Neuroprotective effects of plant polysaccharides: A review of the mechanisms

Polysaccharides are an important class of phytochemicals, and many studies have demonstrated their beneficial effects in the context of a number of pathologies including neurological disorders. Numerous studies have indicated that polysaccharides exhibit neuroprotection through a variety of mechanisms. We performed a comprehensive review of the literature to consolidate studies for the period 2010-2016, and assessed the protection mechanisms on brain function of polysaccharide-rich extracts from natural sources. Studies were identified by conducting electronic searches on PubMed, Web of Science and Google Scholar. Reference lists of articles were also reviewed for additional relevant studies. Only articles published in English were included in this review. In total, 21 types of polysaccharides from 16 kinds of plants sources have shown neuroprotective properties. In vivo and in vitro experiments have demonstrated the ability of polysaccharide-rich extracts to provide neuroprotective effects through promotion of neurite outgrowth, and NF-κB, PI3K/Akt, MAPK, Nrf2/HO-1 signaling pathways. This review will give a better understanding of the neurotrophic effects of polysaccharides and the concomitant modulations of signaling pathways. It is useful for designing more effective agents for management of neurological diseases.