Vulpinic acid is a natural product first found in and important in the symbiosis underlying the biology of lichens.

One biological function of vulpinic acid may be as a repellent that lichens have evolved to deter grazing by herbivores.

[10] It had been shown previously to protect human skin cells in tissue culture against ultraviolet B-induced damage.

[11] Humans have exploited its mammalian toxicity, using lichens containing high amounts of the chemical (e.g., Letharia vulpina) to poison wolves in Scandinavia, sometimes adding it to baits containing reindeer blood and glass.

[3] Vulpinic acid has some antibacterial activity against gram-positive bacteria, and has been shown to disrupt cell division in MRSA.