Saikosaponins are bioactive compounds from the roots of Bupleurm falcatum L. Despite of various pharmacological benefits, the application of those compounds is restrained due to their lower bioavailability and the lack of large-scale separation method. To prepare lipophilic prosaikogenins, saikosaponins were enzymatically transformed in vitro. The separation method for these metabolites was developed using countercurrent chromatography (CCC) and preparative HPLC. Glucose at C-3 position of saikosaponins was eliminated by the enzymatic transformation of saponin-enriched fraction with cellulase. The converted fraction was then successfully separated by CCC. The optimum solvent system, dichloromethane/methanol/water (4:3:2, v/v/v), was selected and the relationship between rotation speed and retention of target compounds was investigated. Prosaikogenin G (PSG G) and prosaikogenin F (PSG F) were preparatively separated from the deglycosylated fraction. The residue in stationary phase on CCC separation (fraction S) was further bio-transformed by α-L-rhamnosidase (fraction SR) and cellulase (fraction SRC) in series. Finally, four prosaikogenins (PSG E1, E3, F, and G) were isolated by enzymatic transformation of major saikosaponins of roots of Bupleurm falcatum L. Through the investigation on the cytotoxicity of the separated compounds against six cancer cell lines and two normal human cell lines (MDA-MB-468, A-549, HepG2, AGS, PANC-1, HCT116, MCF-10A, and NKNT-3), PSG G, most cytotoxic compound, significantly inhibited the viability of cancer cells, while exerting less of an effect on their normal counterparts.
References
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