Protopine is an alkaloid found in Berberidaceae, Ranunculaceae, Rutaceae, Fumariaceae, and Papaveraceae with diverse biological activities. It inhibits platelet aggregation induced by ADP, arachidonic acid , platelet-activating factor (PAF), and collagen in rabbit platelet-rich plasma at a concentration of 100 μM. Protopine inhibits contraction of isolated rat thoracic aorta induced by norepinephrine and is a non-selective inhibitor of ICa, IK, IK1, and INa in guinea pig ventricular myocytes. Protopine inhibits the growth of H. pylori with an MIC50 value of 100 μg/ml. It reduces growth of PC3 and DU145 prostate cancer cells in a dose-dependent manner via induction of mitotic cell cycle arrest. Protopine (0.005 mg/kg) increases latency to first seizure in a mouse model induced by pentylenetetrazole .