Preparative separation of minor saponins from leaves using biotransformation, macroporous resins, and preparative high-performance liquid chromatography.

Background: Ginsenosides with less sugar moieties may exhibit the better adsorptive capacity and more pharmacological activities.

Methods: An efficient method for the separation of four minor saponins, including gypenoside XVII, notoginsenoside Fe, ginsenoside Rd2, and notoginsenoside Fd, from leaves (PNL) was established using biotransformation, macroporous resins, and subsequent preparative high-performance liquid chromatography.

Results: The dried PNL powder was immersed in the distilled water at 50°C for 30 min for converting the major saponins, ginsenosides Rb1, Rc, Rb2, and Rb3, to minor saponins, gypenoside XVII, notoginsenoside Fe, ginsenoside Rd2, and notoginsenoside Fd, respectively, by the enzymes present in PNL. The adsorption characteristics of these minor saponins on five types of macroporous resins, D-101, DA-201, DM-301, X-5, and S-8, were evaluated and compared. Among them, D-101 was selected due to the best adsorption and desorption properties. Under the optimized conditions, the fraction containing the four target saponins was separated by D-101 resin. Subsequently, the target minor saponins were individually separated and purified by preparative high-performance liquid chromatography with a reversed-phase column.

Conclusion: Our study provides a simple and efficient method for the preparation of these four minor saponins from PNL, which will be potential for industrial applications.