Abstract
Syzygium heyneanum is a valuable source of flavonoids and phenols, known for their antioxidant and neuroprotective properties. This research aimed to explore the potential of Syzygium heyneanum ethanol extract (SHE) in countering Parkinson's disease. The presence of phenols and flavonoids results in SHE displaying an IC50 value of 42.13 when assessed in the DPPH scavenging assay. Rats' vital organs (lungs, heart, spleen, liver, and kidney) histopathology reveals little or almost no harmful effect. The study hypothesized that SHE possesses antioxidants that could mitigate Parkinson's symptoms by influencing α-synuclein, acetylcholinesterase (AChE), TNF-α, and IL-1β. Both in silico and in vivo investigations were conducted. The Parkinson's rat model was established using paraquat (1 mg/kg, i.p.), with rats divided into control, disease control, standard, and SHE-treated groups (150, 300, and 600 mg/kg) for 21 days. According to the ELISA statistics, the SHE treated group had lowers levels of IL-6 and TNF-α than the disease control group, which is a sign of neuroprotection. Behavioral and biochemical assessments were performed, alongside mRNA expression analyses using RT-PCR to assess SHE's impact on α-synuclein, AChE, TNF-α, and interleukins in brain homogenates. Behavioral observations demonstrated dose-dependent improvements in rats treated with SHE (600 > 300 > 150 mg/kg). Antioxidant enzyme levels (catalase, superoxide dismutase, glutathione) were significantly restored, particularly at a high dose, with notable reduction in malondialdehyde. The high dose of SHE notably lowered acetylcholinesterase levels. qRT-PCR results indicated reduced mRNA expression of IL-1β, α-synuclein, TNF-α, and AChE in SHE-treated groups compared to disease controls, suggesting neuroprotection. In conclusion, this study highlights Syzygium heyneanum potential to alleviate Parkinson's disease symptoms through its antioxidant and modulatory effects on relevant biomarkers.