A b s t r a c t Beebread is processed pollen stored in the cells of the honeycomb, with the addition of various enzymes and honey, which undergoes lactic acid fermentation. Ethanolic extracts (EBBs) were obtained from three different samples of beebread from Poland. Assays were carried out for the determination of chemical composition (GC/MS), for the total phenolic content, and for the antioxidant and cytotoxic activities. The effects of beebread extracts (10, 20, 30, 50, 100 µg/mL) on the viability of the glioblastoma cell line (U87MG) were studied after 24 h, 48 h, and 72 h. Our results indicated a time-dependent inhibitory effect on the viability of U87MG cells treated EBB. The main inhibitory effect of EBB was observed after 72 h; EBB treatment decreased cell viability to 49 -66%.

In the present study, we investigated the influence of extracts from Salix spp. honey (ESH), beebread (EBB), and royal jelly (ERJ) with and without temozolomide (TMZ) on cell lines derived from a patient with diffuse astrocytoma (DASC), human glioblastoma multiforme (U87MG), and normal human astroglia (SVGp12). DASC was identified by immunocytochemistry. TMZ (20 μM) in combination with ESH (30 μg/mL), EBB (50 μg/mL), and ERJ (30 μg/mL) has stronger cytotoxic activity on U87MG cells after 72 h (20.0, 26.5, and 29.3% of control, respectively) than TMZ alone (about 6% of control). An increase of the cytotoxic effect and inhibition of DNA synthesis in SVGp12 were detected after administering TMZ with the studied extracts. NF-κB p50 subunit was reduced in U87MG cells after treatment with ESH (70.9%) and ESH + TMZ (74.7%). A significant decline of MMP-9 and MMP-2 secretion in cultured U87MG was detected after incubation with EBB (42.9% and 73.0%, respectively) and EBB + TMZ (38.4% and 68.5%, respectively). In conclusion, the use of bee products may increase the cytotoxic effect of TMZ in U87MG but also in SVGp12 cell line. It is important to note that the U87MG cells were sensitive to natural bee products, although there was no influence of natural bee products on the DASC cells.