In vitro endocrine-disrupting effects of the natural toxins Enniatins and Beauvericin on steroidogenesis

Enniatins (ENNs), such as ENN A, A1, B, B1, and Beauvericin (BEA) are mycotoxins produced by Fusarium fungi, mainly found in cereal grains and their products. The concern for their potential endocrine-disrupting activity is increasing; however, the effects of these compounds on steroidogenesis were never investigated simultaneously, especially by using a validated human in vitro method, which represents a gap in their risk assessment. In the frame of the European Partnership for the Assessment of Risks from Chemicals (PARC), we performed the H295R Steroidogenesis Assay (OECD TG 456), to assess effects of ENN A, ENN A1, ENN B, ENN B1 and BEA on steroid hormone synthesis. Cytotoxicity was firstly evaluated (10 pM – 10 μM); then, conditioned medium of H295R cells, treated with non-cytotoxic concentrations of the studied compounds, was analysed for the level of 17β-estradiol (E2) and testosterone (T) by ELISA assays. In addition, these same hormones as well as progesterone, aldosterone and cortisol were also analysed by HPLC-MS/MS. ENN A and A1 were the more cytotoxic compounds, while ENN B was the less toxic. The mycotoxins differently affected hormone synthesis at the highest non-toxic concentrations; in particular, ENN B significantly increased E2 levels whereas ENN A1 induced T synthesis. Progesterone was significantly induced by ENN A1 and BEA but was reduced by ENN B1. Aldosterone levels were increased by ENN A, B1 and BEA, whereas cortisol was induced by ENN B and reduced by ENN A1 and BEA. Overall, the results highlighted different modes of action of these natural toxins, contributing to fill data gaps on their endocrine-disrupting activity.