# Biosynthesis of Zinc Oxide Nanoparticles Using Seaweed: Exploring Their Therapeutic Potentials
## 3 Results
### Ferric Reducing Antioxidant Power (FRAP)  
The FRAP assay showed comparable results to the TAC assay, where the antioxidant activity for the _U. lactuca_, _S. muticum_, and _U. Intestinalis_ ZnO-NPs exhibited significant difference values of 49.57 \(\pm\) 0.98, 35.23 \(\pm\) 0.27, and 26.4 \(\pm\) 1.00 mg AAE/g DW, respectively, at a concentration of 50 \(\mathrm{\SIUnitSymbolMicro\text{g}}\)/mL (Table 4).  
\begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**ZnO-NP Concentration (mg/mL)**} & \multicolumn{4}{c}{**Seaweed**} \\ \cline{2-5}  & _Ulva lactuca_ & _Sargassum_ & _Ulva intestinalis_ & **f Value** \\ \hline
50 & 49.57 \(\pm\) 6.12 & 35.23 \(\pm\) 5.12 & 26.4 \(\pm\) 2.84 & 28.593 ** \\ \hline
25 & 34.52 \(\pm\) 4.63 & 23 \(\pm\) 2.84 & 21.3 \(\pm\) 3.14 & 19.712 ** \\ \hline
12.5 & 18.2 \(\pm\) 2.45 & 15 \(\pm\) 2.37 & 7.9 \(\pm\) 2.15 & 25.665 ** \\ \hline \end{tabular} Each value is the mean of three replicates \(\pm\) standard deviation. _p_? 0.05, nonsignificant; _p_! 0.001, ** highly significant.  
\end{table}
Table 4: Ferric reducing antioxidant power (FRAP) of ZnO-NPs biosynthesized using different seaweeds.  
\begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**ZnO-NPs Concentration (\(\mathrm{\SIUnitSymbolMicro\text{g}}\)/mL)**} & \multicolumn{4}{c}{**Seaweed**} \\ \cline{2-5}  & _Ulva lactuca_ & _Sargassum_ & _Ulva intestinalis_ & **f Value** \\ \hline  & 3.37 & 21.23 \(\pm\) 2.45 & 20.15 \(\pm\) 2.84 & 19.61 \(\pm\) 3.7 & 0.368 * \\ \cline{2-5}  & 6.75 & 37.1 \(\pm\) 4.66 & 34.2 \(\pm\) 4.78 & 31.09 \(\pm\) 5.12 & 1.915 ** \\ \cline{2-5}  & 12.5 & 49.3 \(\pm\) 5.42 & 48.5 \(\pm\) 5.98 & 45.2 \(\pm\) 6.12 & 0.691 * \\ \cline{2-5}  & 25 & 64.2 \(\pm\) 6.37 & 62.1 \(\pm\) 6.59 & 59.8 \(\pm\) 8.47 & 0.466 * \\ \cline{2-5}  & 50 & 86.47 \(\pm\) 7.56 & 84.3 \(\pm\) 8.45 & 78.1 \(\pm\) 6.98 & 1.596 * \\ \hline IC\({}_{50}\) (\(\mathrm{\SIUnitSymbolMicro\text{g}}\)/mL) & & 12.6 \(\pm\) 1.46 & 13.8 \(\pm\) 1.45 & 15.2 \(\pm\) 2.56 & 2.355 ** \\ \hline \end{tabular} Each value is the mean of three replicates \(\pm\) standard deviation. _p_? 0.05, nonsignificant; _p_! 0.005, * significant; _p_! 0.001, ** highly significant.  
\end{table}
Table 2: DPPH radical scavenging activity (%) of the biosynthesized ZnO-NPs of different seaweeds.  
\begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**ZnO-NP Concentration (mg/mL)**} & \multicolumn{4}{c}{**Seaweed**} \\ \cline{2-5}  & _Ulva lactuca_ & _Sargassum_ & _Ulva intestinalis_ & **f Value** \\ \hline
50 & 38 \(\pm\) 5.12 & 35 \(\pm\) 4.08 & 29 \(\pm\) 3.78 & 5.512 * \\
25 & 26 \(\pm\) 3.78 & 25.3 \(\pm\) 2.98 & 21 \(\pm\) 2.45 & 3.769 * \\
12.5 & 14 \(\pm\) 2.8 & 12.9 \(\pm\) 1.65 & 9.9 \(\pm\) 1.15 & 5.684 * \\ \hline \end{tabular} Each value is the mean of three replicates \(\pm\) standard deviation. _p_? 0.05, nonsignificant; _p_! 0.05, * significant.  
\end{table}
Table 3: Total antioxidant capacity (TAC) of the ZnO-NPs biosynthesized using different seaweeds.  
As the seaweed _U. lactuca_ exhibited the best antioxidant activity among the three tested seaweeds, the following experiments were performed to study its effects as a cytotoxic and anti-tumor agent.