Isolation of saponins with viral entry inhibitory activity by combined chromatographic methods

TLDR: Using the charge difference between Rev.1 and Gen.1 at elevated pH, a simpler, more efficient purification scheme is developed that eliminates the yield-limiting preparative TLC step used in the pilot study.

Abstract: High-speed countercurrent chromatography (HSCCC) is a support-free liquid–liquid partition chromatography (Ito, Y. Crit. Rev. Anal. Chem. 1986, 17 (1), 65–143[1]). As an important separation technique, it eliminates complications between solutes and solid supports and has been used for preparative separation and purification for natural products in recent years. Using a series of chromatographic procedures, four triterpenoid saponins, arganine A, arganine C (Rev. 1), arganine D, and tieghemelin (Gen. 1) were isolated from the seed of the fruit of the rain forest tree, Tieghemella heckelli. In an initial pilot study, a HSCCC and preparative thin layer chromatography were used to isolate the herpesvirus entry inhibitors, Rev.1 and Gen.1, two compounds that are structurally identical except at position C-3 of the aglycone where in Rev.1 the sugar moiety is glucose and in Gen.1, it is glucuronic acid. Utilizing the charge difference between Rev.1 and Gen.1 at elevated pH, we were able to develop a si...