## 3 Results and Discussion
### SOD, CAT, and APX Activities of GV Extracts  
Plants remove toxic reactive oxygen species (ROS) generated by metabolic processes through reactions with antioxidant enzymes, including SOD, CAT, and APX [63]. SOD catalyzes the conversion of superoxide radicals (O\({}_{2}\)\({}^{\bullet}\)) into H\({}_{2}\)O\({}_{2}\) and H\({}_{2}\)O. Although H\({}_{2}\)O\({}_{2}\) is toxic to cells, CAT and APX facilitate the conversion of H\({}_{2}\)O\({}_{2}\) to H\({}_{2}\)O and O\({}_{2}\)[64]. In this study, SOD, CAT, and APX activity assays were performed to estimate the antioxidant  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**IC\({}_{50}\) = \(\upmu\)g/\(\upmu\)L** & **GVE** & **GVM** & **GVW** & **Ascorbic Acid** \\ \hline DPPH & 69.4 \(\pm\) 0.4 \({}^{\text{a}}\) & 73.3 \(\pm\) 0.9 \({}^{\text{a}}\) & 182.0 \(\pm\) 17.8 \({}^{\text{b}}\) & 3.2 \(\pm\) 0.0 \\ ABTS & 66.9 \(\pm\) 2.0 \({}^{\text{a}}\) & 53.5 \(\pm\) 1.2 \({}^{\text{a}}\) & 276.2 \(\pm\) 20.7 \({}^{\text{b}}\) & 0.1 \(\pm\) 0.0 \\ FRAP & 56.1 \(\pm\) 1.4 \({}^{\text{a}}\) & 87.3 \(\pm\) 0.9 \({}^{\text{b}}\) & 171.6 \(\pm\) 5.8 \({}^{\text{c}}\) & 0.6 \(\pm\) 0.0 \\ \hline \hline \end{tabular} GVE, G. _verrucos_ ethanol extract; GVM, G. _verrucos_ methanol extract; GVE, G. _verrucos_ water extract; IC\({}_{50}\), half-maximal inhibitory concentration. Different letters (a-c) indicate significant differences within the same row (\(p\) < 0.05).  
\end{table}
Table 3: DPPH, ABTS, and FRAP IC\({}_{50}\) values of _Gracilaria verrucos_ extracts.  
enzyme activities of the different GV extracts (Figure 2). The SOD activity of GV extracts ranged from 0.2 to 2.8 units/mg. Among the extracts, the GVM and GVE showed high SOD activities at 2.79 \(\pm\) 0.40 and 2.26 \(\pm\) 0.46 units/mg, respectively, followed by the GVW. Next, the CAT activity of GV extracts ranged from 0.0 to 0.6 units/mg, and the GVM showed 1.7- and 14-fold higher CAT activities than those of the GVE and GVW, respectively. Finally, the APX activity of the GV extracts ranged from 1.5 to 1.6 units/mg in APX activity. The GVM exhibited the highest APX activity, though not significantly higher than the other extracts.  
[PERSON] et al. [65] analyzed the SOD-like activity of the red _Pyropia yezoensis_ and green _Ulva_ sp. seaweed extracts, which showed high antioxidant activity when the extracts had a high polyphenol content. [PERSON] et al. [66] reported that GVE has the highest polyphenol content and CAT activity, followed by _Gloiopeltis funcata_, _Gracilaria vermiculophylla_, and _Chondracanthus tencellus_ ethanol extract. In this study, the highest polyphenol content in the GV extracts was observed in GVM, followed by GVE and GVW, and the SOD and CAT activities were similar. These results indicate that the polyphenol content of the extracts influences antioxidant enzyme activities and that GVM contains antioxidant substances related to the scavenging of superoxide and H\({}_{2}\)O\({}_{2}\). In addition, [PERSON] et al. [67] showed that treating tomatoes with seaweed extracts significantly increased the levels of antioxidant enzyme activities (SOD, CAT, and APX) and that the seaweed extracts enhanced resistance against tomato _Fusarium_ wilt disease. Additionally, GVM appeared to be more effective in scavenging ROS than GVE and GVW because of the higher levels of SOD, CAT, and APX activity. These results indicate that GVM could potentially be used as a biological control agent. However, the antioxidant enzyme activity of seaweed extracts is affected by various conditions, such as light quality, temperature, and extraction conditions [68, 69]. Therefore, measuring the antioxidant enzyme activity of GV under different light conditions, temperatures, harvest times, and drying methods is necessary in addition to the extraction method used in this study.