Protective effect of xanthohumol against genotoxicity of benzo(a)pyrene (BaP), 2-amino-3methylimidazol[4,5-f]quinoline (IQ) and tert-butyl hydroperoxide (t-BOOH) in HepG2 human hepatoma cells

National Institute of Biology, Department for Genetic Toxicology and Cancer Biology, Vecna pot 111, 1000 Ljubljana, Slovenia.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis (Impact Factor: 3.68). 09/2007; 632(1-2):1-8. DOI: 10.1016/j.mrgentox.2007.03.013
Source: PubMed


Xanthohumol is the major prenylated flavonoid present in the hop plant Humulus lupulus L. (Cannabinaceae) and a common ingredient of beer. Recently, xanthohumol has gained considerable interest due to its potential cancer chemo-preventive effect. The aim of this study was to reveal the possible anti-genotoxic activity of xanthohumol in metabolically competent human hepatoma HepG2 cells, by use of the comet assay. Xanthohumol by itself was neither cytotoxic nor genotoxic to the cells at concentrations below 10microM. However, a significant protective effect against the pro-carcinogens benzo(a)pyrene (BaP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was observed at concentrations as low as 0.01microM. In cells treated with xanthohumol in combination with tert-butyl hydroperoxide (t-BOOH) - an inducer of reactive oxygen species (ROS) - no protective effect was observed and xanthohumol also showed no significant scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. On the other hand, HepG2 cells pre-treated with xanthohumol showed significantly reduced levels of t-BOOH-induced DNA strand breaks, indicating that its protective effect is mediated by induction of cellular defence mechanisms against oxidative stress. As xanthohumol is known to be an effective inhibitor of cytochrome P450 enzymes and an inducer of NAD(P)H: quinone reductase (QR), our findings can be explained by an inhibition of metabolic activation of pro-carcinogens and/or by induction of carcinogen-detoxifying and anti-oxidative enzymes by xanthohumol. These results provide evidence that xanthohumol displays anti-genotoxic activity in metabolically competent human cells.

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Available from: Bojana Zegura, Mar 24, 2014
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    • "All concentrations used were established according to the literature data [Lee et al., 2002; Barcelos et al., 2007; Plazar et al., 2007]. Benzo(a)pyrene: Benzo(a)pyrene (B(a)P, Sigma, CAS: 50-32-8). "
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