Shawurensine, a new C19-diterpenoid alkaloid from Delphinium shawurense

Abstract

The new norditerpenoid alkaloid shawurensine in addition to β-sitosterol and the known alkaloids elatin, delbrulin, and methyllycaconitine were isolated from Delphinium shawurense. A structure for shawurensine was proposed based on spectral data.Plants of the genus Delphinium (Ranunculaceae) are sources of diterpenoid alkaloids. Therefore, many species of this genus are used in folk medicine [1]. However, data on the chemical composition and use of D. shawurense W. T. Wang in folk medicine have not been published. The plant was collected in Xinjiang Autonomous Republic of the Chinese People's Republic during flowering in July 2005.We investigated the alkaloid composition of the aerial part of D. shawurense. Ethanol extraction produced the total alkaloids, the yield of which was 0.56% of the air-dried plant mass. The known C 19 -norditerpenoid alkaloids elatine, delbruline, and methyllycaconitine and the new base 1, which we called shawurensine, in addition to β-sitosterol were isolated from the total alkaloids. The known compounds were identified by comparing their spectral properties with those published [2][3][4][5].Shawurensine (1) was isolated as an amorphous white powder with molecular formula C 37 H 32 N 2 O 11 as determined by high-resolution mass spectrometry (HR-ESI) and confirmed by PMR and 13 C NMR spectra.The PMR spectrum of 1 contained signals for protons of N-ethyl, four methoxyls, 18-and 19-methylenes, NH groups, and o-substituted benzene ring (Table 1). The presence of two N atoms in 1 and the spectral data given above enable 1 to be classified as a C 19 -norditerpenoid alkaloid with a C-18 ester.Chemical shifts (CS) and multiplicities of proton signals at 3.92 ppm (br) and 3.61 (3H, t, J = 4.8 Hz) in the PMR spectrum of 1 confirmed the presence of C-6 and C-14 methoxyls, respectively [6,7]. The 13 C NMR spectrum contained signals for 37 C atoms and confirmed the conclusions made on the basis of the mass and PMR spectra of 1 (Table 2). Furthermore, the 13 C NMR spectrum had signals at 90.8, 88.3, and 77.4 ppm, confirming the presence of a C-6 methoxyl and C-7 and C-8 hydroxyls [7]. CS in the 13 C NMR spectrum of 1 at 83.9 and 55.8 ppm in addition to 82.5 and 56.3 ppm were consistent with C-1 and C-16 methoxyls.The molecular formula of 1 includes 11 O atoms from 4 methoxyls, an ester, 2 hydroxyls, and 2 carbonyls. Therefore, the last O atom belongs to a carboxyl group, which was confirmed by comparing the 13 C NMR spectra of 1 and delavaine A (2) [8], which showed that the CS of the C atoms were similar and differed only by an additional signal for OCH 3 at 51.7 ppm in the spectrum of 2. The compositions differed only by a CH 2 group. The PMR spectrum of 1 had signals at 3.12 ppm (1H, br.s, CH-CH 3 ), 2.96 (2H, br.s, CH 2 COOH), and 1.31 (3H, d, J = 7.2 Hz, CH-CH 3 ), which were due to a [N-(2′′-methylsuccinyl)anthranyl] moiety in 1. Analogous proton signals were observed in spectra of elatine [2], geyerline [9], and grandiflorine [9], which were due to proton signals of the [N-(2′′-methylsuccinimi...

Diterpenoid Alkaloids Isolated from Delphinium brunonianum and Their Inhibitory Effects on Hepatocytes Lipid Accumulation

“…Furthermore, eleven known diterpenoid alkaloids were determined to be delbruline ( 5 ) [ 11 ], delpheline ( 6 ) [ 13 ], lycoctonine ( 7 ) [ 11 ], delbrunine ( 8 ) [ 11 ], delcosine ( 9 ) [ 11 ], uraphine ( 10 ) [ 14 ], anthranoyllycoctonine ( 11 ) [ 15 ], sharwuphinine A ( 12 ) [ 16 ], browniine ( 13 ) [ 11 ], shawurensine ( 14 ) [ 17 ], and delavaine B ( 15 ) [ 17 ] by comparison of their corresponding spectroscopic data with those reported previously in the literature.…”

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

“…Ten known compounds, methyllycaconitine ( 6 ), shawurensine ( 7 ), delavaine A ( 8 ), delavaine B ( 9 ), delsemine A ( 10 ), delsemine B ( 11 ), tianshanisine ( 12 ), delcorine ( 13 ), 6‐deoxydelpheline ( 14 ) and blacknidine ( 15 ), were identified by comparison of their spectroscopic data with the literature data.…”

Diterpenoid Alkaloids from Delphinium aemulans

“…Phytochemical studies have revealed that D. aemulans contains 15 compounds including 11 diterpenoid alkaloids, aemulanitine, deacetylaconorine, 14-acetylaconorine, cammaconine, aconorine, napelline, 1-acetylluciculine, 12acetylnapelline, dehydronapeline, songorine and songoramine [6]. During our further investigation for more bioactive compounds on the whole herb of D. aemulans, one new C 19 -diterpenoid alkaloid aemulansine (1), together with ten known C 19 -diterpenoid alkaloids, delsoline (2) [7], delavaine A (3), delavanie B (4) [8], methyllycaconitine (5) [9], delcosine (6) [10], shawurensine (7) [11], lycoctonine (8) [12], anthranoyllycoctonine (9) [13], delphatine (10) [14] and ajadine (11) [15] were isolated and their structures ( Figure 1) were elucidated by means of spectroscopic analyses and comparison with data reported in the literature. In this paper, the isolation, structural elucidation and cytotoxicity of these compounds are described.…”