Retrorsine

Retrorsine is a pyrrolizidine alkaloid found in various plant species, most notably those belonging to the *Senecio* genus, such as the common ragwort (*Senecio jacobaea*). These alkaloids are known for their hepatotoxic properties, meaning they can cause damage to the liver. Retrorsine itself is a crystalline solid and is considered one of the more toxic members of the pyrrolizidine alkaloid family.

The toxicity of retrorsine arises from its metabolic activation in the liver. Once ingested, it is converted into reactive pyrrolic esters that can bind to cellular macromolecules, including DNA and proteins. This binding can lead to cellular damage, necrosis, and ultimately, liver failure. Symptoms of retrorsine poisoning in animals and humans can include abdominal pain, jaundice, and ascites.

Due to its toxicity, plants containing retrorsine are considered poisonous, particularly to livestock that may ingest them inadvertently in pastures. Efforts are made to control the spread of these plants in agricultural areas. Research into retrorsine and other pyrrolizidine alkaloids continues to focus on understanding their toxic mechanisms, developing methods for their detection, and exploring potential (though limited) medicinal applications, given some related compounds have shown promise in cancer research. However, the significant toxicity remains a primary concern.