## 3 Results and Discussion
### DPPH and ABTS Radical Scavenging Effects  
The DPPH and ABTS assays are commonly used to measure antioxidant capacity. The main differences between the two assays are their reaction mechanisms and type of radicals [36]. The radical reaction occurs as a single electron transfer (SET) to DPPH and a proton-coupled electron transfer (PCET) to ABTS. The radical type is primarily DPPH in solvents and ABTS in aqueous solutions known as sequential proton loss electron transfer (SPLET) [37].  
Thus, the antioxidant ability of _E. globulus_ leaves under different ethanol conditions was evaluated using their quenching potential against DPPH and ABTS radicals. As shown in Table 2, the highest antioxidative condition against DPPH radicals was 30% ethanol with 188.2 ug/mL of SC\({}_{50}\) value, followed by 10%, 50%, and 70% ethanol conditions having SC\({}_{50}\) values of 357.9, 505.3, and 509.3 ug/mL, respectively. Among the extraction conditions, relatively extreme polar or non-polar conditions showed more than 1000 ug/mL of SC\({}_{50}\) value to exhibit little antioxidant ability. Specifically, these values were 5841.7 (0% ethanol), 1008.4 (90% ethanol), and 1304.7 ug/mL (100% ethanol). On the other hand, the ABTS radical scavenging activity assay displayed generally better results than the DPPH assay. It suggested that the antioxidant efficacy of _E. globulus_ leaf extracts was via the PCET scavenging mechanism. Like the DPPH assay, the best antioxidant efficacy was confirmed under 30% and 50% ethanol extraction conditions with SC\({}_{50}\) values of 14.2 and 18.0 ug/mL. In the following order, the antioxidant capacities were observed having 23.1, 20.8, and 24.8 ug/mL of SC\({}_{50}\) values under 10%, 70%, and 90% ethanol conditions, respectively. The 0% and 100% ethanol extracts were found to be the least active with SC\({}_{50}\) values of 171.3 and 34.9 ug/mL, respectively. Their lower potential confirmed the limit of radical scavenging effects under these conditions. Through these results, it was confirmed that _E. globulus_ leaves exhibited more effective antioxidant ability when using a proper combination of water and ethanol than when using only water or ethanol for extraction. The results suggested that a combination of extract solvents was essential to maximize the antioxidant potential relatively.  
\begin{table}
\begin{tabular}{c c c} \hline \multirow{2}{*}{**Extract Conditions**} & \multicolumn{2}{c}{**Radical Scavenging Activity (SC\({}_{50}\), ug/mL)**} \\ \cline{2-3}  & **DPPH** & **ABTS** \\ \hline
0\% ethanol & 5841.7 \(\pm\) 238.4 \({}^{\text{d}}\) & 171.3 \(\pm\) 10.2 \({}^{\text{b}}\) \\
10\% ethanol & 357.9 \(\pm\) 28.0 \({}^{\text{ab}}\) & 23.1 \(\pm\) 2.1 \({}^{\text{a}}\) \\
30\% ethanol & 188.2 \(\pm\) 24.2 \({}^{\text{a}}\) & 14.2 \(\pm\) 0.9 \({}^{\text{a}}\) \\
50\% ethanol & 505.3 \(\pm\) 56.2 \({}^{\text{b}}\) & 18.0 \(\pm\) 1.5 \({}^{\text{a}}\) \\
70\% ethanol & 509.3 \(\pm\) 57.1 \({}^{\text{b}}\) & 20.8 \(\pm\) 1.9 \({}^{\text{a}}\) \\
90\% ethanol & 1008.4 \(\pm\) 121.2 \({}^{\text{c}}\) & 24.8 \(\pm\) 1.4 \({}^{\text{a}}\) \\
100\% ethanol & 1304.7 \(\pm\) 156.5 \({}^{\text{c}}\) & 34.9 \(\pm\) 5.1 \({}^{\text{a}}\) \\ \hline \end{tabular} The different superscript letters indicate significant differences (\(p<0.05\)).  
\end{table}
Table 2: Radical scavenging activity of different _E. globulus_ leaf extract conditions against DPPH and ABTS.