Focusing on Keap1, IKKβ, and Bcl2 proteins: predicted targets of stigmasterol in neurodegeneration

Oxidative stress, driven by excess ROS, damages lipids, proteins, and DNA, leading to neuronal apoptosis and inflammation, a key factor in neurodegenerative diseases. This study explored stigmasterol, a bioactive phytosterol, with neuroprotective potential, revealing strong docking interactions, especially with Keap1 (binding energy of -11.62 Kcal/mol). Stigmasterol formed two hydrogen bonds with Ile258 and Val305 in Keap1, suggesting it could disrupt Keap1-Nrf2 interactions, potentially activating antioxidant responses by promoting Nrf2 translocation to the nucleus. In the Bcl2-stigmasterol complex, which exhibited a binding energy of -8.41 Kcal/mol, hydrophobic interactions with residues Ser50, Gln52, and Leu185 stabilized the complex, indicating stigmasterol's role in inhibiting apoptosis by strengthening of Bcl2 mediated inhibition of pro-apoptotic factors like Bax. Furthermore, the IKKβ-stigmasterol complex displayed a hydrogen bond between Asp385 residue and stigmasterol (2.83 Å), with a binding energy of -8.33 Kcal/mol, suggested that stigmasterol may regulate inflammation by stabilizing IKKβ, thereby preventing NF-κB translocation and reducing inflammation. Molecular dynamics simulations confirmed the stability of stigmasterol's interactions, especially with Keap1, which showed low RMSD values and consistent hydrogen bonding. RMSF and Rg analyses indicated that stigmasterol had stabilizing effects on Bcl2 and IKKβ. These results underscore stigmasterol's potential for neuroprotection through antioxidant and anti-inflammatory actions.