Sodium alginate decreases the permeability of intestinal mucus

Abstract

In the small intestine the nature of the environment leads to a highly heterogeneous mucus layer primarily composed of the MUC2 mucin. We set out to investigate whether the soluble dietary fibre sodium alginate could alter the permeability of the mucus layer. The alginate was shown to freely diffuse into the mucus and to have minimal effect on the bulk rheology when added at concentrations below 0.1%. Despite this lack of interaction between the mucin and alginate, the addition of alginate had a marked effect on the diffusion of 500 nm probe particles, which decreased as a function of increasing alginate concentration. Finally, we passed a protein stabilised emulsion through a simulation of oral, gastric and small intestinal digestion. We subsequently showed that the addition of 0.1% alginate to porcine intestinal mucus decreased the diffusion of fluorescently labelled lipid present in the emulsion digesta. This reduction may be sufficient to reduce problems associated with high rates of lipid absorption such as hyperlipidaemia.

Roles for dietary fibre in the upper GI tract: The importance of viscosity

“…The ability of MUC2 mucin to bind alginate was tested in QCM experiments published elsewhere (Mackie et al, 2015). In these experiments mucin that had previously been adsorbed to a QCM chip was exposed to a solution of alginate.…”

“…Emulsion and digestion A protein stabilised emulsion was produced using the method described in Mackie et al (Mackie, Macierzanka, Aarak, Ridout, & Bajka, 2015). Briefly, 3.0 mg/mL sodium caseinate solution in 150 mm NaCl pH 6.5 stabilised emulsion containing 18% triglyceride (sunflower oil) was prepared by passing a premix of oil and Na-Cas for a total of 6 times at 20,000 psi through a Microfluidiser (Microfluidics, Massachusetts, USA).…”

“…The emulsion was digested using the standardised in vitro digestion protocol recommended by the Infogest COST Action (Minekus et al, 2014), involving 2 hours gastric followed by 2 hours of small intestinal simulation. The mean size (D3,2) of the original emulsion was 1.0 m. The mean size of the emulsion after digestion was 725 nm and the size distributions can be seen in a supplementary figure ( Figure S1) to (Mackie et al, 2015) Diffusion The diffusion coefficients were determined using three different methods. The ability of the sodium alginate to penetrate into porcine mucus was determined using time-lapse microscopy.…”

Marine Algae as a Potential Source for Anti-Obesity Agents

“…The proposed mechanism is that enhanced fecal excretion of bile acid due to reduced intestinal reabsorption could stimulate bile acid synthesis from cholesterol in the liver, resulting in a decrease in plasma cholesterol. Sodium alginate has also been shown to reduce the permeability of intestinal mucus, which implicates that this may reduce problems associated with high rates of lipid absorption such as hyperlipidemia [77]. …”

Cationic carbon quantum dots derived from alginate for gene delivery: One-step synthesis and cellular uptake

“…The CQDs were designed to serve two purposes: as a gene vector to deliver plasmid TGF-b1 into 3T6 cells and as a fluorescent probe to directly monitor the gene delivery process so as to shed light on the cellular uptake mechanisms of the CQDs/pDNA complexes. Sodium alginate, a natural polysaccharide extracted from seaweed, has been widely used in food, medicine, textile, printing and dyeing, paper making, and daily chemical products [33,34]. Recently, it has been employed as an important pharmaceutic adjuvant and biomedical material [35][36][37].…”