New dammarane saponins from Vietnamese ginseng

Panax vietnamensis Ha et Grushv., Araliaceae, is a new Panax species discovered in Central Vietnam in 1973. The plant, which is now commonly known as Vietnamese ginseng, has become an important medicinal plant of Vietnam. From the underground part of P. vietnamensis growing wild, twenty-four known saponins and fourteen new dammarane saponins named vina-ginsenosides-R1 -- R14 were previously isolated and identified. In our course of further study on the saponin composition of P. vietnamensis, ten more new dammarane saponins, vina-ginsenosides-R15 -- R24, were isolated along with two known saponins, pseudo-ginsenoside-RC1 and gypenoside-IX. The structure of the new saponins was elucidated based on chemical and spectroscopic evidence.