Yue, S., et al. Purification of Quillaja saponins QS-21Xyl and QS-21Api by hydrophilic interaction chromatography. Carbohydr Res, 2025 Nov 8, 559:109741.

Yue, S., et al. Purification of Quillaja saponins QS-21Xyl and QS-21Api by hydrophilic interaction chromatography. Carbohydr Res, 2025 Nov 8, 559:109741. PMID: 41223814

• The primary goal of this study was to develop an efficient chromatographic process for purifying high-purity QS-21, a potent vaccine adjuvant derived from Quillaja saponaria bark, which is structurally complex and exists as multiple isomers. The background for this research stems from the challenges associated with isolating pure QS-21 due to its intricate structure and the presence of similar isomers that complicate separation. Existing purification methods often struggle to achieve the necessary purity levels, limiting its application in vaccines. Therefore, the study aimed to improve purification techniques using multidimensional chromatography, particularly hydrophilic interaction chromatography (HILIC), to obtain highly pure QS-21 isomers, ultimately facilitating better quality control and broader use in immunization strategies.
• The authors successfully developed a chromatographic process that efficiently purified QS-21Xyl and QS-21Api from Quillaja saponaria bark extract, achieving a purity greater than 97%. By employing PVP-DVB resin for initial removal of polar impurities, followed by purification using semi-preparative C18 and amide columns under optimized conditions, the researchers effectively separated the QS-21 isomers from structurally similar impurities. MALDI-TOF mass spectrometry confirmed the identification of impurities such as S1, S2, S3, and S5, ensuring the selectivity of the process. 
• The use of HILIC mode in subsequent analysis demonstrated different separation selectivity compared to reverse-phase chromatography, enabling the high-purity isolation of QS-21 isomers. This advancement provides a reliable and efficient method for producing highly pure QS-21, which is crucial for its application as a vaccine adjuvant, thereby supporting improved quality control and broader clinical utilization.

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