Parthenolide is a sesquiterpene lactone of the germacranolide class which occurs naturally in the plant feverfew (Tanacetum parthenium), after which it is named, and in the closely related tansy (Tanacetum vulgare).

[1] It is found in highest concentration in the flowers and fruit.

Parthenolide's molecular structure depiction is often incorrect regarding the stereochemistry of the epoxide, although X-ray single crystal structures are available.

[2][3] Lack of solubility in water and bioavailability limits the potential of parthenolide as a drug.

Parthenolide has a variety of reported in vitro biological activities, including: