Protective effect of broccoli, onion, carrot and licorice extracts againstcytotoxicity of N-nitrosamines evaluated by 5 bromo-2 '-deoxy-uridine (BrdU) assay and determination of total cellular DNA content

The protective effect of nine fruit and vegetable aqueous (H2O) and ethanol ic (EtOH) extracts against cytotoxicity of N-nitrosodimethylamine (NDMA), N -nitrosopyrrolidine (NPYR), N-nitrosodibuthylamine (NDBA) and N-nitrosopipe ridine (NPIP) was evaluated by 5-bromo-2'-deoxy-uridine (BrdU) assay and de termination of total cellular DNA content. When BrdU assay has been used, t wo vegetable extracts exhibited a protective effect(to 100% of DNA synthesi s) and a stimulation of cellular proliferation (> 100% of DNA synthesis) in decreasing order against NDMA and NPYR: onion(H2O) > carrot(EtOH). Licoric e,,, extract showed only a protective effect against NDBA and NPIP and broc coliEtOH extract exhibited a protective effect against all N-nitrosamines t ested at concentrations of 0.1 mg/ml. When determination of total cellular DNA content has been used, a significant protective effect and stimulation of cellular proliferation was found for three vegetable extracts against ND MA and four against NPYR. Decreasing order against NDMA and NPYR were, resp ectively, onion(EtOH) >broccoli(EtOH)> onion(H2O) >licorice(H2O) and Onion( EtOH) > broccoli(EtOH) > onion(H2O) > carrot(EtOH) > licorice(H2O). With th e concentrations used, a protective effect and stimulation of cellular prol iferation was also found for broccoli(EtOH) and carrot(EtOH) extracts again st NDBA and for carrot(EtOH) extract against NPIP.