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

Abstract

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, 13 C 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.The plant Delphinium uralense Nevski has a limited distribution and belongs to the complex D. aggr. dictyocarpum DC. (section Delphinastrum DC) [1]. We reported previously on the isolation from the aerial part of this plant collected during the start of budding in the Southern Urals (Zilair Plateau) of methyllycaconitine, delcorine, and grandiflorine (uraline) [2].In continuation of research on the alkaloid composition of the aerial part of D. uralense, we isolated from the benzene extract of the moderately basic fraction (A, pH 6) [2] by column chromatography and semi-preparative HPLC the known alkaloids dehydrodelcorine, delpheline, deltaline, deltamine, and elasine, and alkaloid 1, which has not previously been described and which we called uraphine. We also isolated deacetylelasine, which was isolated by us for the first time from plant material and has been prepared previously via alkaline hydrolysis of elasine [3]. We isolated the known alkaloids gigactonine and lycoctonine from the strongly basic fraction (B, pH 12).According to IR spectroscopy, 1 contained hydroxyls (3300-3500 cm −1 ). The high-resolution mass spectrum gave molecular weight 465.2715 for 1, which corresponded to the empirical formula C 25 H 39 NO 7 . The fact that the peak for the ion [M -17] + was the base peak suggested that C-1 had an OH group [4]. Peaks for ions [M -56] + and [M -87] + also suggested that there was a hydroxyl in the 1-position and a methoxyl in the 18-position [5,6]. The location of one of the three methoxyls in the C-18 position was confirmed by the presencee in the 13 C NMR of 1 of a triplet at δ 78.5 ppm. The presence in the PMR of 1 of a 1H singlet for H-6α at δ 4.37 ppm placed a β-OH group on C-6 [7]. Furthermore, a 1H triplet (J = 4.5 Hz) was observed at δ 3.71 ppm, indicating that C-14 contained an α-methoxyl [8].

Honatisine, a Novel Diterpenoid Alkaloid, and Six Known Alkaloids from Delphinium honanense and Their Cytotoxic Activity

“…In addition, six known compounds, siwanine E (2) [6], isoatisine (3) [7], atisine (4) [8], delcorinine (5) [9], uraphine (6) [10], and nordhagenine A (7) [11], were identified by comparison of their 1 H-and 13 C-NMR, IR, and MS data with those reported in literature, respectively.…”