Identification of the bioactive material basis of licorice for intestinal barrier repair

Damage to the intestinal barrier is associated with multiple inflammatory and metabolic disorders. Licorice aqueous extract (GC) has shown potential for restoring intestinal barrier integrity. However, its active material basis remains insufficiently defined. To dissect its active constituents, GC was separated into a polysaccharide-enriched fraction (GC-PS) and a small-molecule fraction (GC-SM), and the LPS-induced Caco-2 cell barrier damage model was used for comparative evaluation. Both GC-PS and GC-SM alleviated the barrier disruption, while the whole extract GC showed a stronger overall effect than either fraction alone. Structural characterization indicated that GC-PS is a furan-type heteropolysaccharide rich in α-glycosidic bonds. UPLC-Q-TOF-MS^E analysis identified 63 compounds in GC-SM, among which 26 and 29 prototype compounds were detected in rat serum and colon contents after oral administration, respectively. Combined molecular docking and cellular experiments revealed that liquiritin, licuraside, licorice glycoside C2, glycyrrhizic acid, and GC-PS enhanced intestinal barrier function by upregulating tight junction proteins, increasing TEER, and reducing FITC-dextran flux. These findings provide experimental evidence for understanding the basis of licorice's active components in intestinal barrier repair and offer theoretical support for identifying bioactive components in traditional Chinese medicine.