Characterization of polysaccharides from the flowers of Nerium indicum and their neuroprotective effects.
Degeneration of neurons is a key problem in Alzheimer's disease (AD) and neuroprotection is a possible way to safeguard neurons from neurodegeneration. Polysaccharides isolated from Chinese medicinal herbs have been investigated extensively for their anti-tumor and immune stimulating effects. Yet, little is known about the effects of polysaccharides in neurons. Recently, two pure polysaccharides isolated from the flowers of Nerium indicum were shown to stimulate proliferation and differentiation of PC12 pheochromocytoma cells, an effect similar to that observed from nerve growth factor. In this notion, it is hypothesized that polysaccharides isolated from the flowers of N. indicum could exhibit beneficial effects in neurons. In this study, we isolated, characterized and investigated two new polysaccharides from the flowers of N. indicum for their neuroprotective effects on neurons against serum-deprivation and beta-amyloid (Abeta) peptide toxicity in primary rat cortical neuronal cultures. Pretreatment of the polysaccharides significantly reduced the number of apoptotic neurons revealed by DAPI staining when neurons were exposed to serum-free medium. Besides, the polysaccharides could also decrease the activity of caspase-3 triggered by Abeta peptides. Western blot analysis indicated that polysaccharides stimulated the phosphorylation of PDK-1 (Serine 241) and Akt (Threonine 308). In conclusion, the polysaccharides J2, J3 and J4 isolated from N. indicum provide a lead for future development of neuroprotective agent against neuronal death in neurodegenerative diseases and the neuroprotective mechanism may primarily rely on activation of Akt survival signaling pathway.
Yu
Man-Shan
MS
Laboratory of Neurodegenerative Diseases, Department of Anatomy, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, SAR.
Lai
Sau-Wan
SW
Lin
Kim-Fung
KF
Fang
Ji-Nian
JN
Yuen
Wai-Hung
WH
Chang
Raymond Chuen-Chung
RC
D000818:Animals; D002540:Cerebral Cortex; D004195:Disease Models, Animal; D035264:Flowers / Q000737:chemistry*; D008970:Molecular Weight; D030007:Nerium / Q000737:chemistry*; D009410:Nerve Degeneration / Q000517:prevention & control*; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D008517:Phytotherapy; D011134:Polysaccharides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D011134:Polysaccharides