Gramine (also called donaxine) is a naturally occurring indole alkaloid present in several plant species.

Gramine may play a defensive role in these plants, since it is toxic to many organisms.

[1] Gramine has been found in the giant reed, Arundo donax,[2][3] Acer saccharinum (Silver Maple),[4] Hordeum,[1][3] (a grass genus that includes barley) and Phalaris[3] (another grass genus).

Gramine has been found to act as an agonist of the adiponectin receptor 1 (AdipoR1).

[6] Numerous studies have been done on the toxicity of gramine to insects harmful to crops in order to assess its potential use as an insecticide.