## 3 Results and Discussion
### Chemical Composition of EOs
#### 3.2.2 Comparison to Previous Reports on _C. japonica_ Leaf EO Isolated by SD  
Table 3 and Figure 2 also show the chemical composition of one commercial leaf EO sample obtained by industrial SD from _C. japonica_ also growing in the northeast region of Sao Miguel Island, Azores, but collected in a different season (June 2017) compared with our investigated samples (November 2016). In the EO-SD sample, 32 components were identified, accounting for 97.4% of the total content of identified EO components (Table 3), revealing a higher complexity compared with that in the EO-HD and EO-WSD samples (26 and 28 components, respectively). The study by [PERSON] et al. [8] in bay leaf EO also reports that the EO-SD sample contains more components than the EO-HD sample. According to the authors, it can be due to thermal modification or degradation of certain EO components during contact with boiling water. As can also be seen, the leaf EO chemical composition of the three samples (EO-HD, EO-WSD, and EO-SD) determined using the same analytical conditions revealed that \(\alpha\)-pinene was the main component (34.5%, 46.4%, and 39.3%, respectively), followed by sabinene (20.2%, 11.6%, and 19.3%, respectively) (Table 3). Thus, our _C. japonica_ leaf EO displayed a consistent \(\alpha\)-pinene- and sabinene-rich composition, despite different distillation methods and sampling times, suggesting that the synthesis of these components is deeply dependent on the genetic background of the plant. Furthermore, in the three samples referenced, the content of grouped components decreased as follows: MH + SH (74.4%, 88.3%, and 91.4%, respectively) >> OCM + OCS (20.2%, 9.6%, and 5.1%, respectively) >> DH (3.0%, 0.2%, and 0.9%, respectively) (Figure 2). However, concerning other major components (percentages above 4%), the following results were observed: elemol (10.4%) and \(\beta\)-myrorene (5.9%) in EO-HD; \(\beta\)-myrorene (5.8%), terpinen-4-ol (5.4%) and \(p\)-cymene (4.4%) in EO-WSD, and limonene (8.3%) and \(\beta\)-myrorene (5.7%) in EO-SD (Table 3). Moreover, eight components were detected only in EO-SD: OCM _trans_-2-\(p\)-menthen-1-ol, borneo, linaly acetate, and \(\alpha\)-terphenyl acetate (0.1% each); SH \(\beta\)-elemene (0.2%), \(\beta\)-caryophylle (0.2%), \(\gamma\)-muurulerene (0.7%), and _trans_-calamene (traces). Nonetheless, in general, a more similar pattern was observed between the EO-WSD and EO-SD compositions, except in the OCM group (Table 3 and Figure 2). The study by [PERSON] and [PERSON] [49] on leaf EO isolated by industrial SD from Japanese _C. japonica_ (collected in Akita in October 2010) revealed that the major group was MH (58.0%), with \(\alpha\)-pinene (17.0%) and sabinene (12.0%) being the main components, followed by the OCS group (22.0%), which was dominated by elemol (9.6%). Interestingly, this pattern is similar to the one found in our EO-HD sample. However, a different pattern was found regarding the DH group that consisted of ent-kaurene (6.66%) and phyllocladene (1.73%) in Japanese OE, and of phyllocladene (2.9%) and sandaracopimara-8(14),15-diene (0.1%) in Azorean EO-HD. The effect of different distillation methods (HD and SD) on the composition of _C. japonica_ leaf EO from Taiwan has been studied by [PERSON] et al. [33]. The authors found that the EO sample is dominated by two components (kaur-16-ene and elemol), in both distillation methods and proved that the distillation methods had an effect on the percentage of EO components. These findings are similar to that of our study. Furthermore, the results obtained in similar studies with other aromatic plants, such as the case of lavender EO [50], also revealed that the highest MH and SH contents were observed in the EO isolated using the SD method followed by the WSD and HD methods. According to the authors, this may be due to the non-polar nature of the components possessing strong lipophilic bondages with the fatty (oil) components, which require higher energy to break the bondage.