## 3 Discussion  
Historically, many plant oils and extracts have been used as topical antiseptics, or have been reported to have antimicrobial properties [16]. Thus, it is very important to investigate scientifically those plants that have been used in traditional medicines as potential sources of novel antimicrobial compounds. Beside the high antimicrobial potential, one important advantage of essential oils is the complex mechanism of action arising from a rich mixture composition. In this paper we showed the high antifungal activity of _Thymus vulgaris, Citrus limonium, Pelargonium graveolens, Cinnumum cassia, Ocimum basilicum_, and _Eugenia carophyllus_ essential oils. The maximum concentration that prevented the growth of most _Candida_ isolates was established as 1.25% (with some exceptions for lemon and clove oil). This allows for their potential use in pharmaceutical preparations for external application or inhalation, as using a 2% essential oil dilution  
* RI—averaged RI for analyses. RI\({}_{\text{LR}}\)—RI value for 100% PDMS stationary phase; data taken from NIST 2011 spectral library  
\end{table}
Table 8: _Cont._is generally considered a safe guideline for the topical application of essential oils on adults [17]. Cinnamon, thyme, geranium, and basil oils inhibited the growth of all strains tested, up to the concentration of 1.25%. In the case of lemon oil, only seven out of 183 _C. albicans_ isolates had an MIC value higher than the cutoff value of 1.25%. Quite a similar situation was observed for clove oil: MIC = 2.5% (\(v/v\)) was found for eight _C. albicans_ isolates and one _C. glabrata_. Comparing the differences in activity of oils against two _Candida_ species, no significant differences were observed except for lemon oil, which appeared to be more active toward _C. glabrata_ clinical isolates (for example, 35.5% of isolates revealed MIC values below 0.005%; for _C. albicans_ that was 11.5%). A great activity was established in the case of cinnamon oil. The concentration inhibiting the growth of all strains was not higher than 0.125% (\(v/v\)). The vast majority of isolates revealed MIC values for this oil below 0.021 mg/mL (0.002%). Other investigators recorded similar results. For instance, [PERSON] and coworkers reported that the average MIC value of cinnamon oil tested toward _C. albicans_ clinical isolates was 0.064 mg/mL (MIC range 0.064-0.515 mg/mL) [18]. The research group of [PERSON] showed the anticandidal activity of cinnamon oil against _C. orthopsisosis_ and _C. parapsilosis_ (MIC equal to 0.25 and 0.50 mg/mL, respectively) [19]. High antifungal activity against six _Candidida_ isolates was also reported by [PERSON] (MIC in the range 0.01-0.05% (\(v/v\))) [20]. The activity of cinnamon oil toward bacteria seems to be limited compared to fungi, e.g., the MIC values for _S. aureus_ and _E. coli_ reported by [PERSON] were both 1 mg/mL, while MBC values were equal to 4 mg/mL [21]. The explanation of this fact is connected to the molecular targets for cinnamaldehyde, which are glukan and chitin synthases absent in bacteria. On the other hand, other researchers have shown that cinnamon oil may cause other cellular effects like leakage of small electrolytes, proteins, and nucleic acids [21]. [PERSON] reports that cinnamon oil decreases the intracellular adenosine triphosphate concentration [22]. Additionally, the results of [PERSON] indicate that cinnamon oil produces protrusions and aggregation of cells [23]. In our opinion, all the further destructive effects of cinnamon oil toward pathogen cells are a result of its complex composition, in which remaining compounds have supplementary or synergistic activity. However, cinnamon aldehyde is crucial to the antifungal activity of this product. The GC analysis revealed that the investigated oil contained 42.79% of this component. The highest thyme oil MIC concentration established for both _C. glabrata_ and _C.