Yumi Nakamura

Anti-obesity role of adzuki bean extract containing polyphenols: in vivo and in vitro effects.

BACKGROUND The aim of this work was to evaluate the effects of polyphenol-rich adzuki bean extract on lipid metabolism, triglyceride accumulation and proinflammatory cytokine secretion in vivo and in vitro. RESULTS For the in vivo study, rats were divided into four groups: group C was fed a control diet, group A was fed the control diet with 1% adzuki bean extract, group CF was fed a high fat diet, and group AF was fed a high fat diet with 1% adzuki bean extract. For the in vitro study, the ability of adzuki bean extract to suppress triglyceride incorporation, glycerol phosphate dehydrogenase activity and inflammatory response was investigated in cultured human adipocytes. Data from the animal study showed that adzuki bean extract improved lipid metabolism in both the normal and high-fat diet groups. Adzuki bean extract treatment in the high-fat group resulted in significant reductions in total hepatic lipid accumulation and lipid secretion into the feces. Incubation of adipocytes with adzuki bean extract significantly decreased triglyceride accumulation, glycerol phosphate dehydrogenase activity and inflammatory responses without affecting cell viability. CONCLUSION The results of this study demonstrate that adzuki bean extract has high potential to serve as a natural anti-obesity agent.

Dietary L-Cysteine Improves the Antioxidative Potential and Lipid Metabolism in Rats Fed a Normal Diet

L-Cysteine works as a precursor of the antioxidant, glutathione. We investigated the effects of L-cysteine (1% and 2%) on lipid metabolism and the antioxidative system in rats fed a normal diet. Administering L-cysteine dependently decreased the food intake, fat mass weight and body weight dose. Dietary L-cysteine also decreased the triglyceride levels in the serum and liver. However, there were no significant differences in the hepatic TBARS and glutathione (GSH) levels among the groups. The activities of catalase and glutathione reductase in the rats receiving 2% L-cysteine were significantly higher (p<0.05) than in the control rats. These results suggest that dietary L-cysteine dose-dependently affected the antioxidative enzyme activities, and the lipid levels in the serum and liver which might be related to the reduced food intake.

Amelioration of D-Galactosamine-Induced Acute Liver Injury in Rats by Dietary Supplementation with Betaine Derived from Sugar Beet Molasses

The effects of betaine supplementation on D-galactosamine-induced liver injury were examined in terms of hepatic and serum enzyme activities and of the levels of glutathione and betaine-derived intermediates. The rats induced with liver injury showed marked increases in serum enzyme activity, but those receiving dietary supplementation of 1% betaine showed enzyme activity levels similar to a control group without liver injury. Administration of betaine also increased both hepatic and serum glutathione levels, even following D-galactosamine injection. The activity of glutathione-related enzymes was markedly decreased following injection of D-galactosamine, but remained comparable to that of the control group in rats receiving 1% betaine. The concentrations of hepatic S-adenosyl methionine and cysteine showed similar trends to that observed for hepatic glutathione levels. These results indicate that 1% betaine has a hepatoprotective effect by increasing hepatic and serum glutathione levels along with glutathione-related enzyme activities in rats.

Effect of White Wheat Bread Containing Sugar Beet Fiber on Serum Lipids and Hepatic mRNA in Rats Fed on a Cholesterol-Free Diet

We examined the effects of white wheat bread powder (BP) and white wheat bread powder containing sugar beet fiber (BBP) on serum cholesterol. The total cholesterol (−11%, −16%), HDL-cholesterol (−12%, −11%), non-HDL-cholesterol (−9%, −18%) and triacylglycerol (−44%, −58%) concentrations in the BP and BBP groups, respectively, were significantly different from those in the control group. The fecal excretion of neutral sterols in the BP and BBP groups and of acidic sterols in the BBP group was significantly higher than that in the control group. The hepatic cholesterol 7α-hydroxylase (CYP7A1) mRNA level in the BP and BBP groups was significantly higher than that in the control group. The cecal total short-chain fatty acid concentrations in the BBP group were significantly higher than those in the control group. These results indicate that the observed changes in serum lipid levels in the BP and BBP groups were due to the increased fecal lipid and CYP7A1 mRNA levels.

Effects of Feeding Potato Pulp on Cholesterol Metabolism and Its Association with Cecal Conditions in Rats

To clarify the functional properties of potato pulp (PP), a waste product resulting from extraction of starch from potatoes, we examined the effects of PP on cholesterol metabolism and cecal conditions in rats. Plasma total cholesterol (T-Chol) levels were lower in rats fed a PP-supplemented diet for four weeks than in those fed a control diet. Cecal pH was lowered due to an increase in the levels of cecal total short-chain fatty acids, especially butyrate, in the PP group compared to the control group. Furthermore, animals fed with the PP-supplemented diet showed increased cecal ratios of Lactobacillus and Clostridia and decreased cecal ratios of Bacteroides and Gammaproteobacteria with slightly negative and positive correlations with plasma T-Chol levels, respectively. In conclusion, ingestion of PP for four weeks is likely to improve both cecal conditions and cholesterol metabolism, suggesting that PP has prebiotic effects.

Effect of Fermented Bean Paste on Serum Lipids in Rats Fed a Cholesterol-Free Diet

We examined the effects of fermented bean pastes derived from bean vinegar by-products on serum cholesterol in rats. The rats were fed boiled paste from adzuki (A), kintoki (K), or tebou (T), or fermented paste from adzuki (AP), kintoki (KP), or tebou (TP) for 4 weeks. The serum non-high-density lipoprotein (HDL) cholesterol levels in all the experimental groups, except for A group, were significantly lower than in the control (CN) group. Likewise, the serum triglyceride levels in K and all the fermented bean groups were significantly lower than in the CN group. The levels of hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase mRNA in all the experimental groups except for A were significantly lower than in the CN group. These findings indicate that fermented bean pastes also suppress cholesterol synthesis, resulting in a reduced serum cholesterol concentration. These effects might be related not only to the resistant starch but also to the protein or peptide in the fermented bean paste.

Dietary l-cysteine inhibits d-galactosamine-induced acute liver injury in rats

The effects of l-cysteine (1 and 2%) on the antioxidative system were examined in rats with d-galactosamine (d-GalN)-induced injury. These rats showed increases in serum antioxidative enzyme and hepatic thiobarbituric acid reactive substances (TBARS) activities, with decreased hepatic/serum glutathione (GSH) levels and GSH-related enzyme activities. However, l-cysteine supplementation resulted in a decrease of hepatic TBARS levels, and increased catalase and serum GSH levels. The activities of serum enzymes in rats receiving 2% l-cysteine were significantly (p<0.05) lower than in d-GalN-injected group rats, and similar to levels in control group rats without acute liver injury. In addition, 2% l-cysteine increased the glutathione reductase activity and decreased the serum TBARS level in liver injury group rats. Dietary l-cysteine, especially at a 2% level, exerts a hepatoprotective effect by alteration of the GSH level and antioxidative enzyme activities.