Anti-inflammatory activity of an in vitro digested anthocyanin-rich extract on intestinal epithelial cells exposed to TNF-a

Speciale PJ, Bashllari R, Muscara C, Molonia MS, Saija A, Saha S, Wilde PJ, Cimino . (2022)

Molecules, 27, 2022 Aug 23;27(17):5368

Anthocyanins (ACN) are a large group of compounds, widely distributed in nature, belonging to flavonoid class. Consumption of foods rich in ACN was associated to beneficial properties in various chronic inflammatory disorders such as intestinal bowel diseases (IBD), as they possess anti-inflammatory and antioxidant activity. In particular these effects were attributed not only to a direct antioxidant mechanism but also to the modulation of specific cell redox-dependent signaling. However, ACN bioavailability seems to be low mainly due to poor stability in the digestive tract so that the effects of the gastrointestinal digestion of the ACN should be taken into consideration. Thus, with the aim to have a more realistic knowledge about the potential protective effect of ACN, in this study we performed an in vitro simulated gastrointestinal digestion of an ACN-rich purified and standardized bilberry and blackcurrant extract (BBE), followed by the evaluation of the modification of ACN composition (by HPLC-DAD and pH differential method) and antioxidant activity (by FRAP assay). Then, we further studied the in-situ effect of the gastrointestinal extract of BBE on an in vitro model of intestinal inflammation by using differentiated Caco-2 cells exposed to TNF-a.

The results confirmed the high instability of ACN in the mild alkaline environment of the small intestine reporting a 17% of recovery index. However, despite the high loss of ACN, the digested BBE maintained part of its bioactivity, proved by FRAP assay. Additionally, gastrointestinal extract of BBE inhibited NF-?B pathway induced by TNF-a in Caco-2 cells involving the activation of Nrf2-mediated antioxidant cellular adaptive response.

In conclusion, although ACN stability is affected by gastrointestinal digestion, our data confirm the anti-inflammatory and antioxidant activity of digested extracts. It can therefore be assumed that the loss of ACN can probably be counterweighed by their metabolites also endowed with antioxidant and anti-inflammatory capabilities acting synergistically with their precursors. These results all support that ACN introduced by diet or food supplements could represent a possible approach for the prevention of IBD.

Molecules, 27, 2022 Aug 23;27(17):5368

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