The genus Rhodiola (Crassulaceae) consists of nearly 200 species and among them Rhodiola rosea L. is the best known. The plant is indigenous to the arctic regions of eastern Siberia, but it is also found in the northern parts of Europe and Alaska. Similar to Siberian ginseng, the root of R. rosea is traditionally used as a tonic in Russia, and as an antidepressant and anti inflammatory drug. Rosiridin, a monoterpene, has mainly stimulant properties and elicits the greatest monoamine inhibitory effect. Rosiridin is noted as specifically inhibiting MAO-B to a significant extent (over 80%), and shows potential beneficial effect in depression and senile dementia.