## 3 Results and Discussion
### Chemical Composition of Essential Oil
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Compounds** & **R.T. (min)** & **Obs. LRI *** & **Lit. LRI *** & **Rel. \%** & **Class** \\ \hline
**(+)-\(\alpha\)-Pinene** & **4.2** & **922** & **926** & **6** & **MH** \\ Thujene & 5.3 & 968 & 971 & 0.7 & MH \\ m-Cymene & 6.7 & 1007 & 1011 & 1.8 & MH \\
4-Carene & 6.9 & 1011 & 1009 & 2 & MH \\ Campbell & 8.9 & 1079 & 1080 & 0.9 & OM \\ \(\alpha\)-Thujone & 9.6 & 1089 & 1089 & 0.9 & OM \\ 4-Acetyl-1-methyl-1-cyclohexene & 9.9 & 1099 & 1105 & 0.5 & OM \\ Linalool & 10 & 1100 & 1096 & 0.8 & OM \\
1-Terpinenol & 10.5 & 1119 & 1120 & 0.7 & OM \\ cis-Verbenol & 10.7 & 1122 & 1125 & 0.6 & OM \\ Umbellulone & 11.3 & 1140 & 1146 & 0.5 & OM \\ p-Acetyltoluene & 12.5 & 1158 & 1160 & 0.5 & OM \\
2-Undecyne & 13.1 & 1166 & 1164 & 0.5 & Other \\ Fenchyl acetate & 14.6 & 1201 & 1207 & 0.8 & OM \\ Cummol & 15.4 & 1261 & 1265 & 1.1 & OM \\ Thymol & 15.9 & 1273 & 1275 & 0.5 & OM \\ Carvacrol & 16.2 & 1280 & 1283 & 0.6 & OM \\ Copaene & 18.8 & 1364 & 1367 & 0.7 & SH \\
4-Ehenyl-4,8,8-trimethyl-2-methylene-bicyclo [5.2.0]nonane & 20 & 1400 & UNK & 1 & SH \\ \(\beta\)**-Caryophyllene** & **20.5** & **1419** & **1421** & **4.1** & **SH** \\ cis-\(\alpha\)-Bisabolene & 21.1 & 1440 & 1443 & 1 & SH \\
3-Hydroxy-2-(2-methyl-1-cyclohexen-1-yl)propanal & 21.6 & 1451 & 1449 & 0.5 & Other \\ \(\alpha\)-Guaiene & 22 & 1453 & 1455 & 1.6 & SH \\
2-Guaiene & 22.3 & 1472 & 1473 & 0.9 & SH \\ (+)-\(\gamma\)-Gurjunene & 22.7 & 1481 & 1475 & 2.7 & SH \\ Butylated hydroxytoluene & 22.9 & 1487 & 1490 & 2.3 & OS \\ Chamigrene & 23.2 & 1512 & 1507 & 1.6 & SH \\ Virridilorene & 23.4 & 1517 & 1512 & 0.7 & SH \\
8-Cadinene & 23.5 & 1520 & 1524 & 1 & SH \\
2-Methyl-4-(1-methyl)-2-cyclohexenone & 23.7 & 1521 & 1525 & 0.5 & OM \\ Acorenol & 24.1 & 1538 & 1533 & 1.4 & OS \\
**B-Elemol** & **24.3** & **1539** & **1541** & **7.2** & **OS** \\ E-Nerolidol & 24.8 & 1552 & 1553 & 2.3 & OS \\ Humulene epoxide II & 26 & 1600 & 1602 & 0.8 & OS \\
**Guaiol** & **26.4** & **1616** & **1614** & **4.2** & **OS** \\ Rosifoliol & 26.5 & 1616 & 1613 & 0.5 & OS \\ \(\tau\)-Muurolol & 26.7 & 1627 & 1627 & 2.4 & OS \\ \(\beta\)**-Eudesmol** & **26.8** & **1629** & **1630** & **5.5** & **OS** \\ \(\tau\)-Cadinol & 26.9 & 1630 & 1628 & 1.5 & OS \\ Longifiolaldehyde & 27 & 1631 & 1631 & 1.6 & OS \\ Cadalene & 27.4 & 1653 & 1654 & 1.4 & SH \\ \(\alpha\)-Cadinol & 27.5 & 1655 & 1653 & 1.4 & OS \\ \(\alpha\)**-Bisabolol** & **27.7** & **1658** & **1662** & **4.2** & **OS** \\ \(\alpha\)-Eudesmol & 27.8 & 1665 & 1661 & 0.8 & OS \\
8-Cedrene-13-ol & 28.2 & 1677 & 1678 & 1.4 & OS \\ \(\beta\)-Bisabolol & 28.1 & 1677 & 1671 & 0.8 & OS \\
2,2,5,5-tetramethyl-tricyclo [6.3.0.0(3,7)]undec-1(8)-en-3-ol & 28.3 & 1679 & 1683 & 1.6 & OS \\ Lariconsone & 28.5 & 1691 & UNK & 2 & OD \\ (-)-Isolongiglolol & 30.1 & 1725 & 1726 & 0.7 & OS \\ Zierone & 30.8 & 1750 & 1754 & 2.4 & OS \\
2,6-Ditert-butyl-4-ethylphenol & 31.1 & 1760 & 1758 & 0.8 & OS \\ Phytol & 38.1 & 2071 & 2066 & 0.5 & OD \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Volatile compounds identified in the essential oil from the aerial parts of _Teucrium luteum_ subsp. _flavovirens_ growing wild in Tunisia. The most abundant constituents are reported in bold, and their structures are shown in Figure 2.  
Our results were also compared to those obtained for EOs from other Tunisian _Teucrium_ species. Specifically, the EO of _T. polium_ harvested in Ref (north-western Tunisia), for which the authors did not specify the subspecies [33], is richer in monoterpene hydrocarbons (48.7%) compared to that from the population collected from Monastir in central-eastern Tunisia (10.5%). Oxygenated sesquiterpenes are the main constituents of _T. luteum_ subsp. _flavovirens_, but they are less abundant in the essential oil of _T. polium_ from Ref (5.54%). Furthermore, \(\beta\)-pinene (12.68%), limonene (6.65%), \(\beta\)-myrcene (6.07%), and germacrene-D (5.89%), which were identified as the main organic volatiles in the Ref population, are completely absent in the EO from _T. luteum_ subsp.