Reduction Effect of Calcium Alginate on Blood Triglyceride Levels Causing the Inhibition of Hepatic and Total Body Accumulation of Fat in Rats.

In this study, rats were fed a high-fat diet containing calcium alginate (Ca-Alg) for 5 weeks to examine the effects of Ca-Alg on lipid metabolism including triglyceride (TG) levels in the blood. We also investigated the mechanism of the TG-reducing effect of Alg in vitro. Rats were randomized into 5 groups: high-fat diet group (14% (w/w) lard, HF); three Ca-Alg-containing diet groups (2.5, 5 or 10% (w/w) Ca-Alg) and a resistant maltodextrin (RMD) diet group as a positive control (with 5% (w/w) RMD). The 10% Ca-Alg group showed a significant reduction of body weight increase from the 7th day. In addition, the increase of TG in blood was significantly suppressed, and the amount of TG excreted in feces was increased. Increase of body fat mass was in the order HF > RMD > Ca-Alg 2.5% > Ca-Alg 5% > Ca-Alg 10%, while the total weight of the extracted fat tissues was significantly reduced in the RMD, 5% and 10% Ca-Alg groups. Hepatic pathology showed clear circular vacuoles apparently representing TG accumulation in the HF group, while fewer vacuoles were seen in the Ca-Alg groups. The results of in vitro experiments indicated that Ca-Alg does not directly inhibit lipase activity, but may suppress absorption of TG by forming non-absorbable macromolecular micelles containing TG. These results suggest that Ca-Alg promotes excretion and suppresses absorption of TG, leading to reduced blood TG levels, and decreased hepatic and total body accumulation of fat. The findings should be helpful for designing future clinical trials.

Mechanism of Suppression of Blood Glucose Level by Calcium Alginate in Rats.

Calcium alginate (Ca-Alg) is known to suppress the postprandial increase of blood glucose, and therefore may be helpful for preventing lifestyle-related diseases such as diabetes. In this work, we examined the mechanism of this effect. As α-amylase activity and α-glucosidase activity are involved in the digestion of starch, we examined the in vitro inhibitory effect of Ca-Alg on these enzymes. Ca-Alg showed little inhibition of α-amylase, but markedly inhibited α-glucosidase activity. The direct binding affinity of glucose for Ca-Alg was low. Also, Ca-Alg had essentially no effect on the membrane permeability of glucose. Therefore, we considered that the suppression of blood glucose by Ca-Alg is predominantly due to a decrease in the efficiency of starch digestion as a result of inhibition of α-glucosidase, possibly due to increased viscosity of the gastrointestinal contents. Next, we investigated the optimum amount in the diet and the optimum particle size of Ca-Alg for suppressing postprandial blood glucose level in rats orally administered a diet containing starch with various amounts and particle sizes of Ca-Alg. We found that 5% by weight of 270-mesh-pass Ca-Alg was most effective.

Randomized, Double-Blind, Crossover Clinical Trial of the Effect of Calcium Alginate in Noodles on Postprandial Blood Glucose Level.

We conducted a prospective, randomized, double-blind, 3-group, 3-phase crossover study to evaluate the effect of calcium alginate (Ca-Alg) on the postprandial increase of blood glucose in 15 healthy adult subjects who were given udon noodles containing or not containing Ca-Alg (5 or 8%). The value of ΔCmax (difference between the maximum (Cmax) and pre-feeding (C0) blood glucose levels) was significantly reduced in both Ca-Alg groups, and the area under the blood glucose level-time curve over 120 min (ΔAUC, with C0 as the baseline) was also significantly reduced. Thus, supplementation of noodles with Ca-Alg significantly suppressed both the peak postprandial blood glucose level and the total amount of glucose absorption. Blood calcium (Ca) concentration was significantly increased at 120 min after ingestion, but there was no marked change of other parameter values. A questionnaire indicated that addition of Ca-Alg did not affect the acceptability of the noodles. These results indicate that Ca-Alg might a useful food additive for helping to prevent lifestyle-related diseases without adversely affecting individual eating habits.

The salted radish takuan-zuke shows antihypertension effects in spontaneously hypertensive rats.

Recently, we reported that the antihypertensive compound, γ-aminobutyrate (GABA), increases over time during the dehydration of salted radish, known as takuan-zuke, a popular pickle in Japan. The objective of this study was to clarify the antihypertensive effects of takuan-zuke. We prepared two types of takuan-zuke by sun-drying (hoshi takuan-zuke) and salt-pressing (shio-oshi takuan-zuke) using dehydration processes. The oral administration of takuan-zuke lowered systolic blood pressure in spontaneously hypertensive rats (SHRs). Shio-oshi takuan-zuke (SR) demonstrated a clear antihypertension effect compared with hoshi takuan-zuke (DR), despite equal GABA concentrations in the feed. Furthermore, takuan-zuke demonstrated angiotensin converting enzyme (ACE) inhibition in vitro. These findings indicated that takuan-zuke contains unknown substances that have hypotensive actions independent of GABA. Further evaluation revealed that takuan-zuke contains polyphenols, arginine, and α-linolenic acid as possible antihypertensive factors. Collectively, our results suggest that the salty Japanese food takuan-zuke has antihypertensive effects in vivo, likely involving complex mechanisms.

Nutritional content and health benefits of sun-dried and salt-aged radish (takuan-zuke).

We investigated the nutritional characteristics of salted radish roots (takuan-zuke) prepared using different methods: takuan-zuke based on sun-drying (hoshi) or salt-pressing (shio-oshi) dehydration, different salt-aging temperatures, and salting with rice bran. We examined differences in nutritional substances in salted radish using chromatographic analysis, bioassay methods, and multivariate analysis. We previously reported that the amount of γ-aminobutyrate in takuan-zuke was increased by both dehydration treatments. In the present study, we observed that sucrose and proline were increased by sun-drying treatment, while little change occurred with salt-pressing treatment. Branched-chain amino acids were increased by both treatments. Interestingly, free fatty acids increased with salt-aging duration, irrespective of the dehydration method. Addition of rice bran to long salt-aging treatment increased the levels of niacin, glutamate, and acetate. Metabolite concentrations were higher in hoshi takuan-zuke than shio-oshi takuan-zuke. Our comprehensive analysis reveals effects of specific manufacturing conditions on beneficial components of takuan-zuke.

Generation of the antioxidant yellow pigment derived from 4-methylthio-3-butenyl isothiocyanate in salted radish roots (takuan-zuke).

2-[3-(2-Thioxopyrrolidin-3-ylidene)methyl]-tryptophan (TPMT) is a yellow pigment of salted radish roots (takuan-zuke) derived from 4-methylthio-3-butenyl isothiocyanate (MTBITC), the pungent component of radish roots. Here, we prepared salted radish and analyzed the behavior of the yellow pigment and related substances in the dehydration process and long-term salting process. All salted radish samples turned yellow, and their b(*) values increased with time and temperature. The salted radish that was sun-dried and pickled at room temperature turned the brightest yellow, and the generation of TPMT was clearly confirmed. These results indicate that tissue shrinkage due to dehydration, salting temperature, and pH play important roles in the yellowing of takuan-zuke.

Selenoureas and thioureas are effective superoxide radical scavengers in vitro.

Oxygen radicals, such as superoxide radicals, embellishing DNA, protein, lipids, etc., and carrying out the obstacle of the function of a cell is known. It depends for the oxidant level in the living body on the balance of a generation system and an elimination system of oxygen radicals, and research which controls an oxidant level in the living body is briskly done by taking in the substance which eliminates an oxygen radical. We investigated scavenging effects of superoxide radicals by selenoureas and thioureas using a highly sensitive and quantitative chemiluminescence method. At 330 nM, five selenoureas and five thioureas scavenged fractions of superoxide radicals (O2-) ranging from 8.4% to 87.6%. Among five N,N-unsubstituted selenoureas and N,N-unsubstituted thioureas 1-selenocarbamoylpiperidine and 1-thiocarbamoylpyrrolidine were the most effective scavengers. A possibility that selenoureas could use it as a new superoxide anion-scavenging substance from the result of this research became clear.

Selenocarbamates are effective superoxide anion scavengers in vitro.

We investigated the superoxide anion-scavenging effects of six selenocarbamates and four thiocarbamates, using a highly sensitive quantitative chemiluminescence method. At 333 nM, six selenocarbamates and four thiocarbamates scavenged in the range of 2.9-68.7% of O(2)*-. Se-methyl N-phenylselenocarbamate and Se-methyl N-(4-methylphenyl)selenocarbamate exhibited the strongest superoxide anion-scavenging activity among the Se-selenocarbamates. In contrast, the corresponding S-thiocarbamates had moderate inhibitory effect. The 50% inhibitory concentrations (IC(50)) of Se-methyl-N-phenylselenocarbamate and Se-methyl-N-(4-methylphenyl)selenocarbamate were determined to be 140 nM and 162 nM, respectively. Thus, these compounds acted in vitro as effective and potentially useful O(2)*- scavengers.

Tertiary selenoamide compounds are useful superoxide radical scavengers in vitro.

We investigated the scavenging effects of tertiary selenoamide compounds for super oxide radicals using a highly sensitive and quantitative chemiluminescence method. At 333 nM, tertiary selenoamide compounds scavenged 25.8-81.6% of O(2)(-). N-(Phenylselenocarbonyl) piperidine was the most effective scavenger of superoxide radicals. While N,N-diethyl-2-selenonaphthylamide and N,N-diethyl-4-chloroselenobenzamide was a moderately effective scavenger of superoxide radicals. The IC(50) of N-(phenylselenocarbonyl) piperidine and N,N-diethyl-2-selenonaphthylamide were determined to be 110 and 182 nM, respectively. The results suggest that tertiary selenoamide compounds are useful scavengers of superoxide radicals.