Molecular Interactions between Barley and Oat β-Glucans and Phenolic Derivatives

Abstract

Equilibrium dialysis, molecular modeling, and multivariate data analysis were used to investigate the nature of the molecular interactions between 21 vanillin-inspired phenolic derivatives, 4 bile salts, and 2 commercially available beta-glucan preparations, Glucagel and PromOat, from barley and oats. The two beta-glucan products showed very similar binding properties. It was demonstrated that the two beta-glucan products are able to absorb most phenolic derivatives at a level corresponding to the absorption of bile salts. Glucosides of the phenolic compounds showed poor or no absorption. The four phenolic derivatives that showed strongest retention in the dialysis assay shared the presence of a hydroxyl group in para-position to a CHO group. However, other compounds with the same structural feature but possessing a different set of additional functional groups showed less retention. Principal component analysis (PCA) and partial least-squares regression (PLS) calculations using a multitude of diverse descriptors related to electronic, geometrical, constitutional, hybrid, and topological features of the phenolic compounds showed a marked distinction between aglycon, glucosides, and bile salt retention. These analyses did not offer additional information with respect to the mode of interaction of the individual phenolics with the beta-glucans. When the barley beta-glucan was subjected to enzyme degradation, the ability to bind some but not all of the phenolic derivatives was lost. It is concluded that the binding must be dependent on multiple characteristics that are not captured by a single molecular descriptor.

Adsorption between Quercetin Derivatives and β-Glucan Studied with a Novel Approach to Modeling Adsorption Isotherms

“…Furthermore, according to the mean free energy of adsorption (E), the adsorption could be a physical process (since E < 8000 J/mol) with creation of physical bonds between quercetin derivatives and β-glucan, such as Van der Waals bonds or H bonds. This agrees with earlier studies where it was suggested that hydrophobic interactions, hydrogen bonds and van der Waals interactions are the driving forces of adsorption process of polyphenols with β-glucan [16,17,22,23]. Hydrogen bonds between quercetin derivatives and βglucan could occur through their -OH groups [17] and after the formation of hydrogen bonds, van der Waals interactions could be formed because the distance between the polyphenol molecule and β-glucan rings becomes short [17].…”

“…However, there is still much unknown about polyphenol-dietary fiber interactions (adsorptions). Specifically, there are only a few published papers dealing with β-glucan and polyphenols adsorptions [16,17,[20][21][22][23]. Since polyphenols are a large group of compounds, many of them have never been studied in the adsorption process with β-glucan.…”

Efficiency Assessment of Natural Biopolymers as Encapsulants of Green Tea (Camellia sinensis L.) Bioactive Compounds by Spray Drying

“…Similarly to gum arabic, ionic polysaccharides such as pectins or arabinogalactans can also bind to flavonoids without the presence of proteins (Bordenave et al 2014). In case of catechins, it was determined that galloylation seemed to increase the binding capacity to ß-glucans, which is suggested to be mainly driven by hydrogen bonding interactions (Wang et al 2013;Simonsen et al 2009). Besides the study of these complexes, flavonoids were tried to be entrapped in polysaccharide particles by encapsulation such as the EGCG-loaded nanoparticles made from gum arabic and maltodextrin with improved EGCG stability (Qin et al 2010), quercetin incorporation into a guar gum-based matrix (Peres et al 2011) or pectin-hydroxypropyl methylcellulose tablets for specific delivery to the colon (Wang et al 2013), quercetin complexation with pectin for enhanced bioavailability (Monteiro et al 2007), etc.…”

Comparative spectroscopic and rheological studies on crude and purified soluble barley and oat β-glucan preparations

“…the food industry. Most recently, we employed the present temperature-viscosity profiles of BBG 67 and OBG 30 in the preliminary work on their interactions with phenolic derivatives to monitor the mobility of the small molecules in solution throughout sample handling (Simonsen et al, 2009). The purification of BBG 67 and OBG 30 resulted in increased solution viscosities.…”

“…Special interest in these samples was the detection and characterization of α-glucans and to study the effect of α-glucans on the viscous properties of the sample solutions. Two of the β-glucan samples were recently investigated in a dialysis study targeted at studying the β-glucan affinity with small molecules (Simonsen et al, 2009). …”