A novel polysaccharide from Paeonia lactiflora exerts anti-tumor activity via immunoregulation

An unreported polysaccharide, PLP90-1B, was isolated from Paeonia lactiflora. Structural analysis showed that PLP90-1B contained arabinose and glucose, which was a highly-linear gluco-arabinan having a molecular weight of about 9.5 kDa. The backbone of PLP90-1B consisted of → 5)-α-l-Araf-(1→, →3,5)-α-l-Araf-(1→, →2,3,5)-α-l-Araf-(1→, and → 4)-α-d-Glcp-(1→, terminating with α-l-Araf. PLP90-1B was found to have anti-tumor activity by suppressing the proliferation and migration of HepG2 cells microinjected into the zebrafish. The further mechanism investigation revealed that the anti-tumor activity of PLP90-1B was closely related to immune regulation, which can improve phagocytic ability and enhance the release of NO and cytokines (IL-6, IL-1β, and TNF-α) in RAW264.7 cells. The immunopotentiation activity was further corroborated by zebrafish experiments. All these results exhibited that PLP90-1B may have the potential to become a potentially immune-mediated anti-tumor drug in the future.