Seven new alkaloids [1, (+/-)-2, (+/-)-3, 4, and 5] and one new natural product (6), along with eight known analogues, were isolated from the tubers of Pinellia pedatisecta Schott. Their structures were determined by a comprehensive analysis of spectroscopic data, including HRESIMS, and electronic circular dichroism (ECD). In addition, the results of the bioactivity evaluation showed that compounds (+/-)-3, 6, and 9 exhibited significantly protective effects against A beta 25-35-induced PC-12 cell injury and ameliorated cell viabilities by decreasing the levels of the reactive oxidative species (ROS) and mitochondrial membrane potential (MMP).