Blackcurrant press cake by-product: Increased chemical bioaccessibility and reduced antioxidant protection after in vitro simulation of gastrointestinal digestion.

This study describes the bioaccessibility in terms of total phenolic content (TPC) and antioxidant capacity before and after in vitro digestion from blackcurrant press cake extracts (BPC) and the bioactivity in cell culture, human erythrocytes as well as the in silico analysis. Chemical analysis of BPC presented an increase in TPC (270%) and anthocyanins (136%) after in vitro digestion, resulting in an improvement of antioxidant activity (DPPH 112%; FRAP: 153%). This behavior may be related to the highest activity of cyanidin-3-rutinoside, as confirmed by in silico analysis. The digested BPC did not exert cytotoxicity in cells and showed less antioxidant activity against the oxidative damage induced in endothelial cells and human erythrocytes compared to the non-digested extract. The results raise a question about the reliability we should place on results obtained only from crude samples, especially those that will be used to produce foods or nutraceuticals.

Bridging the gap in antioxidant activity of flavonoids: Correlating the oxidation of human plasma with chemical and cellular assays.

Traditional antioxidant screening relies on chemical assays to assess compounds' potential in combating oxidative processes. However, translating chemical antioxidant activity to complex biological systems poses challenges. In this study, the antioxidant potential of fruit-derived phenolic compounds, hyperoside (HP), epicatechin (EC), and phlorizin (PZ), and their combinations in a specific ratio were investigated using a simplex-centroid design of experiments. The research included in vitro antioxidant assays, plasma protection against oxidation tests, and cytotoxicity assessments in human cell lines. The results revealed the complex relationship between chemical antioxidant activity and its relevance to cellular oxidative and antioxidative processes. HP and EC exhibited significant antioxidant activity, with HP outperforming EC in multiple assessments. Cytotoxicity assay confirmed that these compounds did not induce cell death or hinder proliferation, even at higher concentrations (>100 µmol/mL). In the cell antioxidant activity (CAA) test, HP and EC exhibited higher CAA, while PZ displayed lower antioxidant activity. In conclusion, a synergistic effect emerged when HP, EC, and PZ were combined, particularly in plasma protection, suggesting protective effects and potential health benefits. This research emphasized the need for a nuanced understanding of the interplay between chemical assays and cellular behavior in comprehending the relationship between chemical-based, human plasma oxidation, and CAA.

Influence of spontaneous and inoculated fermentation of açai on simulated digestion, antioxidant capacity and cytotoxic activity.

This work describes the kinetic study of different types (spontaneous, lactic and alcoholic) of açai fermentation in terms of total phenolics and total anthocyanins, as well as antioxidant capacity, before and after simulated digestion (SD). Cytotoxicity (A549, HCT8 and IMR90 cells) and formation of reactive oxygen species (A549 cells) were also evaluated. The results revealed that spontaneous fermentation (SF) for 24 h, followed by SD, generated a product with greater bioaccessibility of phenolics (52.68%) and cyanidin-3-glucoside (27.01%) than unfermented açai. Likewise, lactic fermentation (LF) for 72 h improved the bioavailability of phenolics (64.49%) and cyanidin-3-rutinoside (20.00%). On the other hand, alcoholic fermentation (AF) decreased the bioaccessibility of phenolic compounds and anthocyanins after SD. The SF 24 h (10.16 ± 1.25 µmol Trolox /g) and LF 72 h (15.90 ± 0.51 µmol Trolox /g) significantly increased the antioxidant capacity after SD, when compared to unfermented açai (SF 0 h, 4.00 ± 0.09 µmol Trolox /g; LF 0 h, 10.57 ± 0.91 µmol Trolox /g). It was concluded that the samples did not show cytotoxicity in the cell lines tested and, in addition, AF 24 h showed antioxidant and antimutagenic effects in vitro, reducing about 40% of chromosomal aberrations. The results obtained provide important information that can be used to produce foods with greater bioaccessibility of bioactive compounds.

From waste to the gut: Can blackcurrant press cake be a new functional ingredient? Insights on in vivo microbiota modulation, oxidative stress, and inflammation.

Blackcurrant press cake (BPC) is a source of anthocyanins, and this study evaluated the bioactivity and gut microbiota modulation of blackcurrant diets with or without 1,2 dimethylhydrazine (DMH)-induced colon carcinogenesis in rats. In colon cancer-induced rats (CRC), BPC at the highest dosages increased pro-inflammatory parameters and the expression of anti-apoptotic cytokines, accentuating colon cancer initiation by aberrant crypts and morphological changes. Fecal microbiome analysis showed that BPC altered the composition and function of the gut microbiome. This evidence suggests that high doses of BPC act as a pro-oxidant, accentuating the inflammatory environment and CRC progression.

Enzyme-assisted extraction of anthocyanins and other phenolic compounds from blackcurrant (Ribes nigrum L.) press cake: From processing to bioactivities.

The effects of commercial enzymes (pectinases, cellulases, beta-1-3-glucanases, and pectin lyases) on the recovery of anthocyanins and polyphenols from blackcurrant press cake were studied considering two solid:solvent ratios (1:10 and 1:4 w/v). ß-glucanase enabled the recovery of the highest total phenolic content - 1142 mg/100 g, and the extraction of anthocyanins was similar using all enzymes (∼400 mg/100 g). The use of cellulases and pectinases enhanced the extraction of antioxidants (DPPH - 1080 mg/100 g; CUPRAC - 3697 mg/100 g). The freeze-dried extracts presented antioxidant potential (CUPRAC, DPPH), which was associated with their biological effects in different systems: antiviral activity against both non-enveloped viruses (enterovirus coxsackievirus A-9) and enveloped coronaviruses (HCoV-OC43), and cytotoxicity towards cancer cells (A549 and HCT8). No cytotoxic effects on normal human lung fibroblast (IMR90) were observed, and no anti-inflammatory activity was detected in lipopolysaccharides-treated murine immortalised microglial cells.