A neutral polysaccharide (POPAN) from Portulaca oleracea L. was isolated with alkali and purified to obtain. HPLC analysis suggested POPAN (40.9 kDa) was mainly composed of Ara and Gal with traces of Glc and Man. GC–MS and 1D/2D NMR analysis confirmed POPAN was an arabinogalactan possessing a backbone mainly composing of (1 → 3)-α-l-Araf-linked arabinan and (1 → 4)-β-d-Galp-linked galactan, which was different from structure characterization of typical arabinogalactan reported previously. Importantly, we conjugated POPAN to BSA (POPAN-BSA), and detected the potential and mechanism of POPAN as an adjuvant in POPAN-BSA. The results indicated, in contrast to BSA, POPAN-BSA induced the robust and persistent humoral response in addition to the cellular response with Th2-biased immunity response in mice. Further investigations of mechanism revealed effects of POPAN-BSA were a result of POPAN as the adjuvant to: 1) significantly activate DCs in vitro or in vivo including the upgraded expressions of costimulators, MHCs and cytokines; 2) greatly facilitated the capture of BSA. Overall, present studies demonstrated POPAN can be a potential adjuvant as an immunopotentiator and an antigen delivery vehicle in its conjugate to recombinant protein vaccines.

马齿苋中性多糖(POPAN)经碱分离纯化得到。HPLC 分析表明 POPAN (40.9 kDa) 主要由 Ara 和 Gal 以及痕量的 Glc 和 Man 组成。GC–MS 和 1D/2D NMR 分析证实 POPAN 是一种阿拉伯半乳聚糖，其主链主要由 (1 → 3)-α- l -Ara f-连接的阿拉伯聚糖和 (1 → 4)-β- d -Gal p组成-连接的半乳​​聚糖，这与之前报道的典型阿拉伯半乳聚糖的结构表征不同。重要的是，我们将 POPAN 与 BSA (POPAN-BSA) 偶联，并检测了 POPAN 作为 POPAN-BSA 佐剂的潜力和机制。结果表明，与 BSA 相比，POPAN-BSA 在小鼠中诱导了强大而持久的体液反应以及 Th2 偏向免疫反应的细胞反应。机制的进一步研究表明，POPAN-BSA 的作用是 POPAN 作为佐剂的结果：1）在体外或体内显着激活 DC，包括共刺激因子、MHC 和细胞因子的表达升级；2) 大大方便了 BSA 的捕获。全面的，