Protective role of alkaloids of Calanthe fimbriata against ethanol-induced gastric ulcer in mice: Involvement of anti-gastric acid secretion and suppression of NF-κB/MAPK inflammatory cascades

Ethnopharmacological relevanceCalanthe fimbriata is a Tujia ethnomedicine, with a history of use in the therapy of gastric ulcer, chronic hepatitis, etc. Previous investigations indicated its potent protective efficacy against ethanol-induced gastric injury, with alkaloids potentially being the main active constituents.Aim of the studyThis study aimed to validate the protective role of the alkaloids of C. fimbriata (CfA) in ethanol-induced gastric ulceration and to elucidate their mechanisms of action.Materials and methodsThe gastroprotective efficacy of CfA was evaluated in an ethanol-induced gastric ulcer mouse model. Mechanisms were investigated via ELISA kits, RT-qPCR, and Western blotting. Chemical constituents were isolated and identified through various chromatographic and spectroscopic techniques. Molecular docking was employed to predict the potential targets of active compounds.ResultsCfA considerably ameliorated stomach mucosal damage induced by ethanol, as indicated by a reduced ulcer area, decreased submucosal edema, improved glandular architecture, and diminished loss of epithelial cells. CfA inhibited gastric acid secretion via up-regulation of PGE₂ and down-regulation of gastrin and H+K+-ATPase. Moreover, CfA enhanced antioxidant ability by increasing SOD activity and lowering MDA content in both serum and gastric tissue. It also helped maintain NO levels, thereby preserving gastric mucosal integrity. Furthermore, CfA markedly alleviated inflammation by restraining the MAPK and NF-κB cascades, which consequently decreased the generation of pro-inflammatory cytokines. A phytochemical investigation identified two new indole alkaloids, as well as eight known alkaloids from CfA. Molecular docking studies revealed that the two new indole alkaloids exhibited potent binding affinities with PTGER4, p38 MAPK, and NF-κB p65, suggesting their potential as key bioactive components responsible for the mucosa-repairing and anti-inflammatory activities of CfA.ConclusionCfA protects against ethanol-induced gastric ulcers in mice through anti-gastric acid secretion, antioxidant, and inhibition of NF-κB/MAPK inflammatory cascades. The two newly identified indole alkaloids are proposed as promising active constituents contributing to these protective effects.