Pharmacological evaluation of vitexin, quercitrin, and isoquercitrin on TNF-α-stimulated human macrophages and their implication for chronic inflammatory condition

Abstract

Chronic inflammation, a key factor in the pathogenesis of Inflammatory Bowel Disease (IBD), is characterized by excessive production of pro-inflammatory mediators, including nitric oxide (NO), IL-1ß, and IL-6, as well as intestinal mucosal damage. Vitexin, quercitrin, and isoquercitrin are flavonoid glycosides commonly found in various medicinal plants and have been reported to possess anti-inflammatory activities. This study aimed to evaluate the anti-inflammatory activities and intestinal barrier protective effects of these flavonoid glycosides in TNF-α–stimulated THP-1-derived macrophages. Network pharmacology analysis suggested that the effects of flavonoid glycosides are related to nitrogen metabolism and the MAPK signaling pathway. MTS assay demonstrated that flavonoid glycosides were non-cytotoxic up to a concentration of 100 µM. Vitexin, quercitrin, and isoquercitrin significantly reduced NO and IL-1ß production in a concentration-dependent manner, whereas IL-6 levels showed only minor changes. Among the three compounds, isoquercitrin was the most potent in reducing NO and IL-1ß production. Mechanistic studies revealed that isoquercitrin tended to reduce ERK and p38 phosphorylation. Proteomic analysis indicated that isoquercitrin downregulated the expression of NUDT22 and NOSIP proteins. In addition, vitexin, quercitrin, and isoquercitrin significantly reduced intestinal epithelial permeability in THP-1-derived macrophages co-cultured with Caco-2 cells. Isoquercitrin demonstrated the greatest protective effects on the intestinal epithelial barrier. In conclusion, vitexin, quercitrin, and isoquercitrin exhibit anti-inflammatory activities and protective effects on the intestinal epithelial barrier. Among them, isoquercitrin showed the most potent anti-inflammatory effects, reduced NO and IL-1ß production, which may be associated with a tendency to reduce ERK and p38 phosphorylation, and downregulated NUDT22 and NOSIP protein expression. These findings suggest that isoquercitrin has potential as a therapeutic candidate for chronic inflammatory conditions, particularly in IBD, and warrant further investigation in an in vivo model and additional mechanistic studies.