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Diazinon is an organophosphorus pesticide, which may have potential toxic effects on the liver and immune system; however, the underlying mechanisms remain mostly unidentified. This work is aimed at evaluating the oxidative stress and cell cycle alterations elicited by low-dose diazinon in a rat liver cell line (BRL-3A) and spleen mononuclear cells (SMC) from Wistar rats. Diazinon (10–50 μM) caused early reactive oxygen species (ROS) generation (from 4 h) as well as increased O2•- level (from 0.5 h), which led to subsequent lipid peroxidation at 24 h, in BRL-3A cells. In SMC, diazinon (20 μM) produced similar increases in ROS levels, at 4 and 24 h, with the highest O2•- level being found at 4 h. Low-dose diazinon induced G1-phase arrest and cell death in hepatic cells and SMC. Therefore, diazinon could affect the liver and the immunological system through the premature oxidative stress induction. Abbreviations: O2•-: superoxide anion radical; ROS: reactive oxygen species; SMC: spleen mononuclear cells; TBARS: thiobarbituric acid reactive substances [ABSTRACT FROM AUTHOR]

Human oral exposure to aflatoxin B1 (AFB1) and fumonisin B1 (FB1) is associated with increased hepatocellular carcinoma. Although evidence suggested interactive AFB1-FB1 hepatotoxicity, the underlying mechanisms remain mostly unidentified. This work was aimed at evaluating the possible AFB1-FB1 interplay to induce genetic and cell cycle toxicities in BRL-3A rat hepatocytes, reactive oxygen species (ROS) involvement, and the AFB1 metabolizing pathways cytochrome P450 (CYP) and arachidonic acid (ArAc) metabolism as ROS contributors. Flow cytometry of stained BRL-3A hepatocytes was used to study the cell cycle (propidium iodide), ROS intracellular production (DCFH-DA, HE, DAF-2 DA), and phospholipase A activity (staining with bis-BODIPY FL C11-PC). The CYP1A activity was assessed by the 7-ethoxyresorufin-O-deethylase (EROD) assay. Despite a 48-h exposure to FB1 (30 μM) not being genotoxic, the AFB1 (20 μM)-induced micronucleus frequency was overcome by the AFB1-FB1 mixture (MIX), presumably showing toxin interaction. The mycotoxins blocked G1/S-phase, but only MIX caused cell death. Overall, the oxidative stress led these alterations as the pretreatment with N-acetyl-l-cysteine reduced such toxic effects. While AFB1 had a major input to the MIX pro-oxidant activity, with CYP and ArAc metabolism being ROS contributors, these pathways were not involved in the FB1-elicited weak oxidative stress. The MIX-induced micronucleus frequency in N-acetyl- l-cysteine pretreated cells was greater than that caused by AFB1 without antioxidants, suggesting enhanced AFB1 direct genotoxicity probably owing to the higher CYP activity and ArAc metabolism found in MIX. The metabolic pathways modulation by AFB1-FB1 mixtures could raise its hepatocarcinogenic properties. [ABSTRACT FROM AUTHOR]

The toxicity of FB1 is usually explained through theenzymaticdisruption of lipidic metabolism. However, it may lie in the thermodynamicsof the membrane and its cooperative phase behavior rather than inthe activity of individual proteins. Here, we investigate the effectsof FB1 at the molecular and mesoscopic levels in FB1–phospholipidmixed Langmuir films. Mean molecular area vs FB1 molar fractions (xFB1) and phase diagram analysis allowed us todefine miscibility conditions and phase states at different xFB1. Surface potential measurements, evaluatedas a function of the molecular packing and xFB1, revealed the FB1-induced change in the collective dipolarreorientation leaded to neutralization of charged films. Size, shape,and distribution of 2D-domain analysis from epifluorescence data suggestedthe increase in the mixing entropy and film relaxation rate. Finally,PM-IRRAS revealed the orientation of FB1 with the amine end (zwitterionicand negatively charged monolayers) or the tricarballylic acid end(positively charged monolayers) pointing to the air. The globular-extendedconformational equilibrium of FB1 is dynamically defined by the membranecharge becoming a toxicity enhancing factor. The specificity of thetoxin–protein interaction might also be perturbed by the FB1-inducedremodeling of the membrane topography by affecting the raft-like platformswhere membrane enzymes are considered to be located. [ABSTRACT FROM AUTHOR]

Human oral exposure to aflatoxin B 1 (AFB 1 ) and fumonisin B 1 (FB 1 ) is associated with increased hepatocellular carcinoma. Although evidence suggested interactive AFB 1 -FB 1 hepatotoxicity, the underlying mechanisms remain mostly unidentified. This work was aimed at evaluating the possible AFB 1 -FB 1 interplay to induce genetic and cell cycle toxicities in BRL-3A rat hepatocytes, reactive oxygen species (ROS) involvement, and the AFB 1 metabolizing pathways cytochrome P450 (CYP) and arachidonic acid (ArAc) metabolism as ROS contributors. Flow cytometry of stained BRL-3A hepatocytes was used to study the cell cycle (propidium iodide), ROS intracellular production (DCFH-DA, HE, DAF-2 DA), and phospholipase A activity (staining with bis-BODIPY FL C11-PC). The CYP1A activity was assessed by the 7-ethoxyresorufin-O-deethylase (EROD) assay. Despite a 48-h exposure to FB 1 (30 μM) not being genotoxic, the AFB 1 (20 μM)-induced micronucleus frequency was overcome by the AFB 1 -FB 1 mixture (MIX), presumably showing toxin interaction. The mycotoxins blocked G1/S-phase, but only MIX caused cell death. Overall, the oxidative stress led these alterations as the pretreatment with N-acetyl-l-cysteine reduced such toxic effects. While AFB 1 had a major input to the MIX pro-oxidant activity, with CYP and ArAc metabolism being ROS contributors, these pathways were not involved in the FB 1 -elicited weak oxidative stress. The MIX-induced micronucleus frequency in N-acetyl-l-cysteine pretreated cells was greater than that caused by AFB 1 without antioxidants, suggesting enhanced AFB 1 direct genotoxicity probably owing to the higher CYP activity and ArAc metabolism found in MIX. The metabolic pathways modulation by AFB 1 -FB 1 mixtures could raise its hepatocarcinogenic properties., (© 2017 Wiley Periodicals, Inc.)