# Enhancement of the Neuroprotective Effect of
## 3 Results  
### Extraction Yield and \(\beta\)-Carotene Content of the Extracts  
HPLC analysis exhibited the highest \(\beta\)-carotene content in the \(S\). _maxima_ fermentation products. The concentrations of \(\beta\)-carotene in individual processes were analyzed, and the results are presented in Table 1 and Figure 1.  
To identify the enhancement of the \(\beta\)-carotene content in the _S. maxima_ extracts, three different extraction processes (ultrasonic, conventional hot water, and fermentation process with ultrasonic extraction processes) were compared and analyzed. The \(\beta\)-carotene content of the _S. maxima_ fermentation products was estimated as 1.62 mg/g, and the lowest \(\beta\)-carotene content at 0.81 mg/g was observed in the hot water extract. A \(\beta\)-carotene content of 1.03 mg/g was obtained when only the ultrasonic process was applied, as well as 0.06 mg/g of negligible amount of \(\beta\)-carotene in the culture broth of only the fermentation as another control (data not shown). This result clearly indicate that a larger quantity of \(\beta\)-carotene was eluted through the fermentation with ultrasonic processing, possibly by first softening the cell walls of _Spirulina_, and bioconversion during the fermentation and then accelerating the elution of \(\beta\)-carotene in applying ultrasonic treatment. The highest extraction yield, at approximately 18.26%, was obtained from the _S. maxima_ fermentation products, and the lowest yield (10.66%) was obtained from hot water extraction, showing similar trends in the amount of \(\beta\)-carotene in the extracts. Interestingly, the HPLC chromatogram of the extract from both fermentation and ultrasonic extraction contained more small peaks, which could represent the existence of other components in the extracts that are associated with the highest extraction yield. Therefore, it was shown that the fermentation extraction process was effective in processing the marine alga, _S. maxima_. \begin{table}
\begin{tabular}{c c c} \hline
**Extraction Process** & \(\beta\)**-Carotene Content (mg/g)** & **Extraction Yield (\%)** \\ \hline FE 1 & 1.62 \(\pm\) 0.22 & 18.26 \(\pm\) 1.93 \\ WE 2 & 0.81 \(\pm\) 0.13 & 10.60 \(\pm\) 1.44 \\ UE 3 & 1.03 \(\pm\) 0.34 & 12.77 \(\pm\) 1.68 \\ \hline \end{tabular}
\end{table} 
Table 1: Estimation of \(\beta\)-carotene content from _S. maxima_ in the extracts from various extraction conditions. Figure 1: High-performance liquid chromatography (HPLC) chromatograms of (**a**) \(\beta\)-carotene standard (**b**) fermented _Spirulina maxima_ by _Lactobacillus plantarum_ HY-08 with ultrasonic extraction process, (**c**) _S. maxima_ extracted by only ultrasonic extraction process, (**d**) _S. maxima_ extracted by conventional water extraction. Comparison of Antioxidant and neuroprotective Activities of \(\beta\)-Carotene and the Fermented \(S\). To identify the antioxidant effects of the \(S\). _maxima_ fermentation products based on the above results, the DPPH activities were measured, and the results are presented in Figure 2. In the case of the hot water extract and ultrasonicated extracts, the highest DPPH free radical scavenging activity (approximately 31.98% and 35.12%, respectively) were observed at the highest concentration of 1.0 mg/mL. On the other hand, the \(S\). _maxima_ fermentation products showed a DPPH free radical scavenging activity of approximately 49.01% at the same dosage, indicating that the \(S\). _maxima_ fermentation products exhibited the highest antioxidant activity. Therefore, the neuroprotective activities were measured based on the excellent antioxidant effect of the \(S\). _maxima_ fermentation products analyzed, as described above. The neuroprotective activities were compared and analyzed in the HT22 cells.