Soy protein peptic hydrolysate with bound phospholipids (SPHP) was studied for its cholesterol-lowering effects in 5-week-old male Wistar rats. The crude SPHP (c-SPHP) was prepared by neutral proteolysis of isolated soy protein and lysophospholipid complex, and the SPHP was defined as the high-molecular weight fraction of c-SPHP. The SPHP prevented hypercholesterolemia dose-dependently, and both SPHP and c-SPHP dose-dependently aided recovery from hypercholesterolemia in rats fed a diet containing 0.5% cholesterol for 9 days. The c-SPHP was more effective for recovery from hyperlipidemia and fatty liver in rats compared with partially hydrolyzed sodium alginate, indigestible dextrin, chitosan, and isolated soy protein, which are known to be cholesterol-lowering materials, when added at 5% to a diet containing 0.5% cholesterol.

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Mineral balance is affected by many dietary factors, but the interactions involved are not clear. Therefore, the effects of dietary mineral levels on mineral balance were examined using an orthogonal array, an experimental design which is superior for factorial analysis and factor interaction analysis. Ca, P, Mg, Na, and Zn were selected as the factors, and eight kinds of diet were prepared based on the L₈ (2⁷)-type orthogonal array. The mineral content of the diets was either normal (AIN-76) or 1/3.5 of the normal content. Four-week-old rats (Fischer 344 strain) were fed one of these diets for 4 weeks. Retention of Ca, P, Mg, and Zn was determined by means of a balance test in the last 3 days of the 4-week feeding period. The highest apparent Ca absorption (%) was observed in the rats fed the normal Zn, low Ca diet, and the lowest was observed in those fed the normal Ca, low Zn diet. The highest apparent Ca retention (mg/day) was observed in the rats fed the normal Ca, Mg and Zn, low P diet, and the lowest was observed in those fed the normal P, low Ca, Mg, and Zn diet. The highest apparent P absorption was observed in the rats fed the normal P, low Ca diet, and the lowest was observed in those fed the normal Ca, low P diet. However, the apparent P retention was not affected by the mineral content of the experimental diet. The highest apparent Mg absorption was observed in the rats fed the normal P, low Ca diet, and the lowest Mg absorption was observed in those fed the normal Ca and P diet. The highest apparent Mg retention was observed in the rats fed the normal Mg diet, and the lowest was observed in those fed the low Mg diet. The apparent absorption and retention of Zn were not affected by the mineral content of the experimental diet. Among the five kind of minerals examined, Ca and P contents and their ratio in the diet strongly influenced the absorption and retention of Ca, P, and Mg.

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In order to investigate the effects of ingestion frequency of the nondigestible oligosaccharide galactosylsucrose on transitory diarrhea, a standard daily amount was divided into one, two or three parts, which were then ingested separately by 17 normal female subjects once, twice or three times in a day. Single ingestion of 60g and 45g of galactosylsucrose caused diarrhea in 9 of 14 subjects (64.2%) and 3 of 8 subjects (37.5%), respectively. However, when taken in two or three divided doses in a day, no diarrhea occurred in any of the subjects, even though the total amount ingested in one day was the same (60g or 45g). Furthermore, three divided ingestions of 30g galactosylsucrose (total 90g/day) did not cause diarrhea in 3 of 5 subjects. These results demonstrate that when the same amount of nondigestible oligosaccharide ingested in a day is divided into two or more parts and ingested separately, the level per day inducing transitory diarrhea becomes markedly higher than the laxative threshold estimated using a single ingestion of the test substance. In addition, the laxative threshold of galactosylsucrose was found to be 0.802g/kg body weight, which is greatly higher than that of other nondigestible oligosaccharides.

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The antioxidant activities of hot-water extracts of 15 kinds of commercial tea were compared. The antioxidant components of banaba tea (Lagerstroemia speciosa) were identified, and their antioxidant activities were assessed. Antioxidant activities were determined by Rancimat analysis for evaluation of induction time (IT rancid point), DPPH radical and superoxide scavenging activity. Polyphenols in banaba tea were identified by preparative thin-layer chromatography and high-performance liquid chromatography. The antioxidant activity decreased in the order maidenhair>rooibosh>green>mugwart>banaba>hydrangea>Japanese persimmon>loquat>houttumia heb>taheebo teas. In perticular, maidenhair, rooibosh, and green teas showed higher antioxidant effects than the others. On the other hand, aloe perrye and rose moschata teas had no preventive effect against oxidative deterioration of oil. This preventive effect increased in proportion to the dose for green, barley and maidenhair teas, but persimmon and loquat teas had no antioxidant effect at concentrations below 0.1%. The order of DPPH scavenging activity was gallic acid>green tea>banaba tea. A large number of peaks in the ethyl acetate extract obtained from banaba tea were isolated by HPLC, and identified as gentisic and gallic acids, catechin, and resorcinol. The main polyphenol components were gallic and gentisic acids and catechol. Among the detected polyphenols, gentisic, and gallic acids had the greatest preventive effect against oxidative deterioration of oil.

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Fibroin foam powder prepared from fibroin solution, which can be used as an ingredient in food to produce foam in sponge cake, was studied to examine its effects on serum cholesterol concentration in rats fed diets with or without cholesterol. The digestibility of fibroin foam powder in vitro was 11-25%. Addition of fibroin foam powder to a cholesterol-enriched diet lowered the serum total cholesterol level significantly. The total liver cholesterol in rats fed the cholesterol-enriched diet with fibroin foam powder tended to decrease in comparison with that in rats fed the cholesterol-enriched diet alone. The amounts of excreted bile acids were higher in the rats fed the cholesterol-free and -enriched diets with fibroin foam powder than in the rats fed the same diets without fibroin foam powder. Increases in the amounts of feces and fecal bile acids in the rats fed the fibroin foam powder suggest that the cholesterol-lowering effect of fibroin foam powder is due partly to promotion of bile acid excretion by its indigestible fraction.

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Peptides having strong superoxide scavenging activities were separated from a soybean protein digest by chromatographic methods such as ion-exchange and gel-filtration. The most potent fraction (SP-1) obtained by SP-Sephadex C-25 chromatography was further separated into peptide components using ODS HPLC. The amino acid sequences of these peptides were: Ala-Val-Pro-Tyr-Asn-Leu (AVPYNL) and Leu-Val-Pro-Pro-Gln-Glu-Glu-Gln-Lys (LVPPQEEQK). The IC₅₀ values of AVPYNL and LVPPQEEQK for superoxide scavenging activity were 126μM and 186μM, respectively, determined by the tetrazolium salt XTT method. The IC₅₀ values of AVPYNL and LVPPQEEQK for hydroxyl radical scavenging activity were 6.1μM and 9.2μM, respectivity.

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We have determined the slipping point and the solid fat content (SFC) of lipids in human colostrum (3-5 days postpartum), mature milk (25-44 days postpartum), and some conventional infant formulae. Slipping points were 26.7°C in colostrum and 23.4°C in mature milk. Although the slipping point in one infant formula was higher than that in mature milk, those in others ranged from 20.0 to 22.5°C, which is lower than that in mature milk. Between 10°C and 25°C, the SFC of colostrum was 2% higher than that of mature milk. Lipids in colostrum and mature milk were in the liquid phase over 30°C. SFCs of infant formulae were similar to those of human milk.

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Phagocytosis in alveolar macrophages (AM) was enhanced in rats starved for 2-3 days, and was suppressed by over 4 days of starvation. We investigated the mechanism of this phenomenon. AM from starved rats were separated into four subpopulations, designated I, II, III, and IV, using discontinuous Percoll gradient centrifugation. Phagocytosis was more active in the higher-density fractions (III and IV) than in the lower-density ones (I and II). At 2 days of starvation, the phagocytic activity of the higher-density fractions was higher than that of the same fractions from fed rats. Pulmonary surfactant isolated from rat lung bronchoalveolar lavage fluid had a higher content of surfactant apoprotein A (SP-A) in samples from rats starved for 2 days compared with fed controls, but the level returned to the baseline by 4 days of starvation. Phagocytosis by AM was enhanced dose-dependently by SP-A, and the effect was completely inhibited by an antibody against SP-A. AM subpopulations exposed to SP-A showed enhanced phagocytic activity in the higher-density fractions (III and IV), whereas little change was evident in the lower-density fractions (I and II). These results support the concept that pulmonary surfactant and its apoprotein, SP-A, are factors that regulate the lung defense system including activation of AM, and are effected by starvation.

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