## 3 Results and Discussion
### Essential Oils Characterization by Gas Chromatography-Mass Spectrometry (GC-MS)

Table 2: _Cont._Unlike the _Mentha_ essential oils studied, highly characterized by the presence of the ketone pulegone, the essential oils obtained from _Thapsia gummifera_ (Synonym: _Margotia gummifera_ L.) flowering aerial parts and _Thapsia villosa_ ripe fruits are chemically very distinct (Table 3). The predominance of \(\Upsilon\)-terpinene (33.4%), \(\beta\)-pinene (27.1%) and \(\alpha\)-pinene (20.5%) in this sample of _T. gummifera_ does not reflect the previous findings on the essential composition of other Portuguese samples of this _Thapsia_ species [86]. These authors studied the ripe umbels of this species and determined myrcene and sabinene to be major compounds, even though \(\Upsilon\)-terpinene, \(\alpha\)-pinene (20.5%) and \(\beta\)-pinene were also present but in smaller amounts. The observed differences in our study are possibly because we considered the flowering aboveground parts of _T. gummifera_ for essential oil isolation, instead of only ripe fruits. Also, the differences in harvesting locations may have influenced the observed chemical differences when compared to the work of [PERSON] et al. (2013) [86]. In turn, the chemical characterization of _T. villosa_ showed D-limonene (67.6%) and methyleugenol (29.6%) as major compounds in the ripe umbels collected in Coa Valley (Portugal), in agreement with previous GC-MS characterization of the essential oil extracted from the ripe fruits of this species [87]. Concerning the performed GC-MS analysis of the essential oil of _Agastache foniculum_ (Table 4), this showed the presence of a considerable amount of estragole (57.5%), besides the presence of other compounds, such as D-limonene (10.5%), pulegone (20.6%) and D-menthone (7.1%), with these compounds being consistently reported for this species [88]. For instance, the essential oil of _Lavandula angustifolia_ (Table 4) is mainly characterized by the presence of linaloid (38.8%) followed by the presence of lavanduly acetate (7.9%) \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Identified Compound** & **R.T. (min)** & **RI\({}_{\text{exp}}\)** & **RI\({}_{\text{lit}}\)** & \multicolumn{2}{c}{**Percentage in the Samples (\%)**} \\ \cline{4-6}  & & & & \(M\). & \(M\). \\  & & & & _suaveelens_ & _pulegium_ \\ \hline n.d. & 27.45 & & & 0.3 & - \\ \hline n.d. & 28.05 & & & 0.2 & - \\ \hline _cis_-Jasmone & 28.56 & 1429 & 1404 & 0.3 & - \\ \hline n.d. & 30.02 & & & 2.9 & - \\ \hline n.d. & 31.71 & & & 0.8 & - \\ \hline Isomintlactone & 32.53 & 1527 & 1532 & 0.3 & 0.1 \\ \hline
7a-Hydrozymintlactone & 34.83 & 1583 & 1568 & 1.3 & - \\ \hline Spathulenol & 35.71 & 1605 & 1605 & 0.5 & - \\ \hline Caryophyllene oxide & 35.90 & 1610 & 1613 & 1.0 & - \\ \hline Globulol & 36.24 & 1618 & 1623 & 2.2 & - \\ \hline t-Muurolol & 38.15 & 1665 & 1648 & 0.2 & - \\ \hline n.d. & 38.30 & & & 0.1 & - \\ \hline \(\alpha\)-Cadinol & 38.60 & 1676 & 1652 & 0.6 & - \\ \hline n.d. & 44.64 & & & 0.1 & - \\ \hline n.d. & 45.01 & & & 0.1 & - \\ \hline n.d. & 45.84 & & & 0.1 & - \\ \hline n.d. & 46.34 & & & 0.1 & - \\ \hline n.d. & 49.81 & & & 0.1 & - \\ \hline
**Total identified** & & & & **77.2** & **96.2** \\
**compounds (\%)** & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._and linalyl acetate (6.9%), which are compounds also described for other samples of _L. angustifolia_ from other geographical origins [89]. Regarding _T. mastichina_, this essential oil has been previously characterized by us [48], exhibiting 1,8-cineol (57%) as the major compound, besides \(\alpha\)-terpineol (7.2%) and fenchone (5.36%) (Table A2).