Liquid Chromatography-Electrospray Ionization Mass Spectrometry Analysis of Quil-A: an Aqueous Extract from the Bark of Quillaja saponaria Molina

Quil-A, a commercial product of the aqueous extract of Quillaja saponaria Molina bark, indigenous to Chile has been widely reported for its immuno-modulatory and adjuvant properties. The saponin constituent of the plant extract, which is responsible for these properties, is commonly separated using liquid chromatography techniques. However, the application of this technique is impaired by the non-saponin constituents of the aqueous matrix, leading to the shortening of the column life. Therefore, the study was to develop a reverse-phase liquid chromatography technique to improve the resolution of the aqueous matrix. Applying the reverse phase liquid chromatography using optimized gradient solvent mixtures of water, acetonitrile, and 10 mM ammonium acetate, components from the sample were eluted on a C5 reverse phase column. Liquid chromatography peaks at 214 nm, and electrospray ionization mass spectrometer signals were identified as per the NIST-MS data library. The finding indicates the presence of ions of molecules previously reported. Also, ions of high molecular weight saponin-like molecules, which are yet to be reported, were eluted at early retention times of the chromatography elution. The study suggests the possible presence of molecules, which could be novel and contribute to the ultimate benefits of Quil-A.