Diterpenoid Alkaloids from the Roots of Aconitum sinomontanum and Their Evaluation of Immunotoxicity Jiao Zhang, Yuze Li, Yuwen Cui, Pu Jia, Zhenggang Yue, Bei Song and Xiaomei Song School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang 712046, China The College of Life Sciences, Northwest University, Xi’an 710069, China Department of Pharmacy, Xi’an Medical University, Xi’an 710021, China Shaanxi Collaborative Innovation Center of Chinese Medicinal Resource Industrialization, Shaanxi University of Chinese Medicine, Xianyang 712046, China The Second Affiliated Hospital of Shaanxi University of Chinese Medicine, Xianyang 712046, China Abstract: A new C 18-diterpenoid alkaloid, along with four known diterpenoid alkaloids have been isolated from the roots of Aconitum sinomontanum. Their structures were established as sinomontanine I (1), delcosine (2), lepenine (3), napelline (4), and kirinine B (5) by extensive spectroscopic techniques and chemical methods. The immunosuppressive effects of compounds 1 –4 were evaluated in vitro through ConA-induced or LPS-induced splenocyte proliferation, with IC 50 values of 8.909 μM, 1.515 μM ， 5.078 μM, and 1.167 μM ( ConA-induced ) ， or 3.661 μM, 4.417 μM, 5.129 μM, and 1.830 μM (LPS-induced), and compounds 1 –4 showed a significant cytotoxic effect with CC 50 values of 447.5 μM, 702.2 μM, 310.6 μM and 794.1 μM, respectively. The CC 50/IC 50 value of 2 and 3 suggested that these compounds were potential immunosuppressive agents for the treatment of autoimmune diseases characterized by arthritis, such as rheumatoid arthritis. Keywords: |