## 3 Results
### Grape Extracts Characterization and Cell Viability
Results are expressed as mg of their corresponding standard per g of extract dry weight. * \(p\) < 0.05 significant difference between M and Bv stage. \begin{table}
\begin{tabular}{c c c} \hline \hline  & \multicolumn{2}{c}{**Sk**} \\ \cline{2-3}  & \multicolumn{2}{c}{**Ripening Stage**} \\ \hline
**Polyphenol Subclass** & **Bv** & **M** \\ \hline
**Anthocyanins** & & \\ \hline Delphinidin 3-O-Glucoside & nd & 0.69 \(\pm\) 0.01 \\ \hline Cyanidin 3-O-Glucoside & nd & 0.29 \(\pm\) 0.01 \\ \hline Petunidin 3-O-Glucoside & nd & 0.95 \(\pm\) 0.03 \\ \hline Peonidin 3-O-Glucoside & nd & 1.86 \(\pm\) 0.01 \\ \hline Malvidin 3-O-Glucoside & nd & 4.59 \(\pm\) 0.04 \\ \hline Delphinidin 3-O-Acetyl Glucose & nd & 0.13 \(\pm\) 0.01 \\ \hline Cyanidin 3-O-Acetyl Glucose & nd & 0.05 \(\pm\) 0.01 \\ \hline Petunidin 3-O-Acetyl Glucose & nd & 0.22 \(\pm\) 0.01 \\ \hline Peonidin 3-O-Acetyl Glucose & nd & 0.76 \(\pm\) 0.01 \\ \hline Malvidin 3-O-Acetyl Glucose & nd & 2.27 \(\pm\) 0.05 \\ \hline Delphinidin 3-O-Coumaroyl Glucose & nd & 0.02 \(\pm\) 0.01 \\ \hline Cyanidin 3-O-Coumaroyl Glucose & nd & 0.23 \(\pm\) 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Quantification of anthocyanins and stilbenes in Sk extract of Syrah grapes obtained at two different ripening stages. Results are expressed as mg of their corresponding standard per g of extract dry weight. nd: not detected. * \(p\) < 0.05 significant difference between M and Bv stage. Human SM cells were treated with increasing concentrations (0.1-1-10 \(\upmu\)g/mL) of the GPP extracts over 24 h. Neither Sd-BvPP nor Sd-MPP extracts (Figure 2C) affected cell viability of human SM cells regardless of the concentrations tested. Sk-BvPP extract produced a 27% and 52% decrease in cell viability at doses of 1 and 10 \(\upmu\)g/mL, respectively. Sk-MPP generated a 28% decrease in viability at all concentrations tested. We opted to operate at the concentration exhibiting the lowest toxicity for all the extracts: 0.1 \(\upmu\)g/mL. \begin{table}
\begin{tabular}{c c c} \hline \hline  & \multicolumn{2}{c}{**Sk**} \\ \cline{2-3}  & \multicolumn{2}{c}{**Ripening Stage**} \\ \hline
**Polyphenol Subclass** & **Bv** & **M** \\ \hline Petunidin 3-O-Coumaroyl Glucose & nd & 0.33 \(\pm\) 0.01 \\ \hline Peonidin 3-O-Coumaroyl Glucose & nd & 1.04 \(\pm\) 0.02 \\ \hline Malvidin 3-O-Coumaroyl Glucose & nd & 2.02 \(\pm\) 0.02 \\ \hline
**Stilbenes** & & \\ \hline Trans-resveratrol & 0.03 \(\pm\) 0.01 & 0.19 \(\pm\) 0.01 \({}^{*}\) \\ \hline Cis-resveratrol & 0.01 \(\pm\) 0.01 & 0.03 \(\pm\) 0.01 \({}^{*}\) \\ \hline Trans-piceid & 0.15 \(\pm\) 0.01 & 1.01 \(\pm\) 0.01 \({}^{*}\) \\ \hline Cis-piceid & 0.02 \(\pm\) 0.01 & 0.21 \(\pm\) 0.01 \({}^{*}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._  
Figure 2: GPP extract antioxidant activity and cellular toxicity. (**A**) TPC of GPP extracts measured by the Folin-Ciocalteu method. (**B**) TAC of GPP extracts measured by the DPPH assay. (**C**) Sd-GPP extract toxicity on human SM cells at increasing concentrations (0.1–10 \(\upmu\)g/mL). (**D**) Sk-GPP extract toxicity on human SM cells at increasing concentrations (0.1–10 \(\upmu\)g/mL). For all the experiments, n = 3. Data are expressed as means \(\pm\) SEM. Statistical significance was determined via one-way ANOVA. \({}^{*}\)\(p\)\(\leq\) 0.05, \({}^{**}\)\(p\)\(<\) 0.01, \({}^{***}\)\(p\)\(<\) 0.001 and \({}^{***}\)\(p\)\(<\) 0.0001.