New C19-Diterpenoid Alkaloids from Aconitum piepunense

Abstract

The plant Aconitum piepunense HAND-MAZZ. Symb. Sin. grows in Diqing county, Yunnan province, China at an elevation of 3000 m.1) To our knowledge, no phytochemical investigation of this plant has been undertaken. In the course of our continued studies of diterpenoid alkaloids from Aconitum and Delphinium plants, two new C 19 -diterpenoid alkaloids, piepunensine A (1) and 18-acetylcammaconine (2), along with five known norditerpenoids pengshenine B (3), talatisamine (4), aconosine (5), yunaconitine (6), and talatizidine (7) were isolated from the roots of Aconitum piepunense. This paper reports the isolation and structural elucidation of these alkaloids. Results and DiscussionDuring the course of isolation, five known alkaloids pengshenine B (3), 6) talatisamine (4), 7) aconosine (5), 8) yunaconitine (6), 9) and talatizidine (7) 10) were obtained and their structures were identified by comparison of the NMR data with reported values and co-TLC behavior with authentic samples. It is emphasised that piepunensine A (1) is the first known naturally occuring aconitine-type diterpenoid alkaloid with both the lactam and N-deethyl groups.The molecular formula of piepunensine A (1) (C 22 H 33 NO 6 ) was determined by HR-ESI-MS [MϩNa] ϩ 430.2200. The NMR spectra strongly suggested an aconitinetype alkaloid for 1.2) Its NMR and IR spectra displayed absence of an N-ethyl group and characteristic signals at d ) and 13 C-NMR (d 71.5 s, 75.1 d) spectra also showed to have one each of secondary hydroxyl (14-OH) and tertiary hydroxyl group (8-OH). On the basis of these observations, the structure of piepunensine A was established as 1.18-Acetylcammaconine (2) was isolated as white amorphous powder with mp 123-125°C. The HR-ESI-MS at m/z 450.2862 corresponded to the protonated molecular ion [MϩH] ϩ (C 25 H 40 NO 6 ). The NMR spectrum of 2 exhibited characteristic features of the aconitine-type C 19 -diterpenoid alkaloids, 2) bearing an N-ethyl group (d H 1.06, 3H, t, Jϭ7.2 Hz; d C 13.5 q, 49.3 t), two methoxyl groups (d H 3.28, 3.34, each 3H, s; d C 56.2 q, 56.4 q), and an acetyl group (d H 2.06, s; d C 20.8 q, 171.0 s). Comparison of the MS and NMR spectra of 2 with those of cammaconine (8) 4) showed that it had an additional acetyl group instead of a hydroxyl group. The 13 C-NMR spectra of 2 and 8 are very similar except for C-4 and C-18 due to the substituted effect (OH→OAc) Two new C 19 -diterpenoid alkaloids, piepunensine A (1) and 18-acetylcammaconine (2), have been isolated from the roots of Aconitum piepunense together with five known alkaloids pengshenine B (3), talatisamine (4), aconosine (5), yunaconitine (6), and talatizidine (7). The structures of the new alkaloids were established on the basis of spectral data (1D-and 2D-NMR, HR-MS).

New C18-Diterpenoid Alkaloids from Delphinium anthriscifolium var. savatieri

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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.

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Three New C₁₉-Diterpenoid Alkaloids from <i>Aconitum novoluridum</i>

“…The IR spectrum indicated the absorption peaks for a carbonyl group (1710 cm −1 ), and aromatic ring (1609, 1592, 1515, 1452 cm −1 ). The NMR spectrum of 1 exhibited characteristic features of the aconitine-type C 19 -diterpenoid alkaloids, [10][11][12][13][14][15] bearing an N-ethyl group (δ H 1.01, 3H, t, J = 7.2 Hz; δ C 13.6 q, 49.3 t), and two methoxy groups (δ H 3.19, 3.32, each 3H, s; δ C 56.2 q, 56.4 q). Furthermore, the signals at δ Comparison of the MS and NMR spectra of 1 with those of the known brevicanine A 17) showed that these two compounds exhibited nearly identical 1 H-and 13 C-NMR resonances.…”

“…The NMR spectrum of 1 exhibited characteristic features of the aconitine-type C 19 -diterpenoid alkaloids, [10][11][12][13][14][15] bearing an N-ethyl group (δ H 1.01, 3H, t, J = 7.2 Hz; δ C 13.6 q, 49.3 t), and two methoxy groups (δ H 3.19, 3.32, each 3H, s; δ C 56.2 q, 56.4 q). Furthermore, the signals at δ Comparison of the MS and NMR spectra of 1 with those of the known brevicanine A 17) showed that these two compounds exhibited nearly identical 1 H-and 13 C-NMR resonances. The most obvious difference between compounds 1 and brevicanine A in their NMR spectra was the absence of a methoxy group in 1, thus validating the loss of 14 mass units in brevicanine A as found by mass spectrometry.…”

Chemical Constituents from the Branches and Leaves ofPyrus pashiaBuch.-Ham.ex D.Don

“…文献数据也支持这一判断, 若在 C-8 上形成碳碳 键则 C-6 的化学位移应该在 δ 100 左右 [6] , 若在 C-6 上形 成碳碳键则 C-8 的化学位移在 δ 95 左右 [7] , 而该化合物 中 A 环上的芳香 CH 的化学位移是 δ C 94.58, 由此进一 步确定该 CH 2 与 C-6 形成碳碳键. 仔细分析 1 的 NMR 数据, 发现该化合物中还含有 1 个甲氧基[δ 糖基异头氢的偶合常数为 7.2 Hz [8] , 通过水解测得 的旋光值为 20 [9] ; 对香豆酸酯基的 2 个双键氢的偶合常数 为 15.9 Hz [10] , [12] , HMBC 谱中存在的 δ H 5.18 (H-7)与 δ C 168.7…”