Administration of tomato and paprika beverages modifies hepatic glucose and lipid metabolism in mice: a DNA microarray analysis

The use of transcriptomics to unveil the role of nutrients in Mammalian liver

Liver is the organ primarily responding to diet, and it is crucial in determining plasma carbohydrate, protein, and lipid levels. In addition, it is mainly responsible for transformation of xenobiotics. For these reasons, it has been a target of transcriptomic analyses. In this review, we have covered the works dealing with the response of mammalian liver to different nutritional stimuli such as fasting/feeding, caloric restriction, dietary carbohydrate, cholesterol, fat, protein, bile acid, salt, vitamin, and oligoelement contents. Quality of fats or proteins has been equally addressed, and has the influence of minor dietary components. Other compounds, not purely nutritional as those represented by alcohol and food additives, have been included due to their relevance in processed food. The influence has been studied not only on mRNA but also on miRNA. The wide scope of the technology clearly reflects that any simple intervention has profound changes in many metabolic parameters and that there is a synergy in response when more compounds are included in the intervention. Standardized arrays to systematically test the same genes in all studies and analyzing data to establish patterns of response are required, particularly for RNA sequencing. Moreover, RNA is a valuable, easy-screening ally but always requires further confirmation.

Potent PPARα activator derived from tomato juice, 13-oxo-9,11-octadecadienoic acid, decreases plasma and hepatic triglyceride in obese diabetic mice

Dyslipidemia is a major risk factor for development of several obesity-related diseases. The peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated transcription factor that regulates energy metabolism. Previously, we reported that 9-oxo-10,12-octadecadienoic acid (9-oxo-ODA) is presented in fresh tomato fruits and acts as a PPARα agonist. In addition to 9-oxo-ODA, we developed that 13-oxo-9,11-octadecadienoic acid (13-oxo-ODA), which is an isomer of 9-oxo-ODA, is present only in tomato juice. In this study, we explored the possibility that 13-oxo-ODA acts as a PPARα agonist in vitro and whether its effect ameliorates dyslipidemia and hepatic steatosis in vivo. In vitro luciferase assay experiments revealed that 13-oxo-ODA significantly induced PPARα activation; moreover, the luciferase activity of 13-oxo-ODA was stronger than that of 9-oxo-ODA and conjugated linoleic acid (CLA), which is a precursor of 13-oxo-ODA and is well-known as a potent PPARα activator. In addition to in vitro experiment, treatment with 13-oxo-ODA decreased the levels of plasma and hepatic triglycerides in obese KK-Ay mice fed a high-fat diet. In conclusion, our findings indicate that 13-oxo-ODA act as a potent PPARα agonist, suggesting a possibility to improve obesity-induced dyslipidemia and hepatic steatosis.

Profiling of hepatic gene expression of mice fed with edible japanese mushrooms by DNA microarray analysis: comparison among Pleurotus ostreatus, Grifola frondosa, and Hypsizigus marmoreus

To compare and estimate the effects of dietary intake of three kinds of mushrooms (Pleurotus ostreatus, Grifola frondosa, and Hypsizigus marmoreus), mice were fed a diet containing 10-14% of each mushroom for 4 weeks. Triacylglycerol in the liver and plasma decreased and plasma cholesterol increased in the P. ostreatus-fed group compared with those in the control group. Cholesterol in the liver was lower in the G. frondosa-fed group than in the control group, but no changes were found in the H. marmoreus-fed group. DNA microarray analysis of the liver revealed differences of gene expression patterns among mushrooms. Ctp1a and Fabp families were upregulated in the P. ostreatus-fed group, which were considered to promote lipid transport and β-oxidation. In the G. frondosa-fed group, not only the gene involved in signal transduction of innate immunity via TLR3 and interferon but also virus resistance genes, such as Mx1, Rsad2, and Oas1, were upregulated.

The effects of tomato consumption on serum glucose, apolipoprotein B, apolipoprotein A-I, homocysteine and blood pressure in type 2 diabetic patients

Tomatoes are a rich source of lycopene, β-carotene, potassium, vitamin C, flavonoids, folate and vitamin E that may provide protection against the development of type 2 diabetic patients, so the present study was undertaken to evaluate the effects of tomato intake on serum glucose, homocysteine, apolipoprotein (apo) B, apoA-I and blood pressure in type 2 diabetic patients. In a quasi-experimental study, 32 type 2 diabetes patients received 200 g raw tomato daily for 8 weeks. Serum glucose enzymatically, apoB and apoA-I immunoturbidometrically and homocysteine by high-performance liquid chromatography were measured at the beginning and end of 8 weeks. There were significant decreases in systolic and diastolic blood pressure and also a significant increase in apoA-I at the end of study compared with initial values (P = 0.0001, P = 0.0001 and P = 0.013, respectively). In conclusion, 200 g raw tomato per day had a favored effect on blood pressure and apoA-I so it might be beneficial for reducing cardiovascular risk associated with type 2 diabetes.

9-oxo-10(E),12(E)-Octadecadienoic acid derived from tomato is a potent PPAR α agonist to decrease triglyceride accumulation in mouse primary hepatocytes

SCOPE

Tomato is one of the most common crops worldwide and contains many beneficial compounds that improve abnormalities of lipid metabolism. However, the molecular mechanism underlying the effect of tomato on lipid metabolism is unclear. It has been commonly accepted that peroxisome proliferator-activated receptor α (PPARα) is one of the most important targets for ameliorating abnormalities of lipid metabolism. Therefore, we focused on the activation of PPARα and attempted to detect active compounds activating PPARα in tomato.

METHODS AND RESULTS

To identify such active compounds, we screened fractions of tomato extracts using PPARα luciferase reporter assay. One fraction, rechromatographed-fraction eluted in 57 min (RF57), significantly increased PPARα reporter activity, in which a single compound is detected by LC/MS analysis. On the basis of LC/MS and NMR analyses, we determined the chemical structure of the active compound in RF57 as 9-oxo-10(E),12(E)-octadecadienoic acid (9-oxo-ODA). The RF57 fraction significantly increased the mRNA expression levels of PPARα target genes involved in fatty acid oxidation and O(2) consumption in mouse primary hepatocytes. Furthermore, RF57 inhibited cellular triglyceride accumulation in the hepatocytes.

CONCLUSION

These findings suggest that tomatoes containing 9-oxo-ODA that acts on PPARα are valuable for ameliorating abnormalities of lipid metabolism.