Helenin is a phytochemical mixture found in many plant species, including the Inula helenium (elecampane) of the family Asteraceae. It is a mixture of two isomeric sesquiterpene lactones, alantolactone and isoalantolactone.
The compounds of every Wikipedia article carrying a Chembox or a Drugbox, refreshed daily, with the values their infoboxes give. The pages need JavaScript; the API does not.