INVESTIGATION OF INDOLE ALKALOIDS OF RAUWOLFIA YUNNANENSIS TSIANG

From the fraction of weakly basic alkaloids of the root of Rauwolfia yunnanensis Tsiang, eleven alkaloids (Ⅰ～Ⅺ)were isolated by chromatography. According to melting points, rotational values and spectroscopic data as well as properties of their derivatives, four of them were identified to be known alkaloids previously obtained from the same plant, they are ajmalicine (alkaloid Ⅰ), ajmaline (alkaloid Ⅱ), reserpine(alkaloid Ⅲ) and serpentinine (alkaloid Ⅶ). Tetraphyllicine (alkaloid Ⅸ) and vellosimine (alkaloid Ⅺ) were isolated from Rauwolfia yunnanensis Tsiang for the first time.Alkaloids Ⅳ and Ⅷ are two new indole alkaloids. Their structures and configurations were deduced as 19-epi-ajmalicine and 16, 17-stereoisomer of pseudoreserpine, respectively, by means of spectroscopic analysis (UV, IR, NMR, MS) and biological comparison with the same series of indole alkaloids.The identification of Alkaloids Ⅹ, Ⅴ and Ⅵ is a pending question for further discussion.