Chemical characterization of small-molecule inhibitors of Monoamine oxidase B synthesized by the Acanthopanax senticosus root with affinity ultrafiltration-mass spectrometry.

Discovering and identifying new small-molecule inhibitors of monoamine oxidase B (MAO-B) have the potential to treat many neurodegenerative diseases.

We employed affinity ultrafiltration-liquid chromatography-tandem mass spectrometry (AUF-LC/MSⁿ ) to identify and characterize small-molecule inhibitors of MAO-B from the 30% ethanol extract of Acanthopanax senticosus root (ASR). In vitro tests were performed in stimulated BV2 microglia to evaluate the anti-inflammatory effects of the ASR preparation. An in vitro enzyme activity assay, measuring half-maximal inhibitory concentrations (IC₅₀ ) against MAO-B, determined the inhibitory activity of the potential MAO-B ligands.

ASR treatment significantly inhibited NO release (p<0.01) and attenuated tumor necrosis factor (TNF)-α expression in stimulated BV2 microglia. Nine compounds were isolated from the ASR preparation as potential MAO-B inhibitors, identified as quinic acid, chlorogenic acid, isofraxidin, dicaffeoylquinic acid, pinoresinol diglucoside, medioresinol 4'-O-β-D-glucopyranoside, eletutheroside E, syringaresinol O-β-D-glucoside, and trihydroxy-octadecenoic acid, based on their tandem mass spectra.Our study provides critical data on compounds from ASR extracts, which are suitable for the development of new MAO-B inhibitors as potential therapeutics for neurodegenerative diseases.