Anti-Inflammatory Gallic Acid and Wedelolactone Are G Protein-Coupled Receptor-35 Agonists

G protein-coupled receptor-35 (GPR35) has been shown to be a target of the asthma drugs cromolyn disodium and nedocromil sodium. Gallic acid and caffeic acids are reported to modulate allergic reactions via unknown mode(s) of action. Here we attempt to elucidate whether both phenolic acids share a common mode of action with the two asthma drugs. Label-free dynamic mass redistribution (DMR) assays showed that both phenolic acids triggered robust DMR signals in HT-29 cells, whose characteristics were similar to that of cromolyn disodium. Both phenolic acids resulted in detectable β-arrestin translocation signals in an engineered U2OS cell line stably expressing a C-terminal-modified GPR35, but with lower efficacy than cromolyn disodium. Antiallergic wedelolactone was found to be a potent β-arrestin-biased GPR35 agonist. These results suggest that certain anti-inflammatory phytochemicals including gallic acid and wedelolactone may modulate inflammatory allergic action via their agonism at GPR35. GPR35 may represent a target for the treatment of allergic disorders including asthma.