## 4 Discussion  
A huge body of literature presents the various beneficial and health-promoting effects of phenolic phytochemicals, administered orally either as food components or as purified supplements. The knowledge regarding the underlying mechanisms of their action is constantly expanding, but it is still far from being complete. Our results indicate that Cornelian cherry leaf extract upregulated the level of intestinal differentiation markers in Caco-2/HT-29-MTX 2D co-cultures, which manifested through enhanced ALPI and mucin staining (Figure 2b) and ALPI protein levels as compared to the control (Figure 2g),  
Figure 5: Reactive oxygen production (oxidative burst) in PMA-stimulated Raw 264.7 cells (**a–d**). The plots show luminescent signals using arbitrary units expressed as a percentage of the value of the control at the start of the reaction (time 0), the same letters represent lack of statistically significant differences at \(p\) < 0.05; ns—insignificant differences. (**e**) Concentration of NO metabolites (nitrites nmol/(ml \(\times\) cell)) in the culture supernatant from P388D1 monocytes stimulated with LPS. (**f**) Concentration of IL-1\(\beta\) in the culture supernatant from P388D1 monocytes stimulated with LPS. * \(p\) < 0.05 vs. Con. RL—sea buckthorn extract (10, 50 \(\upmu\)g/mL); RO—sea buckthorn fruit extract (10, 50 \(\upmu\)g/mL); DL—Cornelian cherry leaf extract (10, 50 \(\upmu\)g/mL); DO—Cornelian cherry fruit extract (10, 50 \(\upmu\)g/mL); Con—cells treated with the appropriate amount of solvent. Panels (**e,f**) created with [[https://www.biorender.com/](https://www.biorender.com/)]([https://www.biorender.com/](https://www.biorender.com/)). although the differences in ALPI enzymatic activity were not significant. In spheroid co-cultures, all the tested extracts increased both ALPI's and mucin's staining intensity (Figure 2a). The observations about the positive impact of Correlian cherry fruit extract on the intestinal epithelial differentiation markers are novel and, as far as we are aware, have not been reported yet. ALPI plays an important role in the maintenance of gut homeostasis through bicarbonate release and the regulation of luminal pH, facilitating nutrient absorption and the detoxification of microbial pathogen molecular patterns (PAMPs) such as LPS [33]. Removing phosphate from the lipid A moiety of LPS using ALPI dramatically diminishes LPS recognition by Toll-like receptor 4, which helps to control the immune response to commensal microbiota in the gut [33]. High levels of ALPI in the intestinal mucosa provides protection from exaggerated inflammation, whereas ALPI deficiency or loss of catalytic function causes the development of inflammatory bowel disease (IBD) [34]. Mucins, being a vital part of the innate immune barrier mechanisms of the gastrointestinal tract, play a protective role against infection and the onset of IBD. Mucins create a layer that is difficult to penetrate for pathogenic bacteria and limit the risk of their direct contact with epithelial cells, serve as a carrier for antimicrobial peptides and IgA antibodies, facilitate the chyme passage and provide a friendly environment for commensal beneficial bacteria such as _Akkermansia muciniphila_. Dietary polyphenols and the phytochemical present in the tested extracts can possibly come into contact with goblet cells (in our model HT-29-MTX cells) and stimulate them to secrete mucin. [PERSON] and co-authors [35] observed the increase in trans-membrane mucin Muc17 in Caco-2/HT-29-MTX models after treatment with quercetin, although the expression of Muc2, the main mucin secreted in the gut, was not altered. We did not analyse the particular types of mucins but focused on the staining of mucin glycans with alcian blue, because mucin post-translational modifications, particularly glycosylation, determines mucin's protective functions.