Structure and antiviral activity of a pectic polysaccharide from the root of Sanguisorba officinalis against enterovirus 71 in vitro/vivo

The increasing prevalence and pandemic risk of viral diseases warrant the development of safe and effective treatments. In this study, we aimed to elucidate the structure and anti-enterovirus 71 (EV71) effects of polysaccharides isolated from the roots of Sanguisorba officinalis (SO), traditionally used for infectious diseases. The purified polysaccharide (S-a3) was a homogenous macromolecule (260.4 kDa) with a concave and porous surface. Linkage and NMR analyses confirmed that S-a3 is a polysaccharide interlinked with homogalacturonan, rhamnogalacturonan-I, 1,4-α-glucan, and arabinogalactan. S-a3 significantly inhibited cell death and viral gene expression in EV71-infected Vero cells, and alleviated EV71-induced body weight loss, death, and paralysis in the hSCARB2-transgenic mouse model. The effective dose of S-a3 was non-toxic to cells and mice. The antiviral mechanism of S-a3 was associated with the disruption of EV71 attachment to host cells. Our findings demonstrate that polysaccharides from SO can be a safe and effective treatment for EV71 infection.