Cytotoxicity induced by ochratoxin A, zearalenone and α-zearalenol: effects of individual and combined treatment
Mycotoxins, a series of secondary metabolites generated from moulds, mainly come from food and feed contaminated in the field, during drying and subsequent storage. Among all the mycotoxins, ochratoxin A (OTA), zearalenone (ZEA) and α-zearalenol (α-ZOL) have evoked great concern owing to their high occurrence and serious harm to human health. The co-occurrence of OTA, ZEA and α-ZOL was found in animal feed and milk. The previous reports indicated that the co-occurrence of mycotoxins could increase their cytotoxicity. The aim of the present study was to investigate the cytotoxicity of combined mycotoxins of OTA, ZEA and α-ZOL on human Hep G2 cells by using the tetrazolium salt (MTT) assay and the isobologram analysis. Statistical analysis of data was carried out using SAS9.2, statistical software package. Our results demonstrated the significant (P<0.05) cytotoxic effects of the two-toxin combination and the three-toxin combination on Hep G2 cells in a time- and concentration-dependent manner. The IC50 (inhibit concentration equal to 50%) values of Hep G2 treated with individual mycotoxin after 24 h, 48 h and 72 h of exposure were 1.86-8.89 μM, 29.48-55.79 μM, 20.91-52.30 μM for OTA, ZEA and α-ZOL, respectively. The combined indexes (CI) were 2.73–7.67 for OTA+ ZEA and 1.23–17.82 for OTA+ α-ZOL after 24 h, 48 h and 72 h of exposure at all inhibit concentration(IC) levels (IC10-IC90), indicated an antagonism. The CIs of ZEA+ α-ZOL were 1.29–2.55 after 24 h and 72 h of exposure (IC10-IC90), indicated an antagonism. The CIs of ZEA+ α-ZOL were 0.74-1.68 after 48 h of exposure, indicated an antagonism (IC10-IC40), additive effect (IC50-IC70) or synergism (IC80-IC90). The CIs were 1.41–14.65 for OTA+ ZEA+ α-ZOL after 24 h, 48 h and 72 h of exposure (IC10-IC90), indicated an antagonism. In conclusion, OTA was more toxic than ZEA and α-ZOL. The combined mycotoxins of OTA and ZEA, OTA and α-ZOL, OTA, ZEA and α-ZOL showed antagonism. And the combined mycotoxins of ZEA and α-ZOL showed antagonism, additive effect and synergism at different concentrations. But the result of combined mycotoxins affected by type of cell used endpoint of cytotoxicity, analysis assay of interaction, and other factors. So interaction of combined mycotoxins should be determined or re-validated in continuously toxicological data.
Keywords: ochratoxin A; zearalenone; α-zearalenol