New approaches for the risk assessment of pyrrolizidine alkaloids and their N-oxides present in teas and plant food supplements

Pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs) are plant toxins that can intentionally or unintentionally enter foods such as teas and plant food supplements (PFS). Upon consumption, PANOs can be converted into the more toxic PAs by gut bacteria and liver enzymes, yet limited information exists on the relative potency (REP) of PANOs compared to their corresponding PAs. This thesis applied non-animal experimental approaches combined with computer-based models to predict REP values for a series of PANOs. At dose levels relevant to human dietary intake, structural differences between PANOs were identified as the main factor influencing REP outcomes. Additionally, the thesis conducted a risk assessment of PAs/PANOs in various teas and PFS, revealing that some products may pose health concerns, even under short-term consumption scenarios. Overall, the findings provide tools for evaluating PANOs relative to PAs and highlight the need for risk management actions for PAs/PANOs in teas and PFS.