Mesembryanthemum tortuosum

Mesembryanthemum tortuosum, often referred to by its synonym Sceletium tortuosum, is a succulent plant in the family Aizoaceae, native to the Cape Provinces of South Africa. In English, it is commonly known as kanna (a name derived from the plant's local Khoekhoe name), or alternatively kougoed, an Afrikaans term meaning 'chewable thing', originally referring to a fermented preparation of the plant that was chewed by the Indigenous Khoisan peoples for its medical and psychoactive effects. The plant contains more than 25 alkaloids, with mesembrine-type alkaloids predominating.

It has likely been used by South African pastoralists and hunter-gatherers for thousands of years. The first written account of its use dates to 1662, recorded by Jan van Riebeeck. The dried plant was traditionally chewed with the saliva swallowed. It has also been prepared in various forms, including gel caps, teas, tinctures, snuff, and smoked. It is used in traditional medicine. It is currently classified as a species of least concern, though wild populations face pressure from overharvesting.

Modern research focuses on the potential of its bioactive alkaloids for mental disorders. Limited data suggests shows no statistically significant effect on reducing anxiety symptoms. Two specific compounds derived from it are in clinical trials for anxiety/depressive disorders and premature ejaculation. Clinical data are currently insufficient to support the use of kanna for any specific medical indication. Kanna shows potent inhibition of the serotonin transporter and PDE4. It promotes monoamine release through vesicular monoamine transporter-2 (VMAT2) upregulation, with serotonin reuptake inhibition as a secondary action. It is used as a party drug for its euphoric effects.