated by [PERSON]--0.42 and 1.75% of the sum of peaks area respectively. However, the dominant components of the product were myrcene (34.35% of area under the peak) and terpinene (46.55% of area under the peak). High activity of the tested EOs was also confirmed in a time kill assay. Most EOs in MIC concentration resulted in fungistatic effect (after 6 h incubation, the number of viable cell was stable and at least three logarithmic rows lower than in the control). When MIC and MFC values are equal, we observed very rapid viable cell count reduction (like in the case of basil oil). The usage of cinnamon oil in MFC concentration resulted in a reduction of the cell number to zero after 2 (_C. albicans_) or 4 h (_C. glabrata_), while in terms of MIC concentration _C. glabrata_ was more sensitive (complete elimination of living cells occurred after 4 h). In this study we also aimed to check the effect of EOs on the cell wall and cell membrane. In the case of investigating the effect on cell wall using sorbitol assay, the most puzzling results were obtained for cinnamon oil, as we observed a decrease in MIC value in a medium supplemented with sorbitol as osmoprotectant, instead of the expected increase. The main compound of cinnamon oil is cinnaldehyde, which is thought to inhibit the activity of \(\beta\)-1,3-glucan and chitin synthase [28], two enzymes responsible for producing fungal cell wall components. The fungal cell wall is a dynamic structure that protects the cell from changes in osmotic pressure and other environmental stresses, while allowing the fungal cell to interact with its environment. The structure and biosynthesis of a fungal cell wall is unique to the fungi, and is therefore an excellent target for the development of antifungal drugs [29]. Our results revealed that the effect of cinnamon oil, as well as cinnamaldehyde, in both sorbitol- and glycerol-supplemented mediums was the opposite to what we assumed: MIC values decreased up to 16-fold. Sorbitol/glycerol is an agent stabilizing the osmotic pressure of the cell, and thus the MIC values of strong cell wall inhibitors are believed to be increased in their presence. On the other hand, high osmolarity causes osmotic stress and results in metabolism changes. The most predominant physiological effect is the production of intracellular glycerol to counterbalance the external osmotic pressure. The production of glycerol is a highly glucose-consuming process.