Polysaccharides from Clematis armandii Franch. stems: Stirring-assisted extraction, isolation, structural characterization, and their neuroprotective effect on OGD/R-induced PC12 cells injury

In order to fully develop the economic value and promote the vigorous development of the economic crop Clematis armandii Franch. stems in Sichuan Province, a detailed, in-depth and systematic study on C. armandii stems polysaccharides (CAPs) was carried out. In this study, a highly applicable, practical and efficient stirring-assisted extraction method aimed to fully improve the polysaccharides yield was firstly optimized to liquid-to-solid ratio 40:1 mL/g, extraction temperature 85℃, extraction time 129 min, stirring speed 503 r/min, and the actual CAPs yield was 5.83 ± 0.26% (n = 5). Subsequently, three novel homogeneous polysaccharides (CAP-1, CAP-2 and CAP-3) were obtained via column chromatography for the first time. In order to fully clarify fine structure and neuroprotective effect of them, it was then studied by means of a variety of characterization techniques in systematically and explore their neuroprotective effect on OGD/R-induced PC12 cells injury. The structural characterization results demonstrated that CAP-1 (2.22 ×10 5 Da) and CAP-2 (1.86 ×10 5 Da) were very similar in glycosidic bond types, mainly with →4)- α - D -Glc p -(1→, →3)- α - D -Glc p -(1→ as the skeleton, while CAP-3 (6.89 ×10 5 Da) mainly with →3)- β - D -Gal p -(1→, →6)- β - D -Man p -(1→ as the skeleton, and they have different thermal stability and microstructure. The neuroprotective activity result suggested that CAP-3 presented a better neuroprotective effect against OGD/R-induced PC12 cells injury, mainly by alleviating oxidative stress injury, inhibiting apoptosis, and through the PI3K/Akt/GSK-3β signaling pathway. This study establishes a crucial theoretical basis to facilitate the profound development and optimal utilization of C. armandii stems polysaccharides. • Optimized stirring-assisted extraction achieves 5.45% CAPs yield with scalable industrial parameters. • First isolation of three novel polysaccharides (CAP-1, CAP-2, CAP-3) with distinct structures. • CAP-3 exhibits neuroprotective effects against OGD/R injury by reducing ROS levels in PC12 cells.