## 3 Results and Discussion
### Exhaustive Extraction, Total Phenolics Content and HPLC Analysis  
The high content of total phenolics was observed with the _Folin-Ciocalteu_ assay in the samples dried in the oven, Cult_AD and Sl_AD; these show as well the better quantitative yield of extraction, calculated using the following equation [45]:  
\[Yield\ \%=\ \frac{\left[W_{d.e.}\ (g)\right]}{\left[W_{m}\ (g)\right]}*100 \tag{1}\]  
where \(W_{d.e.}\) is the weight of the dry extract obtained and \(W_{m}\) the mass of the plant macerated. The data for the yield of extraction at different sample preparation and the total phenolics content are shown in Table 4.  
In Table 4 it is possible to point out that samples dried give a higher yield of extraction and total phenolics content with respect to the fresh macerated ones, showing that the total polyphenol contents vary depending on the type of treatment and extraction.  
Comparing the same fresh sample collected in two different months, it is possible to observe that the extraction yield was slightly higher in the sample Cult_J with respect to the Fresh frozen macerated of August, but the total phenolic content is almost unchanged between samples of Cult_J and Cult_AF. This indicates that the different maturation period does not influence the content of secondary metabolites, such as phenols.  
Moreover, the total phenolic content is higher in the dried samples Cult_AD and Sl_AD, probably because drying process is designed to dehydrate the matrix in order to stop the common enzymatic processes; the aqueous environment of the cytoplasm of plant cells could damage the active compounds [52].  
The highest content of total phenols was found in the sample of Sl_AD, perhaps because being a wild ecotype is less affected by climate change, more adaptable than a cultivated plant.  
In Figure 5 are reported the data, obtained by the HPLC analysis, of extractions with solvent.  
Rutin is one of the polyphenols presents in greater amount in the analysed species. Moreover, it is possible to observe that by drug the sample it is possible to obtain extracts with a greater amount of some polyphenols (Cult_AD and Sl_AD).  
As reported in literature ruitin is already described to be present in cladode extracts of different Opuntia species [8; 20].  
Isoquercitrin is another bioactive compound present in our extract in similar quantity in the two species analysed while the quantity of Nicotiflorin and Narcissin are very low in the extracts. The different exposure to the sun or climate change can cause the secondary metabolism of the plant. As a consequence, the antioxidant profile can be influenced.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Plant and Time of Collection**} & \multirow{2}{*}{**Ref.**} & **Sample Preparation** & **Yield of Methanolic Extraction (\%/\%/\%)** & **Total Phenolics Content (mg/100 g Raw Material)** \\  & & & & \\ \hline _OFI cult._ (June) & Cult\_J & Fresh macerated & 2.79 \(\pm\) 0.29 & 170.01 \(\pm\) 2.98 \\ _OFI cult._ (August) & Cult\_AD & Dried macerated & 5.01 \(\pm\) 0.63 & 320.13 \(\pm\) 6.54 \\ _OFI cult._ (August) & Cult\_AF & Fresh frozen & 2.14 \(\pm\) 0.22 & 170.01 \(\pm\) 2.65 \\ _OFI sl.l._ (August) & Sl\_AD & Dried macerated & 4.39 \(\pm\) 0.48 & 414.90 \(\pm\) 9.58 \\ _OFI sl.l._ (August) & Sl\_AF & Fresh frozen & 2.19 \(\pm\) 0.25 & 221.29 \(\pm\) 5.93 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Data for the yield of extraction at different sample preparation and total phenolic content expressed as mg of phenols on 100 g of fresh raw material.