Effect of vitamin E and polyphenols on ochratoxin A-induced cytotoxicity in liver (HepG2) cells

It has been shown that oxidative damage contributes to the wide range of toxic effects of the mycotoxin ochratoxin A (OTA). Therefore, we examined the effects of α-tocopherol (α-TOC) and different polyphenols – catechin (CAT), daidzein (DAI), epicatechin (EC), epigallocatechin gallate (EGCG), genistein (GEN), and quercetin (QUE) – on OTA-induced cytotoxicity in HepG2 liver cells. Incubation of HepG2 cells with increasing concentrations of OTA resulted in a dose- and time-dependent cytotoxicity as measured by the neutral red assay. Half lethal concentrations (LC50) of OTA were 35 and 10 μM after 48 and 72 h incubation, respectively. Incubation of HepG2 cells with image-TOC as well as with different polyphenols (exhibiting different antioxidant potency as determined by the FRAP, TEAC and DPPH assays) did not counteract OTA-induced cytotoxicity. These findings indicate that OTA may exert its toxic effects by affecting other hepatic mechanisms than those directly modulated by image-TOC and polyphenols.