Four new diterpenoid alkaloids from <i>Aconitum sczukinii</i>

Four new diterpenoid alkaloids, including two new C₂₀-diterpenoid alkaloids, sczukinitines A–B (<b>1</b>–<b>2</b>), and two new C₁₉-diterpenoid alkaloids, sczukinidines A–B (<b>3</b>–<b>4</b>), along with five known ones (<b>5</b>–<b>9</b>) were isolated from the roots of <i>Aconitum sczukinii</i>. The structures of the compounds were elucidated based on spectroscopic analyses, including HR-ESI-MS and 1D, 2D NMR.