Three new indole alkaloids, 10-methoxy-16-de(methoxycarbonyl)pagicerine ( ), (5b)-17-O-deacetyl-5,11-dimethoxyakuammiline (2), and ((16S,19E)-N 1 -(hydroxymethyl)isositsirikine (3) were isolated from the roots of Rauvolfia yunnanensis, together with seven known alkaloids. The structures of the new compounds were elucidated by in-depth spectroscopic and mass-spectrometric analyses.
Introduction. -The genus Rauvolfia comprises ca. 135 species mainly distributed in America, Africa, Asia, and Oceania. Nine species and four variants grow in South China . Rauvolfia species are rich sources of bioactive indole alkaloids such as reserpine . Rauvolfia yunnanensis TSIANG, widely distributed in the south and southeast of China, is commonly used as a folklore herb to treat hypertension, snake bites, and insanity [3]. However, it has not been as exhaustively investigated as other Rauvolfia species. Due to its biological and therapeutic significance, we decided to phytochemically investigate this plant.
Herein, we report the isolation of three new indole alkaloids 1 ) from R. yunnanensis, 10-methoxy-16-de(methoxycarbonyl)pagicerine ( ), (5b)-17-O-deacetyl-5,11-dimethoxyakuammiline (2), and ((16S,19E)-N 1 -(hydroxymethyl)isositsirikine (3), together with seven known alkaloids: ajmalicine [4], reserpine [5], ajmaline [6], yohimbine [4], venoterpine [7], 19-epi-ajmalicine [4], and (16R,19E)-isositsirikine [8]. 1 ) Arbitrary atom numbering. For systematic names, see Exper. Part.