A new alkaloid, polyschistine D (1), a new natural product, benzoyldeoxyaconine (2), and three known alkaloids, benzoylaconine (3), deoxyaconitine (4), and aconitine (5) have been isolated from the roots of Aconitum polyschistum Hand-Mazz collected Sichuan province in China. The structures of polyschistine D (1) and benzoyldeoxyaconine (2) were confirmed on the basis of their spectral data and the chemical correlations.In the previous paper, we have reported the isolation and structural elucidation of three new C19 diterpenoid alkaloids, polyschistine A, B and C from the roots of Aconitum polyschistum. Continued investigation of the constituents of this plants has led to the isolation of a new alkaloid, polyschistine D (1), a new natural product, benzoyldeoxyaconine (2) along with known alkaloids, benzoylaconine (3), deoxyaconitine (4) and aconitine (5). Polyschistine D showed the molecular ion peak at m/z 645.3136 (calc. 645.3136, C34 H47 NO11) in its high resolution mass spectrum. The 1H-nmr spectrum of 1 indicated the presence of an N-ethyl [δ 1.10 (3H, t, J=7.1 Hz)], an acetyl [δ 2.08 (3H,s)], four methoxyls [δ 3.26, 3.29, 3.31, 3.72 (3H each, s)] and five aromatic protons [δ 7.43-8.08 (5H)]. The signals at δ 4.92 (1H, dd, J=6.1 and 12.9 Hz, H-3) and at δ 5.02 (1H, d, J=5.1 Hz, H-14) suggested that the acetoxyl and benzoyloxy groups should be located at C-3 and C-14 positions, respectively. In the lower field there were two proton signals which could be assigned to H-6 [δ 4.08 (1H, d, J=7.1 Hz)] and H-15 [δ 4.55 (1H, dd, J=5.4 and 5.5 Hz)]. When the 13C-nmr spectrum of 1 was compared with those of benzoylaconine (3) and some other aconitine type alkaloids, the chemical shift pattern of 1 is very close to that of 3 except for a few changes (see Table I).All these spectral data for 1 indicated that polyschistine D should be assigned as 3-acetylbenzoylaconine. Finally, the structure of 1 was further confirmed by the following chemical correlation.Acetylation of 1 with Ac2O-Py gave an acetate (6) as a sole product which was also obtained by acetylation of benzoylaconine (3) with Ac2O. Furthermore, hydrolysis of 3-acetylaconitine (8) with dioxane-H2O (1 : 1) gave a hydrolyzed product which was identical with polyschistine D. From the results of the chemical reactions mentioned above, the structure of polyschistine D was established as 3-acetylbenzoylaconine (1). The compound (2) showed the molecular ion peak at m/z 587.3055 (calc. 587.3082, C32 H45 NO9) in its high resolution mass spectrum. The 1H-nmr spectrum of 2 disclosed the presence of an N-ethyl [δ 1.23 (3H, t, J=7.0 Hz)] and four methoxyls (δ 3.30, 3.33, 3.47 and 3.73 (3H each, s)]. The multiplet signal at δ 7.42-8.10 (5H) and the doublet signal at δ 4.98 (1H, H-14) suggested the presence of a benzoyloxy group to be situated at C-14 position. In comparison of the 13C-nmr spectral data of 2 with those of 3, the chemical shift pattern of 2 is very close to that of 3 except the C-3 signal (36.9 ppm) resonated in the higher field than that (71.0 ppm) of 3 and furthermore, C-2 and C-4 signals were appeared in the slightly higher field than those of 3, thereby suggesting the lack of the C-3 hydroxyl group.From the above mentioned ms, 1H- and 13C-nmr spectral data, the compound (2) should be benzoyldeoxyaconine which was obtained as a hydrolysis product of lipodeoxyaconine by Kitagawa et al. The structure of 2 was confirmed by the following chemical reaction. Thus, deoxyaconitine (4) was hydrolyzed with 10% aq. H2SO4 to afford a hydrolysis product [mp 230°C, m/z 587 (M+), C32 H45 NO9] which was identical with the natural product (2) in comparison of their spectral data. This is the first report on the isolation of benzoyldeoxyaconine (2) from natural sources.