Food processing and digestion can alter bioactive compound composition of food, affecting their potential biological activity. In this study, we evaluated the direct and protective antioxidant effects of polyphenols extracted from defatted chia flour (DCF) (salviaflaside, rosmarinic and fertaric acid as major compounds), sweet cookies supplemented with DCF (CFC) (same major compounds), and their digested fractions (rosmarinic acid, salviaflaside, fertaric and salvianolic E/B/L acid as major compounds) in HepG2 cells in basal and in oxidative stress conditions. DCF showed protective antioxidant effects by decreasing reactive oxygen species (ROS) and protein oxidation products (POP) while increasing reduced glutathione (GSH). Additionally, CFC revealed similar protective effects and even showed enhanced modulation of the antioxidant system due to the activation of antioxidant enzymes. However, the digested fractions only decreased ROS, indicating continued antioxidant effects. This study underscores the importance of evaluating manufacturing and digestion effects to confirm a food's antioxidant properties.

Bioactive compounds such as polyphenols are ubiquitous in many foods. However, their presence varies in structure, concentration, and action along food manufacturing and digestion. The simulated digestion assays allow for the estimation of variations in bioaccessibility and bioeffectiveness of polyphenols within foods. In this study, a polyphenol-enriched food model was used: sweet cookies with 10% defatted sesame flour (DSF). Polyphenolic extracts were obtained from DSF, a base cookie formulation and cookies enriched with DSF. In addition, extracts of potentially bioaccessible polyphenols from digested cookies in vitro were collected. The HepG2 liver cell line was incubated with all these mentioned extracts and then injured with H₂O₂. The following parameters were analyzed: intracellular oxidative state and viability by flow cytometry, antioxidant enzymes and glutathione content, and oxidation of proteins and lipids by spectrophotometry. The results show that DSF may be considered for functional incorporation in foods, since it may promote antioxidant response, providing preventive benefits and protective action in an oxidative damage context. This study also demonstrates that DSF actions on redox state vary depending on the food matrix and its degree of digestion. Cookies with DSF presented a pro-oxidant effect that could enhance the antioxidant response. Furthermore, after digestion, these cookies continue to show biological activity, evidencing the possibility of advantages from the consumption of these foods. These data show the need to improve the knowledge of the biological actions carried out by certain metabolites present in food and the impact of their digestion over their effective role in health.

White sesame (Sesamum indicum L.) flour, an edible residue resulting from seed oil extraction, may become a novel alternative of healthy products due to its high polyphenols content—compounds with many beneficial effects for human health. In the present study, the antioxidant properties of sesame flour were characterized in human cells in vitro. The hepatic cell line HepG2 was treated for 24 h with degreased sesame flour extracts or pinoresinol—one of the main polyphenols of this flour. Then oxidative stress was induced by H2O2 exposure. Cell viability and reactive oxygen species amount were measured by flow cytometry. Antioxidant enzyme activity of glutathione peroxidase (GPx), reductase (GR) and catalase (CAT) were determined by spectrophotometry. Results showed that pinoresinol decreased H2O2 oxidative effects by up to a 40%, increasing CAT and GR activity without compromising cellular viability. The largest dose of sesame flour extracts decreased H2O2 stress induction by up to 46%, but increased cell death levels. Additionally, sesame flour raised CAT and GPx activity by 100%. These findings suggest that sesame flour has antioxidant properties through antioxidant enzyme activity modulation. Since pinoresinol is one of the major polyphenols of sesame flour, this industrial residue might be a potential source for functional foods with health benefits.