Interactive effects of zearalenone and its metabolites on cytotoxicity and metabolization in ovarian CHO-K1 cells

Zearalenone (ZEA) is a non-steroidal estrogen mycotoxin with high binding affinity to estrogen receptors. ZEA is rapidly absorbed and metabolized in vivo to alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL). So, mixtures of them may be present in biological systems and suppose a hazard to animals and human health. The aims of this study were to determine the cytotoxic effects of ZEA and its metabolites, alone and in combination in ovarian (CHO-K1) cells during 24,48 and 72 h by the MTT assay; and to investigate the metabolism of the CHO-K1 cells on ZEA, and its conversion into alpha-ZOL and beta-ZOL by CHO-K1 cell after 24 and 48 h of exposure. The IC50 value obtained for individual mycotoxins range from 60.3 to >100.0 mu M, from 30.0 to 33.0 mu M and from 55.0 to >75.0 mu M for ZEA, alpha-ZOL and beta-zoL, respectively. Cytotoxic interactions were assayed by the isobologram method, which provides a combination index (Cl) value as a quantitative measure of the degree of the three mycotoxin interaction. The CI values for binary combinations ranged from 0.56 +/- 0.15 (synergism at low concentrations) to 5.25 +/- 5.10 (addition at high concentrations) and tertiary combinations from 2.95 +/- 0.75 (antagonism at low concentrations) to 0.41 +/- 0.23 (synergism at high concentrations). The concentration of ZEA and its metabolites was determined with liquid chromatography coupled to the mass spectrometer detector-linear ion trap (LC-MS-LIT). The percentage of ZEA degradation ranged from 4% (24 h) to 81% (48 h). In the same conditions, alpha-ZOL and beta-ZOL concentration decreased from 8% to 85%. No conversion of ZEA in alpha-ZOL and beta-ZOL was detected. However, at 24 h of exposure other degradation products of ZEA and its derived were detected. (C) 2013 Elsevier Ltd. All rights reserved.