Allium sativum -Derived Alliin and Allicin Stably Bind to α-Synuclein and Prevent Its Cytotoxic Aggregation

Neurodegenerative diseases such as Parkinson's disease are characterized by the pathological aggregation of α-synuclein. Targeting α-synuclein aggregation through natural bioactive compounds offers a promising therapeutic strategy. In this study, sulfur-containing compounds derived from Allium sativum were evaluated for their drug-likeness, pharmacokinetic properties, and ability to inhibit α-synuclein aggregation using a combination of in silico and in vitro approaches. ADMET profiling indicated high gastrointestinal absorption for nine compounds, supporting their drug-like properties. Six compounds were predicted to cross the blood-brain barrier, suggesting potential efficacy in the central nervous system. Molecular docking identified alliin, allicin, E-ajoene, and diallyl disulfide as top binders to α-synuclein, forming stable interactions with key aggregation-prone regions. Molecular dynamics simulations over 100 ns confirmed the structural stability of alliin- and allicin-α-synuclein complexes, with minimal residue fluctuations and persistent hydrogen bonding. MM-GBSA binding energy analysis corroborated these results, showing favorable binding free energies, particularly for alliin and E-ajoene. Principal component analysis (PCA) further supported the role of alliin in stabilizing α-synuclein dynamics. In vitro cellular assays further validated these computational findings. Using an SH-SY5Y cell-based α-synuclein aggregation model, treatment with alliin and allicin significantly reduced α-synuclein aggregation. Furthermore, MTT-based cytotoxicity assays in SH-SY5Y neuroblastoma cells overexpressing α-synuclein revealed that alliin and allicin conferred notable cytoprotective effects by reducing α-synuclein-induced toxicity. Taken together, these findings highlight alliin and allicin as potent lead compounds that not only bind and stabilize α-synuclein but also attenuate its aggregation and associated cytotoxicity.