ABSTRACT
Pyrrolizidine alkaloids (PAs) are a class of secondary metabolites synthesized by plants as a defense mechanism against invertebrate herbivores such as caterpillars (Utetheisa ornatrix). Characterized by a pyrrolizidine structure (composed of two fused five-atom rings bearing one or two hydroxyl groups that may be further esterified with necic acids) (see Figure 104.1), PAs are hepatotoxic, pneumotoxic, genotoxic/tumorigenic compounds with the capacity to cause poisoning (i.e., pyrrolizidine alkaloidosis) in animals as well as humans upon ingestion, leading to hepatocyte necrosis, cirrhosis, liver failure, and hepatic carcinoma. In particular, PAs contained in contaminated food sources (grain, flour, bread, meat, milk, honey, tea, etc.), herbal medicines, and dietary supplements pose a serious health risk to people who are unaware of PA's toxicity [1].
