Anti-pseudo-allergic components in licorice extract inhibit mast cell degranulation and calcium influx

Pseudo-allergic reactions (PARs) widely occur upon application of drugs or functional foods. Anti-pseudo-allergic ingredients from natural products have attracted much attention. This study aimed to investigate anti-pseudo-allergic compounds in licorice. The anti-pseudo-allergic effect of licorice extract was evaluated in rat basophilic leukemia 2H3 (RBL-2H3) cells. Anti-pseudo-allergic compounds were screened by using RBL-2H3 cell extraction and the effects of target components were verified further in RBL-2H3 cells, mouse peritoneal mast cells (MPMCs) and mice. Molecular docking and human MRGPRX2-expressing HEK293T cells (MRGPRX2-HEK293T cells) extraction were performed to determine the potential ligands of MAS-related G protein-coupled receptor-X2 (MRGPRX2), a pivotal target for PARs. Glycyrrhizic acid (GA) and licorice chalcone A (LA) were screened and shown to inhibit Compound48/80-induced degranulation and calcium influx in RBL-2H3 cells. GA and LA also inhibited degranulation in MPMCs and increase of histamine and TNF-α in mice. LA could bind to MRGPRX2, as determined by molecular docking and MRGPRX2-HEK293T cell extraction. Our study provides a strong rationale for using GA and LA as novel treatment options for PARs. LA is a potential ligand of MRGPRX2.