Interaction effects of Fusarium enniatins (A,A1, B and B1) combinations on in vitro cytotoxicity of Caco-2 cells

Foodstuff is usually contaminated by more than one mycotoxin, however toxicological data are lacking as regards the effects in combinations compared to their individual effect. This study investigated the in vitro effects of enniatins (ENs) A, A₁, B and B₁, alone and in combinations, on Caco-2 cells viability by MTT assay after 24 h of exposure. Cells were treated with concentrations ranging from 0.9 to 15.0 μM, individually and in combination of two, three and four mycotoxins. Dose–response curves were generated for each mycotoxin and the isobologram method was used to determine the interactive effects of tested mixtures. Tested ENs produced significant cytotoxic effects both individually and in combination in a dose-dependent manner. IC₅₀ values obtained for all individually tested mycotoxins ranged from 1.3 to >15 μM. In ENs combination tests, synergistic effect in Caco-2 viability are observed for EN B + EN A₁, EN B₁ + EN A₁ and EN A + EN A₁ + EN B (CI = 0.33–0.52). All other combinations showed additive effect at medium and high affected fraction with exception of lower fraction affected and the EN B + EN B₁ mixture that produced antagonistic effect (CI = 1.76–10.36). The use of combination index-isobole method could help to better understand the potential interaction between co-occurring mycotoxins and may contribute to their risk assessment.