Mesembrenone is an alkaloid found in Sceletium tortuosum (Kanna) and minor constituent of Lampranthus aureus and Lampranthus spectabilis. Mesembrenone is a MAO-B inhibitor, that means it blocks the enzyme that breaks down dopamine in the brain resulting in increased dopamine levels when consumed, either orally, smoked, or snorted.
It is a potent (IC<sub>50</sub> < 1 üM) selective inhibitor of the serotonin transporter (SERT) (that is, a selective serotonin reuptake inhibitor; K<sub>i</sub> = 27 nM) and also a phosphodiesterase 4 (PDE4) inhibitor (K<sub>i</sub> = 470 nM).
Other alkaloids present in Kanna include: