Pyrrolizidine alkaloids (PAs) are a class of naturally occurring compounds found in various plants, particularly in the Asteraceae and Boraginaceae families. They are characterized by a bicyclic structure containing a pyrrolizidine ring. PAs serve various ecological roles, including deterring herbivores due to their toxicity. In culinary contexts, they are not intentionally used but can contaminate herbal teas and supplements. PAs are known for their hepatotoxicity and potential carcinogenic effects, making them a significant concern in food safety and herbal medicine. Their sensory characteristics are not well-defined due to their toxicity, but they can impart bitterness. Health-wise, they are studied for their effects on liver function and potential links to cancer.