Urolithin A is a metabolite generated from ellagic acid and ellagitannins by the intestinal microbiota after consumption of fruits such as pomegranates or strawberries. The objective of this study was to determine the cytoprotective capacity of this polyphenol in Neuro-2a cells subjected to oxidative stress, as well as its direct radical scavenging activity and properties as an inhibitor of oxidases. Cells treated with this compound and H₂O₂ showed a greater response to oxidative stress than cells only treated with H₂O₂, as mitochondrial activity (MTT assay), redox state (ROS formation, lipid peroxidation), and the activity of antioxidant enzymes (CAT: catalase, SOD: superoxide dismutase, GR: glutathione reductase, GPx: glutathione peroxidase) were significantly ameliorated; additionally, urolithin A enhanced the expression of cytoprotective peroxiredoxins 1 and 3. Urolithin A also acted as a direct radical scavenger, showing values of 13.2 μM Trolox Equivalents for Oxygen Radical Absorbance Capacity (ORAC) and 5.01 µM and 152.66 µM IC₅₀ values for superoxide and 2,2-diphenyss1-picrylhydrazyl (DPPH) radicals, respectively. Finally, inhibition of oxidizing enzymes, such as monoamine oxidase A and tyrosinase, was also detected in a dose-dependent manner. The cytoprotective effects of urolithin A could be attributed to the improvement of the cellular antioxidant battery, but also to its role as a direct radical scavenger and enzyme inhibitor of oxidases.

Cranberry (Vaccinium macrocarpon) and blueberry (Vaccinium myrtillus) juices are commonly consumed as a source of antioxidants. The aim of this study was to compare bioactivities as well as the differences in the polyphenol content and anthocyanin profile of both juices. Polyphenol and anthocyanin contents were quantified using spectrophotometric and chromatographic methods. Bioassays were carried out in terms of antioxidant properties in cell and cell free systems as well as inhibition of physiological enzymes that are targets involved in the prevention of chronic diseases (monoamine oxidase A, tyrosinase, acetylcholinesterase, α-glucosidase and dipeptidyl peptidase-4). Both juices contained a significant amount of anthocyanins (3.909 mg anthocyanins per mg extract for blueberry juice and 0.398 for cranberry juice) and also exhibited antioxidant properties against DPPH, superoxide radicals and hydrogen peroxide. These juices showed inhibitory effects on the enzymes, showing substantial potential as antioxidant, neuroprotective and anti-hyperglycaemic agents. The total anthocyanin and polyphenol content was higher in blueberry juice, which is indicative of a higher antioxidant activity. Both juices were also able to inhibit monoamine oxidase A, tyrosinase, α-glucosidase and dipeptidyl peptidase-4 in a dose-dependent manner. However, cranberry juice had a greater capacity than blueberry juice as an α-glucosidase inhibitor, revealing a similar activity to acarbose.

Date (Phoenix dactylifera L.) seeds are a valuable and abundant by-product with various potential food applications and a source of functional and bioactive ingredients. In this study, date seeds from eight cultivars (Ourous “OUR”, Tazizaout “TAZ”, Tazarzeit “TAR”, Tazoughart “TAG”, Ouaouchet “OUC”, Oukasaba “OUK”, Delat “DEL” and Tamezwertn'telet “TWT”) cultivated in the M'zab oasis (south of Algeria) were analyzed for their chemical and phytochemical compositions, antioxidant capacities and in vitro inhibition of some enzymes. Variations in chemical compositions were observed in the studied date seeds. The greatest contents of total phenolic compounds (476 mg GAE per g dw), total flavonoids (6.52 mg QE per g dw), anthocyanins (1.26 mg Q3GE per g dw), flavonols (3.36 mg Q3GE per g dw), proanthocyanidins (85.13 mg CE per g dw), and ascorbic acid were detected in the seeds of the TAG cultivar. All extracts manifested good antioxidant activities tested by ORAC and FRAP assays. The OUC and OUR extracts displayed the most potent antioxidant capacity against DPPH˙ free radicals (IC₅₀ = 37.30 μg ml⁻¹) and ABTS˙⁺ cation radicals (IC₅₀ = 13.89 μg ml⁻¹), respectively. The antioxidant activity evaluated through a xanthine/xanthine oxidase system demonstrated that the TAZ extract was more efficient as a superoxide radical scavenger (IC₅₀ = 9.08 μg ml⁻¹). Date seed extracts (DSE) exhibited inhibitory activities on enzymes, showing substantial potential as skin-whitening, neuroprotective, anti-hyperglycemic or anti-hyperlipidemic agents; the inhibitory potential was tested using tyrosinase (TYR), acetylcholinesterase (AChE), α-glucosidase (α-GLU) and lipase. All date seed cultivars were able to inhibit tyrosinase and α-glucosidase in a dose-dependent manner reaching the maximum inhibition.