Effects of short-term feeding of rats with a highly purified phaseolin preparation

Phaseolin from Phaseolus vulgaris bean modulates gut mucin flow and gene expression in rats

Dietary protein might modulate mucin flow and intestinal mucin gene expression. Since unheated phaseolin from Phaseolus vulgaris bean is resistant to digestion and increases gut endogenous protein losses, we hypothesised that unheated phaseolin influences mucin flow and gene expression, and that phaseolin heat treatment reverses these effects. The hypothesis was tested using a control diet containing casein as the sole protein source and three other diets with casein being replaced by 33 and 67 % of unheated and 67 % of heated phaseolin. The rats were fed for 6 d and euthanised. Digesta and faeces were collected for determining digestibility and mucin flow. Gut tissues were collected for mucin (Muc1, Muc2, Muc3 and Muc4) and Trefoil factor 3 (Tff3) gene expressions. Colonic mucin flow decreased linearly with increasing the dietary level of unheated phaseolin (P < 0·05). Unheated phaseolin increased N flow in ileum, colon and faeces (P < 0·05), and reduced apparent N digestibility linearly (P < 0·01). Heat treatment reversed all these changes (P < 0·05 to < 0·001), except mucin flow. The expressions of Muc mRNA in gut tissues were influenced by dietary phaseolin level (ileum and colon: Muc3 and Muc4) and thermal treatment (ileum: Muc2; colon: Muc2, Muc3, Muc4 and Tff3) (P < 0·05 to 0·001). In conclusion, phaseolin modulates mucin flow and Muc gene expression along the intestines differentially.

Influence of thePhaseolus vulgarisphaseolin level of incorporation, type and thermal treatment on gut characteristics in rats

Phaseolus vulgarisphaseolin has been shown to stimulate faecal losses of endogenous N in rats. Experiments with purified phaseolin were carried out in rats to test the hypothesis that these losses reflect intestinal disorders. Phaseolin composition varies depending on its constitutive subunits. Therefore, three phaseolin types (S, T, I) were tested. Phaseolin T was incorporated in varying levels (0, 33, 67 or 100% of the dietary protein) as raw material in experiment 1. In experiment 2, the three phaseolin types were incorporated at 50%, with or without previous thermic treatment. Raw casein was the basal protein source and was also heated in experiment 2. Faecal digestibility of phaseolin and gut integrity were evaluated in both experiments. The incorporation level or type of phaseolin had little effect on gross anatomy of gut segments but these factors influenced the weight and pH of fresh contents of the stomach and caecum (P<0·05). Raw phaseolin T incorporated at various levels led to an enlargement of duodenal villi together with a tendency for increased crypt depth in the jejunum (P=0·06). Activities of both alkaline phosphatase in the duodenum and aminopeptidase N in the ileum decreased (P<0·05) after thermal treatment of casein while they increased (P<0·05) for heat-treated phaseolin S and T, respectively. In conclusion, raw phaseolin had no effect on the tissue weight of gut segments and induced limited alterations in the small intestine. Differences due to phaseolin level or type were limited too.

Nutritional Evaluation of Raw and Extruded Kidney Bean (Phaseolus vulgaris L. var. Pinto) in Chicken Diets

An experiment was conducted to study the effect of inclusion of different concentrations (0, 100, 200, and 300 g/kg) of raw kidney bean and extruded kidney bean in broiler chick (0 to 21 d of age) diets on performance, digestive organ sizes, protein and amino acid digestibilities, intestinal viscosity, cecal pH, and blood parameters. Data were analyzed as a 3 x 2 factorial arrangement with 3 levels of kidney bean with and without extrusion. Positive control without kidney bean was used. Increasing the kidney bean content in the diet reduced weight gain and consumption, and increased the feed-to-gain ratio. Relative pancreas, liver, and jejunum weights, and intestinal viscosity were increased in response to increasing kidney bean concentration in the diet. The inclusion of different concentrations of kidney bean did not affect the apparent ileal digestibility of essential and nonessential amino acids, except for Met, Phe, and Cys, which were increased. Increasing kidney bean in the diet did not affect blood parameters, except for total protein, which was increased, and for androstenedione and testosterone, which were reduced. Extrusion significantly improved weight gain, feed consumption, and feed conversion. Relative pancreas, liver, and jejunum weights were reduced and spleen weight, cecal and intestinal viscosity were increased by extrusion. Apparent ileal digestibility of crude protein and all essential and nonessential amino acids were improved by extrusion. Like-wise, extrusion increased significantly the concentrations of cholesterol, triglycerides, glucose, and testosterone. We concluded that the inclusion of kidney bean in chicken diets cause a negative effect on performance and CP and amino acid digestibilities, and modified digestive organ sizes, intestinal viscosity, cecal pH, and some blood parameters. These effects were counteracted by the extrusion of kidney bean. However, the inclusion of extruded kidney bean in a chick diet resulted in poorer performance compared with that obtained with a corn-soybean diet.

Differential effect of lentil feeding on proteosynthesis rates in the large intestine, liver and muscle of rats

The aim of this work was to test the hypothesis that the trophic effect of lentil feeding on large intestine results from a stimulation of protein synthesis and to determine whether it interferes with protein metabolism in other splanchnic or peripheral organs. Two groups of growing Sprague Dawley male rats were pair-fed iso-caloric iso-nitrogenous balanced diets containing either cooked lentils (Lens esculenta puyensis) or casein as unique protein source. Protein synthesis rates were measured in vivo, in large intestine, liver and gastrocnemius at the postprandial state. In large intestine, protein and ribonucleic acid contents were higher in the lentil-fed group than in the control group, and the amount of proteins synthesized was also higher (+57%). By contrast, liver protein and ribonucleic acid contents as well as protein synthesis rates were significantly lower in the lentil-fed group than in the control group. In the gastrocnemius muscle protein and ribonucleic acid contents were significantly lower and the amount of protein synthesized was also lower (-18%) in the lentil fed group than in the control group. This study suggests that stimulation of protein synthesis in the large intestine is compensated for by a decrease in liver and muscle.

Purification and acute toxicity of a lectin extracted from tepary bean (Phaseolus acutifolius)

Lectins are proteins or glycoproteins known for their ability to agglutinate cells, especially erythrocytes. Several lectins are toxic to mammalian cells both in vitro and in vivo, inhibit growth when incorporated into the diet and are toxic when injected into animals. On the other hand, the use of lectins has been suggested as an alternative in cancer treatment. The objective of the present study was to evaluate the acute toxicity of a lectin extracted and purified from tepary bean (Phaseolus acutifolius, G-400-34) on CD-1 mice. Fetuin affinity chromatography, electrophoretic pattern and Western-immunoblot techniques were used to purify and partially characterize the lectin. This tepary bean line presented high levels of lectin activity. Western blot revealed that the sera reacted with the known PHA subunits in the 34-40 kD range. Four major lectin and lectin-related glycopolypeptides were identified. The purified lectin from tepary bean was a tetrameric one that ran at about 115-120 kD. The LD(50) (ip) was 1100 mg/kg body weight for males and 1120 mg/kg body weight for females. The body weight of experimental animals decreased in a dose-dependent manner. The main target organs affected were small intestine, spleen and thymus. The lectin isolated from tepary bean showed affinity towards fetuin, with high agglutination values and low acute toxicity.

Nutritional and physiological responses of young growing rats to diets containing raw cowpea seed meal, protein isolate (globulins), or starch

The nutritional and physiological effects of raw cowpea (Vigna unguiculata (L) Walp.) seed meal, protein isolate (globulins), or starch on the metabolism of young growing rats have been evaluated in 14-day trials. Wet and dry weight gain, feed conversion efficiency, and lipid and protein accretion were significantly reduced as a result of inclusion of seed meal, globulins, or starch in the diet, with growth retardation being most marked with the seed meal. The proportional weights of the small intestine and pancreas were increased by meal diets, and serum cholesterol levels were slightly reduced. The globulins and raw starch also increased relative small intestine weights but had no effect on the pancreas or serum constituents. The effects of cowpeas on rats appeared to be due primarily to the combined actions of globulins, resistant starches, protease inhibitors, and possibly fiber and non-starch polysaccharides on intestinal and systemic metabolism.

Nutritional utilization by the rat of diets based on lentil (Lens culinaris) seed meal or its fractions

The nutritional effects in the rat of raw lentil meal or its fractions have been evaluated in three feeding trials. Growth, gain/feed ratio, apparent N digestibility, and N retention were significantly (p < 0.05) reduced by the inclusion of whole lentil meal, dehulled lentil meal, or ethanol-extracted lentil meal as the sole source of protein in the diet. Pure lentil lectin and lectin-depleted albumin proteins had no significant negative effect on nutritional performance. In contrast, growth, gain/feed ratio, protein conversion efficiency, N digestibility, and N retention were significantly (p < 0.05) reduced by diets containing lentil globulins or lentil hulls. The poor nutritional quality of raw lentil meal for rats is therefore likely to be primarily due to the combined effects of these two components.

Immunochemical studies on gastric and intestinal digestion of soybean glycinin and beta-conglycinin in vivo

Two experiments were conducted to study gastric and small intestinal digestion of soybean glycinin and beta-conglycinin in preruminant calves fed milk replacers containing a mixture of skim milk powder and antigenic heated soybean flour. In experiment 1, duodenal passage of immunoreactive beta-conglycinin lasted for a much longer time after the morning meal than that of glycinin. Western blotting revealed the early abomasal outflow of glycinin subunits that associated nearly intact basic polypeptides to partially degraded acidic polypeptides. Intact beta-conglycinin was evidenced at most sampling times. In experiment 2, intact basic glycinin (M(r) = 21000) associated with partially digested acidic glycinin (7000 < M(r) < 25000) was demonstrated in ileal digesta up to 8-10 h after the meal. beta-Conglycinin immunoreactivity could not be evidenced by Western blotting in ileal digesta.