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At least 199 records · Page 11Linked to original sources
PubMed2003

Development of enteric-coated pectin-based matrix tablets for colonic delivery of theophylline.

The present work was aimed at developing a new colonic drug delivery system which takes advantage of the combined approaches of a specifically colon-biodegradable pectin matrix with a pH-sensitive Eudragit S100 polymeric coating. The developed system was able to suitably retard the onset of drug release and to provide a colon-specific delivery, thus overcoming the problems of pectin solubility in the upper gastrointestinal tract and low site-specificity of simple pH-dependent systems. Due to the poor compactability properties of pectin, it was used in mixture with Emdex, a hydrophilic directly-compressible material, in order to make it possible to prepare tablets by direct compression. Theophylline (TP) was used as model drug due to its suitable pharmacokinetic properties for colonic delivery and good absorption in the large intestine. The effects of varying the type of pectin (low and high methoxylated, or amidated), the pectin:Emdex ratio and the level of the pH-dependent polymeric coating on drug release behavior were investigated. Release tests were performed using sequential liquids simulating the physiological variation of pH and the effect of the presence or not of pectinolytic enzymes into the simulated colonic medium was evaluated. Thirty percent (w/w) was the the minimum content of Emdex for obtaining directly compressible tablets with sufficient hardness to withstand the coating process and 27% (w/w) was the minimum coating amount for obtaining an adequate lag time before the onset of drug release. After lag time, linear nearly zero-order profiles were obtained whose slope (i.e. the drug release rate) depended on both the Emdex content and the pectin type. Comparison of the results obtained in the presence or not of pectynolitic enzymes allowed selection of the high methoxylated pectin as the most interesting candidate for specific colonic delivery since it was the least water-soluble and the most susceptible to enzymatic degradation, thus assuring a greater site-specificity of drug release. Finally, the importance of using appropriate dissolution test conditions to adequately characterize the drug release profiles from delivery systems endowed with a microflora-activated drug release triggering mechanism has been demonstrated.

Bronchodilator Agents↗
PubMed1985

Effect of increased amounts of pectin on a solid-liquid meal digestion in healthy man.

The effect of three concentrations of high-methoxy apple pectin (5, 10, and 15 g), on solid-liquid meal digestion was studied in 12 healthy men by the gastrointestinal intubation technique. The gastric emptying of water and carbohydrates is significantly reduced only after 10 and 15 g pectin. The changes in gastric pH are similar for pectin-free and pectin-containing meals. Cumulative lipase and trypsin outputs are not significantly different with and without pectin. When gastric uronic acid concentration is above 6 g/l, the duodenal absorption of carbohydrates is significantly reduced (p less than 0.001). The mean blood glucose levels with 10 and 15 g pectin are significantly higher than the control values at 180 min (p less than 0.05). Pectin does not modify serum concentrations of secretin, cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP), gastric inhibitory polypeptide (GIP), and somatostatin but serum motilin and gastrin levels are below the control values after high fiber meal.

Adult↗
PubMed1988

Methanol production from the degradation of pectin by human colonic bacteria.

When ingested, pectin can lower serum cholesterol levels in humans. Pectin is degraded by fecal bacteria in the colon. We examined the release of methanol (MeOH) by this degradation. A 0.2% glucose (2 g/L) mixture was used as the control medium. A pure culture of pectinolytic Erwinia carotovora was the control bacterium. The chief substrates were, in set 1, 0.2% pectin (2 g/L) and, in set 2, 0.1% glucose (1 g/L) and 0.1% pectin (1 g/L). Cultures of fecal bacteria and E carotovora grew for 72 h in each of the solutions. By 72 h the fecal flora culture in set 1 cleaved 30% of the possible methoxyl groups on pectin. The fecal flora in set 2 cleaved 90.7% of all possible methoxyl groups. Balance studies suggest that all of the free MeOH comes from methoxyl groups on pectin. This study demonstrates that fecal bacteria are capable of degrading pectin to release MeOH.

Bacteria↗
PubMed1976

Influence of fat level and type of carbohydrate on the capacity of pectin in lowering serum and liver lipids of young rats.

The effect of pectin on lowering cholesterol and fat concentration in tissues of the rat was investigated in relation to the level of fat and the type of carbohydrate. Groups of rats were fed nutritionally complete diets containing equal protein: energy, varied with 5% (low-fat, 2% corn oil plus 3% beff tallow) or 20% (high-fat, 2% corn oil plus 18% beef tallow) fat and cornstarch or sucrose as carbohydrate for 2 weeks. Although there were no interactions, the feeding of pectin reduced the cholesterol level in liver and serum from dietary cholesterol to a greater degree in rats fed the low-fat than in those fed the high-fat diet. This effectiveness also varied with type of carbohydrate. In the low-fat diet, this effectiveness was higher with sucrose than with cornstarch, but in the high-fat diet, it was reversed. The size of perirenal fat pads and the concentrations of total liver lipid and cholesterol were less in rats fed the high-fat pectin diet than in those fed the high-fat diet without pectin, indicating that pectin also had an ability to lower fat absorption. When the level of serum alkaline phosphatase was lowered, pectin was more effective in lowering cholesterol level. This phenomenon, however, seemed due to the type of carbohydrate and fat rather than the cholesterol in the diet. Dietary cholesterol had no effect on the size of perirenal fat pads, but increased liver lipid content greatly in rats fed the high-fat diet. Dietary pectin increased the rate of removal of serum cholesterol, and a similar trend was shown in liver cholesterol which had accumulated from the pre-fed hyper-cholesterol diet.

Adipose Tissue↗
PubMed1982

Dietary Pectin's effect on starch utilization in rats.

Dietary pectin's effects on intestinal 14C-starch absorption, oxidation to 14CO2 and intestinal weight were studied. Rats were adapted to either a 5% pectin diet or a control diet for 10 or more days before test meals of the same composition but containing 14C-starch were fed., One hour after the test meal, more 14C label remained in the stomach as well as the entire gastrointestinal tract of pectin-fed rats. Also, less 14C had reached the distal quarter of the small intestine at one hour. Rats eating the 5% pectin diet had higher wet and dry weights of the small intestine. A separate group of pectin-fed rats exhaled more 14CO2 than controls during the first hour after the test meal. Amount of 14C in the gastrointestinal tract and exhalation of 14CO2 did not differ between diet groups at 2, 3, or 4 hours after the test meal. Results indicate that dietary pectin caused a decrease in starch absorption during the fist hour after the meal and it led to an increase in small intestinal weight. Dietary pectin also resulted in a higher percentage of ingested 14C appearing as 14CO2 during the first hour after the test meal.

Animals↗
PubMed1983

The effect of pectin on the utilization of marginal levels of dietary protein by weanling rats.

The effect of dietary pectin levels on protein utilization was studied in weanling rats. Levels of 0, 4.8, 16.7 and 28.6% pectin were used in diets containing 10% protein from casein, bread or bread supplemented with lysine or lysine and threonine. Food intake, energy digestibility and protein digestibility were lowered by dietary pectin, resulting in very strong decreases in digestible energy and digestible protein intakes, protein being affected relatively more than energy. The weight gain of the experimental animals was also incrementally inhibited, with a net loss of weight occurring at the 28.6% pectin level. At this level of pectin addition, the mortality of the experimental groups averaged 50%, death occurring within the first 2 weeks of feeding the experimental diets. Dietary pectin worsened the animal's feed conversion and affected negatively the efficiency with which dietary protein was utilized for growth as measured by the net protein ratio, this effect being much more severe for the higher quality protein diets. It seems to have brought the animals' net protein utilization (NPUs) toward intermediate values, increasing the NPUs of the groups fed the bread-based diets and diminishing those of the other protein groups. The cause of these effects is not clear, although they may be due in part to a lower ratio of digestible protein to digestible energy with increasing dietary pectin. Other participating mechanisms may be the development of adverse intestinal microflora or binding of some essential amino acids to a greater extent than others.

Animals↗
PubMed1992

Structure of dietary pectin, iron bioavailability and hemoglobin repletion in anemic rats.

The effects of the degree of esterification (DE) and the molecular weight (MW) of pectins on iron bioavailability were investigated in anemic rats. The pectins prepared differed (in DE and MW, respectively) as follows: P-A (73%, 860,000), P-B (75%, 89,000), P-C (22%, 1,260,000) and P-D (24%, 114,000). Rats were fed an iron-deficient diet (8 mg Fe/kg diet) for 14 d. The anemic rats were then fed a ferrous sulfate-supplemented basal diet (47 mg Fe/kg diet) or the basal diet containing one of the pectins (80 g/kg diet) for 10 d. None of the pectins used caused any significant reduction in the bioavailability of ferrous sulfate. Addition of pectin P-B to the diet resulted in significantly greater iron repletion. Compared with control rats fed with ad libitum access or pair-fed, rats fed P-B showed higher (P < 0.05) hemoglobin regeneration efficiency, hematocrit, serum iron concentration, and transferrin saturation, and lower unsaturated iron-binding capacity and total iron-binding capacity. Pectins P-A and P-D also slightly improved the hematological indices compared with P-C and control. The observed effects were dependent on the physicochemical properties of each pectin as determined by its MW and DE.

Anemia, Hypochromic↗
PubMed1996

Pectin feeding influences fecal bile acid excretion, hepatic bile acid and cholesterol synthesis and serum cholesterol in rats.

This study was designed to investigate the effects of pectin on cholesterol and bile acid metabolism and to elucidate the mechanisms involved in its hypolipidemic effect in rats. The key regulatory enzymes in cholesterol and bile acid metabolism, 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) and cholesterol 7alpha-hydroxylase, were determined. Circulating, hepatic, and biliary lipid concentrations and fecal bile acid excretion were also measured. Male Wistar rats were fed a fiber-free or a pectin-supplemented (7 g/100 g) diet for 4 wk. Bile flow and the biliary secretion of both bile acids and cholesterol were not significantly different than controls in pectin-fed rats. The addition of pectin to the diet resulted in lower serum and liver cholesterol concentrations (-27 and -17%, respectively). Fecal bile acid excretion (+168%) and the hepatic activity of cholesterol 7alpha-hydroxylase (+70%) were significantly higher in pectin-fed animals. HMG-CoA reductase activity was also significantly greater (+11%) in the presence of dietary pectin. Results of our study indicate that pectin, by enhancing fecal bile acid excretion, may cause increased hepatic synthesis of bile acids and liver depletion of cholesterol in rats, which results in a higher rate of cholesterol synthesis and reduced serum cholesterol concentrations.

Animals↗
PubMed1996

Pectin with low molecular weight and high degree of esterification increases absorption of 58Fe in growing rats.

Effects of pectins with different degrees of esterification (DE) and molecular weights (MW) on iron bioavailability were investigated in healthy growing rats by following erythrocyte incorporation of a dose of 58Fe. Rats were fed a control diet for 8 d and then deprived of food for 16 h. Two hours after the start of feeding iron-deficient diets, with or without pectin (80 g/kg diet), a dose of FeSO4 rich in 58Fe (60.28%) was intubated into the stomach; rats were then allowed to feed for an additional 4 h before withdrawal of food for 10 h. Rats were then fed iron-adequate diets for 9 d. The pectins differed in DE and MW, respectively, as follows: P-A (73%, 860,000), P-B (75%, 89,000), P-C (22%, 1,260,000) and P-D (24%, 114,000). Rats fed pectin-free diet with free access to food or restricted to the same quantity consumed by a respective pectin group served as controls. Iron absorption was 48% in the control group and 57% in rats fed P-B. Rats fed P-B had higher (P 2 < or = 0.05) serum iron, transferrin saturation, hematocrit and liver and spleen iron than the control group or the group fed P-C. These indices, except for transferrin saturation, were also higher In rats fed P-A and P-D compared with those fed P-C and controls, but to a lesser extent than in rats fed P-B. The data indicate that bioavailability of dietary non-heme iron was enhanced when pectin of low MW and high DE was added to the diet. This improvement was not evident with pectins having high MW and/or low DE.

Absorption↗
PubMed1994

Reduction of tomato polygalacturonase beta subunit expression affects pectin solubilization and degradation during fruit ripening.

The developmental changes that accompany tomato fruit ripening include increased solubilization and depolymerization of pectins due to the action of polygalacturonase (PG). Two PG isoenzymes can be extracted from ripe fruit: PG2, which is a single catalytic PG polypeptide, and PG1, which is composed of PG2 tightly associated with a second noncatalytic protein, the beta subunit. Previous studies have correlated ripening-associated increases in pectin solubilization and depolymerization with the presence of extractable PG1 activity, prior to the appearance of PG2, suggesting a functional role for the beta subunit and PG1 in pectin metabolism. To assess the function of the beta subunit, we produced and characterized transgenic tomatoes constitutively expressing a beta subunit antisense gene. Fruit from antisense lines had greatly reduced levels of beta subunit mRNA and protein and accumulated < 1% of their total extractable PG activity in ripe fruit as PG1, as compared with 25% for wild type. Inhibition of beta subunit expression resulted in significantly elevated levels of EDTA-soluble polyuronides at all stages of fruit ripening and a significantly higher degree of depolymerization at later ripening stages. Decreased beta subunit protein and extractable PG1 enzyme activity and increased pectin solubility and depolymerization all cosegregated with the beta subunit antisense transgene in T2 progeny. These results indicate (1) that PG2 is responsible for pectin solubilization and depolymerization in vivo and (2) that the beta subunit protein is not required for PG2 activity in vivo but (3) does play a significant role in regulating pectin metabolism in wild-type fruit by limiting the extent of pectin solubilization and depolymerization that can occur during ripening. Whether this occurs by direct interaction of the beta subunit with PG2 or indirectly by interaction of the beta subunit with the pectic substrate remains to be determined.

Amino Acid Sequence↗
PubMed2003

PaeX, a second pectin acetylesterase of Erwinia chrysanthemi 3937.

Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. Pectin is a complex polysaccharide. The main chain is constituted of galacturonate residues, and some of them are modified by methyl and/or acetyl esterification. Esterases are necessary to remove these modifications and, thus, to facilitate the further degradation of the polysaccharidic chain. In addition to PaeY, the first pectin acetylesterase identified in the E. chrysanthemi strain 3937, we showed that this bacterium produces a second pectin acetylesterase encoded by the gene paeX. The paeX open reading frame encodes a 322-residue precursor protein of 34,940 Da, including a 21-amino-acid signal peptide. Analysis of paeX transcription, by using gene fusions, revealed that it is induced by pectic catabolic products and affected by catabolite repression. The expression of paeX is regulated by the repressor KdgR, which controls all the steps of pectin catabolism; by the repressor PecS, which controls most of the pectinase genes; and by catabolite regulatory protein, the global activator of sugar catabolism. The paeX gene is situated in a cluster of genes involved in the catabolism and transport of pectic oligomers. In induced conditions, the two contiguous genes kdgM, encoding an oligogalacturonate-specific porin, and paeX are both transcribed as an operon from a promoter proximal to kdgM, but transcription of paeX can also be uncoupled from that of kdgM in noninduced conditions. PaeX is homologous to the C-terminal domain of the Butyrivibrio fibriosolvens xylanase XynB and to a few bacterial esterases. PaeX contains the typical box (GxSxG) corresponding to the active site of the large family of serine hydrolases. Purified PaeX releases acetate from various synthetic substrates and from sugar beet pectin. The PaeX activity increased after previous depolymerization and demethylation of pectin, indicating that its preferred substrates are nonmethylated oligogalacturonides. PaeX is mostly found in the periplasmic space of E. chrysanthemi. These data suggest that PaeX is mainly involved in the deacetylation of esterified oligogalacturonides that enter the periplasm by the KdgM porin.

Amino Acid Sequence↗
PubMed1984

Effect of pectin on jejunal glucose absorption and unstirred layer thickness in normal man.

The effect of high methoxy apple pectin, a carbohydrate gelling agent, on the intestinal absorption of glucose, water, and sodium was studied in man. The effect of intraluminal fibre was evaluated in 22 healthy volunteers by the intestinal perfusion technique under an occlusive balloon. The test solutions (NaCl 130 mM, KCl 5 mM, glucose or mannitol 30 mM, PEG 4000 5 g/l) were perfused just beyond the ligament of Treitz at a rate of 10 ml/min. A 25 cm segment was studied. Three concentrations of pectin were tested: 6, 10, and 15 g/l. The effect of this pectin at two concentrations, 6 and 10 g/l, on the jejunal unstirred layer thickness was evaluated in nine other healthy subjects by an electrical technique. In mannitol solution, pectin reversed water and sodium absorption, whatever its concentration was, while in glucose solution it significantly reduced absorption of water and sodium at 10 and 15 g/l only (p less than 0.01). It significantly reduced glucose absorption at all concentrations (p less than 0.01). This reduction was found to be correlated with the solution viscosity (p less than 0.01). Pectin did not alter the glucose dependent sodium transport but increased significantly (p less than 0.001) the unstirred layer thickness. These results suggested that, in healthy man, pectin acutely given may impair intestinal absorption by means of an increased unstirred layer resistance. This effect could contribute to the diminished postprandial glycaemia observed in human subjects fed pectin.

Body Water↗
PubMed1992

Christmas candy maker's asthma. IgG4-mediated pectin allergy.

We evaluated a 29-year-old candy maker with no history of asthma who developed asthma after exposure to pectin, a compound manufactured from fruits and fruit rinds. Following eight years of employment during which he added pectin to a recipe for Christmas candies, the candymaker developed acute respiratory symptoms. Challenge testing with the pectin mixture caused a 40 percent decrease in FEV1. Skin prick testing was positive to the pectin extract. Total IgE was normal and pectin-specific IgE antibodies were not detected. A strongly positive pectin-specific IgG4 antibody response was present that was not detected in a control serum and could be inhibited by the addition of pectin. Antigen-specific IgG4 should be sought in IgE negative cases of occupational asthma.

Adult↗
PubMed1992

Effect of pectin on formyl methionyl-leucyl-phenylalanine (FMLP)-injured intestinal mucosa of rat.

(1) We investigated the trophic effect of pectin on the intestinal mucosa injured by formyl methionyl-leucyl-phenylalanine (FMLP), a chemoattractant produced by the intestinal bacterial flora. (2) We first demonstrated that oral administration of FMLP for 7 days reduced the disaccharidase activities and increased the permeability, measured by fluorescein-isothiocyanate-conjugated dextran, of rat small intestine. (3) After 7 days of FMLP administration, rats were divided into fiber-free group which was given liquid elemental diet (Elental) and the pectin group which was given Elental supplemented with 2.5% pectin. (4) After 3 days of feeding (Day 3), the maltase activities of the pectin group was significantly greater than that of the fiber-free group and than that of the initial level just after the 1 week administration of FMLP. At Day 7, there was no difference of maltase activity between the two groups. The sucrase activity of the pectin group was also significantly greater than that of fiber-free group at Day 3. (5) Plasma enteroglucagon was significantly increased in the pectin group. We conclude that pectin-supplemented diet promoted the recovery of disaccharidase activities in the FMLP-injured intestinal mucosa which may be mediated by enteroglucagon.

Animals↗
PubMed1984

Unstirred water layers in rabbit intestine: effects of pectin.

Pectins have been shown to affect the absorption of several different nutrients in clinical studies; however, the mechanisms for decreased absorption have not been defined. A possibility not studied with regards to pectin, but previously demonstrated to be important in absorption, is the effect of change in the unstirred water layer. As the unstirred water layer increases in thickness, the rate of absorption decreases for certain nutrients. The effect of pectin on the unstirred water layer in the lumen of rabbit jejunum was examined by previously described techniques. It was observed that: (1) increases in pectin concentration resulted in an increased thickness of the unstirred water layer; (2) for any stir rate, the addition of pectin increased the thickness of the unstirred water layer; and (3) stir rate is inversely related to the thickness of the unstirred water layer. It was concluded from these results that pectin increases the thickness of the unstirred water layer in rabbit jejunum. This mechanism may explain, in part, the reduction of the rate of absorption of certain nutrients seen following pectin ingestion.

Animals↗
PubMed2001

Pectin: cell biology and prospects for functional analysis.

Pectin is a major component of primary cell walls of all land plants and encompasses a range of galacturonic acid-rich polysaccharides. Three major pectic polysaccharides (homogalacturonan, rhamnogalacturonan-I and rhamnogalacturonan-II) are thought to occur in all primary cell walls. This review surveys what is known about the structure and function of these pectin domains. The high degree of structural complexity and heterogeneity of the pectic matrix is produced both during biosynthesis in the endomembrane system and as a result of the action of an array of wall-based pectin-modifying enzymes. Recent developments in analytical techniques and in the generation of anti-pectin probes have begun to place the structural complexity of pectin in cell biological and developmental contexts. The in muro de-methyl-esterification of homogalacturonan by pectin methyl esterases is emerging as a key process for the local modulation of matrix properties. Rhamnogalacturonan-I comprises a highly diverse population of spatially and developmentally regulated polymers, whereas rhamnogalacturonan-II appears to be a highly conserved and stable pectic domain. Current knowledge of biosynthetic enzymes, plant and microbial pectinases and the interactions of pectin with other cell wall components and the impact of molecular genetic approaches are reviewed in terms of the functional analysis of pectic polysaccharides in plant growth and development.

Cell Wall↗
PubMedDate not supplied

Effect of temperature and high pressure on the activity and mode of action of fungal pectin methyl esterase.

Pectin was de-esterified with purified recombinant Aspergillus aculeatus pectin methyl esterase (PME) during isothermal-isobaric treatments. By measuring the release of methanol as a function of treatment time, the rate of enzymatic pectin conversion was determined. Elevated temperature and pressure were found to stimulate PME activity. The highest rate of PME-catalyzed pectin de-esterification was obtained when combining pressures in the range 200-300 MPa with temperatures in the range 50-55 degrees C. The mode of pectin de-esterification was investigated by characterizing the pectin reaction products by enzymatic fingerprinting. No significant effect of increasing pressure (300 MPa) and/or temperature (50 degrees C) on the mode of pectin conversion was detected.

Aspergillus↗
PubMedDate not supplied

Temperature-independent pectin gel method for coliform determination in dairy products: collaborative study.

Ten laboratories participated in a collaborative study to compare a pectin-based violet red bile (VRB) method with the VRB agar-based standard method for estimation of coliform bacterial counts in 7 different dairy food groups: cream, cheddar cheese, cottage cheese, homogenized milk, raw milk, sour cream, and yogurt. Each laboratory analyzed 8 samples of each food group as sample pairs prepared at high, medium, and low inoculum levels, and an uninoculated control pair. Overall mean log counts were higher for the pectin gel method in 18 of 21 cases (7 samples at 3 inoculum levels); 12 results were significantly higher (P less than 0.01) than those for the VRB agar method. Of the 3 higher VRB agar method means, 2 were not significant at P less than 0.10, and one was of borderline significance (0.05 less than P less than 0.06). Repeatability variation (sr) favored the pectin gel method in 14 of 21 cases; 7 were highly significant differences (P less than 0.01). None of the 7 results favoring the VRB agar method was statistically significant. Reproducibility variation (sR) favored the pectin gel method in 14 of 21 results. These data indicate that the pectin gel method gives higher recovery of coliforms with better precision than does the VRB agar method, and strongly support the suitability of the pectin gel method as an alternative to the agar-based VRB method for coliform counts in dairy products. The pectin gel method has been adopted official first action.

Culture Media↗