Bioassay-guided fractionation of an n-BuOH extract of the lateral roots of Aconitum carmichaeli DEBX. led to the isolation of 5 cardioactive C 19 -diterpenoid alkaloids: N-deethylaconine (1), beiwutinine (2), hypaconine (3), mesaconine (4), and 15α-hydroxyneoline (5). N-Deethylaconine and beiwutinine are new aconitinetype C 19 -diterpenoid alkaloids. Hypaconine was isolated from this species for the first time. Among them, mesaconine, hypaconine, and beiwutinine showed the strongest cardiac actions on the isolated perfused bullfrog heart. Furthermore, mesaconine has protective effects, including improved inotropic effect and left ventricular diastolic function, on myocardial ischemia-reperfusion injury in rat at a dose of 10 −9 mol/L. However, mesaconine has almost no effect on heart rate.

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Thirty three C 19-diterpenoid alkaloids, twenty-two prepared from known C 19-diterpenoid alkaloids and eleven isolated from Aconitum and Delphinium spp. were evaluated for their cardiac activity in the isolated bullfrog heart assay. Among them, eleven compounds exhibited cardiac activity, with average rate of amplitude increase in the range of 16-118%. Compound 7, mesaconine (17), hypaconine (25), and beiwutinine (26) exhibited strong cardiac activities relative to the reference drug. The structure-activity relationship data acquired indicated that an -hydroxyl group at C-15, a hydroxyl group at C-8, an -methoxyl or hydroxyl group at C-1, and a secondary amine or N-methyl group in ring A are important structure features necessary for the cardiac activities of the aconitinetype C 19-diterpenoid alkaloids without any ester groups. In addition, an -hydroxyl group at C-3 is also helpful for the cardiac activity of these alkaloids.

In the course of comparative research of new activities of alkaloids and evaluation of chemotaxonomy of the diterpenoid alkaloids from the Aconitum and Delphinium species, [1][2][3] we investigated the alkaloids of D. anthriscifolium var. savatieri (FRANCHET) MUNZ. The plant is endemic to China, especially the Sect. Anthriscifolium of Subgen. Delphinium, 4) of which no plants have been phytochemically reported yet, implying that the study is very important value for the chemotaxonomy of genera Delphinium. Our research of the whole herbs of D. anthriscifolium var. calleryi sevealed five new C 18 -diterpenoid alkaloids, anthriscifolcines A, B, C, D, and E, together with a known C 19 -diterpenoid alkaloid delcorine (6). 5) In this paper, we report the isolation and structural elucidation of these alkaloids. Results and DiscussionAnthriscifolcine A (1) was isolated as an amorphous powder, mp 135-137°C. Its molecular formula C 26 H 39 NO 7 , was established based on HR-ESI-MS and 13 C-NMR. The IR (KBr) spectrum of 1 showed absorption bands at 1740 cm Ϫ1 ascribable to carbonyl groups. The NMR data showed the presence of an N-ethyl group (d H 1.03, 3H, t, Jϭ7.2 Hz, 2.73, 2.78, 2H, m; d C 50.3 t, 13.8 q), three methoxyl groups (d H 3.27, 3.34, 3.45, each 3H, s; d C 55.7 q, 56.1 q, 57.7 q), an acetyl group (d H 2.04, 3H, s; d C 170.4 s, 21.6 q), and a methylenedioxyl group (d H 4.91, 2H, s; d C 93.5 t). The single non-oxygenated quaternary carbon signal (d C 49.9 s) suggested that compound 1 was a C 18 -diterpenoid alkaloid from combined NMR data 6) and biogenesis. The three methoxyl groups were attributed to C-1, C-14, and C-16, respectively, based on the long-range correlations (1-OCH 3 /C-1, 14-OCH 3 /C-14, 16-OCH 3 /C-16) in the HMBC spectrum (Fig. 1). The one-proton triplet signal at d H 3.66 (Jϭ4.8 Hz) in the 1 H-NMR spectrum of (1) was assigned to H-14b based on the multiplicity and the coupling constant.7) The only acetoxyl group was located at C-6 due to the HMBC correlation between 6-OAc (d C 170.4 s) and H-6 (d H 5.21 s), and its configuration was determined as b-orientation based on the multiplicity of H-6 (singlet) in the 1 H-NMR spectrum. Finally, the structure of anthriscifolcine A was established as 1 by careful analyses of the 1D-NMR and 2D-NMR ( 1 H-1 H COSY, HMQC and HMBC) spectra.Anthriscifolcine B (2) was a white amorphous powder, mp 75-77°C. The HR-ESI-MS of 2 exhibited a protonated molecular ion peak at m/z 436.2686 (Calcd 436.2694) corresponding to a molecular formula of C 24 H 38 NO 6 (42 mass units lower than that of 1), suggesting that 2 is a hydrolytic derivative of 1, the 13 C-NMR spectra of 2 were similar to those of 1 except for the lack of an acetyl group. Meanwhile, the signal of H-6 in 1 was shifted upfield from d H 5.21 to d H 4.25 in 2 indicting that 6-OAc was substituted for 6-OH. Finally, the structure of 2 was confirmed by NaOH-CH 3 OH treatment of 1 to give the same alkamine with 2 and by full analysis of its NMR data (Table 1). Thus the structure of anthriscifolcine B was deduce...

New aconitine‐type C19‐diterpenoid alkaloids, N‐deethylaconine (I) and beiwutinine (II), are isolated together with hypaconine, mesaconine and 14α‐hydroxyneoline.