Abstract
Fucoidan extracts may have beneficial effects in age-related macular degeneration (AMD). Over-the-counter fucoidan preparations are generally undefined, crude extracts. In this study, we investigated the effect of a crude fucoidan extract from Fucus distichus subspecies evanescens (Fe) on the retinal pigment epithelium (RPE). Fe extract was investigated for chemical composition and molar mass. It was tested in primary RPE and RPE cell line ARPE19. Oxidative stress was induced with tert-butyl hydroperoxide, cell viability evaluated with MTT assay, VEGF secretion assessed in ELISA. Phagocytosis was evaluated in a fluorescence microscopic assay. Wound healing ability was tested in a scratch assay. Additionally, the inhibition of elastase and complement system by Fe extract was studied. The Fe extract contained about 61.9% fucose and high amounts of uronic acids (26.2%). The sulfate content was not as high as expected (6.9%). It was not toxic and not protective against oxidative stress. However, Fe extract was able to reduce VEGF secretion in ARPE19. Phagocytosis was also reduced. Concerning wound healing, a delay could be observed in higher concentrations. While some beneficial effects could be found, it seems to interfere with RPE function, which may reduce its beneficial effects in AMD treatment.
Highlights
Fucoidans are sulfated polysaccharides derived from brown seaweed, consisting mainly of sulfated fucose
Fucoidans have been shown to be protective against oxidative stress in various cell assays [10,11,12,13], and we have shown such a protective, anti-oxidative stress effect of fucoidan from Fucus vesiculosus in ocular cells as well [14]
We have investigated a fucoidan extract from Fucus distichus subspecies evanescens
Summary
Fucoidans are sulfated polysaccharides derived from brown seaweed, consisting mainly of sulfated fucose. Many different biological activities have been described for fucoidan, but fucoidans are heterogeneous, varying strongly between different species [1]. Among the biological activities described for fucoidans are those interesting for potential treatment of age-related macular degeneration (AMD) [2]. Its pathogenesis is complex and multifactorial yet accepted as a major factor in the development of AMD is oxidative stress [3,4,5]. The retina is exposed to high degrees of oxidative stress through constant exposure to high-energetic sun light, due to a high activity of mitochondria in photoreceptors and retinal pigment epithelial cells (RPE), and due to the presence of oxidized fatty acids. The retinal pigment epithelium, a monolayer between the photoreceptors
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