Biochemical, sensory characterization of bee bread and in vitro determination of its biological activity

Past and present research demonstrates that natural bee products can be used as preventative or therapeutic against many diseases. Apitherapy, a traditional, complementary, and functional medicine practice, is a natural treatment method that utilizes bee products (honey, beeswax, propolis, bee pollen, royal jelly, bee bread, bee venom, apilarnil, and beehive air). Bee bread (perga), a relatively lesser-known bee product used in apitherapy, is a product of the mixture of flower nectar and pollen collected by bees with their own bodily secretions, honey, and beeswax, which is then stored in honeycomb cells and subsequently formed through lactic acid fermentation under anaerobic conditions with the help of bacteria and yeast. In this study, it was aimed to determine the physicochemical, biochemical and sensory properties of bee bread, which has attracted attention in recent years, and to investigate its biological activity by cytotoxicity with MTT and NRU analyses, genotoxicity and antigenotoxicity with COMET and MN tests, and epigenetic effects with total 5mC determination. Identification of aroma substances and their percentage ratios were carried out using the SPME technique on the GC-MS device. The total protein content of bee bread was found as 19.06%; moisture content was found as 17.89%; ash content was found as 2.53%; fat content was found as 9.16%. Total phenolic content of bee bread was found as 9.91 mg GAE/g, total flavonoid content was found as 0.32 mg QE/g. According to antioxidant capacity analyses of bee bread, ABTS.+ capacity value was determined as 0.55 mM Trolox/mL, CUPRAC value was determined as 12.97 mg Trolox/g. When the results obtained in the study were compared with the results of previous studies, it was determined that although there were minor differences, the results supported each other. The physicochemical, antioxidant capacity and sensory characterization properties of bee bread vary depending on many parameters such as the region where the product is collected, climate, vegetation, collection and storage method, bee species, and the condition of the bee colony. In order to evaluate its biological activity, it was determined that the exposure concentrations of bee bread (6.25-800 µg/mL) did not show cytotoxic effect according to the MTT and NRU cytotoxicity tests performed on BEAS-2B and A549 cells. According to the genotoxicity results evaluated with the comet test, bee bread applied at concentrations of 100, 200, 400, 800 µg/mL did not show a genotoxic effect on BEAS-2B and A549 cells compared to the untreated negative control group, on the other hand, when its antigenotoxic effect was evaluated in cells subjected to DNA damage with H2O2, it was determined that it reduced the damage compared to the positive control. According to the genotoxicity results evaluated by the MN test, bee bread applied at concentrations of 100, 200, 400, and 800 µg/mL did not cause a statistically significant increase in human lymphocyte cells compared to the untreated negative control group and did not cause a genotoxic effect. On the other hand, when its antigenotoxic effect was evaluated in cells subjected to DNA damage with H2O2, it reduced the damage compared to the positive control treated with H2O2 alone. Following 24-hour application of bee bread to BEAS-2B cells, a decrease in total genomic DNA methylation was determined in all treatment groups compared to the control group. The results obtained revealed that bee bread exhibits cell and DNA damage-reducing activity due to its strong antioxidant activity.