Elucidation of  Antioxidant and Neuroprotective Potential of Fucoxanthin Isolated from Brown Seaweed Sargassum oligocystum

Abstract

Fucoxanthin belonging to the carotenoid family has different bioactive properties as anti-oxidant, anti-obesity, anti-diabetic, and anti-cancer effects. This study presents the results of the extraction and purification of fucoxanthin from Sargassum olygocystum Montagne, 1845 using thin-layer chromatography, column chromatography, and high-performance liquid chromatography. Furthermore, this study demonstrated the antioxidant activities, expression of antioxidant enzymes, and inhibition of acetylcholinesterase (AChE) of fucoxanthin. The chemical structure, molecular formula (C42H58O6), and molecular weight (658) of fucoxanthin were determined by nuclear magnetic resonance spectroscopy. Fucoxanthin isolated from S. olygocystum showed no cytotoxic effects, moreover, it showed potent antioxidant activity as assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method (with an IC50 value of 3.42 ± 0.15 mg mL− 1), and AchE inhibitory activity (with an IC50 value of 130.12 ± 6.65 µg mL− 1). At concentrations of 50 and 100 µg mL− 1, fucoxanthin protected against amyloid β-protein fragment 25–35 - induced neurotoxicity on the C6 neuronal cell line with the survival of C6 cells higher than 81.01 and 80.98%, respectively, compared to the control group (59%). Moreover, antioxidant enzyme activity and quantitative PCR analysis revealed that the neuroprotective effect of fucoxanthin, was possibly due to not only regulation of gene expression of antioxidant enzyme (CAT and GPx), ER pathway (caspase-3 and Bax) but also promoting expression of genes involved in PI3K/Akt signaling (GSK-3β), autophagy (p62 and ATG5) and the biosynthesis of ACh (VAChT and ChAT). Therefore, fucoxanthin extracted from the Sargassum olygocystum is a potential feedstock source for the production of health foods with neuroprotective effects.