Purity >98%. Tetrandrine is a natural, bis -benzylisoquinoline alkaloid first isolated from the root of the plant R. stephania tetrandrae . It acts a calcium channel blocker (IC50 s = 8 and 20 μM for L-type and T-type calcium channels, respectively) and induces apoptosis, which produces anti-inflammatory, immunomodulating, anti-proliferative, and free radical scavenging effects. Tetrandrine has also been shown to increase glucose utilization by enhancing hepatocyte glycogen synthesis.