## 3 Results and Discussion
### Proximate Composition  
The data found for spirulina's proximal composition are shown in Table 5. It is well known that seaweeds, especially spirulina, typically have high protein and low lipid contents. Indeed, the protein content of the present sample was 54.84 g/100 g dw and the value is in line with the literature data [44,45]. Data in the same range as in the literature were also found for ash content, with the value of 6.99 g/100 g/dw [46]. Conversely, for the lipid content we found a lower value (0.27 g/100 g dw) in comparison to the USDA FoodData Central results (i.e., 7.72 g/100 g), although it was comparable with the results of [PERSON] et al. [46], which reported a value fat content of 1.10% dry weight. Anyway, as already reported in the literature, it is known that nutritional content may depend on geographical area, year, season, and environmental conditions, as well as the food processing procedures [47]. Total Antioxidant Capacity (TAC) of Spirulina Samples Extracted with Different Solvents (PBS, MetOH 80%)  
The TAC of spirulina samples was evaluated using two different extraction solutions (i.e., PBS and MetOH 80%) and two different methods based on different chemical reactions (i.e, FRAP and ABTS**). In particular, FRAP assessed the reducing power, whereas ABTS** assessed the free radical scavenging activity. The data, reported in Table 6, showed that although comparable results between the two different extractions were found through FRAP analysis (although statistically higher for the extract in PBS in comparison to the MetOH 80% extract), ABTS** failed to find such values following lipophilic extraction in MetOH 80%. Therefore, as already reported in the literature [22], hydrophilic PBS extraction is confirmed as the most suitable for determining the TAC of spirulina samples. \begin{table}
\begin{tabular}{c c c} \hline \hline \(\mathbf{N}^{\circ}\) & **Components** & **(\%)** \\ \hline \hline \multicolumn{3}{c}{**Carbohydrates**} \\ \hline
1 & methyl \(\alpha\)-glucofuranoside & 9.0 \(\pm\) 0.05 \\
2 & methyl galactoside & 11.3 \(\pm\) 0.09 \\
3 & 3-\(\alpha\)-mannobiose & 4.2 \(\pm\) 0.04 \\
4 & 2-\(\alpha\)-mannobiose & 3.2 \(\pm\) 0.02 \\
5 & ribofuranose & 2.9 \(\pm\) 0.03 \\
6 & trehalose & 1.9 \(\pm\) 0.10 \\
7 & glyceryl glucoside & 55.5 \(\pm\) 0.21 \\ \hline \multicolumn{3}{c}{**Alcohols**} \\ \hline
8 & sclareol & 2.8 \(\pm\) 0.05 \\
9 & glycerol & 0.5 \(\pm\) 0.02 \\
10 & adipol 2 EH & 1.2 \(\pm\) 0.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Chemical composition (percentage values) of spirulina dried flakes after derivatization, as determined by GC–MS. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \(\mathbf{Protein}^{1}\) & \(\mathbf{Fat}\) & **Carbohydrate 2** & **Ash** & **kcal/100 g dw** & **kJ/100 g dw** \\ \hline
54.84 \(\pm\) 0.13 & 0.27 \(\pm\) 0.01 & 37.90 & 6.99 \(\pm\) 0.009 & 373.39 & 1562.29 \\ \hline \hline \end{tabular} Data are means \(\pm\) standard deviation of two (n = 2) replicates; 1 Conversion factor: 6.25. 2 As difference (i.e., 100 \(-\) (g [protein +fat + ash] in 100 g of dry weight sample)).  
\end{table} 
Table 5: Proximal composition (g/100 g dry weight). Spirulina as a dietary supplement is known for its high antioxidant power [2]. Reactive oxygen species (ROS) attack and damage molecules in biological systems, causing various disorders and diseases. Therefore, considering that oxidative stress plays a key role in the evolution of many pathologies, much attention has recently been paid to natural products that are sources of molecules with high antioxidant potential such as spirulina. Several in vitro and in vivo studies have in fact demonstrated that spirulina significantly reduces oxidative stress. This antioxidant effect is mediated by many of its phytoconstituents [48]. The antioxidant activity values can vary depending on the investigated form of the spirulina (fresh or dried). In a previous comparative study, it was demonstrated that higher values were obtained starting from fresh material [49].