This study aimed to investigate the influence of kappa ($\mathsf{\kappa }$)-carrageenan on the initial stages of the foreign body response against pectin gel. Pectin-carrageenan (P-Car) gel beads were prepared from the apple pectin and $\mathsf{\kappa }$-carrageenan using gelling with calcium ions. The inclusion of 0.5% $\mathsf{\kappa }$-carrageenan (Car0.5) in the 1.5 (P1.5) and 2% pectin (P2) gel formulations decreased the gel strength by 2.5 times. Car0.5 was found to increase the swelling of P2 gel beads in the cell culture medium. P2 gel beads adsorbed 30–42 mg/g of bovine serum albumin (BSA) depending on pH. P2-Car0.2, P2-Car0.5, and P1.5-Car0.5 beads reduced BSA adsorption by 3.1, 5.2, and 4.0 times compared to P2 beads, respectively, at pH 7. The P1.5-Car0.5 beads activated complement and induced the haemolysis less than gel beads of pure pectin. Moreover, P1.5-Car0.5 gel beads allowed less adhesion of mouse peritoneal macrophages, TNF-$\mathsf{\alpha }$ production, and NF-$\mathsf{\kappa }$B activation than the pure pectin gel beads. There were no differences in TLR4 and ICAM-1 levels in macrophages treated with P and P-Car gel beads. P2-Car0.5 hydrogel demonstrated lower adhesion to serous membrane than P2 hydrogel. Thus, the data obtained indicate that the inclusion of $\mathsf{\kappa }$-carrageenan in the apple pectin gel improves its biocompatibility.

The aims of the study were to evaluate the influence of pectin isolated from fireweed (FP) on the mechanical and rheological properties of agar (A) gel, to investigate the release of phenolic compounds (PCs) and pectin from A-FP gels at simulated digestion in vitro, and to evaluate the oral processing and sensory properties of A-FP gels. The hardness of A-FP gels decreased gradually with the increase in the concentration of FP added (0.1, 0.4, and 1.6%). The hardness of A-FP1.6 gel was 41% lower than A gel. Rheological tests found A gel was a strong physical gel (storage modulus (G′) >>loss modulus (G″)), and the addition of FP up to 1.6% did not significantly change its G’. The G″ value decreased in A-FP gels compared to A gel. The release of galacturonic acid (GalA) was 3.4 ± 0.5, 0.5 ± 0.2, 2.4 ± 1.0, and 2.2 ± 0.7 mg/mL after digestion of A-FP1.6 gel in the oral in vivo phase (OP) and subsequent incubation in simulated gastric (SGF), intestinal (SIF), and colonic (SCF) fluids in vitro. The incubation medium after OP, SGF, and SIF digestion of A-FP1.6 contained 24–64 μg GAE/mL of PCs, while SCF contained 144 μg GAE/mL, supposing a predominant release of antioxidant activity from the gel in the colon. Chewing to readiness for swallowing A-FP gel required less time and fewer chews with less activity of the masseter and temporalis muscles. A-FP1.6 gel had a lower likeness score for taste and consistency and a similar score for appearance and aroma when compared with A gel. Thus, A-FP gels were weakened compared to A gel and required less time and muscle activity for oral processing. A-FP gel had antioxidant activity due to the PCs associated with pectin, while A gel had no antioxidant activity.

The study aims to develop gel beads with improved functional properties and biocompatibility from hogweed (HS) pectin. HS4 and AP4 gel beads were prepared from the HS pectin and apple pectin (AP) using gelling with calcium ions. HS4 and AP4 gel beads swelled in PBS in dependence on pH. The swelling degree of HS4 and AP4 gel beads was 191 and 136%, respectively, in PBS at pH 7.4. The hardness of HS4 and AP4 gel beads reduced 8.2 and 60 times, respectively, compared with the initial value after 24 h incubation. Both pectin gel beads swelled less in Hanks’ solution than in PBS and swelled less in Hanks’ solution containing peritoneal macrophages than in cell-free Hanks’ solution. Serum protein adsorption by HS4 and AP4 gel beads was 118 ± 44 and 196 ± 68 μg/cm² after 24 h of incubation. Both pectin gel beads demonstrated low rates of hemolysis and complement activation. However, HS4 gel beads inhibited the LPS-stimulated secretion of TNF-α and the expression of TLR4 and NF-κB by macrophages, whereas AP4 gel beads stimulated the inflammatory response of macrophages. HS4 gel beads adsorbed 1.3 times more LPS and adhered to 1.6 times more macrophages than AP4 gel beads. Thus, HS pectin gel has advantages over AP gel concerning swelling behavior, protein adsorption, and biocompatibility.

The above-ground part of the Salsola passerine was found to contain ~13% (w/w) of polysaccharides extractable with water and aqueous solutions of ammonium oxalate and sodium carbonate. The fractions extracted with aqueous sodium carbonate solutions had the highest yield. The polysaccharides of majority fractions are characterized by similar monosaccharide composition; namely, galacturonic acid and arabinose residues are the principal components of their carbohydrate chains. The present study focused on the determination of antioxidant activity of the extracted polysaccharide fractions and elucidation of the structure of polysaccharides using nuclear magnetic resonance (NMR) spectroscopy. Homogalacturonan (HG), consisting of 1,4-linked residues of α-D-galactopyranosyluronic acid (GalpA), rhamnogalacturonan-I (RG-I), which contains a diglycosyl repeating unit with a strictly alternating sequence of 1,4-linked D-GalpA and 1,2-linked L-rhamnopyranose (Rhap) residues in the backbone, and arabinan, were identified as the structural units of the obtained polysaccharides. HMBC spectra showed that arabinan consisted of alternating regions formed by 3,5-substituted and 1,5-linked arabinofuranose residues, but there was no alternation of these residues in the arabinan structure. Polysaccharide fractions scavenged the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical at 0.2–1.8 mg/mL. The correlation analysis showed that the DPPH scavenging activity of polysaccharide fractions was associated with the content of phenolic compounds (PCs).