Sesamin, a sesame lignan, decreases fatty acid synthesis in rat liver accompanying the down-regulation of sterol regulatory element binding protein-1

Comparative analysis of sesame lignans (sesamin and sesamolin) in affecting hepatic fatty acid metabolism in rats

Effects of sesamin and sesamolin (sesame lignans) on hepatic fatty acid metabolism were compared in rats. Rats were fed either a lignan-free diet, a diet containing 0.6 or 2 g/kg lignan (sesamin or sesamolin), or a diet containing both sesamin (1.4 g/kg) and sesamolin (0.6 g/kg) for 10 d. Sesamin and sesamolin dose-dependently increased the activity and mRNA abundance of various enzymes involved in hepatic fatty acid oxidation. The increase was much greater with sesamolin than with sesamin. These lignans increased parameters of hepatic fatty acid oxidation in an additive manner when added simultaneously to an experimental diet. In contrast, they decreased the activity and mRNA abundance of hepatic lipogenic enzymes despite dose-dependent effects not being necessarily obvious. Sesamin and sesamolin were equally effective in lowering parameters of lipogenesis. Sesamolin accumulated in serum at 33- and 46-fold the level of sesamin at dietary concentrations of 0.6 and 2 g/kg, respectively. The amount of sesamolin accumulated in liver was 10- and 7-fold that of sesamin at the respective dietary levels. Sesamolin rather than sesamin can account for the potent physiological effect of sesame seeds in increasing hepatic fatty acid oxidation observed previously. Differences in bioavailability may contribute to the divergent effects of sesamin and sesamolin on hepatic fatty acid oxidation. Sesamin compared to sesamolin was more effective in reducing serum and liver lipid levels despite sesamolin more strongly increasing hepatic fatty acid oxidation.

Effect of dietary sesame oil as antioxidant on brain hippocampus of rat in focal cerebral ischemia

Oxidative stress may be regarded as an imbalance between free radical production and opposing antioxidant defenses. Free radical oxidative stress is implicated in rat cerebral ischemia and naturaceutical antioxidants are dietary supplements that have been reported to have neuroprotective activity. Many studies have reported dietary sesame oil (SO) as an effective antioxidant. In the present study the neuroprotective effect of dietary SO was evaluated against middle cerebral artery occlusion (MCAO)-induced cerebral ischemia injury in rats. Rats were fed on diet (20% SO) for 15 days. The middle cerebral artery of adult male Wistar rat was occluded for 2 h and reperfused for 22 h. The antioxidant properties of brain were measured as levels of reduced glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxide (GPx), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD) and thiobarbituric acid reactive substance (TBARS). A decrease in the activity of all the enzymatic and non-enzymatic antioxidants was observed along with an increase in lipid peroxidation (LPO) in MCAO group. The neurobehavioral activity of rats was also observed by using videopath analyzer. Dietary SO improved the antioxidant status in MCAO+SO group when compared with MCAO group. The results of neurobehavioral activity also support our biochemical data. The results obtained suggest protective effect of SO against cerebral ischemia in rat brain through their antioxidant properties.

Inhibitory effect of sesaminol glucosides on lipopolysaccharide-induced NF-κB activation and target gene expression in cultured rat astrocytes

The inflammatory reaction plays an important role in the pathogenesis of the neurodegenerative disorder including Alzheimer's disease (AD). Sesame lignan compounds such as sesaminol glucosides (SG) exhibit a range of pharmacological activities including anti-oxidative and anti-inflammatory action. In this study, we tried to elucidate possible effects of SG on lipopolysaccharide (LPS)-induced inflammatory reaction and its underlying mechanism in cultured astrocytes. SG (10-100 microg/ml) inhibited LPS-induced generation of nitric oxide (NO) and reactive oxygen species (ROS), as well as inhibited LPS-induced cytosolic phospholipase A2 (cPLA2), cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) expression dose-dependently. This inhibitory effect of SG on NO and ROS generation was enforced by addition of glutathione (GSH) in culture. In addition, SG prevented LPS-induced DNA binding and transcriptional activity of nuclear factor KappaB (NF)-kappaB. Consistent with the inhibitory effect on NF-kappaB activity, SG inhibits phosphorylation and degradation of inhibitory KappaB (IkappaB), thereby translocation of p50 of NF-kappaB. These data show that SG has an anti-inflammatory effect through inhibition of NF-kappaB, and may be a useful agent for prevention of inflammatory disease like AD.

Increased gene expression of liver SREBP-2 in experimental chronic renal failure

Sterol regulatory element-binding protein-2 (SREBP-2) is a transcription factor regarded as the main regulator of cholesterol homeostasis. Therefore, increased level of SREBP-2 could be responsible for hypercholesterolemia, which is observed in experimental chronic renal failure (CRF). This study was designed primary to evaluate the impact of experimental CRF (5/6 nephrectomy model) on rat liver SREBP-2 gene expression. In CRF rats, a twofold increase in SREBP-2 mRNA level, as well as in mature SREBP-2 protein abundance was found, when compared to control animals. It was associated with enhanced activity and mRNA abundance of liver HMG-CoA reductase, a rate-limiting enzyme for cholesterol biosynthesis. A twofold increase in liver cholesterologenesis rate was also noted. We conclude that experimental CRF is associated with increased liver SREBP-2 gene expression. This is probably the cause for enhanced HMG-CoA reductase gene expression and, consequently, for increase in liver cholesterol synthesis in CRF rats. Despite increased SREBP-2 gene expression we found LDL-receptor mRNA level to be lower than in controls, suggesting SREBP-2 independent mechanisms of LDL-receptor transcriptional regulation in CRF rats. Enhanced cholesterol synthesis and decreased LDL-receptor mRNA level are probably responsible for an almost fourfold increase in serum cholesterol concentration in CRF rats.

Antioxidant activity of aryltetralone lignans and derivatives from Virola sebifera (Aubl.)

Aryltetralone lignans bearing methylenedioxy groups (1a-b; 2a-b) were isolated from seeds of Virola sebifera. Their antioxidant activities were evaluated by inhibition of lipid peroxidation as indicated by TBARS and chemiluminescence emission (CL) assays. The lignan 1c, 'having a 2'-hydroxy-4',5'-methylenedioxyphenyl group, was the most active compound with TBARS/CL Q 1/2 values of 0.89 and 0.10 microg/mL, respectively. The catechol derivatives 3 and 4, obtained by demethylenation of lignans 1a and 2a, were of similar activity to 1c, and all were much more effective as antioxidants than alpha-tocopherol.

Ingested cocoa can prevent high-fat diet-induced obesity by regulating the expression of genes for fatty acid metabolism

OBJECTIVE

We previously found that ingested cocoa decreased visceral adipose tissue weight in rat. To elucidate the molecular mechanisms of that effect, we carried out experiments aimed at analyzing biochemical parameters and gene expression profiles.

METHODS

Rats were fed either of two high-fat diets, differing only in supplementation with real or mimetic cocoa. On day 21, body weights, mesenteric white adipose tissue weights, and concentrations of serum triacylglycerol were measured. To investigate the molecular mechanisms underlying the effects of cocoa on lipid metabolism and triacylglycerol accumulation, we examined gene expression profiles in liver and mesenteric white adipose tissues using the GeneChip microarray system.

RESULTS

Final body weights and mesenteric white adipose tissue weights were significantly lower in rats fed the real cocoa diet than in those fed the mimetic cocoa diet (P<0.05), and serum triacylglycerol concentrations tended to be lower in rats fed the real cocoa diet (P=0.072). DNA microarray analysis showed that cocoa ingestion suppressed the expression of genes for enzymes involved in fatty acid synthesis in liver and white adipose tissues. In white adipose tissue, cocoa ingestion also decreased the expression of genes for fatty acid transport-relating molecules, whereas it upregulated the expression of genes for uncoupling protein-2 as a thermogenesis factor.

CONCLUSIONS

Ingested cocoa can prevent high-fat diet-induced obesity by modulating lipid metabolism, especially by decreasing fatty acid synthesis and transport systems, and enhancement of part of the thermogenesis mechanism in liver and white adipose tissue.

Association of maximum voluntary dietary intake of freeze-dried garlic with Heinz body anemia in horses

OBJECTIVE

To characterize hematologic and clinical consequences of chronic dietary consumption of freeze-dried garlic at maximum voluntary intake in horses.

ANIMALS

4 healthy sex- and age-matched horses.

PROCEDURE

An initial garlic dose (0.05 g/kg, twice daily) was fed to 2 horses in a molasses carrier as part of their normal ration and was gradually increased to maximum voluntary intake (0.25 g/kg, twice daily) over 41 days. Dietary supplementation then continued for a total of 71 days. Two control horses were fed molasses with no garlic with their ration. Blood samples were collected weekly and analyzed for hematologic and biochemical changes, including the presence of Heinz bodies. Recovery of affected blood values was followed for 5 weeks after termination of dietary supplementation with garlic.

RESULTS

At a daily dose of > 0.2 g/kg, horses fed garlic developed hematologic and biochemical indications of Heinz body anemia, as characterized by increases in Heinz body score (HBS), mean corpuscular volume (MCV), mean corpuscular hemoglobin, platelet count, and serum unconjugated and total bilirubin concentrations and decreases in RBC count, blood hemoglobin concentration, mean corpuscular hemoglobin concentration, and serum haptoglobin concentration. Recovery from anemia was largely complete within 5 weeks after termination of dietary supplementation with garlic. Heinz body score and MCV remained high at the end of the 5-week recovery period.

CONCLUSIONS AND CLINICAL RELEVANCE

Horses will voluntarily consume sufficient quantities of garlic to cause Heinz body anemia. The potential for garlic toxicosis exists when horses are chronically fed garlic. Further study is required to determine the safe dietary dose of garlic in horses.

Food and Botanical Groupings and Risk of Breast Cancer: A Case-Control Study in Shanghai, China

Breast cancer incidence rates more than double in Chinese women as they migrate from China to Hong Kong to the United States, suggesting that environmental factors contribute to the international variation in breast cancer incidence. Several dietary factors, which differ between the United States and the Chinese population, including intake of soy, meat, and fruits and vegetables, have been suggested to affect breast cancer risk. This report describes results from a case-control study of diet and risk of breast cancer nested in a randomized trial of breast self exam in Shanghai, China. Participating breast cancer cases (n = 378) and frequency age-matched controls (n = 1,070) completed a comprehensive food frequency questionnaire and a risk factor questionnaire. After adjustment for age, total energy intake, and total years of breast-feeding, women in the highest quartile of fruit and vegetable intake (≥3.8 servings/d) were significantly less likely to have breast cancer (odds ratio, 0.48; 95% confidence interval, 0.29-0.78) as compared with women in the lowest quartile of intake (≤2.3 servings/d). Egg consumption was also significantly inversely associated with risk of breast cancer (odds ratio for ≥6.0 eggs/wk versus ≤2.0 eggs/wk is 0.56; 95% confidence interval, 0.35-0.91). There was no difference in soy consumption between cases and controls. None of the associations with a single botanical family explained the strong inverse relationship between fruits and vegetables and breast cancer risk. These results provide additional evidence in support of the important role of fruits and vegetables in breast cancer prevention.

Interaction of dietary fat types and sesamin on hepatic fatty acid oxidation in rats

The interaction of sesamin, one of the most abundant lignans in sesame seed, and types of dietary fats affecting hepatic fatty acid oxidation was examined in rats. Rats were fed purified experimental diets supplemented with 0% or 0.2% sesamin (1:1 mixture of sesamin and episesamin), and containing 8% of either palm, safflower or fish oil for 15 days. Among the groups fed sesamin-free diets, the activity of various fatty acid oxidation enzymes was higher in rats fed fish oil than in those fed palm and safflower oils. Dietary sesamin increased enzyme activities in all groups of rats given different fats. The extent of the increase depended on dietary fat type, and a diet containing sesamin and fish oil in combination appeared to increase many of these parameters synergistically. In particular, the peroxisomal palmitoyl-CoA oxidation rate and acyl-CoA oxidase activity levels were much higher in rats fed sesamin and fish oil in combination than in animals fed sesamin and palm or safflower oil in combination. Analyses of mRNA levels revealed that a diet containing sesamin and fish oil increased the gene expression of various peroxisomal fatty acid oxidation enzymes and PEX11alpha, a peroxisomal membrane protein, in a synergistic manner while it increased the gene expression of mitochondrial fatty acid oxidation enzymes and microsomal cytochrome P-450 IV A1 in an additive manner. It was concluded that a diet containing sesamin and fish oil in combination synergistically increased hepatic fatty acid oxidation primarily through up-regulation of the gene expression of peroxisomal fatty acid oxidation enzymes.

Species differences in the physiological activity of dietary lignan (sesamin and episesamin) in affecting hepatic fatty acid metabolism

The effect of sesame (Sesamum orientale) lignan preparation containing equivalent amounts of sesamin and episesamin on hepatic fatty acid metabolism was compared in rats, mice and hamsters. Animals were fed on either a diet free of lignan or a diet containing 2 g lignan/kg for 15 d. The lignan preparation greatly increased hepatic activity and the mRNA levels of enzymes involved in fatty acid oxidation, while it strongly down-regulated those of enzymes involved in lipogenesis in rats. In contrast, lignan did not modify these variables in mice and hamsters. Changes observed, if any, were more attenuated in these mice and hamsters than in rats. Sesamin and episesamin concentrations in serum and liver of animals fed on lignan-containing diets were significantly greater (P<0.05) in rats than in mice and hamsters. Moreover, sesamin:episesamin values in tissues were far from that expected from the value in the lignan preparation given to the animals and were dependent on the animal species. Liver microsomes from each animal species degraded sesamin and episesamin in the presence of NADPH. The combined value of sesamin and episesamin degradation rates was lower in rats than in mice and hamsters. In addition, there was considerable diversity in the specificity of the enzyme reaction toward sesamin and episesamin among animal species. The differences in the amounts of lignan remaining in the tissues may account for the species dependence of the physiological activity of sesame lignan in affecting hepatic fatty acid oxidation and synthesis.

Divergent effects of eicosapentaenoic and docosahexaenoic acid ethyl esters, and fish oil on hepatic fatty acid oxidation in the rat

The physiological activity of fish oil, and ethyl esters of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) affecting hepatic fatty acid oxidation was compared in rats. Five groups of rats were fed various experimental diets for 15 days. A group fed a diet containing 9.4% palm oil almost devoid of n-3 fatty acids served as a control. The test diets contained 4% n-3 fatty acids mainly as EPA and DHA in the form of triacylglycerol (9.4% fish oil) or ethyl esters (diets containing 4% EPA ethyl ester, 4% DHA ethyl ester, and 1% EPA plus 3% DHA ethyl esters). The lipid content of diets containing EPA and DHA ethyl esters was adjusted to 9.4% by adding palm oil. The fish oil diet and ethyl ester diets, compared to the control diet containing 9.4% palm oil, increased activity and mRNA levels of hepatic mitochondrial and peroxisomal fatty acid oxidation enzymes, though not 3-hydroxyacyl-CoA dehydrogenase activity. The extent of the increase was, however, much greater with the fish oil than with EPA and DHA ethyl esters. EPA and DHA ethyl esters, compared to the control diet, increased 3-hydroxyacyl-CoA dehydrogenase activity, but fish oil strongly reduced it. It is apparent that EPA and DHA in the form of ethyl esters cannot mimic the physiological activity of fish oil at least in affecting hepatic fatty acid oxidation in rat.

Dietary cyanidin 3-O-beta-D-glucoside-rich purple corn color prevents obesity and ameliorates hyperglycemia in mice

Anthocyanins, which are used as a food coloring, are widely distributed in human diets, suggesting that we ingest large amounts of anthocyanins from plant-based foods. Mice were fed control, cyanidin 3-glucoside-rich purple corn color (PCC), high fat (HF) or HF + PCC diet for 12 wk. Dietary PCC significantly suppressed the HF diet-induced increase in body weight gain, and white and brown adipose tissue weights. Feeding the HF diet markedly induced hypertrophy of the adipocytes in the epididymal white adipose tissue compared with the control group. In contrast, the induction did not occur in the HF + PCC group. The HF diet induced hyperglycemia, hyperinsulinemia and hyperleptinemia. These perturbations were completely normalized in rats fed HF + PCC. An increase in the tumor necrosis factor (TNF)-alpha mRNA level occurred in the HF group and was normalized by dietary PCC. These results suggest that dietary PCC may ameliorate HF diet-induced insulin resistance in mice. PCC suppressed the mRNA levels of enzymes involved in fatty acid and triacylglycerol synthesis and lowered the sterol regulatory element binding protein-1 mRNA level in white adipose tissue. These down-regulations may contribute to triacylglycerol accumulation in white adipose tissue. Our findings provide a biochemical and nutritional basis for the use of PCC or anthocyanins as a functional food factor that may have benefits for the prevention of obesity and diabetes.

Activity and mRNA levels of enzymes involved in hepatic fatty acid synthesis and oxidation in mice fed conjugated linoleic acid

The effects of dietary conjugated linoleic acid (CLA) on the activity and mRNA levels of hepatic enzymes involved in fatty acid synthesis and oxidation were examined in mice. In the first experiment, male ICR and C57BL/6J mice were fed diets containing either a 1.5% fatty acid preparation rich in CLA or a preparation rich in linoleic acid. In the second experiment, male ICR mice were fed diets containing either 1.5% linoleic acid, palmitic acid or the CLA preparation. After 21 days, CLA relative to linoleic acid greatly decreased white adipose tissue mass but caused hepatomegaly accompanying an approximate 10-fold increase in the tissue triacylglycerol content irrespective of mouse strain. CLA compared to linoleic acid greatly increased the activity and mRNA levels of various lipogenic enzymes in both experiments. Moreover, CLA increased the mRNA expression of Delta6- and Delta5-desaturases, and sterol regulatory element binding protein-1 (SREBP-1). The mitochondrial and peroxisomal palmitoyl-CoA oxidation rate was about 2.5-fold higher in mice fed CLA than in those fed linoleic acid in both experiments. The increase was associated with the up-regulation of the activity and mRNA expression of various fatty acid oxidation enzymes. The palmitic acid diet compared to the linoleic acid diet was rather ineffective in modulating the hepatic lipid levels or activity and mRNA levels of enzymes in fatty acid metabolism. It is apparent that dietary CLA concomitantly increases the activity and mRNA levels of enzymes involved in fatty acid synthesis and oxidation, and desaturation of polyunsaturated fatty acid in the mouse liver. Both the activation of peroxisomal proliferator alpha and up-regulation of SREBP-1 may be responsible for this.

Phytochemical constituents from the fruits of Acanthopanax sessiliflorus

Six compounds were isolated from the fruits of Acanthopanax sessiliflorus. Their structures were elucidated as (-)-sesamin, scoparone, protocatechuic acid, ursolic acid, hyperin and 5-hydroxymethylfurfural by physicochemical and spectroscopic analysis. Among them, scoparone, ursolic acid and 5-hydroxymethylfurfural were isolated for the first time from Acanthopanax species.