A DFT study on degradation of aflatoxin B1 using some reactive oxygen and nitrogen species of plasma-activated water

The degradation mechanism of aflatoxin B1 using some reactive oxygen and nitrogen species of plasma-activated water have been investigated theoretically at the M06-2X/aug-cc-pVTZ//M06-2X/6-31G(d) level. Diffusion rate coefficient for all studied reactions was calculated to be ∼10⁹ M^-1 s^-1 and related activation energy was about 18-19 kJ mol^-1. The most favorable pathways of degradation were addition the vinyl bond of terminal furan ring. The apparent rate coefficients triggered by ^•OH, ozone, ^•O₂^-, ^•NO, and NO₃^- at 298.15 K were 10⁹, 10⁴, 10^-8, 10^-7, and 10^-41 M^-1 s^-1, implying that ^•OH and ozone play efficient role in the degradation while the effect of ^•O₂^-, ^•NO, and NO₃^- species can be ignored. Overall activation energies associated with the apparent rate coefficients for addition of ^•OH and ozone to the vinyl bond of terminal furan ring were 17.02 and 18.96 kJ mol^-1, while corresponding branching ratios were 82.8 % and 86.28 %, respectively. Ecotoxicity and mutagenicity of major degradation adducts have been estimated using the quantitative structure activity relationships methodologies. Aflatoxin B1 as mutagenic compound does not show acute and chronic toxicity to earthworm and aquatic organisms but was toxic for rats. Mutagenicity of the most abundant oxidation products was negative while the toxicity of them was less than AFB1.