## 3 Results and Discussion
### Chemical Composition of EOs

Table 3: Percentage of components of leaf essential oil (EO) from _Cryptomeria japonica_ growing in the northeast region of São Miguel Island (Azores), isolated by hydrodistillation (HD), water-steam distillation (WSD), and industrial steam distillation (SD). Concerning the chemical composition of the leaf EO samples studied, analyzed using the GC-FID and GC-MS methods and confirmed by \({}^{13}\)C NMR, 26 and 28 components were identified in the EO-HD and EO-WSD samples, respectively, accounting for 97.6% and 98.1% of the total content of identified EO components (Table 3) and grouped into five classes: monoterene hydrocarbons (MH), oxygen-containing monoterpenes (OCM), sesquiterpene hydrocarbons (SH), oxygen-containing sesquiterpenes (OCS), and diterpene hydrocarbons (DH), as illustrated in Figure 2. The leaf EO-HD sample was characterized by a high content of MH (72.8%) followed by OCS (17.1%), OCM (3.1%), and DH (3.0%), but a low content of SH (1.6%). In general, a similar pattern was reported for _C. japonica_ leaves collected in summer in Faiai Island, Azores [11]. On the other hand, the leaf EO-WSD sample was also characterized by a high content of MH (86.7%), followed by OCM (7.2%), OCS (2.4%), SH (1.6%), and DH (0.2%). The main components (percentages above ca 3%) in leaf EO-HD were \(\alpha\)-pinene (34.5%), sabinene (20.2%), ellemol (10.4%), \(\beta\)-myrcene (5.9%), camphene (3.5%), \(\alpha\)-eudesmol (3.4%), and phyllochalene (2.9%), while in leaf EO-WSD, they were \(\alpha\)-pinene (46.4%), sabinene (11.6%), \(\beta\)-myrcene (5.8%), terpinen-4-ol (5.4%), \(p\)-cymrene (4.4%), camphene (3.8%), limene (3.2%), \(\alpha\)-thujene (2.8%), and \(\gamma\)-terpinene (2.6%). Moreover, sandacrojima-8(14),15-diene was detected only in EO-HD, whereas \(\alpha\)-terpineol, \(\alpha\)-muvendene, and \(\gamma\)-cadinene were present only in EO-WSD, with all of these EO components being found in low amounts (0.1 to 0.2%). The results show that MH \(\alpha\)-pinene and sabinene were the main components of the leaf EO extracted using both methods and that MH \(\beta\)-myrcene and camphene presented similar levels in both EOs. Furthermore, in both the EO-HD and EO-WSD samples, the content of grouped components decreased as follows: MH + SH (74.4 vs. 88.3%) >> OCM + OCS (20.2% vs. 9.6%) >> DH (3.0% vs. 0.2%), with SH having the same value (1.6%). The results also show that the EO-HD sample was richer in OCS (mainly elemol and \(\alpha\)-eudesmol) and DH (mostly phyllochalene), while the EO-WSD sample was richer in OCM (mainly terpinen-4-ol) and in MH \(p\)-cymrene, limonene, \(\alpha\)-thujene, and \(\gamma\)-terpinene. The above results indicate that the qualitative composition of the Sao Miguel _C. japonica_ leaf EO extracted using two different distillation methods was similar, whereas the relative contents of certain components varied. In fact, of the twenty-nine components identified in our _C. japonica_ leaf EO, only thirteen (namely tricyclene, \(\alpha\)-thujene, camphene, \(\beta\)-myrcene, \(\alpha\)-phellandrene, \(\delta\)-3-carene, \(\alpha\)-terpinene, \(\beta\)-phellandrene, terpinolene, bornyl acetate, \(\delta\)-cadinene, \(\tau\)-cadinol, and \(\tau\)-muvrolol) presented similar relative contents in both methods with concentrations that ranged between 0.1% and 5.9% of the total EO composition. The results obtained in similar studies with other aromatic plants, such as the case of _Pelargonium_ sp. EO [9], also proved that the distillation methods (HD and WSD) had a  
Figure 2: Grouped components (%) of leaf essential oil (EO) from _Cryptomeria japonica_ growing in northeast region of São Miguel Island (Azores), isolated by hydrodistillation (HD), water-steam distillation (WSD), and industrial steam distillation (SD). Data from the OE–SD sample were provided by Marques, S.A. Legend: MH—monoterpene hydrocarbons; OCM—oxygen-containing monoterpenes; SH—sesquiterpene hydrocarbons; OCS—oxygen-containing sesquiterpenes; DH—diterpene hydrocarbons. strong effect on the percentage of EO components.