D-Psicose, a C3 epimer of D-fructose, is known to lower body weight and adipose tissue weight and affect lipid metabolism. The precise mechanism remains unknown. It has been reported that D-psicose has a short half-life and is not metabolized in the body. To determine how D-psicose modifies lipid metabolism, rats were fed diets with or without 3% D-psicose for 4 weeks. Rats were decapitated without fasting every 6 h over a period of 24 h. Changes in serum and liver lipid levels, liver enzyme activity, and gene expression were quantified in experiment 1. Rats fed D-psicose had significantly lower serum insulin and leptin levels. Liver enzyme activities involved in lipogenesis were significantly lowered by the D-psicose diet, whereas gene expression of a transcriptional modulator of fatty acid oxidation was enhanced. In experiment 2, feeding the D-psicose diet gave significantly lower body weight (389 ± 3 vs 426 ± 6 g, p < 0.05) and food intake (23.8 ± 0.2 vs 25.7 ± 0.4 g/day, p < 0.05) compared to the control diet. Rats fed the D-psicose diet gave significantly higher energy expenditure in the light period and fat oxidation in the dark period compared to rats fed the control diet, whereas carbohydrate oxidation was lower. In summary, these results indicate that the D-psicose diet decreases lipogenesis, increases fatty acid oxidation, and enhances 24 h energy expenditure, leading to d-psicose's potential for weight management.
In a project to produce a new fermented tea product from non-used tea leaves harvested in the summer, we found that kneading tea leaves ( Camellia sinensis ) with fresh loquat leaves ( Eriobotrya japonica ) accelerated the enzymatic oxidation of tea catechins. The fermented tea obtained by tea-rolling processing of tea and loquat leaves had a strong, distinctive flavor and a plain aftertaste, which differed from usual black, green, and oolong teas. The phenolic constituents were similar to those of black tea. However, the concentrations of theaflavin 3-O-gallate, theaflavin 3,3'-di-O-gallate, and thearubigins were higher in the tea leaves kneaded with loquat leaves than in tea leaves kneaded without loquat leaves. The results from in vitro experiments suggested that acceleration of catechin oxidation was caused by the strong oxidation activity of loquat leaf enzymes and a coupled oxidation mechanism with caffeoyl quinic acids, which are the major phenolic constituents of loquat leaves.
Phenolic constituents of a new functional fermented tea produced by tea-rolling processing of a mixture (9:1) of tea leaves and loquat leaves were examined in detail. The similarity of the phenolic composition to that of black tea was indicated by high-performance liquid chromatography comparison with other tea products. Twenty-five compounds, including three new catechin oxidation products, were isolated, and the structures of the new compounds were determined to be (2R)-2-hydroxy-3-(2,4,6-trihydroxyphenyl)-1-(3,4,5-trihydroxyphenyl)-1-propanone 2-O-gallate, dehydrotheasinensin H, and acetonyl theacitrin A by spectroscopic methods. In addition, theacitrinin A and theasinensin H were obtained for the first time from commercial tea products. Isolation of these new and known compounds confirms that reactions previously demonstrated by in vitro model experiments actually occur when fresh tea leaves are mechanically distorted and bruised during the production process.
Coffee bean extract (CBE) was prepared from raw green coffee beans and contained 10.0% caffeine and 27.0% chlorogenic acid. Male Sprague-Dawley rats were fed a diet containing 1% CBE for 4 weeks. Although there was no difference in food intake between rats fed the control diet without CBE and those fed the CBE-containing diet, body weight gain and white adipose tissue weight were significantly decreased in CBE-fed rats than in control rats. The CBE-fed group exerted a significant and extreme reduction in serum and liver triglyceride concentrations compared to the control group. Also, in the CBE-fed group, activities of fatty acid synthetic enzymes in the hepatic cytosol were significantly decreased, while that of fatty acid oxidative enzymes in the hepatic mitochondria was significantly increased. Our results suggest that CBE has potent anti-obesity and hypotriglyceridemic properties, and there is a possibility that these effects are exerted at least in part by the suppression of lipogenesis and the acceleration of lipolysis.
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