T. M. Gabbasov

Uraphine, a new norditerpene alkaloid from the aerial part of Delphinium uralense

The new norditerpene alkaloid uraphine, for which the structure 1α,6β-dihydroxy-7,8-methylenedioxy-14α,16β,18β-trimethoxy-N-ethylaconitane was proposed based on PMR, 13C NMR, IR, and mass spectral data, was isolated from the aerial part of Delphinium uralense N. The known alkaloids dehydrodelcorine, delpheline, deltaline, deltamine, elasine, deacetylelasine, gigactonine, and lycoctonine were also isolated from the total alkaloids.

Amides of N-Deacetyllappaconitine and Amino Acids

Amides were prepared from N-deacetyllappaconitine and the amino acids glycine, taurine, and γ-aminobutyric acid.

Oxidation of Diterpene Alkaloids by the Urea–H2O2 Complex

Oxidation of the diterpene alkaloids lappaconitine, triacetyllappaconine, and talatisamine by the urea–H2O2 complex (UHP) under various conditions produced the corresponding nitrones.

6-Oxocorumdephine and 18-methoxyeladine, new norditerpene alkaloids from the aerial part of Delphinium uralense

The new norditerpene alkaloids 6-oxocorumdephine and 18-methoxyeladine were isolated from the aerial part of Delphinium uralense N. The structures 16β-hydroxy-7,8-methylenedioxy-6-oxo-1α,14α,18-trimethoxy-N-ethylaconitane and 6β,16β-dihydroxy-7,8-methylenedioxy-1 α,14 α,18-trimethoxy-N-ethylaconitane were proposed based on PMR, 13C NMR, IR, and mass spectra.

Uraline, a New Norditerpenoid Alkaloid from Aerial Parts of Delphinium uralense Nevski

Uraline, a new norditerpenoid alkaloid, was isolated from aerial parts of Delphinium uralense. The structure of 1α,7,8-trihydroxy-6β,14α,16β-trimethoxy-18-N-(2-methyl)succinylanthranoyloxyaconane was ascribed to the new compound on the basis of 1H and 13C NMR, IR, and mass spectra. The known alkaloids methyllycaconitine and delcorine were also isolated from the plant.

Isoxazolidine Derivatives of Lappaconitine and Talatisamine

Isoxazolidine derivatives of lappaconitine and talatisamine were prepared by [3 + 2]-cycloaddition of lappaconitine and talatisamine nitrones to allyl alcohol.

Flexiosine, a New C20-Diterpene Alkaloid from Roots of Delphinium flexuosum

Methyllycaconitine and the new C20-diterpene alkaloid flexiosine were isolated from roots of Delphinium flexuosum M. Bieb. The structure of the latter was elucidated using PMR, 13C NMR, and IR spectroscopy and mass spectrometry.

Alkaloids from Aconitum neosachalinense

Aconitum neosachalinense is endemic to Sakhalin Island. Only one study of its alkaloid composition has appeared [1]. The known diterpene alkaloids isodelphinine, sachaconitine, and miyaconitine were observed in the plant using GC-MS. We studied samples of roots (1, Sept. 2008; 2, July 2012) and leaves (3, July 2012) from A. neosachalinense collected on Sakhalin Island, Makarovskii District, at the foot of the eastern slope of Zhdanko Mountain. Alkaloids were isolated from the samples by extraction with aqueous Me2CO (Me2CO–H2O, 7:3). The extracts were combined. The Me2CO was evaporated. The solution was acidified with H2SO4 solution (3%) to pH 3 in order to remove non-alkaloidal impurities and extracted once with CHCl3. Alkaloids were separated according to base strength by fractional basicification of the acidic solutions followed by extraction with CHCl3 to produce fractions of weakly (A, pH 7), moderately (B, pH 9), and strongly (C, pH 12) basic alkaloids. Table 1 presents the alkaloid contents in samples 1–3. Fraction 1A was separated by column chromatography (CC) over Al2O3 using CH2Cl2 with an increasing concentration of i-PrOH. The known alkaloids hypaconitine (0.5% i-PrOH) [2, 3] and mesaconitine (5% i-PrOH) [4, 5] were isolated and identified. Their contents were 16% and 6% of the fraction, respectively. Total alkaloids of 1B were separated over a column of Al2O3. The fraction obtained upon elution with CCl3–i-PrOH (5%) was additionally purified by CC over SiO2 (CH2Cl2–MeOH). Elution by mobile phase containing 3% MeOH isolated the known alkaloid neoline (6% of the fraction) [6, 7]. CC over SiO2 of fraction 2B [C6H6–MeOH (1%)] also isolated neoline (5.5% of the fraction). Fractions of weakly and moderately basic alkaloids from sample 3 were separated by CC over SiO2 using C6H6–MeOH and CHCl3–MeOH of increasing polarity. Weakly-basic fraction 3A afforded the aporphine alkaloid glaucine (3% of the fraction) [8, 9]; fraction 3B, glaucine (3%), N-methyllaurotetanine (2%) [10, 11], and isoboldine (1.5%) [12, 13]. The isolated known alkaloids were identified using mass and IR spectroscopy, several 1D and 2D NMR experiments, and comparisons with the literature. Thus, six known alkaloids were isolated for the first time from A. neosachalinense. They included the three diterpene alkaloids hypaconitine, mesaconitine, and neoline from the roots and the three aporphine isoquinoline alkaloids glaucine, N-methyllaurotetanine, and isoboldine from the leaves.

Complete assignments in 1H and 13C NMR Spectra of uraphine and 6-oxocorumdephine using 2D NMR spectroscopy

We reported earlier on the isolation from the aerial part of Delphinium uralense Nevski of the unreported norditerpene alkaloids uraphine (1) and 6-oxocorumdephine (2) [1, 2]. The structures of these alkaloids were determined based on PMR, 13C NMR, and IR spectroscopy and mass spectrometry in addition to a comparison with the corresponding literature data on closely related compounds. We performed a series of DEPT, 2D COSY, 2D HSQC, 2D HMBC, and 2D NOESY experiments in order to assign more reliably resonances in the PMR and 13C NMR spectra. The starting point for solving 2D spectra of 1 were resonances of methylenedioxy protons ( H 5.12, 5.09 ppm), which had cross peaks in the 2D HMBC spectrum with resonances of quaternary C atoms C-7/C-8. Of these C atoms, only one had a cross peak with proton H-14. This fact enabled the resonances of C-7 and C-8 to be differentiated. The characteristic triplet for the C-14 proton had two cross peaks in the 2D COSY spectrum for coupling with resonances of H-9 and H-13. Of these, only one had a cross peak with C-8 in the HMBC spectrum. These data as a whole enabled the resonances of H-9 and H-13 to be differentiated. Cross peaks in the 2D COSY spectrum were noted for coupling of H-13 with one of the H-12 protons and the H-16 proton. The cross peak for coupling of H-9 was used to find the resonance of H-10, which in turn had a cross peak with one of the H-12 protons. The presence of cross peaks between the resonances for C-14, C-16, and protons of the corresponding methoxyls in the 2D HMBC spectrum helped to differentiate these groups. Relying on the basic correlations in the 2D COSY (Fig. 1) and 2D HMBC spectra tuned to through-space 1H–13C SSCC and DEPT and 2D HSQC spectra, we made further assignments of resonances in the PMR and 13C NMR spectra of 1, including resonance lines of C atoms without H atoms (Table 1). The series of 2D spectral experiments were used to switch the chemical shifts for C-2 and C-3, and for C-9 and C-10 compared with those proposed earlier [1]. Additional proof of the structure was obtained from an analysis of 2D NOESY spectra. The presence of a NOE between H-10 and H-1, and between H-10 and H-14, and additional effects between H-1 and H-5 confirmed that these protons were closely spaced and had identical -orientations. For -oriented proton H-14, NOE should be observed between H-14 and one of H-15, H-14, and H-16; for -H-6, coupling with H-9 and H-10, which were absent in the 2D NOESY spectrum. 2D spectra for 2 were solved using the fragment with characteristic NMR parameters, namely the C-6=O group, as the starting point. The resonance of this C atom in the 13C NMR spectrum was observed at weak field at C 217.1 ppm. Cross peaks between C-6 and protons of two CH groups were noted in the 2D HMBC spectrum tuned to through-space 1H–13C SSCC. These could be assigned only to H-5 and H-17. One of these protons also had cross peaks with the resonance of one of the two quaternary C atoms bound to the methylenedioxy (C-7/C-8) and the C atom of the CH2(Et) group. This enabled it to be identified as H-17 and differentiated H-5 and H-17. Their C resonances were determined using the 2D HSQC spectrum.

19-Oxodeltaline, a norditerpene alkaloid from the aerial part of Delphinium uralense

The IR spectrum of 1 indicated hydroxyl (3300–3500 cm–1), ester (1736), and amide (1622) groups were present. High-resolution mass spectrometry found that 1 had the formula C27H39NO9, [M] + 521.263. The mass spectrum of 1 had series of peaks characteristic for lycoctonine compounds in addition to a medium-intensity peak for [M – 59]+. PMR spectra of 1 were consistent with three methoxyls ( 3.21, 3.32, 3.42 ppm), methyl of N-ethyl (1.11), and methylenedioxy (4.90, 4.92). A 1H singlet at 5.38 ppm in addition to a 3H singlet at 2.04 in the PMR spectrum of 1 indicated that C-6 contained a -OAc group [5]. A weak-field shift of the characteristic triplet for H-14 (4.13, J = 4.8 Hz) suggested that C-14 had an -methoxyl; C-10, a -OH group [6]. The appearance in the 13C NMR spectrum of the resonance for C-19 at 172.8 ppm and a strong-field shift of the N–CH2 resonance to 42.9 confirmed that C-19 had an oxo group. A 3H singlet in the PMR spectrum at 1.20 and a resonance at 21.5 in the 13C NMR spectrum were consistent with a methyl group on C-4 in 1. The PMR, 13C NMR, IR, and mass spectra for 19-oxodeltaline (1), which was isolated for the first time from a plant, were identical to those for synthetic 19-oxodeltaline [4], which was prepared by us from deltaline (2) by KMnO4 oxidation in aqueous acetone. IR spectra were recorded in mineral oil on a Specord M-82 spectrometer. Mass spectra (EI, 70 eV) were obtained in a Thermo Finnigan MAT 95 XP mass spectrometer by matching peaks. PMR and 13C NMR spectra were recorded in CDCl3 on a Bruker AMX III-300 instrument (300.13 MHz) with Me4Si internal standard.