Retronecine is a

pyrrolizidine alkaloid Pyrrolizidine alkaloids (PAs), sometimes referred to as necine bases, are a group of naturally occurring alkaloids based on the structure of pyrrolizidine. Pyrrolizidine alkaloids are produced by plants as a defense mechanism against insect he ...

found in a variety of plants in the genera ''

Senecio ''Senecio'' is a genus of flowering plants in the daisy family (Asteraceae) that includes ragworts and groundsels. Variously circumscribed taxonomically, the genus ''Senecio'' is one of the largest genera of flowering plants. Description Morp ...

'' and ''

Crotalaria ''Crotalaria'' is a genus of flowering plants in the family Fabaceae (subfamily Faboideae) commonly known as rattlepods. The genus includes over 700 species of herbaceous plants and shrubs. Africa is the continent with the majority of ''Crotalar ...

'', and the family

Boraginaceae Boraginaceae, the borage or forget-me-not family, includes about 2,000 species of shrubs, trees and herbs in 146, to 156 genera with a worldwide distribution. The APG IV system from 2016 classifies the Boraginaceae as single family of the order ...

. It is the most common central core for other pyrrolizidine alkaloids.

References

Pyrrolizidine alkaloids {{alkaloid-stub