Genotoxic potential of methyleugenol and selected methyleugenol metabolites in cultured Chinese hamster V79 cells.

摘要

Methyleugenol, which belongs to the group of alkylbenzenes found in spices, fruits and colorants, is classified by the EU's Scientific Committee on Food as a genotoxic carcinogen. Cytotoxicity, genotoxicity and mutagenicity caused by methyleugenol and selected oxidative methyleugenol metabolites was determined in Chinese hamster lung fibroblasts V79 cells. Cytotoxicity was measured using 2 cell proliferation assays; water soluble tetrazolium salt (WST) 1 and sulforhodamine B (SRB). Genotoxicity was determined using single cell gel electrophoreses (comet assay) and the in vitro micronuclei test, while mutagenicity was investigated with the hypoxanthinephosphoribosyl transferase (hprt) assay. Methyleugenol and 1'-hydroxymethyleugenol showed no or marginal cytotoxic effects, but caused DNA strand breaks at concn. >=10 muM. The metabolites methyleugenol-2',3'-epoxide and 3'-oxomethylisoeugenol exhibited growth inhibitory properties with IC₅₀ values of 70-90 muM after 48 or 72 h of incubation. These metabolites enhanced cytotoxicity and DNA damage markedly after 1 h of incubation. Overall, no increase in formamidopyrimidine DNA glycosylase sensitive sites were detected using the comet assay. The metabolites 1'-hydroxymethyleugenol and methyleugenol-2',3'-epoxide exceeded the DNA strand breaking properties of the parent compound methyleugenol. However, only 3'-oxomethylisoeugenol and methyleugenol-2',3'-epoxide induced the formation of micronucleated cells in comparison to the negative control. These compounds were found to be weakly mutagenic at the hprt locus. Results suggested that phase I metabolites exceeded the cytotoxic and genotoxic properties of the parent compound methyleugenol.