## 3 Results and Discussion
### Extraction with Supercritical Fluids and HPLC Analysis  
The yields extractions are calculated by using the following equation according to [PERSON] et al. [45]:  
\[Yield\ \%=\ \frac{\left[W_{extract}\ (g)\right]}{\left[W_{load}\ (g)\right]}*100\]  
where \(W_{extract}\) is the weight of the extract obtained, which is the difference between the mass of glass trap with extract and the mass of empty glass trap and \(W_{load}\) is the mass of sample load in the column before the extraction. The results are reported in Table 5; instead, the results of HPLC quantification on mg of the compound for 100 g of material loaded (mean \(\pm\) S.D. of two determinations) for _OFI cult._ are shown in Figure 6, instead of _OFI s.l._ in Figure 7. \begin{table}
\begin{tabular}{c c c} \hline
**Plant** & **Ref.** & **Yield of Extraction (\%)** \\ \hline _OFI cult._ & CULT\_20D & 0.48 \(\pm\) 0.07 \\ _OFI cult._ & CULT\_20P & 1.00 \(\pm\) 0.13 \\ _OFI cult._ & CULT\_90E\_20O & 0.88 \(\pm\) 0.11 \\ _OFI cult._ & CULT\_30E\_20O & 2.14 \(\pm\) 0.35 \\ _OFI cult._ & CULT\_C\_20D & 1.81 \(\pm\)0.15 \\ _OFI s.l._ & SL\_30E\_20D & 0.10 \(\pm\) 0.03 \\ _OFI s.l._ & SL\_90E\_20O & 0.25 \(\pm\) 0.05 \\ _OFI s.l._ & SL\_90E\_20D & 0.02 \(\pm\) 0.01 \\ \hline \end{tabular}
\end{table} 
Table 5: Yield % of extraction (mean \(\pm\) S.D. of two determinations) of different samples by SFE-CO\({}_{2}\). Figure 5: Quantification in mg of standards in 100 g of dry extract. The yields of extraction with SFE-CO\({}_{2}\) are lower than that one with solvent as well as the amount of polyphenols, but the resulting extracts do not need to be separated from solvent, they are purer and cleaner. It is possible to observe that the better results were obtained with the samples of _OFI cult_. despite the _OFI s.l._ In particular, the best yield of extraction was 2.14% \(\pm\) 0.35, obtained with the sample CULT_30E_20O of _OFI cult_ dehydrated at 30% and added with 20% (of the total weight loaded for the extraction) of Ottawa Sand at 110 bar. Given the results obtained from the extractions, it is possible to assume that Ottawa sands, hydrophobic natural silica particles, guarantee a better dispersion than diatomaceous earth, which also acts as a drying agent, being hydrophilic. The Ottawa sands, therefore, by favoring a homogeneous dispersion, under the same initial conditions (type of sample and initial drying conditions), guarantee a tighter  
Figure 6: Quantification in mg of four different polyphenols for 100 g of loaded material for _OFI cult_. Figure 7: Quantification in mg of four different polyphenols for 100 g of loaded material for _OFI s.l._  
contact between the matrix and the supercritical fluid. At the increase of the dehydration to 90% for the sample CULT_90E_20O, a decrease in the yields' % follows, but an improvement is obtained concerning the selective extraction of polyphenols. In this sample, it is possible to observe the highest quantities of Rutin, Narcissin and Nicotilforin, in accordance with the extractions by maceration, where the greatest quantity of polyphenols was obtained for the samples first dried and then macerated in methanol (Table 4). The treatment of _OFI cult_. with 20% of Diatomee Sand (sample CULT_20D) implies a reduction of both quantity and selectivity of extraction of polyphenols, perhaps because the Diatomee Sand is hygroscopic. This sand absorbs water from the surrounding environment reducing the function of co-solvent of water naturally present in the matrix. Being polyphenols polar compounds, the pressure was then raised to 250 bar for the sample CULT_20P, maintaining the same sand, trying to increase the polarity of CO2, but the effect of the sand was stronger. It was obtained a reduction of both yield % and selectivity of polyphenols; this shows that high pressures result in a loss of bioactive principles sensitive as polyphenols. When the sample is centrifuged (sample CULT_C_20D) to remove water, it was obtained a good increase of the yield % of extraction and a little improvement on the selectivity of polyphenols.