Pavel A. Markov

Pectic polysaccharides of the fresh plum Prunus domestica L. isolated with a simulated gastric fluid and their anti-inflammatory and antioxidant activities

A pectic polysaccharide, designated as PD, was extracted from fresh plums (Prunus domestica L.) with a simulated gastric fluid. Galacturonan, which was partially substituted with methyl and O-acetyl ester groups, and rhamnogalacturonan were the main constituents of the linear regions of the sugar chains of PD. The ramified region contained mainly 1,4-linked β-d-galactopyranose residues and, to a lesser extent, 1,5-linked α-l-arabinofuranose residues. The separation of PD, by DEAE-cellulose column chromatography, yielded two pectic fractions: PD-1 and PD-2, eluted with 0.1 and 0.2 M NaCl, respectively. Enzymatic digestion of PD with 1,4-α-d-polygalacturonase yielded the fraction PD-E. The parent pectin PD and the PD-1 fraction were found to diminish the adhesion of peritoneal leukocytes at the concentrations of 0.05-1.0mg/ml. However, the PD-E fraction failed to have an effect on cell adhesion at the concentrations of 0.05-0.1mg/ml. PD, PD-1 and PD-E were found to inhibit the production of superoxide anion radicals by reducing xanthine oxidase activity by 38%, 97% and 47%, respectively. Therefore, the PD-1 fraction appeared to be an active fragment of pectic macromolecule isolated from fresh plum with a simulated gastric fluid.

Anti-inflammatory activity of pectins and their galacturonan backbone

It has been shown that pectin polysaccharides from different plants, depending on their structure, can either protect the intestinal walls of mammals against damage and inhibit the development of inflammation or, on the contrary, have proinflammatory effects. At the same time, galacturonan isolated from any pectin, being the main carbohydrate chain (backbone) of its macromolecule, shows a marked anti-inflammatory effect. A decrease in the quantity of neutrophiles in the intestinal wall after induced inflammation indicates that the anti-inflammatory effects of pectins can be based on their influence on the functional activity of leukocytes.

Swelling and morphology of calcium pectinate gel beads obtained from Silene vulgaris callus modified pectins.

The aim of this research is to investigate the swelling properties and morphology of the calcium pectinate gel (CaPG) beads made from pectins of campion callus cultured using various medium nutrients (carbon sources, concentration of sucrose, calcium and 2,4-dichlorophenoxyacetic acid (2,4-D)). Gelled spheres were prepared by ionotropic gelation. The mean diameter, total surface area and volume of the dried beads varied depending on the plant cell culture conditions. The swelling of dried CaPG beads in solutions with pH 2 and pH 4 was demonstrated to occur more slowly (within 4 or 24h) with increasing sucrose and calcium concentrations or in the absence of auxin. All beads swelled less when placed in acidic media (pH 2 and pH 4) and swelled most extensively in NaCl (pH 6). The surface morphology of the CaPG beads was demonstrated to depend on the presence of sugars, calcium and auxin in the plant cell culture medium used. The slow swelling of dried CaPG beads was apparently related to their grooved surfaces. An applied strategy involving changing the composition and concentration of media components altered the swelling behavior of the CaPG beads and enhanced the acid and water resistance of the resultant pectinate hydrogels in physiological environments. In particular, the swelling of Ca 4.5, 2,4-D0, Suc30 and Suc100 CaPG beads occurred more slowly.

Chemical characterization and anti-inflammatory effect of rauvolfian, a pectic polysaccharide of Rauvolfia callus.

The pectic polysaccharide named rauvolfian RS was obtained from the dried callus of Rauvolfia serpentina L. by extraction with 0.7% aqueous ammonium oxalate. Crude rauvolfian RS was purified using membrane ultrafiltration to yield the purified rauvolfian RSP in addition to glucan as admixture from the callus, with molecular weights 300 and 100–300 kD, respectively. A peroral pretreatment of mice with the crude and purified samples of rauvolfian (RS and RSP) was found to decrease colonic macroscopic scores, the total area of damage, and tissue myelope roxidase activity in colons as compared with a colitis group. RS and RSP were shown to stimulate production of mucus by colons of the colitis mice. RSP appeared to be an active constituent of the parent RS. The glucan failed to possess anti-inflammatory activity.

Preparation and biocompatibility evaluation of pectin and chitosan cryogels for biomedical application

Today, there is a need for the development of biomaterials with novel properties for biomedical purposes. The biocompatibility of materials is a key factor in determining its possible use in biomedicine. In this study, composite cryogels were obtained based on pectin and chitosan using ionic cryotropic gelation. For cryogel preparation, apple pectin (AP), Heracleum L. pectin (HP), and chitosan samples with different physical and chemical characteristics were used. The properties of pectin-chitosan cryogels were found to depend on the structural features and physicochemical characteristics of the pectin and chitosan within them. The addition of chitosan to cryogels can increase their mechanical strength, cause change in surface morphology, increase the degradation time, and enhance adhesion to biological tissues. Cryogels based on AP were less immunogenic when compared with cryogels from HP. Cryogels based on AP and HP were hemocompatible and the percentage of red blood cells hemolysis was less than 5%. Unlike cryogels based on HP, which exhibited moderate cytotoxicity, cryogels based on AP exhibited light cytotoxicity. Based on the results of low immunogenicity, light cytotoxicity data as well as a low level of hemolysis of composite cryogels based on AP and chitosan are biocompatible and can potentially be used in biomedicine.

Mechanical properties, structure, bioadhesion and biocompatibility of pectin hydrogels

The surface structure, biocompatibility, textural, and adhesive properties of calcium hydrogels derived from 1, 2, and 4% solutions of apple pectin were examined in this study. An increase in the pectin concentration in hydrogels was shown to improve their stability toward elastic and plastic deformation. The elasticity of pectin hydrogels, measured as Youngs modulus, ranged from 6 to 100 kPa. The mechanical properties of the pectin hydrogels were shown to correspond to those of soft tissues. The characterization of surface roughness in terms of the roughness profile (Ra) and the root-mean-square deviation of the roughness profile (Rq) indicated an increased roughness profile for hydrogels depending on their pectin concentration. The adhesion of AU2% and AU4% hydrogels to the serosa abdominal wall, liver, and colon was higher than that of the AU1% hydrogel. The adhesion of macrophages and the non-specific adsorption of blood plasma proteins were found to increase as the pectin concentration in the hydrogels increased. The rate of degradation of all hydrogels was higher in phosphate buffered saline (PBS) than that in DMEM and a fibroblast cell monolayer. The pectin hydrogel was also found to have a low cytotoxicity.

In vitro gastrointestinal-resistant pectin hydrogel particles for β-glucuronidase adsorption

Abstract Pectin hydrogel particles (PHPs) were prepared by ionotropic gelation of low methylesterified pectin of Tanacetum vulgare L. with calcium ions. Wet PHPs prepared from TVF exhibited a smaller diameter and the lower weight as well as exhibited the best textural properties in terms of hardness and elasticity compared to the PHPs prepared from commercial low methylesterified pectin (CU701) used for comparison. Upon air drying, PHPs prepared from CU701 became small and dense microspheres whereas the dry PHPs prepared from TVF exhibited a drop-like shape. The morphology of dry PHPs determined by scanning electron microscopy revealed that the surface of the TVF beads exhibited fibred structures, whereas the PHPs prepared from CU701 exhibited a smooth surface. The characterization of surface roughness using atomic force microscopy indicated less roughness profile of the PHPs prepared from TVF than CU701. PHPs prepared from TVF were found to possess in vitro resistance to successive incubations in simulated gastric (SGF), intestinal (SIF), and colonic fluid (SCF) at 37 °C for 2, 4 and 18 h, respectively. The PHPs prepared from CU701 swelled in SGF and then lost their spherical shape and were fully disintegrated after 4 h of incubation in SIF. The PHPs from TVF, which were subjected to treatment with SGF, SIF and SCF, were found to adsorb microbial β-glucuronidase (βG) in vitro. The data obtained offered the prospect for the development of the PHPs from TVF as sorbents of colonic βG for the inhibition of re-absorption of estrogens.

Adsorption of β-glucuronidase and estrogens on pectin/lignin hydrogel particles

ABSTRACT The objective of this study was to generate supramolecular complexes of pectin and lignin with properties necessary to interrupt the enterohepatic circulation (EHC) of estrogens. Three types of pectin hydrogel particles were prepared from citrus pectin (PHP), citrus pectin/wheat lignin (PLWHP), or citrus pectin/oak lignin (PLOHP). The surface of PHP was smooth, whereas the surface of PLWHP had irregularly arranged structures and PLOHP contained pores. PHP actively adsorbed microbial β-glucuronidase and moderately adsorbed estrogens. PLWHP had moderate and PLOHP high affinity for estrogens. Thus, PLOHP meets the requirements of a complex capable of interrupting the EHC of estrogens. GRAPHICAL ABSTRACT

Adjuvant Effect of Lemnan, Pectic Polysaccharide of Callus Culture of Lemna minor L. at Oral Administration

A pectic polysaccharide, lemnan LMC, was extracted from the callus of duckweed Lemna minor L. and was tested for adjuvant properties at oral administration with protein antigen. Mice were orally immunized thrice with weekly interval with free hens egg lysozyme or lysozyme with LMC. Lemnan LMC was shown to increase delayed type hypersensitivity and serum antilysozyme IgG responses. LMC was established to increase levels of both serum IgG1 and IgG2a subclasses. The concentration of malondialdehyde and myeloperoxidase activity were found to be higher in the tissue samples obtained from small intestine of mice immunized with mixture of lysozyme/LMC than those immunized with lysozyme only. Thus, lemnan appeared to be useful as the adjuvant for oral immunization.

Injectable hydrogel from plum pectin as a barrier for prevention of postoperative adhesion

An injectable hydrogel was obtained from the high methyl-esterified plum Prunus domestica L. (PD) pectin and calcium ions (Ca2+). PD hydrogel showed a weak gel-like behavior and could be squeezed out of the syringe with an injection force of ca. 9 N. PD hydrogel was not suitable for the NIH/3T3 fibroblast cell adhesion in vitro. The live/dead fluorescence and MTT (3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide) assays indicated that the PD hydrogel had a low cytotoxicity in relation to both the adhered and gel surrounding fibroblasts. PD hydrogel was found to inhibit adhesion formation in the sidewall defect-cecum abrasion rat model. In the control group, the occurrence of adhesion of the cecum to the peritoneal wall was found in seven of the total seven rats operated. Only four of the seven animals that were treated with the PD hydrogel were noted to have any adhesions. These adhesions were of a minimum grade of 1, 2, and 3 and were represented by a thin film that could be easily broken. The protective effect of PD hydrogel was found to be comparable with that of hyaluronic acid hydrogel used as a positive control. PD hydrogel appeared to possess enhanced in vivo residence stability on the injury sites compared to hyaluronic acid hydrogel as measured by staining of healing tissue with periodic acid-Schiff reagent. The data obtained offered the prospect for the development of the pectin-based gels as new barrier materials for surgery.