The effect of in vitro gastrointestinal digestion on the anti-inflammatory activity of Vitis vinifera L. leaves

Botanicals are widely consumed all over the world for health purposes, with increased usage in the general population, in many different types of products, including foods and plant food supplements. Several reports support for the beneficial effects of botanicals against gastrointestinal inflammation. However, no studies regarding the anti-inflammatory activity in the gastrointestinal tract of red vine leaves have been reported so far. The present work investigates the biological activity of Vitis vinifera L. water extract (VVWE) from dried leaves in two in vitro models of gastric and intestinal inflammation. The extract was characterized by a validated HPLC-DAD method, and tested on human epithelial gastric (AGS) and intestinal (Caco-2) cells with the aim to investigate the inhibitory effect on IL-8 secretion and promoter activity, before and after in vitro gastric or gastrointestinal digestion. Our results show that the water extract from red vine leaves inhibits TNFα-induced IL-8 secretion and expression in human gastric epithelial cells; the effect should be maintained, although to a lesser extent, after gastric digestion. In contrast, the effect after intestinal digestion is dramatically decreased since degradation of the active components in the gut does not allow the extract to efficiently counteract TNFα or IL-1β induced IL-8 expression and the NF-κB pathway. The main molecular target of VVWE at the gastric level includes TNFα-induced activation of NF-κB and occurs at concentrations easily reachable after PFS consumption based on red vine leaf water extract as the ingredient. Our findings suggest that PFS containing water extracts from Vitis vinifera L. leaves could be useful to inhibit/attenuate gastric inflammation inhibiting IL-8 secretion and expression through impairment of the NF-κB pathway.