Identification of ursolic acid from Wumei as a syk-targeting anti-allergic agent using a piezoresistive cantilever biosensor.

Wumei (WM), a historical food and medicine homology fruit in China, is reported to have anti-allergic effect, yet its active components and mechanisms remain unclear. Here, a novel spleen tyrosine kinase-based piezoresistive cantilever array (Syk-PCA) biosensor was developed for screening anti-allergic components in WM. Once the biosensor composition was confirmed by X-ray photoelectron spectroscopy (XPS), its specificity was evaluated based on the differential electrochemical responses toward piceatannol and protocatechualdehyde. The biosensors were subsequently used to screen for Syk-binding compound of WM extract as a predictor of potential anti-allergic properties, including succinic acid, tartaric acid, chlorogenic acid, citric acid, and ursolic acid. The biosensor demonstrated high specificity and sensitivity, achieving a femtomolar-level interaction for ursolic acid with a surface equilibrium dissociation constant (KD, sur) of 2.37 fM and a linear detection range from 1 fM to 1 pM. Using this platform, ursolic acid was identified as the key active component targeting Syk. The activity was validated through in vitro and in silico approaches, including RBL-2H3 cell model, cellular thermal shift assay (CETSA), molecular docking and molecular dynamics simulation. The binding affinity between ursolic acid and Syk was demonstrated by the elevated thermostability of ursolic acid-Syk complex. Molecular docking and molecular dynamics simulation results indicated that the complex remained stable, with interactions mediated by hydrogen bonds and hydrophobic interactions. These findings reveal that ursolic acid exerts anti-allergic effects by targeting Syk, and the Syk-PCA biosensor provides a rapid, cost-effective tool for targeted drug discovery.