Structure and absolute stereochemistry of 19-epi-(+)-echitoveniline. A new indole alkaloid of the leaves of Alstonia venenata r.br.

Abstract: Eight new monoterpenoid indole alkaloids, alstoyunines A-H (1-8), along with 17 known analogues, were isolated from Alstonia yunnanensis. The structures of. the new alkaloids were established by means of extensive spectroscopic methods. Alstoyunines C (3), E (5), and F (6) showed selective inhibition of Cox-2 (>75%). Alstoyunine F (6) showed weak cytotoxicity against the human myeloid leukemia HL-60 (IC(50) = 3.89 mu M) and hepatocellular carcinoma SMMC-7721 (IC(50) = 21.73 mu M) cell lines.

Abstract: Publisher Summary This chapter describes characteristic features of the nuclear magnetic resonance (NMR) spectra of alkaloids, illustrated by examples taken predominantly from papers published during the period January 1969–June 1972. In many of these papers, alkaloid structures have been assigned using NMR structure correlations established prior to the period under review and in some cases this work has been included. The classification of the alkaloids into groups follows that adopted in the Chemical Society specialist report on alkaloids. The classification occasionally differs from that in alkaloid texts on the basis of the volume of NMR data available, a relatively small alkaloid group may be allotted a full sub-section and an important family incorporated into a related group. In addition, if NMR spectral similarities between certain alkaloids are great enough then these alkaloids are discussed together even though this necessitates removal of the alkaloid from its “natural” section. S0066410308603282

Abstract: Three new monoterpenoid indole alkaloids, (14 alpha,15 alpha)-14,15-epoxyaspidofractinine (1) and maireines A and 13 (2 and 3, resp.), together with 19 known alkaloids, were isolated from the leaves and twigs of Alstonia mairei. The structures of the new compounds were elucidated by 1D- and 2D-NMR spectroscopic methods in combination with MS experiments.

Abstract: RW-47 und Venoterpin sind identisch. Die absolute Konfiguration ist durch ORD-CD, Vergleiche mitl-(−)-actinidin ableitbar.

Abstract: Structures and absolute stereochemistry of (-)-echitoveniline, (-)-11-methoxyechitoveniline and (-)-11-methoxyechitovenedine, three new indole alkaloids of the vincadifformine type, isolated from the fruits and leaves of Alstonia venenata R.Br., have been established as 3b , 3c and 3d , respectively, on the basis of spectral and chemical evidence. A plausible mechanism of the LAH reduction of the δ-lactones 8b and 8c to the corresponding diols 9b and 9c has been discussed.

Abstract: The structure of echitoserpidine, a new alkaloid of the fruits of Alstonia venenata has been established as ( 1 ) on the basis of spectral and chemical evidence.