The biological activity of the novel vitamin C derivative, 2-O-α-D-glucopyranosyl-L-ascorbic acid (AA-2G), was evaluated in vitro and in vivo. The percutaneous absorption of AA-2G was determined in five Japanese males. The excretion of ascorbic acid (AA) in the subjects administered AA-2G was sustained for a longer period than in the subjects administered ascorbic acid 2-phosphate (AA-2P), which is a conventional vitamin C derivative. An analysis of the distribution of AA in the skin showed that small black specks assumed to be AA were observed in the epidermis even 3 d after applying AA-2G. The melanin synthesis in B16 melanoma cells was inhibited more by AA-2G than by AA-2P, and AA-2G also prevented more UV-induced damage of human skin keratinocytes and fibroblasts than AA-2P did. From these in vivo and in vitro results, it is supposed that the conversion of AA-2G to AA is sustained for a long time compared with that of AA-2P, and that AA-2G is an effective and available compound having vitamin C activity in human subjects.
Recent reports have indicated that trienzyme treatment before folate determination is essential to obtain the proper folate content in foods. Trienzyme treatment is performed by using α-amylase and protease for folate extraction from carbohydrate and protein matrices, and folate conjugase for the hydrolysis of polyglutamyl folates. We evaluated the conditions of pH and incubation time for the treatment with α-amylase and protease. Four food items, including fresh beef, white bread, cow's milk, and fresh spinach, were selected for this investigation. We found that optimal pHs for α-amylase treatment of beef and cow's milk were 7.0 and 5.0, respectively, whereas those for white bread and spinach were not distinctive at pHs from 2.0 to 7.0. The optimal incubation time for a-amylase was 4 h for fresh beef and cow's milk, whereas no distinctive optimal incubation period was found for white bread and fresh spinach. Our data indicate that the conditions for enzyme treatments vary de-pending on food items. Trienzyme treatment resulted in an increase of more than 50% in the mean folate content over folate conjugase treatment alone. It is necessary to treat food samples with not only traditional folate conjugase, but also with a-amylase and protease before folate deter-mination to obtain the actual folate content.
The hypoglycemic effect and the α-glucosidase activity inhibition of acarbose (AC: α-glucosidase inhibitor) were investigated in normal and KK-Ay mice, an animal model of noninsulin-dependent diabetes mellitus (NIDDM). AC improved hyperglycemia after an oral administration of maltose or sucrose, dose dependently in normal mice (l, 10, and 50mg/kg body weight) and in KK-Ay mice (50mg/kg). Furthermore, AC (50mg/kg) significantly inhibited maltase and sucrase activities in the small intestines of normal and KK-Ay mice (inhibitory efficacy: sucrase>maltase). The enzymatic inhibition in KK-Ay mice is stronger than in normal mice. However, AC (50mg/kg) did not suppress the blood glucose in oral lactose tolerance and did not inhibit the lactase activity in either normal or KK-Ay mice. These findings indicate that the AC effect on the inhibition of α-glucosidase activity is selective for sucrase and maltase in normal and NIDDM mice.
To determine the absorption and biodistribution of iron from microencapsulated ferrous sulfate (SFE-171), used to fortify dairy products with iron, a comparative study in four groups of 30 mice each was carried out. In two of the groups, the absorption of iron from ferrous ascorbate in water (13.3±4.3%) and from ferrous sulfate in water (12.7±3.9%) was determined and taken as reference standards. In the third group the iron absorption from SFE-171 in milk was determined, giving a value of 12.1±4.2%, which statistically does not differ from the data obtained with either reference standard. In the fourth group, the absorption of iron from ferrous sulfate in milk showed a value of 7.7±3.4%, which statistically differs with a p<0.01 from the data corresponding to the other three groups. The biodistribution studies showed that the iron from SFE-171 follows the same metabolic pathway as the iron from the reference standards thus, giving a higher radioac-tivity percentage and radioactivity concentration in organs or systems, principally blood, that are closely related to iron metabolism. Our studies allow us to conclude that the iron from SFE-171 in milk follows the same behavior as the nonhemic iron, with a higher absorption than that of ferrous sulfate in milk.
A case-control study was completed at the Princess Marie Louise Hospital in Accra, Ghana, to identify risk factors for the prevalence of underweight and severe malnutrition in urban African children. A total of 170 children, aged 8 to 36 mo, with normally nutritional status (≥80% W/A of NCHS reference), underweight (moderate malnutrition) (60-80% W/A), or severe malnutrition (<80% W/A and presence of edema, or <60% of W/A) were recruited at the clinical ward and at the public health service section of the hospital. Anthropometric measurements and physical examinations were completed, and the guardians were interviewed about their children's health status, birth weight, child care, and household conditions. The severely malnourished children were more likely to have young mothers (p<0.05) and low weight at birth (p<0.05). The under-weight children were also observed to have low birth weight (p<0.05). The severely malnourished group showed the tendencies of less feeding frequency (p<0.01), less access to breast-feeding (p<0.01), and less support by both parents (p<0.05). Moreover, the parents of the severely malnourished children had lower educational levels and lower-income jobs, compared with those of the normal children (mother's education, p<0.001; father's education, p<0.001; mother's occupation, p<0.05; father's occupation, p<0.001). No significant differences in most variables existed between the normal and underweight groups. Multivariable analysis resulted in the conclusion that the Z-score of weight-for-age, birth weight, and mother's educational level were highly associated with one another. We conclude that low birth weight is one of the important risk factors for the prevalence of underweight and severe malnutrition and that the lack of a mother's education is also a risk factor for the prevalence of severe malnutrition in the urban children in Ghana.
Female Sprague-Dawley rats, 9 weeks of age, were assigned to four groups: Group 0 (n=8) was dissected for base-line control, and the other three groups were fed for 3 mo: Group 1 (n=9), sedentary controls; Group 2 (n=6), running rats housed in a cage with a treadmill and pair-fed with Group 1; and Group 3 (n=7), running rats, pair-fed and allowed free access to additional glucose. The distances of voluntary running did not significantly differ between Groups 2 and 3. Menstrual cycles in these rats were apparently maintained as observed from daily running distances. The amount of glucose taken by rats in Group 3 was 3.5±0.4 (mean and SE) g/d. Body weight (BW) at the end of the experiment for Groups 1, 2, and 3 were 295.0±7.9, 211.7±5.4 (p<0.001 vs. Group 1), and 259.0±3.5g (p<0.01 vs. Group 2), respectively. The parameters of bone mass such as ash weights of the femur and bone mineral content of the lumbar spine and the tibia in Groups 1 and 2 did not differ, but the values were significantly greater in Group 3 than in Group 2. However, these parameter values corrected for BW were significantly greater in Group 2 than in Group 1 and did not significantly differ between Groups 2 and 3. The parameters of bone formation, such as serum bone alkaline phosphatase activity levels and trabecular bone formation rates corrected for BW, were significantly greater in Group 2 than in Group 1 but did not differ between Groups 2 and 3. However, the parameters of bone resorption, such as serum tartrate resistant acid-phosphatase levels, were significantly less in Group 3 than in Group 2. These results suggest that voluntary running augments the age-dependent increase in bone mass by modulating the bone turnover when an adequate energy source is supplied under conditions of normal menstruation, and an adequate supply of energy could be necessary to enhance the age-dependent increase in bone mass.
Konjac (konnyaku) glucomannan was examined for its deg radation in human intestines and fermentation products. The konjac glucomannan was degraded almost 100% by soluble enzymes in human feces to give 4-O-β-D-mannopyranosyl-D-mannopyranose (β-1, 4-D-man nobiose), 4-O-β-D-glucopyranosyl-D-glucopyranose (cellobiose), 4-O-β-D glucopyranosyl-D-mannopyranose, and small amounts of glucose and mannose. These three disaccharides were further degraded by a cell associated enzyme(s) to glucose or mannose, or to both. Konjac gluco mannan underwent fermentation by intestinal anaerobic bacteria and produced formic acid, acetic acid, propionic acid, and 1-butyric acid. These fatty acids were different in their proportions among test subjects, their total amounts ranging from 17.1% to 48.8% of the initial konjac glucomannan.
The bioavailability of roasted and ground soybean (kinako) magnesium (Mg) in Fischer 344 strain male rats with respect to serum Mg level, bone Mg contents, kidney calcification, and Mg absorption was evaluated. Four-week-old male rats were divided into four groups of six rats each. The four groups were the control (20SC), Mg-deficient diet (1/3 Mg20SC), 20SCK diet, and 20SCDK diet. The 20SCK and 20SCDK diets were prepared to contain amounts of Mg equal to that in the 20SC diet with kinako or defatted kinako as the Mg source, respectively. After a 4-week experimental period, rats were decapitated and blood serum, right femur, and right kidney were collected, and Mg, calcium (Ca), and phosphorus (P) concentrations in those tissues were determined. The Mg balance was also investigated. The serum Mg concentration in the 1/3 Mg20SC group was half the level in the 20SC group, and the serum Ca concentration was higher than in the 20SC group, indicating ap parent hypercalcemia. Serum Mg and Ca concentrations in the 20SCK and 20SCDK groups did not significantly differ from those in the 20SC group. Femur Mg concentration in the 1/3 Mg20SC group was lower than in the 20SC group. Femur Mg concentrations in the 20SCK and 20SCDK groups were lower than in the 20SC group, but significantly higher than in the 1/3 Mg20SC group. The kidney Ca concentrations in the 20SCK and 20SCDK groups were significantly higher than those in the 205C and 1/3 Mg20SC groups, and there was also kidney calcification. These results indicated that kinako and defatted kinako Mg were used effective ly as a serum and femur Mg source, but that kinako and defatted kinako carry a risk of kidney calcification when used as the only Mg source.
Micellar calcium phosphate (MCP) in bovine milk was separated as the complex with casein phosphopeptide (CPP) by the following procedures. Rennet curd obtained from skim milk was suspended in water, the pH was adjusted to 4.6, and the suspension was centrifuged at 1, 000×g. CPP was separated from the precipitated casein by tryptic hydrolysis and ethanol precipitation. The supernatant, which contained calcium and inorganic phosphate liberated from casein micelles by acidification, and CPP were mixed; the pH was adjusted to 6.7; and then the solution was lyophilized. From 1 L of skim milk, 3.16g of the MCP-CPP complex was obtained. The dried MCP-CPP complex was easily dissolved in water and contained 12.7% calcium, 0.3% magnesium, 3.4% inorganic phosphorous, and 2.2% organic phosphorous. No crystal structure of hydroxyapatite was shown in the MCP-CPP complex by the X-ray diffraction analysis, although the pattern of NaCI crystal was observed. The X-ray diffraction pattern of commercial whey mineral, which was prepared by precipitation at alkaline pH from rennet whey, was similar to that of hydroxyapatite. It was confirmed by high-performance gel chromatographic analysis that the form of calcium phosphate in the MCP-CPP complex was similar to that of casein micelles. The MCP-CPP complex was also separated from commercial rennet casein. The method for the separation of MCP-CPP complex described above can be applied to the large-scale preparation.
We investigated different means of achieving methyl de pletion by feeding weanling rats modified AIN diets depleted of folate (FD), folate + choline (FCD), and folate + choline + methionine (FCMD), and examined the consequent effects on folate status, homocysteine levels, and methylation status. Control rats were fed a 12% protein diet consisting of either casein or soy protein isolate (SPI) and containing 2mg/kg folate, 0.2% choline, and 0.4% methionine. After the rats had been on the diets for 4 and 8 weeks, whole blood folate concentration was measured and found to be significantly depleted in the folate deficient treatments com pared with controls at 4 weeks (p <0.001), this reduction being significantly greater (p<0.03) in casein-fed rats (60%) than in SPI-fed rats (32%). The omission of choline and methionine from the diet had no further influence on whole blood folate. A significant inverse correlation was observed in the casein-fed rats after 8 weeks between mean plasma homocysteine concentration and decreasing methyl content of the diet (r2=0.978, p<0.002), an effect not seen in the corresponding SPI-fed rats. Hypo methylation of hepatic DNA evidenced by a reduction in 5-methylcytosine content was present in the casein rats fed FCD and FCMD relative to control (p<0.05). No hepatic DNA methylation changes were observed in the SPI-fed rats. The results obtained in the present work demonstrate that a soy-based diet can compensate against methyl group depletion by maintaining plasma homocysteine levels and an adequate level of DNA methylation, a result we attribute to endogenous folate content.
Gastrointestinal symptoms and fecal frequency following ingestion of yogurt containing 15 g of galacto-oligosaccharides (GOS) per d were observed in 12 healthy volunteers. The effect of GOS on intestinal microflora was also studied in six volunteers. Defecation frequency increased during the administration period, but gastrointestinal symptoms, especially flatulence, also increased. The level of fecal bifidobacteria did not increase by the yogurt intake, but a significant increase was observed in the fecal bacteria growing on MRS media. The results indicate that dietary GOS increase gastrointestinal symptoms and fecal frequency in normal adults and have an effect on intestinal microecosystem.
We examined the effect of L-lactic acid on calcium absorption in male Wistar rats made achlorhydric by dietary omeprazole, a proton pump inhibitor. The dietary omeprazole intake (0.03g/100 g of diet) increased the gastric pH and decreased the apparent calcium absorption ratio. Dietary famotidine (0.03g/100g of diet), an H2-receptor antagonist, and lower doses of omeprazole (0.005 or 0.01g/100g of diet) did not affect the gastric pH or the calcium absorption. In a second experiment, dietary lactic acid (0.5, 1.0, or 2.5g/100g of diet) increased the intestinal calcium absorption dose dependently in rats fed omeprazole (0.03g/100g of diet). The gastric pH was significantly decreased only in the rats fed higher doses of lactic acid (1.0, or 2.5g/100g of diet). In a third experiment, a dietary sour milk beverage containing lactic acid (0.5g/100g of diet) increased the intestinal calcium absorption, but did not affect the gastric pH in rats fed omeprazole (0.03g/100g of diet). Although the significance of gastric acid in terms of overall calcium absorption is not known, under the present experimental conditions, the inhibition of gastric acid secretion by dietary omeprazole decreased the apparent calcium absorption, and the dietary lactic acid prevented the calcium absorption in rats fed omeprazole.