## 3 Results and Discussion
### Effect of Alkaloid Extracts on TDH in PC-12 Cells Induced by OS with H\({}_{2}\)O\({}_{2}\)
Relative to the control group, the H\({}_{2}\)O\({}_{2}\)-treated group exhibited a significant surge in TOS and OSI levels (\(p<0.05\)) and a noteworthy decline in TAS (\(p<0.05\)). When compared to the H\({}_{2}\)O\({}_{2}\) group, the cells treated with varying concentrations of the alkaloid extracts displayed a marked reduction in TOS and OSI levels and a significant rise in TAS levels (\(p<0.05\)). In terms of potency, the 500 ug/mL concentration proved most effective, followed by 250 ug/mL and 100 ug/mL. Regarding the solvent effect, for TAS, chloroform was most effective, succeeded by methanol and water. However, for TOS and OSI, methanol took the lead, followed by chloroform and then water (as illustrated in Figure 4). In their studies, [PERSON] et al. [80] and [PERSON] et al. [81] compared the serum and plasma TOS and TAS levels between ND patients and a healthy control cohort. They observed notably elevated TOS levels in the ND group, with a concomitant significant decline in TAS levels. Similarly, [PERSON] et al. [46] noted in their research that _Ziziphus juibua_, known for its rich alkaloid content, effectively mitigated the H\({}_{2}\)O\({}_{2}\)-induced rise in TOS and OSI levels while concurrently elevating the H\({}_{2}\)O\({}_{2}\)-suppressed TAS levels. Our findings resonate with these studies. The structural presence of free phenolic (hydroxyl) and catechol groups in isoquinoline alkaloids is instrumental in maintaining the equilibrium of TOS, TAS, and OSI levels [82; 83]. Thanks to their multifaceted properties such as free radical scavenging, metal ion chelation, lipid peroxidation prevention, ROS hydrogen/electron donation, and the stimulation of antioxidant and detoxification enzymes, isoquinoline alkaloids can harmonize these oxidative balance markers [84; 85; 86]. The antioxidant actions exhibited by our alkaloid extracts, such as scavenging of hydroxyl and superoxide anion radicals, coupled with metal ion and lipid peroxidation chelation abilities, further endorse this perspective. Impact of Alkaloid Extracts on PON1, SOD, CAT, and GPx Enzyme Levels in PC-12 Cells Induced by OS with H\({}_{2}\)O\({}_{2}\)  
The antioxidant system is broadly categorized into two groups: the enzymatic antioxidant system and the non-enzymatic antioxidant system. Key components of the enzymatic system include superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and other endogenous antioxidant enzymes such as paraoxonase 1 (PON1). Collectively, these enzymes serve as the primary defense against oxidative stress (OS) [87]. SOD primarily neutralizes superoxide radicals by converting them into H\({}_{2}\)O\({}_{2}\) and oxygen. Additionally, SOD helps detoxify peroxynitrite, a potent oxidant formed from the interaction of nitric oxide and superoxide radicals [88]. CAT, a heme-containing redox enzyme, prevents potential damage from H\({}_{2}\)O\({}_{2}\) by converting it into oxygen and water without generating free radicals [89]. GPx, a selenoenzyme, utilizes reduced glutathione (GSH) to transform organic hydroperoxides into alcohol and water [90]. PON1 aids in degrading lipid peroxides, safeguarding plasma lipoproteins from oxidative changes [91]. Given this background, we assessed the impact of alkaloid extracts on the levels of PON1, SOD, CAT, and GPx enzymes in PC-12 cells exposed to OS via H\({}_{2}\)O\({}_{2}\) using specialized assay kits. The H\({}_{2}\)O\({}_{2}\) treatment group showed a notable decrease in the levels of PON1, SOD, CAT, and GPx compared to the control group (\(p<0.05\)). However, alkaloid extract treatments, depending on their concentration, led to significant elevations in these enzyme levels when compared to the H\({}_{2}\)O\({}_{2}\) group (\(p<0.05\)). The potency of the alkaloid concentrations was ranked as 500 ug/mL \(>\) 250 ug/mL \(>\) 100 ug/mL. Solvent influence differed based on enzyme activity, with chloroform as the most effective for SOD, CAT, and GPx, and methanol standing out for PON1.