Do fumonisins induce oxidative stress and mitochondrial dysfunction?

Fumonisins, particularly Fumonisin B1 (FB1), are potent mycotoxins that interfere with cellular homeostasis by disrupting lipid metabolism and bioenergetic pathways. Evidence from a wide range of experimental models suggests that these toxins possess significant pro-oxidative and mitochondriotoxic properties.

Evidence for oxidative stress

FB1 exposure consistently induces oxidative stress across multiple species and cell types.

• Oxidative biomarkers: Research in rodent models and human cell lines (e.g., HepG2 and U87MG) shows that FB1 triggers a surge in reactive oxygen species (ROS), leading to a significant increase in 8-hydroxy-2'-deoxyguanosine (8-OHdG), a primary marker for oxidative DNA damage.
• Antioxidant depletion: Toxicity is characterized by the depletion of critical antioxidant defenses, including glutathione (GSH), superoxide dismutase (SOD), and catalase, alongside elevated levels of malondialdehyde (MDA), indicating extensive lipid peroxidation.

Mitochondrial dysfunction and bioenergetics

Fumonisins act as mitochondrial toxicants by compromising the integrity of the electron transport chain and ATP production.

• Mitochondrial Membrane Potential (MMP): FB1 exposure leads to the depolarization and collapse of the MMP. This process is often an early event in FB1-induced apoptosis, observed in models ranging from C. elegans to porcine and murine tissues.
• Respiratory impairment: Toxicological studies indicate a decrease in oxygen consumption rates (OCR) and the inhibition of oxidative phosphorylation (OXPHOS). Mechanistically, this is linked to the downregulation of critical respiratory chain proteins, such as Ndufv1 and Cox4, which leads to a direct reduction in cellular ATP levels.

Mechanistic pathways

The primary mechanism of action for fumonisins is the inhibition of the enzyme ceramide synthase.

• This inhibition blocks the de novo sphingolipid synthesis pathway, leading to an accumulation of sphingoid bases (sphinganine and sphingosine).
• The resulting imbalance in the sphinganine-to-sphingosine ratio (Sa/So) is closely linked to ROS generation and mitochondrial membrane instability, providing a clear mechanistic link between lipid disruption and subsequent organelle failure.

Human and clinical implications

While direct clinical trials are ethically restricted, the evidence for these effects in humans is considered highly plausible.

• Epidemiological data from high-exposure regions link fumonisin consumption to increased oxidative biomarkers in human populations.
• Given that sphingolipid metabolism is highly conserved across species, the molecular disruptions observed in human hepatic and intestinal cell lines provide strong evidence that human tissues are susceptible to similar oxidative and mitochondrial damage.

Bottom line

Fumonisins induce oxidative stress and mitochondrial failure by inhibiting ceramide synthase and increasing ROS production. While most data originate from experimental models and human cell lines, the conservation of the target pathways makes these effects highly plausible in humans, potentially contributing to systemic toxicity in exposed individuals.