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At least 19 recordsLinked to original sources
PubMed1991

Pectin methylesterase, metal ions and plant cell-wall extension. Hydrolysis of pectin by plant cell-wall pectin methylesterase.

The hydrolysis of p-nitrophenyl acetate catalysed by pectin methylesterase is competitively inhibited by pectin and does not require metal ions to occur. The results suggest that the activastion by metal ions may be explained by assuming that they interact with the substrate rather than with the enzyme. With pectin used as substrate, metal ions are required in order to allow the hydrolysis to occur in the presence of pectin methylesterase. This is explained by the existence of 'blocks' of carboxy groups on pectin that may trap enzyme molecules and thus prevent the enzyme reaction occurring. Metal ions may interact with these negatively charged groups, thus allowing the enzyme to interact with the ester bonds to be cleaved. At high concentrations, however, metal ions inhibit the enzyme reaction. This is again understandable on the basis of the view that some carboxy groups must be adjacent to the ester bond to be cleaved in order to allow the reaction to proceed. Indeed, if these groups are blocked by metal ions, the enzyme reaction cannot occur, and this is the reason for the apparent inhibition of the reaction by high concentrations of metal ions. Methylene Blue, which may be bound to pectin, may replace metal ions in the 'activation' and 'inhibition' of the enzyme reaction. A kinetic model based on these results has been proposed and fits the kinetic data very well. All the available results favour the view that metal ions do not affect the reaction through a direct interaction with enzyme, but rather with pectin.

Calcium↗
PubMed1976

[Retention of apple starch in production of pectin by the aluminum pectinate procedure].

Apple pectin produced by means of the aluminum pectinate procedure contains less starch than apple pectin obtained by precipitation with ethanol. The degradatin of the starch which occurs during production depends to a great extent upon the conditions of pomace digestion. The absorption maxima of the amylose-iodine complexes range in general from 550 to 570 nm. Model experiments with highly esterified pectin and partially degraded (by mechanolysis) apple starches were performed to establish favourable conditions for fractionating the pectin and starch components which are obtained when the pectin is precipitated as aluminum pectinate and when the granular coagulate is washed with water.

Aluminum↗
PubMed1979

Comparison of kaolin-pectin and activated charcoal for inhibition of aspirin absorption.

The effects of kaolin-pectin suspension and of activated charcoal on aspirin absorption were compared. Ten fasting volunteers each received on five separate occasions three 325-mg aspirin tablets with: (1) 240 ml of water, (2) 10 g of activated charcoal in a slurry with 240 ml of water, (3) 30 ml of kaolin-pectin suspension with 210 ml of water, (4) 60 ml of kaolin-pectin with 180 ml of water, and (5) 90 ml of kaolin-pectin with 150 ml of water. Aspirin bioavailability was estimated from spectrophotometric assay of total 48-hour urinary salicylate recovery. The mean urine salicylate recovery following administration of activated charcoal (69.5%) was significantly less (p less than 0.01) than that following administration of 30, 60 or 90 ml of kaolin-pectin (90.6, 94.6 and 95.3%, respectively) or of water only (98.6%). The mean percent aspirin recoveries for the 30-ml and 60-ml kaolin-pectin treatments were significantly less than that for water only (p less than 0.05). Neither activated charcoal nor kaolin-pectin delayed the rate of aspirin absorption. Although kaolin-pectin reduces the absorption of aspirin, the effect would be of marginal clinical importance. Kaolin-pectin suspension is not recommended as a treatment for aspirin poisoning.

Adult↗
PubMed1992

Adhesion of bacteria on pectin casted films.

Pectin and non-pectin degrading bacteria were tested for their ability to adhere to a film casted of low methoxylated pectin (polygalacturonic acid). Klebsiella oxytoca and a newly isolated strain of Escherichia coli adhered to the film, whereas only K. oxytoca was able to utilize pectin as a sole carbon source. Other E. coli strains, containing plasmids with pectinolytic enzymes, did not adhere to the solid pectin film. Therefore, the ability of the bacteria to adhere to the films was not correlated with their ability to degrade pectin. When the solubilization (dissolution) of pectin matrices (tablets) was analysed with and without K. oxytoca, a significant retardation in the dissolution rate was observed in the presence of K. oxytoca, suggesting the formation of a biofilm on the matrix or sedimentation of insoluble pectin salts.

Bacterial Adhesion↗
PubMed1979

The effect of wheat bran and pectin on paracetamol absorption in the rat.

1. The absorption of an oral dose of paracetamol was measured in rats given either a basal fibre-free diet, or the basal diet with either pectin or bran added. 2. Urinary excretion of the oral dose was significantly greater during the first 8 h in the pectin-fed rats compared with those on basal diet, though cumulative excretion after 72 h was the same. 3. Free paracetamol levels in the plasma were significantly higher in the pectin-fed rats compared with those on basal diet at 30, 60, 90 and 120 min after the oral dose. 4. The plasma half-life of intravenously-injected paracetamol was shorter in the pectin-fed rats than in those on basal diet alone, but the antipyrine half-lives were not significantly different. 5. Pectin feeding had no effect on either the apparent volume of distribution of paracetamol and antipyrine, or on the rate of gastric empyting. 6. Perfusion of the whole length of the small bowel showed a significantly greater capacity for paracetamol absorption in the pectin-fed rats. 7. Bran had no effect on paracetamol absorption. 8. It was concluded that dietary fibre intake affects drug absorption and that the effect varies with the type of fibre. Unexpectedly pectin accelerates rather than retards absorption of paracetamol, though the mechansim of this effect is unknown.

Acetaminophen↗
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↗
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↗
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↗
PubMed1979

The effect of pectin on the structure and function of the rat small intestine.

1. The effect of pectin on the structure and function of the rat small intestine was compared with that of a standard pellet diet and of a fibre-free basal diet. 2. The length and wet weight of the small bowel was significantly greater inpect in-fed rats than in either pellet- or basal-diet-fed rats. 3. Histological measurements of longitudinal sections from the small bowel showed a significantly greater crypt depth and muscle layer thickness in the mid-jejunum and ileum of the pectin fed rats. Villous height showed less variation. 4. The specific activity of alkaline phosphatase (EC 3.1.3.1) and leucyl-beta-naphthylamidase (EC 3.4.11.1) in mucosal scrapings was significantly lower in the upper jejunum of pectin-fed rats compared with either of the other dietary groups. The differences were not so marked in mid-jejunum or ileum. 5. Glucose absorption measured in vivo from jejunal and ileal loops was similar in all three dietary groups. 6. With two minor exceptions there were no significant differences in any of these measurements between the pellet- and basal-diet-fed rats. 7. These findings could be explained by increased epithelial cell turnover caused by pectin. The possible mechanisms of this are discussed. 8. The effect of pectin on the human small bowel requires study before it can be widely prescribed in man.

Alkaline Phosphatase↗
PubMed1992

Plasma beta-carotene response in humans after meals supplemented with dietary pectin.

The purpose of this study was to determine the effect of pectin on plasma response to beta-carotene in humans. Using a crossover design, we evaluated the effect on plasma beta-carotene in seven subjects when 12 g citrus pectin was added to a 2092 kJ (500 kcal) controlled meal with 25 mg beta-carotene. Plasma samples were collected at 0, 8, 30, 48, and 192 h after the meals. Plasma beta-carotene was quantified with the use of HPLC. The increase in plasma beta-carotene concentration was significantly reduced by pectin at 30 and 192 h (paired t test; P less than 0.005 and less than 0.05, respectively). Mean percent increase in plasma beta-carotene concentration at 30 h after the meal with beta-carotene was reduced by more than one-half when pectin was added to the meal. These results indicate that the inhibitory effect of pectin may provide one explanation for observations of reduced plasma beta-carotene response in humans after the ingestion of carotenoid-rich foods when compared with equivalent doses of beta-carotene supplements.

Adult↗
PubMed1978

Effect of pectin, gum arabic and agar on cholesterol absorption, synthesis, and turnover in rats.

A series of five experiments was conducted to determine the effect of pectin, gum arabic and agar (5%) on cholesterol absorption, biosynthesis and turnover in rats. In the study of cholesterol absorption, a tracer dose of labeled cholesterol was included in the last meal. The rats were killed 12 hours later. The proportion of the labeled cholesterol recovered in the whole body was used as an estimation of the efficiency of absorption of dietary cholesterol. Cholesterol biosynthesis was estimated by determining the activity of labeled digitonin-precipitable sterols biosynthesized from labeled glucose which was included in a test meal. In turnover studies, rats were injected intravenously with labeled cholesterol using serum as a vehicle, and the activity of labeled cholesterol in tissues was determined after various time intervals. All three complex carbohydrates decreased cholesterol absorption and pectin had the greatest effect. Pectin and gum arabic increased cholesterol biosynthesis in rats fed a cholesterol-containing diet, but had no effect in a cholesterol-free diet. Pectin slightly increased the turnover of cholesterol, but gum arabic and agar had no effect. This work supports the hypothesis that pectin lowers cholesterol levels by interfering with cholesterol absorption and by increasing cholesterol turnover. The study also suggests that complex carbohydrates differ in their effects on cholesterol metabolism. The reason for these differences remains to be determined.

Absorption↗
PubMed1992

Prickly pear (Opuntia sp.) pectin reverses low density lipoprotein receptor suppression induced by a hypercholesterolemic diet in guinea pigs.

The effects of prickly pear pectin on plasma LDL metabolism were investigated by feeding guinea pigs either a diet containing 15 g/100 g lard and 0.25 g/100 g cholesterol (LC diet) or the LC diet in which cellulose was partially replaced (2.5 g/100 g) by prickly pear pectin (LC-P diet). The LC-P diet lowered plasma LDL cholesterol concentrations by 33% (P < 0.001). Low density lipoprotein composition was modified by intake of prickly pear pectin; the relative percentages of free and esterified cholesterol were lower and triglycerides were higher in LDL from animals fed the LC-P diet (P < 0.05). Intake of prickly pear pectin did not affect hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity; however, hepatic free and esterified cholesterol concentrations were lowered by 46 and 64%, respectively. Hepatic apolipoprotein B/E receptor expression (Bmax) was 60% higher in animals fed the LC-P diet (P < 0.01). Similar to the in vitro data, receptor-mediated LDL fractional catabolic rates were 190% higher in animals fed the LC-P diet (P < 0.05), whereas apolipoprotein LDL flux rates were not affected. Apolipoprotein LDL pool size and fractional catabolic rates exhibited a significant correlation (r = -0.52, P < 0.01). These data indicate that an increase in apolipoprotein B/E receptor expression is a major metabolic response by which intake of prickly pear pectin decreases plasma LDL concentrations.

Animals↗
PubMedDate not supplied

The effect of dietary pectin on rapid catch-up weight gain and urea kinetics in children recovering from severe undernutrition.

The rates of weight gain and urea kinetics were measured in 12 children receiving one of two energy dense, isonitrogenous formulae (711 kJ/kg/day, 170 kcal/kg/day) during recovery from severe undernutrition. Both formulations contained added arachis oil but in one a source of complex carbohydrate was added in the form of pectin (3.4% of total energy). The children taking the pectin diet had a rate of weight gain which was highly significantly less (7 g/kg/day) than the children not receiving pectin (14 g/kg/day). Urea production was significantly less on the pectin diet (0.37 +/- 0.07 vs 0.55 +/- 0.18 gN/kg/day). On the pectin diet there was a reduction in the rate of excretion of urea in urine and in the rate at which urea nitrogen was salvaged by the lower bowel, but these differences failed to reach statistical significance.

Ammonia↗
PubMed1992

Pectin decomposition and associated nitrogen fixation by mixed cultures of Azospirillum and Bacillus species.

Cocultures of different Azospirillum species with Bacillus polymyxa or Bacillus subtilis allow the efficient utilization of pectin as carbon and energy sources for nitrogen fixation. The nitrogenase activity obtained with cocultures was as high as 30-80 nmol C2H4 h-1 mL-1, a much higher value than that obtained with pure cultures of either Azospirillum (up to 13 nmol C2H4 h-1 mL-1) or B. polymyxa (up to 2 nmol C2H4 h-1 mL-1) alone. To establish to what extent each partner contributed to nitrogenase activity, acetylene reduction was assayed as a function of time and it was also measured on Azospirillum cultivated in the cultures filtrates of the Bacillus. The results suggested that the nitrogenase activity was mostly produced by Azospirillum. The nitrogenase activity occurred at the expense of the degradation and fermentation products of the pectin. The new pectinolytic species, Azospirillum irakense, utilized both degradation and fermentation products of pectin, whereas the nonpectinolytic strains (Azospirillum brasilense, Azospirillum lipoferum, Azospirillum amazonense) utilized only the fermentation products of pectin, including acetic and succinic acids. These cocultures can be considered as metabolic associations, where the Bacillus produces degradation and fermentation products of pectin, which can be used by Azospirillum species.

Azospirillum↗
PubMed1979

Effect of dietary alfalfa, pectin, and wheat bran on azoxymethane-or methylnitrosourea-induced colon carcinogenesis in F344 rats.

The effect of dietary alfalfa, pectin, and wheat bran on colon carcinogenesis was studied in female inbred F344 rats. Weanling rats were fed semipurified diets containing 0 or 15% alfalfa, pectin, or wheat bran. At 7 weeks of age, all animals except controls were given azoxymethane (AOM) sc at a dose rate of 8 mg/kg body weight/week for 10 weeks or methylnitrosourea (MNU) intrarectally at a dose rate of 2 mg/rat twice a week for 3 weeks. The AOM-treated group was autopsied 40 weeks and the MNU-treated group 30 weeks after the first injection of the carcinogen. No tumors were observed in the colon or other organs of untreated rats fed the various diets. The animals fed the alfalfa diet and treated with MNU had a higher incidence of colon tumors than did those fed the control diet or the diets containing pectin or wheat bran. The incidence of MNU-induced colon tumors did not differ between the animals fed the control diet or the diets containing pectin or wheat bran. However, the incidence of AOM-induced colon tumors in rats fed diets containing pectin or wheat bran was lower than that in rats fed the control diet or the alfalfa diet. These results thus indicate that the effect of fiber in colon carcinogenesis depends on the type of fiber and, possibly, the fiber's mode of action.

Animals↗
PubMed1977

[Protein isolation by means of complexing agents. 2. Formation of insoluble complexes of sunflower albumins with alginate or pectin].

The formation of insoluble complexes of sunflower seed albumin and alginate or pectin is studied by means of turbidimetric titration and by determining the pH-dependent precipitability of protein. The complex formation that is based on electrostatic interaction is a function of the pH value and the protein-polyanion ratio. Consequently, it is affected by the neutral salt content of the solutions. 90% and more of the dissolved protein may be precipitated if the proportion of the precipitant amounts to 20%. A sodium chloride content of 0.6% reduces the precipitability by alginate to 74%. In the presence of 0.3% sodium chloride, at most 55% of protein are still precipitated by pectin. The difference in strength between the albumin-alginate and the albumin-pectin complex is also expressed by the dye-binding power. Albumin-pectin complexes bind the same amount of amido black as free protein. On the contrary, albumin-alginate complexes exhibit reduced dye-binding power due to stronger binding of the protein to the polyanion. The results obtained by turbidimetric titration of model systems can, in principle, be extrapolated to the precipitation of albumins from protein extracts. In accordance with the heterogenicity of the protein, the turbidimetric titration of the albumin-alginate and the albumin-pectin complexes exhibits two maxima.

Albumins↗