Petasin
Petasin is a natural chemical compound found in plants of the genus Petasites.  Chemically, it is classified as a sesquiterpene and is the ester of petasol and angelic acid.

Petasin is believed to be responsible, at least in part, for the anti-inflammatory effects of common butterbur (Petasites hybridus) extracts.

A 2021 study reported that petasin can inhibit tumor growth and metastasis in an animal model of cancer.

References

Sesquiterpenes
Carboxylate esters