Cucurbitin is an

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

and a

carboxy In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl group (e.g. ...

pyrrolidine Pyrrolidine, also known as tetrahydropyrrole, is an organic compound with the molecular formula (CH2)4NH. It is a cyclic secondary amine, also classified as a saturated heterocycle. It is a colourless liquid that is miscible with water and most ...

that is found in ''

Cucurbita is a genus of herbaceous fruits in the gourd family, Cucurbitaceae (also known as ''cucurbits'' or ''cucurbi''), native to the Andes and Mesoamerica. Five edible species are grown and consumed for their flesh and seeds. They are variously know ...

'' seeds. Cucurbitin causes degenerative changes in the reproductive organs of parasitic flatworms called flukes.Annual Reports in Medicinal Chemistry
Cornelius Kennedy Cain, 1966, Academic Press,

References

2,3-Diaminopropionic acids Pyrrolidines Plant toxins {{heterocyclic-stub