New C19- and C18-Diterpenoid Alkaloids from Delphinium anthriscifolium var. savatieri

Abstract

In a continuation of our phytochemical studies on the pharmacologically interesting plants Aconitum and Delphinium, we obtained a series of structurally and chemotaxonomically interesting diterpenoid alkaloids. [1][2][3] It was very intriguing that we also discovered a novel diterpene from one of these plants. 4) Delphinium anthriscifolium var. savatieri (FRANCHET) MUNZ 5) belongs to the Sect. Anthriscifolium (which consists of only 4 plants) of the genus Delphinium. Our earlier chemical investigation of a small batch of specimens of this plant led to the discovery of some new C 18 -diterpenoid alkaloids, which presented a chemotaxonomical advantage for the genus Delphinium.6) Further investigation of a large batch of recollected samples resulted in the isolation of three new C 19 -diterpenoid alkaloids, anthriscifoldines A-C (1-3), and two new C 18 -diterpenoid alkaloids anthriscifolcines F and G (5, 6), together with five known alkaloids. In this paper, we report the isolation and structural elucidation of these new alkaloids. Results and DiscussionAnthriscifoldine A (1) was obtained as a white amorphous powder. Its molecular formula was deduced to be C 25 H 37 NO 7 from a pseudomolecular ion at m/z 464.2661 [MϩH] ϩ in its HR-ESI-MS. The 1 H-NMR spectrum ( 7) implying the presence of the only acetoxy group at the C-14 position. The two methoxy groups were attributed to C-8 and C-16 based on the long-range correlations between 8-OCH 3 and C-8, and 16-OCH 3 and C-16 in its heteronuclear multiple bonding connectivity (HMBC) spectrum. Along with the above-mentioned signals, its 13 C-NMR spectrum (Table 2) Pharmacy, Sichuan University; No. 17, Duan 3, Renmin Nan Road, Chengdu 610041, P. R. China. Received September 8, 2008; accepted October 18, 2008; published online November 12, 2008 Three new C 19 -diterpenoid alkaloids, anthriscifoldines A-C (1-3), and two new C 18 -diterpenoid alkaloids, anthriscifolcines F and G (5, 6), were obtained from the whole herbs of Delphinium anthriscifolium var. savatieri during our further investigation on a larger scale of recollected plants. Their structures were elucidated based on the interpretation of NMR and high-resolution ESI-MS data, and chemical transformation. In addition, five known C 19 -diterpenoid alkaloids were also isolated and identified as nudicaulamine (4), delbruninol (7), blacknine (8), winkleriline (9), and deltaline (10).

Diterpenoid Alkaloids from Delphinium anthriscifolium var. majus

“…for C 27 H 42 NO 8 , 508.2910). The NMR spectroscopic data of 5 were similar to those of 4 , suggesting 5 was also a lycoctonine C 19 –diterpenoid alkaloid with an acetyl group, an N –ethyl group, three methoxyl groups, and a methylenedioxy group 13 . In the HMBC spectrum of 5 , critical correlations for the protons of the methylenedioxy/C–7 and C–8, OCH 3 –1/C–1, OCH 3 –16/C–16, OCH 3 –18/C–18, H–14/OAc, suggested the location of three methoxyl groups at C–1, C–16 and C–18, the acetyl group at C–14, and the methylenedioxy group at C–7 and C–8.…”

“…for C 25 H 38 NO 6 , 448.2699), corresponding to the molecular formula C 25 H 37 NO 6 . Its NMR data indicated seven methylene (one oxymethylene), seven (two oxymethines), and five quaternary carbons (a carbonyl and two oxygen–bearing), in addition to a methylenedioxy group, an N –ethyl, and three methoxy substituents, suggesting that 4 was a typical lycoctonine C 19 –diterpenoid alkaloid 13 . The 2D NMR and NOESY experiments confirmed the NMR data and configuration assignments of 4 .…”

Five New C19‐Diterpenoid Alkaloids from Delphinium tianshanicum W.T.Wang

“…The signal at δ (H) 3.88 (1 H, t , J = 4.2 Hz) in the 1 H‐NMR spectrum was ascribed to H β –C(14), suggesting the presence of a OH group at the C(14) position. [ ][ ] The remaining OH group was assigned to C(7) based on HMBCs between C(7) ( δ (C) 88.7) and H–C(5) ( δ (H) 1.58), H–C(6) ( δ (H) 1.42), H–C(17) ( δ (H) 3.23) …”

An overview of the chemical constituents from the genus Delphinium reported in the last four decades

“…savatieri. 25,26 Most of them contain a 10-OH substituent, and the exceptions are alkaloids 10-11 and 16. Three of the ranaconitine-type C 18 -DAs, namely, delboxine (18) from D. bonvalotii, 27 14-demethyltuguaconitine (19) from D. stapeliosum, 28 and tiantaishansine (20) from D. tiantaishanense, 29 contain a 3,4-epoxide unit.…”