Dietary soybean peptides containing a low-molecular fraction can lower serum and liver triglyceride levels in rats.

We investigated the effects of dietary soybean peptides, particularly low-molecular-weight peptides, on serum and hepatic concentrations of lipids in rats. Soybean protein isolate (SPI) was digested with protease to produce low-molecular-weight peptides (LD) or a mixture of high- and low-molecular-weight peptides (HLD). Rats were fed diets containing 20% casein, SPI, LD or HLD as a nitrogen source, with or without 0.5% cholesterol, for 2 wk. Next, rats were fed cholesterol-free diets containing 0%, 5%, 10%, or 20% LD at the expense of casein for 2 wk. Serum triglyceride levels were the lowest in the LD group, and liver triglyceride levels were significantly lower in rats fed SPI and LD/HLD diets than in those fed casein diets, both in the presence and absence of dietary cholesterol. In addition, dietary LD significantly lowered serum and liver triglyceride levels in a dose-dependent manner. These results suggest that low-molecular-weight soybean peptides have a potent hypotriglyceridemic effect and may be beneficial for improving lipid metabolism.

Acute effect of soybean beta-conglycinin hydrolysate ingestion on appetite sensations in healthy humans.

A hydrolysate prepared from soybean beta-conglycinin reduced food intake through cholecystokinin release in rats; however, effects of the hydrolysate on human appetites are unknown. In this study, healthy volunteers ingested 3g of the beta-conglycinin hydrolysate (BconB) and/or a soy protein hydrolysate (HN) contained in a beverage or in a jelly. Appetite profiles (hunger, fullness and prospective consumption) after the ingestion and palatability of test jellies were recorded. Fullness was rated higher, and hunger was rated lower after BconB ingestion as compared to HN ingestion. These results demonstrate that 3g of BconB is effective to enhance fullness and reduce hunger sensations in healthy humans.

Screening of soy protein-derived hypotriglyceridemic di-peptides in vitro and in vivo.

BACKGROUND: Soy protein and soy peptides have attracted considerable attention because of their potentially beneficial biological properties, including antihypertensive, anticarcinogenic, and hypolipidemic effects. Although soy protein isolate contains several bioactive peptides that have distinct physiological activities in lipid metabolism, it is not clear which peptide sequences are responsible for the triglyceride (TG)-lowering effects. In the present study, we investigated the effects of soy protein-derived peptides on lipid metabolism, especially TG metabolism, in HepG2 cells and obese Otsuka Long-Evans Tokushima fatty (OLETF) rats. RESULTS: In the first experiment, we found that soy crude peptide (SCP)-LD3, which was prepared by hydrolyze of soy protein isolate with endo-type protease, showed hypolipidemic effects in HepG2 cells and OLETF rats. In the second experiment, we found that hydrophilic fraction, separated from SCP-LD3 with hydrophobic synthetic absorbent, revealed lipid-lowering effects in HepG2 cells and OLETF rats. In the third experiment, we found that Fraction-C (Frc-C) peptides, fractionated from hydrophilic peptides by gel permeation chromatography-high performance liquid chromatography, significantly reduced TG synthesis and apolipoprotein B (apoB) secretion in HepG2 cells. In the fourth experiment, we found that the fraction with 0.1% trifluoroacetic acid, isolated from Frc-C peptides by octadecylsilyl column chromatography, showed hypolipidemic effects in HepG2 cells. In the final experiment, we found that 3 di-peptides, Lys-Ala, Val-Lys, and Ser-Tyr, reduced TG synthesis, and Ser-Tyr additionally reduced apoB secretion in HepG2 cells. CONCLUSION: Novel active peptides with TG-lowering effects from soy protein have been isolated.

Soybean ß-conglycinin bromelain hydrolysate stimulates cholecystokinin secretion by enteroendocrine STC-1 cells to suppress the appetite of rats under meal-feeding conditions.

A peptic digest of soybean ß-conglycinin (BconP) suppresses the appetite in rats through cholecystokinin (CCK) secretion by enteroendocrine cells. We investigate in this study more appetite-suppressing hydrolysates. ß-Conglycinin hydrolyzed with food-processing proteases thermolysin (BconT), bromelain (BconB), chymotrypsin, protease S, and protease M was examined for CCK-secreting activity in a CCK-producing cell line for comparison with BconP. The potent CCK-releasing hydrolysates were then tested for their suppression of the food intake by rats. BconB, BconT, and BconP stimulated high CCK secretion, with the highest by BconB. Orogastric preloading by BconB, but not by BconT, suppressed the 60-min food intake. A meal-feeding trial twice a day in the morning (a.m.) and evening (p.m.) for 10 d showed that BconB preloading before every meal attenuated the p.m. meal size, but not that a.m., resulting in an overall reduction of the daily meal size. These results demonstrate that the bromelain hydrolysate of ß-conglycinin having potent CCK-releasing activity suppressed the appetite of rats under meal-feeding conditions.

Effects of dietary soybean peptides on hepatic production of ketone bodies and secretion of triglyceride by perfused rat liver.

Soybean protein isolate (SPI) was digested with protease to produce a peptides containing the low-molecular fraction (LD3) or a mixture of high- and low-molecular fractions (HD1). Rats were fed a diets containing SPI, LD3, or HD1 at a protein level equivalent to the 20% casein diet for 4 weeks. The serum triglyceride concentration was lower in rats fed SPI, LD3, and HD1 diets than in rats fed the casein diet, and the differences were significant for the cholesterol-enriched diet. The value for the LD3 group was the lowest among all groups for both the cholesterol-free and -enriched diets. The level of triglyceride in the post-perfused liver was significantly lower in the LD3 and HD1 groups and the SPI group than in the casein group irrespective of the presence of cholesterol in the diet. In the cholesterol-free diet, LD3 feeding as compared to casein feeding caused a reduction in triglyceride secretion from the liver to perfusate and an increment of hepatic ketone body production. The addition of cholesterol to the diets somewhat attenuated these effects of LD3. These results suggest that the low-molecular fraction in soybean peptides causes triglyceride-lowering activity through a reduction in triglyceride secretion from the liver to the blood circulation and the stimulation of fatty acid oxidation in the liver. There is a possibility that soybean peptides modulate triglyceride metabolism by changes in the hepatic contribution.

Study of the role of the carbohydrate and protein moieties of soy soluble polysaccharides in their emulsifying properties.

The objective of this work was to investigate the role played by the protein fraction of soy soluble polysaccharide (SSPS) during its adsorption at oil/water interfaces. SSPS was separated in a high (HMF; 310 kDa) and low (LMF; 20 kDa) molecular weight fraction by gel filtration. SSPS/HMF consisted of 91.6% carbohydrate and 2.2% protein and showed better emulsifying properties than those of the whole SSPS, whereas SSPS/LMF seemed to affect negatively the adsorption behavior of SSPS. SDS-PAGE of the protein fraction obtained from SSPS/HMF showed a molecular mass of 50 kDa, was composed predominantly of proline (23.1%) and glutamic acid (15.2%), and still contained 8.8% of neutral sugar and 5.3% of uronic acid. Results indicated that not all of the protein material present in SSPS contributes to SSPS functionality but that only the material associated with HMF aids in the adsorption of SSPS onto oil/water interfaces.

Properties of rice cooked with commercial water-soluble soybean polysaccharides extracted under weakly acidic conditions from soybean cotyledons.

It has been found that commercial water-soluble soybean polysaccharides (SSPS) can make cooked rice and noodles non-sticky and prevent rice grains and noodles from adhering to each other. We studied in detail the phenomenon of rice cooked with SSPS. We assumed that the phenomenon resulted from the interaction between SSPS and starch during cooking, and studied the effects of SSPS on the gelatinizing behavior of rice starch by using a Rapid-Visco-Analyzer. The addition of SSPS reduced the viscosity of the gelatinized starch. This lower final viscosity of the rice starch was more distinct from than that of potato starch. These results imply that the properties of SSPS in forming a non-sticky condition might result from a decrease in the viscosity of the gelatinized starch.

Ingestion of water-soluble soybean fiber prevents osteopenia and hypercholesterolemia induced by ovariectomy in rats.

This study examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on intestinal calcium (Ca) absorption, bone mineral content, and serum total cholesterol levels using female Sprague-Dawley rats (5 weeks old) with or without ovariectomy (OVX). The rats in each group were fed a WSSF (50 g/kg of diet) or WSSF-free diet for 4 weeks. Ca absorption was higher in OVX rats fed the WSSF diet than in OVX rats fed the WSSF-free diet. Femoral Ca content in both sham and OVX rats fed the WSSF diet was higher than that in rats fed the WSSF-free diet. The serum total cholesterol levels were elevated after OVX compared with that in the sham rats, and this elevation was prevented by the WSSF diet. In conclusion, ingestion of WSSF prevented osteopenia and hypercholesterolemia induced by ovariectomy in rats.

[POCT and system].

POCT refers to a medical test which is carried out at sites other than a central laboratory. It includes a simple test that medical service staff carry out at the scene of a medical treatment and self-care tests that patients can perform by themselves at home. This concept has been established in the U.S. since the late 1980's. In recent years, doctor's offices and clinics have been leaders in primary care and are now paying close attention to immediate testing facilities inside their hospitals to provide better service to patients. Now, we can see more and more POCT equipment being introduced to such places. Since it is unlikely that specially trained technicians can staff the hospital around the clock, physicians or nurses have must operate the POCT instrument themselves. Based on this fact, easily accessible instruments that produce reliable data are strongly required. ARKRAY introduces the "CARE LAB" system that combines special data management software "MEQNET" with various POCT devices. These systems facilitate establishing an "in-clinic inspection station" in a general practitioner or clinic. This article presents detailed information on various POCT products and the "MEQNET" program that make up the "CARE LAB" System.

Structural studies by stepwise enzymatic degradation of the main backbone of soybean soluble polysaccharides consisting of galacturonan and rhamnogalacturonan.

Soybean soluble polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides and have a pectin-like structure. The results of a structural analysis of SSPS by using polygalacturonase (PGase) and rhamnogalacturonase (RGase) clarified that the main backbone consisted of galacturonan (GN) and rhamnogalacturonan (RG), which were composed of the diglycosyl repeating unit, -4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-. The side chains of beta-1,4-galactans, branched with fucose and arabinose residues, were linked to the C-4 side of rhamnose residues in the RG regions. The degree of polymerization (dps) of GN, which linked the RG regions together, was estimated to be about 4-10 residues, and some were modified with xylose residues on the C-3 side of the galacturonates. The dps of GN at the reducing end of SSPS was estimated to be about 7-9 residues. Moreover, the fragment of the basic structure of the RG region, -[4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-]2-, some of which had long-chain beta-1,4-galactans branched on the C-4 side of rhamnose residues, were liberated from SSPS by the RGase treatment. The dps of the galactan side chain was estimated to be about 43-47 residues by an analysis of the digestion products from the beta-galactosidase treatment.

Analysis of the molecular construction of xylogalacturonan isolated from soluble soybean polysaccharides.

Soluble soybean polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides, and exhibited a pectin-like structure. After digesting galacturonan with polygalacturonase, two novel galacturonan (GN) fragments, which were directly linked to xylosyl oligosaccharides, were obtained. One consisted of (beta-D-Xyl)7 branched at the C-3 site of 1,4-linked (alpha-D-GalA)4, and the other consisted of (beta-D-Xyl)4 branched at the C-3 site of 1,4-linked (alpha-D-GalA)3.

Ingestion of water-soluble soybean fiber improves gastrectomy-induced calcium malabsorption and osteopenia in rats.

OBJECTIVE: Total gastrectomy produces calcium malabsorption and osteopenia. We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on calcium absorption and bone characteristics in totally gastrectomized rats. METHODS: Male Sprague-Dawley rats were assigned to two groups: sham operation and gastrectomy. After the postoperative recovery period, rats of each group were fed diets with or without WSSF (50 g/kg diet) for 4 wk. RESULTS: Net calcium absorption and femoral dry weight and calcium content and maximum breaking force were lower in the gastrectomy groups than in the sham groups. In the gastrectomy groups, calcium absorption and these femoral parameters were higher in rats fed the WSSF diet than in rats fed the WSSF-free diet. Feeding WSSF increased the concentrations of short-chain fatty acids and soluble calcium and decreased the pH in cecal contents. Net calcium absorption in gastrectomized rats correlated positively with the concentration of total short-chain fatty acids (the sum of acetic, propionic, and butyric acids) in cecal contents (r = 0.545, P < 0.05) and negatively with cecal pH (r = -0.628, P < 0.05). CONCLUSIONS: These findings indicate that ingestion of WSSF partly prevents the diminished calcium absorption after total gastrectomy in rats, resulting in the improvement of postgastrectomy osteopenia. The increase of calcium absorption may be associated with cecal fermentation of WSSF.