## 3 Results
### Chemical Composition of T. capitatus Extracts  
The successive extractions of _T. capitatus_ were performed with two solvents of increasing polarity and different properties as far as the hydrogen bonding is concerned. Ethyl acetate is a solvent of low polarity and non-protic (hydrogen bond acceptor), while ethanol presents higher polarity, and the extraction of compounds is based on the donation of hydrogen bonds by the solvent (protic, hydrogen bond donor). Ethyl acetate was expected to extract compounds of low polarity, such as residual EO components, lipids, etc., and, to a lesser extent, phenolics.  
Ethyl acetate extract yielded 4% of the total solids of distilled _T. capitatus_, while the main component was residual carvacrol. Since a residual quantity of carvacrol was detected in the ethyl acetate extract, the compound was quantified according to a calibration curve performed with the respective standard using HPLC analysis. Carvacrol was quantified at 176 mg/g dried extract. Tercenic monophenols, such as thymol and carvacrol, presented quite a high signal each, at 280 nm, while terpenic hydrocarbons, like \(p\)-cymene and  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Component** & \multicolumn{3}{c}{**Percentage \%**} \\  & **S. thymusm** & **O. hirthum** & _T. capitatus_ \\ \hline \(\gamma\)-terpinene & 40.1 & 9.0 & 2.9 \\ \(p\)-cymene & 9.3 & 6.5 & 5.8 \\ carvacrol & 30.8 & 27.2 & 81.8 \\ thymol & 0.1 & 48.1 & 0.4 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Percentage (%) of the main components of _S. thymusm_, _O. hirthum_, and _T. capitatus_ EO, as derived by GC-MS analyses.  
\(\gamma\)-terpinene, did not respond in the HPLC-DAD analysis. The extract was also injected into the GC-MS system in order to verify the composition of the residual EO. The analysis revealed that only carvacrol remained as residual volatile in the herbal material after distillation, a fact that is reasonable since carvacrol is a \"heavy\" volatile with a boiling point of 238 \({}^{\circ}\)C, distilling slowly, while \(\gamma\)-terpinene and \(p\)-cymene are \"lighter\" volatiles, (boiling points at 183 and 177 \({}^{\circ}\)C, respectively), and their distillation rates are much higher than those of carvacrol. The distillation process quantitatively recovered the terpenic hydrocarbons, and a residue of carvacol remained. Thymol is an isomer of carvacrol with an equally high boiling point (232 \({}^{\circ}\)C), but it was barely detectable in the ethyl acetate extract, according to the GC-MS analysis, attributed to the very low content of the compound in the herb, i.e., 0.4%, as presented in Table 1.  
The extract also contained rosmarinic acid, but at a lower concentration of 13 mg/g dried extract. Both chromatograms of ethyl acetate and ethanol extracts are presented in Figure 1. The peaks eluted between rosmarinic acid and carvacrol possessed characteristic UV spectra of flavonoids. The majority belongs to the subclasses of flavonoids and flavones. Ethyl acetate extract contained 60 mg total flavonoids/g dried extract.  
Ethanol yielded 6.1% of total solids, and carvacrol was detected in traces (0.2%). The main group of compounds was flavonoids that amounted to 117 mg/g dried extract. Rosmarinic acid was determined at 31 mg/g dried extract.