Assesment of the Radioprotective Effects of Propolis and Its Polyphenolic Compounds in Mice Using Micronucleus Test in Reticulocytes

Hematopoietic stem cells of mice are extremely sensitive to the effects of ionizing radiation. Genome damage lead to formation of micronuclei (MN) that remain in the cytoplasm, in contrast to the nucleus, which during maturation of erythrocytes is expelled from the cell. Micronuclei can be detected by sensitive staining methods using dyes which specifically bind to DNA. This principle is used in the so called in vivo MN test. The aim of this study was to evaluate the radioprotective effects of propolis and its polyphenolic compounds: quercetin, caffeic acid, chrysin and naringin on the level of genome damage in Swiss albino mice. The mice were treated for three days with the test substances (100 mg/kg, i.p.) and then radiated F067-irradiation at a dose 4 Gy. Non-irradiated animals were studied simultaneously. 48 h after irradiation blood samples were collected and blood smears were prepared. Following staining with acridine-orange, preparations were analysed under fluorescent microscope. In each sample 2000 reticulocytes were counted, and the total number and distribution of MN was determined. Groups of mice that were pre-treated with propolis and flavonoids had a smaller number of MN compared to the irradiated mice. Particularly effective radioprotector was quercetin. Test substances did not cause significant damage to the genome of non-irradiated mice. The obtained results speak in favour of further research of natural compounds with radioprotective properties, especially to clarify the mechanisms of their protective effect on DNA, and to establish their potential use as food supplements in patients who undergo radiotherapy or in subjects occupationally exposed to ionising radiation. (author).