## 3 Results and Discussion
### Antioxidant Activities of Alkaloid Extracts  
Reactive oxygen species (ROS), including the hydroxyl radical, superoxide anion radical, and hydrogen peroxide, are a group of molecules with oxygen that are highly reactive due to their unpaired electrons. In the presence of iron ions, hydrogen peroxide can react in the Fenton reaction, generating hydroxyl radicals. High levels of ROS can cause significant oxidative damage to biological macromolecules, such as lipids, proteins, and nucleic acids, either within or outside the cell. Elevated ROS can trigger neurodegenerative diseases (NDs) via oxidative stress (OS) [56; 57]. Current research is focused on discovering natural antioxidants that can halt ND progression. Furthermore, studies have suggested that alkaloid extracts can be a primary source of natural antioxidants with potent antioxidant properties [58]. In this context, we assessed the antioxidant potential of _G. grandiform_ alkaloid extracts using various assays such as DPPH, hydroxyl, and superoxide anion radical scavenging, lipid peroxidation prevention, and metal ion chelation. Figure 2 illustrates the antioxidant activities of these extracts. The effectiveness based on the volume of the alkaloid extract was highest with 250 uL, decreasing in order to 50 uL. However, the preferred solvent for extraction varied depending on the specific antioxidant activity. For instance, chloroform was superior for DPPH radical scavenging and metal ion chelating,while methanol excelled in hydroxyl radical scavenging, lipid peroxidation prevention, and superoxide anion radical scavenging. When considering overall antioxidant activities, the order was DPPH radical scavenging > superoxide anion radical scavenging > hydroxyl radical scavenging > lipid peroxidation prevention > metal ion chelation. The antioxidant potential of isoquinoline alkaloids is attributed to the presence of a lone electron pair on their nitrogen atom [59]. [PERSON] et al. [60] explored the radical scavenging capabilities of isoquinoline alkaloids and found that both DPPH and hydroxyl radicals react with these alkaloids to form two intermediates and a transition state. The hydroxy group present in isoquinoline alkaloids reportedly enhances its antioxidant properties. Key to this antioxidant activity are aromatic hydroxyl groups in the alkaloid structure [61]. [PERSON] et al. [62] demonstrated a strong correlation between the hydroxyl radical scavenging capacities of isoquinoline alkaloids and their metal ion chelating abilities, with functional groups such as hydroxy and methylenedioxy enhancing these properties. Another study by [PERSON] et al. [63] found that the isoquinoline alkaloid berberine exhibited notable antioxidant and chelating activities. Their findings indicated that berberine's lipid peroxidation inhibition might be related to its iron ion chelating capability. Our results align with these studies, suggesting that the hydroxy and methylenedioxy groups in the alkaloids under investigation contribute to their antioxidant effects. Further structural analyses are essential to validate these assumptions.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Solvents** & **Extract \({}^{\text{a}}\)** & **Alkaloid \({}^{\text{b}}\)** \\  & **(mg/g Plant)** & **(mg/g Extract)** \\ \hline Chloroform & 4.04 \(\pm\) 0.40 \({}^{\text{a}}\) & 133.43 \(\pm\) 4.42 \({}^{\text{a}}\) \\ Methanol & 5.03 \(\pm\) 0.22 \({}^{\text{a}}\) & 153.21 \(\pm\) 6.21 \({}^{\text{a}}\) \\ Water & 3.01 \(\pm\) 0.51 \({}^{\text{a}}\) & 80.19 \(\pm\) 7.14 \({}^{\text{a}}\) \\ \hline \hline \end{tabular} The tables were presented as mean \(\pm\) SD. [PERSON]’s test was used in the case of \(p\) < 0.05. \({}^{\text{a}}\) There was a significant difference between solvents in terms of extract (m: 3 for each bar) \({}^{\text{a}}\) and alkaloid (n: 10 for each bar) \({}^{\text{b}}\).  
\end{table}
Table 2: Alkaloid amount of extracts.  
Figure 1: Structures of major alkaloids in \(G\). _grandiforum_ extracts.