engleski

Cytotoxicity and genotoxicity of versicolorins and 5-methoxysterigmatocystin in A549 cells

Aspergillus versicolor and A. flavus are primary colonisers in damp dwellings and they produce sterigmatocystin (ST) and aflatoxin B1 (AFB1), respectively. These hepatotoxic and carcinogenic mycotoxins and their precursors and derivates possess a furofuran ring, which has proven responsible for their toxicity. The aim of this study was to investigate the cytotoxicity and genotoxicity of versicolorin A (VER A) and versicolorin B (VER B), as the furofurane precursors of aflatoxins (AF) and sterigmatocystin (ST), and of 5-methoxysterigmatocystin (5-MET-ST), a methoxy derivative of ST, in human adenocarcinoma lung cells A549. The IC50 of the tested compounds were obtained by the cell proliferation MTT test as follows: 109 uM (VER A) ; 172 uM (VER B) and 181 uM (5-MET-ST). The comet assay and micronucleus test were used to assess their genotoxic potential after 24 h of treatment with concentrations corresponding to ½ and ¼ IC50 in comparison with AFB1 and ST, applied in concentrations corresponding to ½ IC50, as previously determined in A549 cells. DNA damage parameters assessed by the comet assay were tail length, tail intensity and tail moment, while the level of DNA damage in the micronucleus test was evaluated by the number of formed micronuclei (MN), nuclear buds (NB) and nucleoplasmic bridges (NPB) in 1000 binucleated cells. Considering the three comet parameters, all applied toxins exerted significant DNA damage compared to the control, while ST and VER B produced the highest DNA damage. All toxins provoked a statistically significant increase of MN, and a slightly decreased formation of NB and NPB. AFB1, ST and 20 μM VER A showed a statistically significant increase in all three micronucleus parameters compared to the control, and the highest increase in the number of MN occurred in cells treated with 50 μM VER A. The differences between results obtained by the micronucleus test and comet assay could be explained by the fact that the micronucleus detects irreversible DNA damage, which is usually correlated with the previously determined cytotoxic potential of the AFB1 precursors.

aflatoxins; sterigmatocystin; versicolorin A; versicolorin B; 5-methoxysterigmatocystin; bisfuran ring; comet assay; micronucleus test; A549 cells

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