## 3 Results and Discussion
### Essential Oils Characterization by Gas Chromatography-Mass Spectrometry (GC-MS)
Therefore, the essential oils characterization of these samples is paramount to track the exact chemotype that we are working with (Table 2). In both samples, _Menttha suaveolens_ and _Menttha pulegium_, the main volatile compound identified is pulegone, representing 55.7 and 50.6% of the referred essential oils, respectively. Interestingly, the ketone pulegone has been previously determined by us as a major volatile in the essential oil of _Menttha cervina_ L. from Coa Valley [48]. Besides pulegone, _M. pulegium_ essential oil is also characterized by the presence of L-menthone (29.6%), which highly reflects the chemical characterization reported by other authors on several samples from _M. pulegium_ of Portugal [84]. Meanwhile, some authors argue about the chemical variability of _M. suaveolens_ essential oils from several locations, reporting, besides pulegone, major compounds like piperitone oxide, among others [85]. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Identified Compound**} & \multirow{2}{*}{**R.T. (min)**} & \multirow{2}{*}{**RI\({}_{\text{exp}}\)**} & \multirow{2}{*}{**RI\({}_{\text{lit}}\)**} & \multicolumn{2}{c}{**Percentage in the**} \\  & & & & **Samples (\%)** \\ \hline \multirow{2}{*}{\(\alpha\)-Pinene} & \multirow{2}{*}{8.02} & \multirow{2}{*}{925} & \multirow{2}{*}{933} & \multirow{2}{*}{**-**} & \multirow{2}{*}{0.3} \\  & & & & **M.** & **M.** \\ \hline \multirow{2}{*}{\(3\)-Methylcyclohexanone} & \multirow{2}{*}{8.63} & \multirow{2}{*}{940} & \multirow{2}{*}{958} & \multirow{2}{*}{-} & \multirow{2}{*}{0.1} \\  & & & & **saveol \begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & & & & \multicolumn{2}{c}{**Percentage in the**} \\ \multicolumn{1}{c}{**Identified Compound**} & \multicolumn{1}{c}{**R.T. (min)**} & \multicolumn{1}{c}{**RI\({}_{\text{exp}}\)**} & \multicolumn{1}{c}{**RI\({}_{\text{lit}}\)**} & \multicolumn{1}{c}{**Samples (\%)**} \\ \cline{2-5}  & & & & & \multicolumn{1}{c}{} & M. & _M._ \\  & & & & & _suaveolens_ & _pallegium_ \\ \hline
3-Octanol acetate & 16.39 & 1127 & 1124 & - & 0.1 \\ \hline n.d. & 17.11 & & & 0.2 & - \\ \hline \(p\)-Menth-3-en-8-ol & 17.38 & 1155 & 1149 & 0.7 & - \\ \hline
**Menthone** & **17.65** & 1161 & 1160 & 0.2 & **29.6** \\ \hline Neo-Menthol & 18.13 & 1173 & 1167 & - & 8.4 \\ \hline Menthol & 18.49 & 1182 & 1170 & - & 0.3 \\ \hline Isopulegone & 18.65 & 1186 & 1177 & 2.9 & 1.4 \\ \hline Terpinen-4-ol & 18.69 & 1187 & 1177 & 2.0 & - \\ \hline
3-\(p\)-Menthanol & 18.98 & 1194 & 1186 & - & 0.1 \\ \hline n.d. & 19.08 & & & 0.2 & - \\ \hline \(p\)-Cymen-8-ol & 19.08 & 1195 & 1185 & 0.1 & - \\ \hline \(\alpha\)-Terpineol & 19.33 & 1202 & 1190 & 0.5 & 0.1 \\ \hline Estragole & 19.71 & 1212 & 1196 & - & 0.3 \\ \hline n.d. & 20.23 & & & - & 0.2 \\ \hline n.d. & 20.42 & & & - & 0.3 \\ \hline n.d. & 20.53 & & & - & 1.4 \\ \hline n.d. & 20.55 & & & 0.3 & - \\ \hline n.d. & 21.09 & & & 0.6 & - \\ \hline n.d. & 21.11 & & & - & 0.1 \\ \hline
**Pulegone** & **21.58** & **1258** & **1244** & **55.7** & **50.6** \\ \hline Carvone & 21.72 & 1262 & 1252 & 0.1 & 0.3 \\ \hline n.d. & 22.03 & & & - & 0.4 \\ \hline n.d. & 22.04 & & & 0.2 & - \\ \hline Piperitone & 22.21 & 1273 & 1253 & - & 0.2 \\ \hline n.d. & 22.67 & & & - & 0.7 \\ \hline n.d. & 22.67 & & & 1.6 & - \\ \hline \(p\)-Menth-2-en-1\(A\)-diol & 22.88 & 1290 & 1259 & 0.4 & - \\ \hline n.d. & 23.50 & & & 0.6 & - \\ \hline n.d. & 23.56 & & & 0.7 & - \\ \hline Anethelo & 23.64 & 1308 & 1285 & - & 0.1 \\ \hline n.d. & 23.77 & & & 11.1 & - \\ \hline Thymol & 24.00 & 1317 & 1297 & - & 0.1 \\ \hline Carvacrol & 24.40 & 1327 & 1317 & - & 0.2 \\ \hline n.d. & 24.48 & & & 0.9 & - \\ \hline n.d. & 24.53 & & & 0.3 & - \\ \hline Piperitenone & 26.03 & 1367 & 1341 & - & 0.9 \\ \hline n.d. & 26.29 & & & - & 0.1 \\ \hline n.d. & 26.46 & & & 0.4 & - \\ \hline n.d. & 26.89 & & & 0.4 & - \\ \hline \hline \end{tabular}
\end{table}