DEPT, g 1H- 1H COSY, gHSQC, and gHMBC experiments were carried out with the pulse sequences given by Bruker. 1D and 2D NMR spectra were obtained on Bruker AV400 δ H values are expressed in parts per million relative to the solvent (CDCl 3) signal. IR spectra were recorded using a Thermo Nicolet Nexus spectrophotometer.
On the basis of the above spectral data, compound 1 was determined to be 1,15-dimethoxy-3-hydroxy-14-benzoyl-16-ketoneoline ( Figure 1). In addition, it is noteworthy that the chemical shift of H-14 in compound 1 was more deshielded than the same proton in chasmanine as the result of the steric effect of the carbonyl group at C-16. The gHMBC correlations from C-1ʺ to H-14 and H-3ʺ confirmed the position of a benzoyl group. Further analysis of the 13C NMR data suggested that C-16 in compound 1 could be a carbonyl group, and not methoxyl group. In the gHMBC spectrum, the correlations between H-18 and C-3, and between H-15 and CH 3O-15 were important to confirm the presence of oxygen groups at C-3 and C-15. The main differences are that the chemical shifts of C-3, C-15, C-16 and H-14 are δ C 71.0, 85.8, 211.8 and δ H 5.44 (d, J = 5.0 Hz) respectively in compound 1, and δ C 35.0, 38.7, 81.9 and δ H 4.12 (t, J = 4.5 Hz) respectively in chasmanine, which suggested that C-3, C-15 and C-16 in compound 1 belong to an oxygen-containing group. The 1H-NMR and 13C-NMR resonances of compound 1 were similar to those of chasmanine, which was also isolated from roots of Aconitum kusnezoffii Reichb., except for the different configurations of C-3, C-15, C-16 and C-14. The g 1H– 1H COSY, gHSQC and gHMBC spectra allowed the complete assignment of the chemical shifts of compound 1 ( Table 1). After further analysis of the spectroscopic data, compound 1 was identified as a neoline-type diterpenoid alkaloid. The 13C-NMR and DEPT spectra of 1 revealed the presence of 32 carbons, which were assignable to a tertiary methyl group at δ C 12.2 (C-2), an oxygenated methylene group at δ C 76.3 (C-18), an oxygenated quaternary carbon at δ C 77.5 (C-8), two quaternary carbons at δ C 43.6 (C-4) and 51.2 (C-11), four methylene groups at δ C 31.8 (C-12), 32.6 (C-2), 48.5 (C-1ʹ) and 49.3 (C-19), two carbonyl groups at δ C 166.0 (C-1ʺ) and 211.8 (C-16) and aromatic hydrocarbon signals at δ C 128.7 (C-4ʺ), 129.1 (C-2ʺ), 129.7 (C-3ʺ) and 133.8 (C-5ʺ), respectively. Its molecular formula was determined to be C 32H 4 3O 9N by ESI-MS (M/Z 586. Ĭompound 1 was obtained as a white solid. Herein, the structure of the new compound was determined based on MS, IR, and NMR spectral data, and the known ones were identified by comparing their NMR data with those in the literature. This led to the isolation of the new diterpenoid alkaloid 1,15-dimethoxy-3-hydroxy-14-benzoyl-16-ketoneoline, along with two known diterpenoid alkaloids, benzoylaconine and aconitine. In the search for biologically active alkaloids from the roots of Aconitum kusnezoffii Reichb., a detailed study was carried out. To our knowledge, diterpenoid alkaloids extracted from the genus Aconitum L. Diterpenoid alkaloids and polysaccharide have been isolated from its roots to date. had been long used in Traditional Chinese Medicine as an analgesic and cardiotonic herbal medicine. Although recently there were some reports on flowers and leaves of this plant, roots of Aconitum kusnezoffii Reichb.
Aconitum kusnezoffii Reichb., belonging to the genus Aconitum L., is distributed in the Xinjiang, Sichuan and Jilin provinces of China.
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