## 3 Results and Discussion
Based on the obtained quantitative results, the methanolic leaf extracts of the following plants--listed in descending order--are also rich sources of CA and therefore serve as important raw materials for its isolation: _S. pomifera_ subsp. pomifera, S. officialis., S. fruticosa, S. rosmarirus_ o var. _prostratus_ P., _S. canariensis, S. microphylla_ and _S. rosmarirus_. The highest amount of CS was measured in the leaf extract of _S. somalensis_, with a value of 4.24 \(\pm\) 0.04 mg/g of dried material, followed by _S. fruticosa_, _S. officialis_ and _S. canariensis_. In descending order, 12-\(O\)-methylcarnosic acid showed the highest amounts in _S. microphylla_, _S. officials._, _S. fruticosa_, _S. rosmarirus_ and _S. pomifera_ subsp. pomifera_. Therefore, the leaves of _S. microphylla_ are the best raw material for the isolation of 12 MCA. \begin{table}
\begin{tabular}{l c c c} \hline
**Plants** & **12 MCA** & **CA** & **CS** \\ \hline _Salvu rosmarirus_ Spenn. \({}^{\alpha}\) & 2.03 \(\pm\) 0.66 & 6.99 \(\pm\) 0.81 & 1.07 \(\pm\) 0.13 \\ _Salvu rosmarirus_ var. _prostratus_ & 0.42 \(\pm\) 0.03 & 8.10 \(\pm\) 0.92 & 0.56 \(\pm\) 0.05 \\ Pasq. \({}^{\alpha}\) & & & \\ _Salvu officinalis_ L & 6.12 \(\pm\) 2.30 & 11.66 \(\pm\) 4.33 & 1.11 \(\pm\) 0.43 \\ _Salvu fruticosa_ Mill. \({}^{\alpha}\) & 1.93 \(\pm\) 0.63 & 10.28 \(\pm\) 1.50 & 1.57 \(\pm\) 0.38 \\ _Salvu fruticosa_ Mill. \({}^{\beta}\) & 1.02 \(\pm\) 0.10 & 6.52 \(\pm\) 1.02 & 0.82 \(\pm\) 0.27 \\ _Salvu fruticosa_ Mill. \({}^{\gamma}\) & 3.05 \(\pm\) 0.29 & 12.50 \(\pm\) 1.56 & 0.18 \(\pm\) 0.07 \\ _Salvu argente_ L. \({}^{\alpha}\) & tr & 0.68 \(\pm\) 0.09 & 0.13 \(\pm\) 0.03 \\ _Salvu pomifera_ subsp. _pomifera_ L. \({}^{\gamma}\) & 1.68 \(\pm\) 0.30 & 21.64 \(\pm\) 0.60 & 0.80 \(\pm\) 0.01 \\ _Salvu pomifera_ subsp. _alycina (Sm)_ & 0.29 \(\pm\) 0.03 & tr & 0.52 \(\pm\) 0.08 \\ [PERSON] \({}^{\delta}\) & & & \\ _Salvu canariensis_ L. & n.d. & 8.10 \(\pm\) 0.21 & 1.13 \(\pm\) 0.32 \\ _Salvu microphylla_ [PERSON] \({}^{\alpha}\) & 10.68 \(\pm\) 3.27 & 7.35 \(\pm\) 2.48 & 0.87 \(\pm\) 0.24 \\ _Salvu somalensis_ [PERSON] \({}^{\alpha}\) & n.d. & 32.15 \(\pm\) 0.93 & 4.24 \(\pm\) 0.04 \\ _Salvu verticillata_ L. \({}^{\alpha}\) & n.d. & tr & tr \\ _Salvu aurita_ L. \({}^{\alpha}\) & n.d. & tr & - \\ _Salvu glutinosa_ L. \({}^{\alpha}\) & 0.43 \(\pm\) 0.05 & tr & tr \\ _\({}^{\alpha}\)_ & 0.28 \(\pm\) 0.02 & 0.14 \(\pm\) 0.02 & tr \\ _Salvu praternsis_ L. \({}^{\alpha}\) & n.d. & 0.86 \(\pm\) 0.11 & - \\ _Salvu virgata_ [PERSON]. \({}^{\alpha}\) & n.d. & 0.36 \(\pm\) 0.03 & 0.26 \(\pm\) 0.03 \\ _Mentha spicata_ L. \({}^{\delta}\) & n.d. & 0.19 \(\pm\) 0.02 & n.d. \\ _Mentha longifolia_ (L.) L. \({}^{\delta}\) & n.d. & 0.20 \(\pm\) 0.03 & n.d. \\ _Melissa officinalis_ L. \({}^{\delta}\) & n.d. & 0.48 \(\pm\) 0.06 & n.d. \\ _Ocimum basililicum_ L. \({}^{\alpha}\) & n.d. & 0.52 \(\pm\) 0.09 & tr \\ \hline \end{tabular} n.d.: not detected. tr. trace. \({}^{\alpha}\) Dionedes Botanic Garden, National and Kapodistrian University of Athens. \({}^{\beta}\) Wild, from Ano Melpia of Messinia. \({}^{\gamma}\) Wild, from Mount Psiloritis, island of Crete. \({}^{\delta}\) Wild, from Mount Pámonas, Arcadia.  
\end{table} 
Table 3: The results for plants in the Labiatae family, analyzed both quantitatively and qualitatively, for the following compounds—carnosic acid (CA), carnosol (CS), and 12-methoxy-carnosic acid (12 MCA)—are presented as the mean \(\pm\) standard deviation (mg/g of dried leaves). 7-O-methyl-_epi_-rosmanol (7 MER) was not identified in any of the extracts. The substance is derived from CA and CS after reaction with methanol. The fact that it was not identified in the studied extracts may be due to the fact that a more extended extraction time is required than the half hour used, or that the quantities that may have been produced are below the detection limit of the \({}^{1}\)H-qNMR method. As we presented in previous work, 7 MER was isolated from the leaves of _S. rosmarius_, which remained in contact with methanol for 2 months.