Helenalin

Helenalin is a sesquiterpene lactone with potent anti-inflammatory and antitumor effects found in Arnica montana and Arnica chamissonis foliosa. It is the main compound responsible for the therapeutic effects of Arnica.

While it is not completely known how sesquiterpene lactones exert their anti-inflammatory effect, helenalin has been shown to selectively inhibit the transcription factor NF-κB, which plays a key role in regulating immune response, through a unique mechanism. In vitro, it is also a potent, selective inhibitor of human telomerase —which may partially account for its antitumor effects—, has anti-trypanosomal activity, and is toxic to Plasmodium falciparum.

Animal and in vitro studies have also suggested that helenalin can reduce the growth of Staphylococcus aureus and reduce the severity of S. aureus infection.

Helenalin is a highly toxic compound.