Significance of neuroprotective polysaccharide from the flowers of Nerium indicum in beta-amyloid peptides neurotoxicity

Abstract

Polysaccharides purified from Chinese medicinal herbs have been investigated extensively for their biological activities and therapeutic effects. Most of them showed anti-tumor and immune stimulating effects. However, little is known about their effects on neurons. Our previous study has demonstrated that polysaccharides (J2, J3 and J4) isolated from the flowers of Nerium indicum (Oleander) exert partial protection in cortical neurons stressed by beta-amyloid (Aβ) peptides. In this study, we have characterized a fraction of new polysaccharide from N. indicum (named as J6) and aim to investigate whether it can protect cortical neurons against Aβ-induced apoptosis. Primary cortical neurons prepared from embryonic day 17 SD rats were employed. Pretreatment of the polysaccharide J6 significantly decreased the activity of caspase-3 as well as the cytotoxicity triggered by Aβ peptides. Western blot analysis indicated that J6 could markedly inhibit the Aβ peptide-stimulated phosphorylation of JNK-1. Taken together, the polysaccharide J6 extracted from the flowers of N. indicum can serve as potential neuroprotective agent against neuronal death in Alzheimer’s disease and the neuroprotective mechanism may primarily rely on inactivation of JNK signaling pathway.