## 2 Results and Discussion
### Enantiomeric Distribution of Terpene Isomers
Unlike monoterpene hydrocarbons, the enantiomeric excess of oxygenated monoterenes (e.g., (\(-\))-4-terpineol (mo15), (\(+\))-4-terpineol (mo16), (\(-\))-bornyl acetate (mo23), and (\(+\))-bornyl acetate \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Volatile Compounds1**} & \multirow{2}{*}{**Extraction Methods**} & \multicolumn{6}{c}{**Enantionmeric Excess(e.e, \%) 2**} \\ \cline{3-8}  & & \multicolumn{2}{c}{**CP**} & \multicolumn{2}{c}{**CO**} & \multicolumn{2}{c}{**TO**} \\ \cline{3-8}  & & **Confgn. 3**  & **e.e** & **Confgn.** & **e.e** & **Confgn.** & **e.e** \\ \hline \multirow{3}{*}{\(\alpha\)-Pinene} & SPME & + & 86.96 & + & 90.31 & + & 71.55 \\  & SD & + & 87.89 & + & 93.91 & + & 66.91 \\  & SE & + & 87.79 & + & 94.25 & + & 67.78 \\ \hline \multirow{3}{*}{Sabinene} & SPME & & nd 4  & +/\(-\) & 100.00 & +/\(-\) & 18.26 \\  & SD & & nd & +/\(-\) & 100.00 & +/\(-\) & 41.51 \\  & SE & & nd & +/\(-\) & 100.00 & +/\(-\) & 38.29 \\ \hline \multirow{3}{*}{Limonene} & SPME & + & 49.57 & + & 91.52 & + & 24.09 \\  & SD & + & 56.70 & + & 96.74 & + & 23.29 \\  & SE & + & 58.54 & + & 97.48 & + & 29.89 \\ \hline \multirow{3}{*}{\(\beta\)-Phellandrene} & SPME & \(-\) & 100.00 & \(-\) & 100.00 & \(-\) & 100.00 \\  & SD & \(-\) & 52.92 & + & 17.25 & \(-\) & 96.68 \\  & SE & \(-\) & 41.44 & \(-\) & 100.00 & \(-\) & 98.01 \\ \hline \multirow{3}{*}{4-Terpineol} & SPME & \(-\) & 100.00 & \(-\) & 66.05 & + & 57.09 \\  & SD & + & 12.08 & \(-\) & 100.00 & + & 4.27 \\  & SE & + & 18.95 & & nd & + & 6.65 \\ \hline \multirow{3}{*}{Bornyl acetate} & SPME & \(-\) & 100.00 & \(-\) & 87.59 & \(-\) & 100.00 \\  & SD & \(-\) & 100.00 & \(-\) & 75.16 & \(-\) & 55.63 \\  & SE & \(-\) & 96.59 & \(-\) & 78.93 & \(-\) & 100.00 \\ \hline \multirow{3}{*}{\(\gamma\)-Muurolene} & SPME & +/\(-\) & 47.84 & +/\(-\) & 100.00 & +/\(-\) & 72.85 \\  & SD & & nd & +/\(-\) & 100.00 & +/\(-\) & 61.79 \\  & SE & +/\(-\) & 2.51 & +/\(-\) & 13.46 & +/\(-\) & 22.32 \\ \hline \multirow{3}{*}{Caryophyllene} & SPME & \(-\) & 64.50 & \(-\) & 56.53 & \(-\) & 92.56 \\  & SD & \(-\) & 100.00 & + & 100.00 & \(-\) & 91.06 \\  & SE & \(-\) & 45.95 & \(-\) & 19.85 & \(-\) & 93.47 \\ \hline \multirow{3}{*}{\(\gamma\)-Curcumene} & SPME & +/\(-\) & 52.10 & & nd & +/\(-\) & 51.40 \\  & SD & +/\(-\) & 100.00 & nd & +/\(-\) & 100.00 \\ \cline{1-1}  & SE & & nd & & nd & & nd \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Enantiomeric excess (e.e) and configuration of chiral terpen extracted from three different cultivars based on three different extraction methods. (mo24)) in samples differed among the three extraction methods. In CP and TO, the optical purity of 4-terpineol was diminished when SD and SE were applied. Moreover, the enantiomeric excess of bornyl acetate in all samples was slightly reduced in extracts with SD or SE. Regarding the extraction conditions, differences in the enantiomeric excess of oxygenated monoterenes have also been found in previous studies of the enantiomeric distribution [11; 30]. According to a previous study, partial or total racemization could occur depending upon the temperature and pH value of the medium, and, in particular, the neutral medium (pH 6.9 and pH 6.3) keeps their strong enantiomeric excess unchanged [30]. Also, the enantiomeric distribution of distilled lime oils showed similar results in 4-terpineol and \(\alpha\)-terpineol as well as linalool, possibly due to acid-catalyzed reaction [31]. Thus, acidic or thermal conditions and rearrangements during SD or SE can cause the racemization of oxygenated monoterenes. In the present study, the relatively reduced enantiomeric excess of 4-terpineol and bornyl acetate with SD and SE may have been due to the occurrence of thermally induced rearrangements. A higher enantiomeric excess was observed for sesquiterpenes in SD: (+/-)-\(\gamma\)-muurolene (sh10 and sh12 in CO), (+/-)-caryophyllene (sh13 and sh14 in both CP and CO), and (+/-)-\(\gamma\)-curcumene (sh16 and sh19 in both CP and TO).