Tannins from Chestnut (Castanea sativa Mill.) leaves and fruits show promising in vitro antiinflammatory properties in gastric epithelial cells

IL-8 plays a central role in the immune-pathogenesis of H. pylori-induced tissue injury. H. pylori cag ⁺ strains are clinically related to more severe outcomes of gastritis, like ulcers and cancer. The present study investigated the biological effect of tannins-containing extracts from Castanea sativa Mill., using in vitro models of gastric inflammation. Gastric epithelial cells (AGS and GES-1) were stimulated with TNFα (10 ng/mL) or co-cultured with different bacterial strains from clinical samples. Interestingly, IL-8 and IL-6 release after 6 h was found cagA independent. Basing on our previous work on TNFα-challenged cells and chestnut fruits, we tested the effect of the extracts in AGS co-cultured with H. pylori cag ⁺ (ATCC strain). Extracts from fruit episperm and pericarp, both rich in condensed tannins, inhibited H. pylori-induced IL-8 release at 25 μg/mL, compared to 5 μg/mL during previous TNFα treatments. Moreover, we investigated the effect of an extract from chestnut leaves, rich in tannins, which was never previously evaluated against gastric inflammation, in addition to castalagin and vescalagin, ellagitannins which occur in bark and leaves. Leaves extract inhibited TNFα and H. pylori-induced IL-8 secretion at 10 μg/mL and 50 μg/mL, respectively. Both ellagitannins strongly inhibited TNFα-induced IL-8 with the same IC50 (0.04 μM), whereas H. pylori-induced IL-8 was impaired at 50 μM. Although the extracts exhibited a lower inhibitory potency in co-culture model with respect to TNFα induced gastric epithelial cells, the higher concentrations of extracts tested (25-50 μg/mL) may be easily achieved in vivo after oral consumption.