Cholinesterase Inhibition and Antioxidant Potential of Syzygium zeylanicum (L.) DC. Leaf Extract: An In-Vitro Comparison with Donepezil

Syzygium zeylanicum (L.) DC. is a medicinal plant traditionally valued for its bioactive properties. This study aimed to evaluate the phytochemical composition and in vitro antioxidant potential of its hydro-alcoholic leaf extract. Dried leaves (200 g) were subjected to Soxhlet extraction using 70% ethanol for 72 hours, and the extract was concentrated under reduced pressure. Preliminary phytochemical screening revealed the presence of carbohydrates, phenols, glycosides, flavonoids, lignans, phytosterols, saponins, terpenoids, proteins, and amino acids, while alkaloids and tannins were absent. The antioxidant potential was assessed using the DPPH (2,2-diphenyl-1- picrylhydrazyl) radical scavenging assay, which demonstrated dose-dependent activity with an IC₅₀ value of 21.79 µg/mL, comparable to ascorbic acid (IC₅₀ = 19.34 µg/mL). These findings indicate that the leaf extract possesses significant free radical scavenging activity, likely due to its phenolic and flavonoid content. While the study provides preliminary insights into its bioactive profile and antioxidant efficacy, further investigations involving neuroprotective assays, acetylcholinesterase inhibition studies, and in vivo models are warranted to explore its therapeutic potential, particularly in oxidative stress-related neurodegenerative disorders such as Alzheimer’s disease (AD). The findings suggest the leaf extract has strong scavenging properties against free radicals, most likely because of its flavonoid and phenolic content. Although the study offers some initial insights into its bioactive profile and antioxidant efficacy, more research through in vivo models, acetylcholinesterase inhibition studies, and neuroprotective assays is necessary to fully explore its therapeutic potential, especially in neurodegenerative diseases like Alzheimer's disease that are linked to oxidative stress.