Sulfated polysaccharides of some seaweeds exhibit neuroprotection via mitigation of oxidative stress, cholinergic dysfunction and inhibition of Zn \u2013 induced neuronal damage in HT-22 cells

Tosin A Olasehinde,Ademola O Olaniran,Anthony I Okoh

doi:10.1186/s12906-020-03047-7

Abstract

BackgroundSulfated polysaccharides from marine algae are known to possess antioxidative activities, however, their therapeutic role in metal-induced neurodegeneration has not been explored. In this study, the neuroprotective potentials of sulfated polysaccharides isolated from Ecklonia maxima (PKPM), Gelidium pristoides (PMNP), Ulva lactuca (PULV), Ulva rigida (PURL) and Gracilaria gracilis (PGCL) against Zn-induced neurodegeneration in rats’ hippocampal neuronal cells (HT-22) were assessed.MethodsCells were cultured and maintained at 37 °C. Control cells did not contain Zinc sulphate (ZnSO4) while other experimental groups contain Zn (50 μM) alone or in combination with sulfated polysaccharides (0.4 or 0.8 mg/mL). Cell viability was assessed using MTT assay while apoptotic assay was also determined using acridine orange and ethidium bromide staining technique. Oxidative stress parameters (superoxide dismutase and catalase activities, glutathione and nitric oxide levels) and acetylcholinesterase activity were also assessed in neuronal cells treated with or without Zn.ResultsZn significantly reduced cell viability to about 50%. However, sulfated polysaccharides improved cell viability to about 95%. The sulfated polysaccharides also prevented late apoptosis and necrosis triggered by Zn. Furthermore, superoxide dismutase and catalase activities including glutathione content were significantly low in cells induced with Zn. Treatment with sulfated polysaccharides triggered a significant increase in antioxidant enzymes and glutathione content as well as a decrease in the activity of acetylcholinesterase in cells treated with Zn.ConclusionPKPM, PGCL, PURL, PULV and PMNP exhibit neuroprotective effects against neuronal damage induced by Zn and this may be attributed to inhibition of apoptosis, oxidative damage and acetylcholinesterase activity. These polysaccharides may be good therapeutic agents to protect neuronal cells against Zn - induced pathological processes associated with Alzheimer’s disease.

Highlights

Sulfated polysaccharides from marine algae are known to possess antioxidative activities, their therapeutic role in metal-induced neurodegeneration has not been explored
PKPM, Sulfated polysaccharides from G. gracilis (PGCL), Sulfated polysaccharides from U. rigida (PURL), Sulfated polysaccharides from U. lactuca (PULV) and PMNP exhibit neuroprotective effects against neuronal damage induced by Zn and this may be attributed to inhibition of apoptosis, oxidative damage and acetylcholinesterase activity
The result obtained from the MTT assay revealed that none of the sulfated polysaccharides showed cell viability below 95% at concentrations of 0.4 and 0.8 mg/mL

Summary

Introduction

Sulfated polysaccharides from marine algae are known to possess antioxidative activities, their therapeutic role in metal-induced neurodegeneration has not been explored. Alzheimer’s disease (AD) is one of the most common devastating neurodegenerative disorder which occurs mostly in elderly individuals It is characterized by progressive memory decline, behavioural dysfunction, and learning problems [1]. Over 46 million individuals have been diagnosed with AD and this is expected to increase to about 74.7 million by 2030 [2] Neuropathological processes such as beta-amyloid aggregation, cholinergic dysfunction, oxidative stress-induced neurodegeneration are believed to contribute to the development and progression of AD [3]. Sulfated polysaccharides have been identified as antioxidants due to their metal chelating and radical scavenging activities [11]. Algal polysaccharides are used as nutraceuticals, functional foods, cosmeceuticals, and novel drugs [11]

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