The E-screen test and the MELN gene-reporter assay used for determination of estrogenic activity in fruits and vegetables in relation to pesticide residues

Abstract

Endocrine-disrupting chemicals (EDCs) may lead to adverse systemic effects by interfering with normal hormone homeostasis, and diet is considered to be among the main routes of EDC exposure. The present study investigated the total estrogenic activity of fruits and vegetables by calculating the 17-β-estradiol equivalent quantity (EEQ) using two in vitro tests: the human breast cancer cell line (MCF-7 BUS) proliferation assay (E-screen test) and the luciferase-transfected human breast cancer cell line (MELN) gene-reporter assay. Of the 24 analyzed fruits and vegetables, 14 contained from 1 to 4 pesticide residues in concentrations ranging from 0.02 to 1.19 ppm, whereas the other 10 did not contain any pesticide residues. The EEQ values for all positive samples ranged from 0.010 to 0.616 μg/100g for the above in vitro tests. Our study demonstrates that estrogenic activity was present in fruits and vegetables and that the concentration of allowable pesticide residues and EEQ values were positively correlated; however, no correlation was found by comparing the estrogenic activity and the intrinsic content of phytoestrogens obtained from the available literature. A theoretical adult dietary intake of 0.7-0.9 ng EEQ/L/day from fruits and vegetables was calculated.

Keywords: 17b-estradiol; COU; DMEM; Dulbecco’s Modified Eagle Medium; E-screen; E2; EC50; EDCs; EEF; EEQ; EFSA; EU; Estrogenic activity; European; European food safety authority; FCS; GC-MS; HPLC; In vitro test; LIG; MELN; MRLs; PE; Pesticides; RPE; SPE; TRANS; Tam; Vegetables; WHO; World Health Organization; coumestrol; effective concentration 50; endocrine disruptor compounds; estradiol equivalency factor; estradiol equivalency quantity; fetal calf serum; gas chromatography-mass spectrometry; high-performance liquid chromatography ISO, isoflavones; increased rate of luciferase gene expression; lignans; maximum residue levels; proliferative effect; rS; relative proliferative effect; solid phase extraction; spearman rank correlation; tamoxifen.