Supplementation of whole persimmon leaf improves lipid profiles and suppresses body weight gain in rats fed high-fat diet.

The objective of this study was to investigate the hypolipidemic effects of powdered whole persimmon leaf supplement in rats fed high-fat diet. Three groups of male Sprague-Dawley rats during 6 weeks were fed different diet: normal control (NC), high-fat (HF), and high-fat supplemented with powdered whole persimmon leaf (PL; 5%, wt/wt) groups. Body weight and relative weight of interscapular brown adipose tissue were significantly lower in the PL group than in the HF group, while plasma leptin concentration was higher. The supplementation of persimmon leaf significantly lowered the plasma total cholesterol and triglyceride concentrations, whereas elevated the ratio of HDL-C/total-C and improved the atherogenic index. Persimmon leaf supplementation led the hepatic cholesterol and triglyceride values to similar levels to the NC group. Accumulation of hepatic lipid droplets and the epididymal white adipocyte size of PL group were diminished comparing to the HF group. Hepatic HMG-CoA and ACAT activities were significantly higher in the PL group than in other groups. Contents of fecal triglyceride, cholesterol and acidic sterol were significantly higher in the PL group than in the HF group. Accordingly, we suggest that supplementation of the powdered whole persimmon leaf improves plasma and hepatic lipid levels profile partly via the increased fecal lipids in high-fat fed rats. These beneficial effects may be due to the properties of its phenolic compounds (1.15 g/100g) and high fiber (63.48 g/100g) content in the powdered persimmon leaf.

Contribution of a high dose of L-ascorbic acid to carnitine synthesis in guinea pigs fed high-fat diets.

Ascorbate is a cofactor of two-enzyme hydroxylation in the pathway of carnitine biosynthesis. The purpose of this study was to investigate the contribution of ascorbate to endogenous carnitine in guinea pigs fed high-fat diets. The contents of carnitine in plasma, urine and tissues of guinea pigs supplemented with L-ascorbic acid were determined and compared with those supplemented with carnitine. Albino-Hartley guinea pigs were fed vitamin C-deficient diets containing lard throughout the experiment. They were administered orally with 5 mg L-ascorbic acid/d/animal for 14 d, and then divided into three groups and administered orally with the following supplements (/d/animal) for 14 d; L (5 mg L-ascorbic acid), LASA (100 mg L-ascorbic acid), and LCAR (10 mg carnitine plus 5 mg L-ascorbic acid). As a control, a normal group was fed vitamin C-deficient diets and administered orally with 5 mg L-ascorbic acid/d/animal for 28 d. The animals fed high-fat diets (L group) had higher free-carnitine contents in the muscle and urine than the normal group. The groups of LCAR and LASA had significantly higher contents of acid-soluble carnitine (p < 0.05) in plasma than the L group. Urinary excretion of carnitine in the LASA group was decreased to the same level as that in the normal group, although no significant difference between the groups of L and LCAR was observed. Moreover, the supplement of ascorbic acid, but not of carnitine, induced a significantly lower content of triacylglycerol in the plasma of the LASA group as compared to the L group (p < 0.05). These data suggest that high doses of ascorbic acid in guinea pigs fed high-fat diets contribute to the enhancement of carnitine synthesis and improvement of the triacylglycerol content in the plasma.

Ascorbate indirectly stimulates fatty acid utilization in primary cultured guinea pig hepatocytes by enhancing carnitine synthesis.

L-Ascorbic acid is required for the synthesis of L-carnitine, which is essential for the oxidation of long-chain fatty acids. The purpose of this study was to investigate the role of ascorbate on the oxidation of long-chain fatty acids in primary cultured guinea pig hepatocytes. The hepatocytes were incubated in medium containing carnitine in the presence or absence of fatty acids. Exogenous fatty acids had no influence on the uptake of total carnitine into cells, but they lowered the free carnitine and consequently raised the concentration of short-chain acyl carnitine. Furthermore, carnitine supplementation of the medium in the presence of fatty acids led to a decrease of triglycerides in cells and an increase in the secretion of beta-hydroxybutyrate. These changes were also induced by the supplementation of the medium with both ascorbate and the precursor of carnitine (gamma-butyrobetaine) in the presence of fatty acids, although either ascorbate of gamma-butyrobetaine alone had no effect. In addition, increasing the concentration of supplemental ascorbate resulted in an enhancement of ketogenesis and a decrease of triglyceride accumulation. These results suggest that ascorbate enhances carnitine synthesis, which in turn stimulates beta-oxidation of fatty acids.

The regulatory effect of ascorbate on the carnitine synthesis in primary cultured guinea pig hepatocytes.

The effect of ascorbate (AsA) on the synthesis of carnitine from gamma-butyrobetaine (BB) in primary cultured guinea pig hepatocytes was investigated. The hepatocyte monolayers preloaded with AsA were incubated for 4 h in medium with various concentrations of BB as the precursor of carnitine. The accumulation of carnitine reached a maximum when the cells were incubated with 0.05-1.0 mM BB and significantly decreased with excess BB (5 mM). In contrast, increasing concentrations of AsA supplemented to medium led to an increase in carnitine content, but AsA and total AsA contents in cells decreased by BB supplementation. Regarding the enhancement of hydroxylation of BB in the hepatocytes, AsA was the most effective among such other reducing agents as glutathione and dithiothreitol. Although erythorbate (ErA) also stimulated the hydroxylation of BB, carnitine content in cells preloaded with ErA was only 60% of that with AsA. These results suggest that AsA is specifically required for the hydroxylation of BB. Furthermore, AsA can regulate carnitine synthesis in the primary cultured guinea pig hepatocytes.

The effect of graded doses of ascorbic acid on the tissue carnitine and plasma lipid concentrations.

Ascorbic acid (AsA) is known to be required for the synthesis of carnitine. The present study was designed to clarify the effect of AsA on the carnitine synthesis and lipid metabolism in guinea pigs. The animals were divided into four groups, and fed AsA-free diets for three weeks. Each group was supplemented with AsA in the following doses; high-AsA group, 100 mg AsA/day/animal; control group, 5 mg AsA/day/animal; AsA-deficient group, 0.1 mg AsA/day/animal; pair-fed group, 5 mg AsA/day/animal. The pair-fed group was restricted to the amount of diet consumed by the AsA-deficient group. Tissue carnitine levels of the AsA-deficient group were significantly lower than not only the control group but the pair-fed group. Total cholesterol and phospholipid levels in plasma of the AsA-deficient group were found to be similar to those of the pair-fed group; however, plasma triglyceride levels were significantly higher than that of the pair-fed group. Furthermore, there was an inverse relationship between tissue AsA and plasma triglyceride levels. We concluded that carnitine synthesis and triglyceride metabolism in guinea pigs may be impaired by the decrease of tissue AsA level rather than by the insufficient food intake. It is suggested that tissue carnitine level altered by tissue AsA content affects plasma triglyceride level.