Effects of the polysaccharide SPS-3-1 purified from Spirulina on barrier integrity and proliferation of Caco-2 cells

Following ultrasonication combined with a hot water extraction, a new type of bioactive polysaccharide, SPS-3-1, was purified from Spirulina using ultrafiltration centrifugation and gel filtration chromatography. The structure of SPS-3-1 was determined with high performance gel permeation chromatography, gas chromatography, periodate oxidation, fourier transform infrared spectroscopy, nuclear magnetic resonance, and atomic force microscopy performance. SPS-3-1 is a homogeneous beta-pyran polysaccharide with 1 -> 2, 1 -> 3, and 1 -> 4 glycosyl bonds, mainly composed of D-ribose, L-rhamnose, L-arabinose, L-foucose, and D-glucose. The molar ratio of these components is 1:0.70:1.03:2.1:6.59. The molecular weight of SPS-3-1 is 623.02 kDa. SPS-3-1 has a linear filament structure with a width of 34.132 nm and a height of 819.169 pm. We found that SPS-3-1 significantly enhanced transepithelial electrical resistance, a tight junction integrity marker, in a Caco-2 intestinal cell monolayer model. Analysis of the effect of SPS-3-1 on cell proliferation showed that SPS-3-1 inhibited the in vitro growth of Caco-2 and HepG2 cells with an IC50 of 566.67 mu g/mL and 1078.95 mu g/mL, respectively. (C) 2020 Elsevier B.V. All rights reserved.