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A comparative study of radioprotection by propolis and its polyphenolic/flavonoids compounds and synthetic protector AET in the mouse.

Considering that product of beekeeping possess antiinflamatory, immunomodulative, hemostimulative and antioxidant action, manifestitation of their radioprotective characteristic should be expected. In this study radioprotective effect of two preparation of propolis (water and ethanolic extract of propolis ; WSDP or EEP) and their polyphenolic compounds (caffeic acid, naringin, chrysin, quercetin) and synthetic protector 2-aminoethylisothiouronium bromide hydrobromide (AET) have been compared by examing DNA damage of lymphocytes using the single-cell gel electophoresis assay (comet assay) in irradiated mice.Healthy adult CBA mice were injected intraperitoneally (ip) with at dose of 100 mg kg-1 body weight and/or double distilled water or 1% solution of ethanol with water as control, for 3 conecutive days before or after whole body  -irradiation (WBI).Mice were exposed to whole body  -irradiation (WBI) with 9 Gy of 60Co  -radiation source. Thirty minutes after iradiation and/or treatment with test components we examined DNA damage of lymphocytes using the single-cell gel electophoresis assay (comet assay). The WBI of mice resulted in a significant elevation of DNA damage of lymphocytes as compared with unradiated mice. Pretreatment of mice with WSDP, EEP and its flavonoids as well as AET produced the reduction in oxidative DNA damage of lymphocytes as compared with radiation control, test components were ranked in decreasing order of potency as follows: naringin (2.98%) ; chrysin (16.84%) ; quercetin (33.67%) ; AET (48.52%) ; caffeic acid (49.51%) ; EEP (53.47%) ; and WSDP (54.46%). Treatment with preparations of propolis and its polyphenolic/flavonoids compounds and AET after irradiation resulted in a significant reduction of DNA damage as follows: caffeic acid (32.31%) ; AET (75.39%) ; naringin (78.46%) ; EEP (80%) ; chrysin (83.08%) ; quercetin (84.62%) ; and WSDP (89.24%). Propolis and its flavonoids (with exeption of caffeic acid) showed better radioprotective effect than AET. However, WSDP and EEP were the most effective against reduction of DNA damage of lymphocytes indicating synergistic antioxidative effect of different polyphenolic flavonoids components present in EEP or WSDP. Neither of test components induced any systemic toxicity, even at dose of 200 mg kg-1. Considering the low dose needed for protection and the high margin between the effective and toxic dose, propolis and its polyphenolic compounds may be promising for human radiation protection. The clinical potential of these protectors in cancer theraphy needs to be investigated.

propolis; flavonoids; radiation; radioprotection; mice; comet assay

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