Two novel 8,15-seco C(19)-diterpenoid alkaloids, nagarines A (1) and B (2), were isolated from the roots of Aconitum nagarum Stapf (Ranunculaceae), a folk herbal medicine used to treat rheumatism and arthritis in Southwestern China, Northern Burma and Northeastern India. They are the first C(19)-diterpenoid alkaloids possessing unprecedented opened D ring formed by the cleavage of the bond between C-8 and C-15. Compounds 1 and 2 showed certain inhibition activities of interleukin-6 in LPS-activated RAW 264.7 cells with IC(50) values of 72.63鈥?/-鈥?.39鈥痬uM and 52.98鈥?/-鈥?.50鈥痬uM, respectively. CI - Copyright (c) 2019 Elsevier B.V. All rights reserved.