The Comparison of Honey Enriched with Laboratory Fermented Pollen vs. Natural Bee Bread in Terms of Nutritional and Antioxidant Properties, Protein In Vitro Bioaccessibility, and Its Genoprotective Effect in Yeast Cells.

The aim of the study was to compare the nutritional value and bioactivity of honey enriched with a 10% addition of natural bee bread and its substitutes obtained as a result of laboratory fermentation of bee pollen. Physicochemical parameters, antioxidant properties, as well as the bioaccessibility of proteins using an in vitro static digestion model were analyzed. The bioactivity of the obtained enriched honeys was tested using the yeast model. The research indicates the similarity of honeys with the addition of "artificial bee bread" to honey with natural ones. During in vitro digestion, good bioaccessibility of the protein from the tested products was demonstrated. The ability of the products to protect yeast cells against hydrogen superoxide-induced oxidative stress was demonstrated using a qualitative spot test, which was stronger in the case of enriched honey than in pure rapeseed control honey. Significant inhibition of the growth of both strains of yeast exposed to bee pollen-enriched honeys was also demonstrated. Furthermore, all tested samples showed significant genoprotective activity against the genotoxic effect of zeocin and the reduction of the number of DNA double-strand breaks by a minimum of 70% was observed.

In Vitro Evaluation of Antioxidant and Protective Potential of Kombucha-Fermented Black Berry Extracts against H2O2-Induced Oxidative Stress in Human Skin Cells and Yeast Model.

The fruits of R. nigrum L., A. melanocarpa Michx., and V. myrtillus L. are well-known natural plant materials with proven antioxidant activity. This work attempts to compare the antioxidant properties of extracts of these plants and ferments obtained during their fermentation using a consortium of microorganisms referred to as kombucha. As part of the work, a phytochemical analysis of extracts and ferments was carried out using the UPLC-MS method and the content of the main components was determined. The antioxidant properties of the tested samples and their cytotoxicity were assessed with the use of DPPH and ABTS radicals. The protective effect against hydrogen peroxide-induced oxidative stress was also assessed. The possibility of inhibiting the increase in the intracellular level of reactive oxygen species was carried out on both human skin cells (keratinocytes and fibroblasts) and the yeast Saccharomyces cerevisiae (wild-type strains and sod1Δ deletion mutants). The conducted analyses showed that the ferments obtained are characterized by a greater variety of biologically active compounds; in most cases they do not cause a cytotoxic effect, show strong antioxidant properties, and can reduce oxidative stress in both human and yeast cells. This effect depends on the concentration used and the fermentation time. The results obtained indicate that the tested ferments can be considered as an extremely valuable raw material protecting cells against the negative effects of oxidative stress.