South African Kanna (Sceletium) is a plant native to South Africa that has been used for a wide variety of health benefits by the local population for millenia. The alkaloids mesembrine, mesembrenone, mesembrenol and tortuosamine present in the plant are thought to give it its beneficial effects.
 
Sceletium generally contains about 1–1.5% total alkaloids, Mesembrine is a major alkaloid present in Sceletium tortuosum and serves as a serotonin reuptake inhibitor with less prominent inhibitory effects on phosphodiesterase 4 (PDE4). Mesembrenone on the other hand serves as a more balanced serotonin reuptake inhibitor and PDE4 inhibitor. Sceletium is also reported to be an acetylcholinesterase inhibitor and cannabinoid agonist.