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a specific chemical configuration which is common to a number of naturally occurring compounds called the pyrrolizidine alkaloids. Common plant sources are in the genera Crotalaria, Echium, Heliotropium, Senecio.
the disease caused by poisoning with pyrrolizidine alkaloids. The hepatic lesion tends to be chronic and is characterized by necrosis, megalocytosis of hepatocytes due to inhibition of mitosis, biliary ductule, proliferation, vasculitis and perivenous fibrosis. Lesions are most severe in the liver and result in the syndrome of jaundice, photosensitization and hepatic encephalopathy. Some alkaloids cause lung damage characterized by edema, fibrosis, alveolar epithelialization and emphysema, e.g. jaagsiekte. Megalocytosis also occurs in the kidney and there may be extensive nephrosis. There may also be ulceration of the mucosa of the esophagus, stomach and intestines and carcinogenesis is a feature in some animals. An incidental pathogenesis is a concurrent chronic copper poisoning causing the disease toxemic jaundice.