In vitro gastrointestinal-resistant pectin hydrogel particles for ß-glucuronidase adsorption.

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 ß-glucuronidase (ßG) in vitro. The data obtained offered the prospect for the development of the PHPs from TVF as sorbents of colonic ßG for the inhibition of re-absorption of estrogens.

Impact of cabbage pectin-protein complex on microbial ß-glucuronidase activity.

We previously demonstrated that pectin-protein complex (PPC) isolated from white cabbage adsorbs the ß-glucuronidase (ßG) enzyme of E. coli. Concurrently, we discovered a significant increase in ßG activity in the presence of PPC. The aim of this study is to identify the structural components of PPC that are responsible for ßG adsorption and activation. PPC was isolated from white cabbage using a saline solution containing hydrochloric acid (pH 1.5) at 37 °C for 4 h. PPC proteins were precipitated by aqueous 10% (m/v) trichloroacetic acid to yield the pectin-protein fractions PPC1 and PPC2. PPC was digested using 1,4-α-d-galacturonase, yielding the PPC6 fraction. Partial acid hydrolysis of PPC revealed the galacturonan fraction, PPC3, to be the core of the macromolecule. The purified PPC4 and PPC5 fractions were isolated from PPC by ion-exchange chromatography on DEAE-cellulose. ßG activity and its adsorption in the PPC fractions were studied in vitro. Crystalline cellulose was used as a control. This study found that the PPC3 fraction (the galacturonan core) does not adsorb ßG and does not affect its activity. The adsorption of ßG in the PPC samples is inversely proportional to the degree of methyl esterification of its carbohydrate component. The PPC4 and PPC5 fractions adsorb the highest proportion of ßG (51.2% and 54%, respectively). The stimulation of ßG enzyme activity is directly proportional to the protein content of the PPC sample. The PPC and PPC1 samples have the greatest ability to increase ßG activity (57.6% and 52.1%, respectively).