## 3 Results  
### Total Phenolic and Flavonoid Compounds Content  
Considering the chemical characterization and polarity of the different bioactive compounds present in the seeds and stems of the studied samples, extracts for bioactive compound determination were prepared in different solvents (aqueous, ethanolic, and hydroalcoholic).  
According to Table 1, regarding the determination of TPC and TFC of seed extracts from the four varieties studied, ethanol is the solvent with the greatest extractive power. According to Table 2, the same pattern of behavior can be seen for the extracts from the stems of the previously mentioned varieties, apart from the TPC of the Tina Roriz variety. In a general way, water is the solvent that has the lowest extractive power in all tests for determining TPC and TFC in seeds, and this compartment was also verified for the TPC of the stems. For the quantification of TFC from stems, the hydroalcoholic mixture resulted in the lowest concentration values, therefore having a lesser extractive capacity.  
Comparing the TPC values of the stems of the four grape varieties under study (Table 2), the extracts from Tina Roriz present higher values in water and in hydroalcoholic mixtures, showing Touriga Franca to have a higher content in ethanol. The Tina Roriz variety presents the highest TFC values, while Touriga Franca shows the lowest content when in aqueous or ethanolic extract.  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Variety** & **Extractor** & **TPC** & **TFC** & **DPPH** & **FRAP** \\
**Solvent** & **Solvent** & **(mg GAE/100 g)** & **(mg CE/100 g)** & **(\(\mu\)mol TE/100 g)** & **(\(\mu\)mol FSE/100 g)** \\ \hline \multirow{4}{*}{Touriga Franca} & W & 61.3 \(\pm\) 0.7 & 37.1 \(\pm\) 1.4 & 974.8 \(\pm\) 1.2 & 2037.7 \(\pm\) 1.2 \\  & E & 210.8 \(\pm\) 0.4 & 70.3 \(\pm\) 1.1 & 2096.3 \(\pm\) 0.5 & 3756.8 \(\pm\) 10.0 \\  & E:W & 187.6 \(\pm\) 1.4 & 61.4 \(\pm\) 1.0 & 1749.8 \(\pm\) 1.1 & 3019.0 \(\pm\) 1.0 \\  & (50:50 \(\
u\)/v) & & & & \\ \hline \multirow{4}{*}{Touriga Nacional} & W & 74.8 \(\pm\) 1.0 & 93.9 \(\pm\) 1.0 & 1041.7 \(\pm\) 1.4 & 2984.7 \(\pm\) 0.3 \\  & E & 393.1 \(\pm\) 1.8 & 195.0 \(\pm\) 6.4 & 3323.6 \(\pm\) 3.5 & 3780.9 \(\pm\) 1.6 \\  & E:W & 264.4 \(\pm\) 4.4 & 102.0 \(\pm\) 1.1 & 2791.5 \(\pm\) 1.1 & 3064.7 \(\pm\) 0.6 \\ \hline \multirow{4}{*}{Viosinho} & W & 60.6 \(\pm\) 0.8 & 37.5 \(\pm\) 2.3 & 400.0 \(\pm\) 1.9 & 791.0 \(\pm\) 1.8 \\  & E & 80.2 \(\pm\) 1.3 & 41.2 \(\pm\) 0.8 & 792.1 \(\pm\) 2.7 & 1490.7 \(\pm\) 8.9 \\ \cline{1-1}  & E:W & 66.0 \(\pm\) 2.0 & 27.7 \(\pm\) 0.5 & 601.8 \(\pm\) 0.8 & 1022.5 \(\pm\) 1.3 \\ \cline{1-1}  & (50:50 \(\
u\)/v) & & & & \\ \hline \multirow{4}{*}{[PERSON]} & W & 72.4 \(\pm\) 0.7 & 40.2 \(\pm\) 1.1 & 494.4 \(\pm\) 1.1 & 1040.6 \(\pm\) 0.9 \\ \cline{1-1}  & E & 106.3 \(\pm\) 6.7 & 62.1 \(\pm\) 0.5 & 1005.3 \(\pm\) 1.5 & 2032.1 \(\pm\) 0.9 \\ \cline{1-1}  & E:W & 99.1 \(\pm\) 0.8 & 54.4 \(\pm\) 0.6 & 949.4 \(\pm\) 1.0 & 1981.1 \(\pm\) 1.1 \\ \hline \end{tabular}
\end{table}
Table 1: Content of phenolic compounds, flavonoids, and antioxidant capacity of the seeds of the studied varieties.  
It can also be seen that the TPC and TFC values of the seeds are much lower than those of the stems of the same grape variety when the extracts are prepared with the same solvent.