Synthetic Studies of Complex Immunostimulants from <i>Quillaja saponaria</i>:  Synthesis of the Potent Clinical Immunoadjuvant QS-21A<sub>a</sub><sub>pi</sub>
                                
                                    
                                        作者:Yong-Jae Kim、Pengfei Wang、Mauricio Navarro-Villalobos、Bridget D. Rohde、DerryBerry、David Y. Gin                                    
                                    
                                        DOI:10.1021/ja062364i
                                    
                                    
                                        日期:2006.9.1
                                    
                                    QS-21 is one of the most promising new adjuvants for immune response potentiation and dose-sparing in vaccine therapy given its exceedingly high level of potency and its favorable toxicity profile. Melanoma, breast cancer, small cell lung cancer, prostate cancer, HIV-1, and malaria are among the numerous maladies targeted in more than 80 recent and ongoing vaccine therapy clinical trials involving QS-21 as a critical adjuvant component for immune response augmentation. QS-21 is a natural product immunostimulatory adjuvant, eliciting both T-cell- and antibody-mediated immune responses with microgram doses. Herein is reported the synthesis of QS-21A(api) in a highly modular strategy, applying novel glycosylation methodologies to a convergent construction of the potent saponin immunostimulant. The chemical synthesis of QS-21 offers unique opportunities to probe its mode of biological action through the preparation of otherwise unattainable nonnatural saponin analogues.