High-throughput discovery of highly selective reversible hMAO-B inhibitors based on at-line nanofractionation

Human monoamine oxidase B (hMAO-B) has emerged as a pivotal therapeutic target for Parkinson's disease. Due to adverse effects and shortage of commercial drugs, there is a need for novel, highly selective, and reversible hMAO-B inhibitors with good blood-brain barrier permeability. In this study, a high-throughput at-line nanofractionation screening platform was established with extracts from Chuanxiong Rhizoma, which resulted in the discovery of 75 active compounds, including phenolic acids, volatile oils, and phthalides, two of which were highly selective novel natural phthalide hMAO-B inhibitors that were potent, selective, reversible and had good blood‒brain permeability. Molecular docking and molecular dynamics simulations elucidated the inhibition mechanism. Sedanolide (IC₅₀ = 103 nmol/L; SI = 645) and neocnidilide (IC₅₀ = 131 nmol/L; SI = 207) demonstrated their excellent potential as hMAO-B inhibitors. They offset the limitations of deactivating enzymes associated with irreversible hMAO-B inhibitors such as rasagiline. In SH-SY5Y cell assays, sedanolide (EC₅₀ = 0.962 μmol/L) and neocnidilide (EC₅₀ = 1.161 μmol/L) exhibited significant neuroprotective effects, comparable to the positive drugs rasagiline (EC₅₀ = 0.896 μmol/L) and safinamide (EC₅₀ = 1.079 μmol/L). These findings underscore the potential of sedanolide as a novel natural hMAO-B inhibitor that warrants further development as a promising drug candidate.