Sceletium tortuosum (also called kanna) is a South African herb that has been used by local people for many centuries as a mood enhancer, energy booster and natural anti-depressant. It can also be used to reduce stress an anxiety. The active ingredients in this herb are a variety of alkaloids, which influence the brain’s serotonin and dopamine receptors. The key alkaloid is mesembrine, which is thought to be a potent serotonin re-uptake inhibitor.