Evaluation of the genotoxic, antigenotoxic and teratogenic effects of water-based Turkish propolis, and its chemical composition

Abstract

Propolis exhibits a wide range of biological properties, including antimicrobial, anti-inflammatory, anti-allergic, antioxidant, anticancer, antitumour and antigenotoxic effects. It mostly contains flavonoids and phenolic compounds. Since propolis is used for therapeutic purposes, its effects should be investigated in detail. This study aims to evaluate the potential genotoxic and antigenotoxic effects of water-based organic Turkish propolis using the Hen's Egg Test for Micronucleus Induction (HET-MN), as well as its chemical composition (by HPLC-DAD). Three different doses (500 µg per egg, 250 µg per egg and 50 µg per egg) of propolis were injected into fertilized chicken eggs at incubation day 8 to determine genotoxic effects. Cyclophosphamide (50 µg per egg) was used as genotoxic agent. In addition, propolis doses were administered together with cyclophosphamide to determine the antigenotoxic effect. Ascorbic acid (50 µg per egg) was used as antigenotoxic agent. Embryonic peripheral blood smears were prepared and stained on 11th day of incubation. The frequencies of micronucleus and nuclear abnormalities in erythrocytes were determined using light microscopy. According to the statistical analysis, water-based organic Turkish propolis did not show any genotoxic effect at the three tested doses. However, only the lowest dose of the propolis showed antigenotoxic effect. In addition, embryos were macroscopically examined for teratogenicity. To evaluate bone development, some embryos were stained with Alizarin Red S, and no teratogenic effects or delays in bone development were observed. Nevertheless, all three propolis doses caused significant decreases in both the number of live embryos and relative embryo weight. HPLC-DAD analysis revealed that benzoic acid was the main component (272.5 µg ml⁻¹), followed by caffeic acid (265.4 µg ml⁻¹) and ferulic acid (53.8 µg ml⁻¹). While the anti-genotoxic effect of low doses of propolis may be attributed to its high antioxidant content, its effect on reducing embryo weight at high doses may be related to its high caffeic acid content. Our findings suggest that low doses of propolis are relatively safe, whereas exposure to high doses could pose potential risks.