Exploring the potential of phenolic compounds from the coffee pulp in preventing cellular oxidative stress after in vitro digestion

The coffee pulp, a by-product of the coffee industry, contains a high concentration of phenolic compounds and caffeine. Simulated gastrointestinal digestion may influence these active compounds' bioaccessibility, bioavailability, and bioactivity. Understanding the impact of the digestive metabolism on the coffee pulp's phenolic composition and its effect on cellular oxidative stress biomarkers is essential. In this study, we evaluated the influence of in vitro gastrointestinal digestion of the coffee pulp flour (CPF) and extract (CPE) on their phenolic profile, radical scavenging capacity, cellular antioxidant activity, and cytoprotective properties in intestinal epithelial (IEC-6) and hepatic (HepG2) cells. The CPF and the CPE contained a high amount of caffeine and phenolic compounds, predominantly phenolic acids (3',4'-dihydroxycinnamoylquinic and 3,4-dihydroxybenzoic acids) and flavonoids (3,3',4',5,7-pentahydroxyflavone derivatives). Simulated digestion resulted in increased antioxidant capacity, and both the CPF and the CPE demonstrated free radical scavenging abilities even after in vitro digestion. The CPF and the CPE did not induce cytotoxicity in intestinal and hepatic cells, and both matrices exhibited the ability to scavenge intracellular reactive oxygen species. The coffee pulp treatments prevented the decrease of glutathione, thiol groups, and superoxide dismutase and catalase enzymatic activities evoked by tert-butyl hydroperoxide elicitation in IEC-6 and HepG2 cells. Our findings suggest that the coffee pulp could be used as a potent food ingredient for preventing cellular oxidative stress due to its high content of antioxidant compounds.