Protective effects of coffee against induction of DNA damage and pre-neoplastic foci by aflatoxin B1
Aim of the study was to investigate the protective properties of coffee towards aflatoxin B1 (AFB1) induced formation of pre-neoplastic hepatic foci and the identification of the constituents and molecular mechanisms that account for these effects.
Materials and methods
Rats consumed three different brews and were subsequently treated with AFB1 (0.75 mg/kg b.w. intraperitoneally). Ten weeks later, the numbers and areas of hepatic foci were determined. Furthermore, the impact of the brews on AFB1-induced DNA damage was quantified in single cell gel electrophoresis assays and the activities of drug metabolising enzymes and glutathione-related parameters were monitored. Additionally, single cell gel electrophoresis assay experiments were conducted with pure caffeine.
All brews reduced the frequencies of the hepatic foci. The most pronounced protection (reduction 82%) was seen with the caffeine containing metal and paper filtered brews. DNA migration was reduced between 65 and 75% with the caffeine containing brews. In additional experiments, clear protective effects were found with caffeine at dose levels that corresponded to those contained in the coffee. This observation indicates that the alkaloid accounts partly for the protective effects of coffee. Furthermore, our findings indicate that induction of UDP-glucuronosyltransferase contributes to the chemopreventive effects of coffee since all brews increased the activity of this detoxifying enzyme.