Monodemethylated Metabolites of Orally Administered Nobiletin: Identification and Quantitation in Rat Plasma and Tissues.

Although nobiletin (Nob) is a promising functional food component in view of its multifaceted physiological activity, the metabolism of this flavonoid remains underexplored. Herein, we examine the pharmacokinetics and tissue distribution of orally ingested Nob in rats, focusing on the six monodemethylnobiletin (MDNob) isomers as the main Nob metabolites. Two of these metabolites, namely, 6-MDNob and 8-MDNob, are chemically prepared for the first time, and a method for the simultaneous determination of all six MDNobs is developed. The obtained results demonstrate the production of 8-MDNob as a novel Nob metabolite and confirm the previously reported generation of 6-MDNob and 7-MDNob as oral metabolites of Nob in vivo. Finally, a quantitative relationship is established between the amount of metabolically generated MDNobs and that of administered Nob. Thus, this work paves the way for the broad applications and safe usage of Nob.

Tyrosine Is a Booster of Leucine-Induced Muscle Anabolic Response.

Leucine (Leu), an essential amino acid, is known to stimulate protein synthesis in the skeletal muscle via mTOR complex 1 (mTORC1) activation. However, the intrinsic contribution of other amino acids to Leu-mediated activation of mTORC1 signaling remains unexplored. This study aimed to identify amino acids that can promote mTORC1 activity in combination with Leu and to assess the effectiveness of these combinations in vitro and in vivo. We found that tyrosine (Tyr) enhanced Leu-induced phosphorylation of S6 kinase (S6K), an indicator of mTORC1 activity, although it exerted no such effect individually. This booster effect was observed in C2C12 cells, isolated murine muscle, and the skeletal muscles of mice orally administered the amino acids. To explore the molecular mechanisms underlying this Tyr-mediated booster effect, the expression of the intracellular Leu sensors, Sestrin1 and 2, was suppressed, and the cells were treated with Leu and Tyr. This suppression enabled Tyr alone to induce S6K phosphorylation and enhanced the booster effect, suggesting that Tyr possibly contributes to mTORC1 activation when Sestrin-GAP activity toward Rags 2 (GATOR2) is dissociated through Sestrin knockdown or the binding of Sestrins to Leu. Collectively, these results indicate that Tyr is a key regulator of Leu-mediated protein synthesis.

4″-Sulfation Is the Major Metabolic Pathway of Epigallocatechin-3-gallate in Humans: Characterization of Metabolites, Enzymatic Analysis, and Pharmacokinetic Profiling.

Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, has beneficial effects on human health. This study aimed to elucidate the detailed EGCG sulfation process to better understand its phase II metabolism, a process required to maximize its health benefits. Results show that kinetic activity of sulfation in the human liver and intestinal cytosol is 2-fold and 60- to 300-fold higher than that of methylation and glucuronidation, respectively, suggesting sulfation as the key metabolic pathway. Moreover, SULT1A1 and SULT1A3 are responsible for sulfation in the liver and intestine, respectively. Additionally, our human ingestion study revealed that the concentration of EGCG-4″-sulfate in human plasma (Cmax: 177.9 nmol·L-1, AUC: 715.2 nmol·h·L-1) is equivalent to free EGCG (Cmax: 233.5 nmol·L-1, AUC: 664.1 nmol·h·L-1), suggesting that EGCG-4″-sulfate is the key metabolite. These findings indicate that sulfation is a crucial factor for improving EGCG bioavailability, while also advancing the understanding of the bioactivity and toxicity of EGCG.

Properties of arabinogalactan-proteins in European pear (Pyrus communis L.) fruits.

Arabinogalactans (AGs) and arabinogalactan-proteins (AGPs) were partially purified from an extract of fruits of the European pear (Pyrus communis L.) by DEAE-cellulose ion-exchange and Sepharose 6B gel-filtration chromatography. Among 7 AG(P)-containing fractions, a neutral AGP (SE-1) was confirmed to be highly purified (Mr 67,000) and rich in L-Ara and Gal; this fraction included a small amount (2.6%, w/w) of protein and showed the highest reactivity forming precipitate with ß-Glc Yariv reagent among the 7 fractions, the intensity of which was comparable to that of gum arabic, a standard AGP. Another accompanying minor low-Mr neutral AGP (SE-2; Mr approx. 7200) still contained other polysaccharide (starch fragments) and did not show Yariv reactivity. The carbohydrate moieties of SE-1 consisted of consecutive (1 → 3)-linked ß-galactosyl backbone chains substituted with side chains of (1 → 6)-linked ß-galactosyl residues at O-6, to which mainly single α-l-arabinofuranosyl residues were attached through O-3. This structural feature was also observed for SE-2. Successive digestion of SE-1 with α-l-arabinofuranosidase and exo-ß-(1 → 3)-galactanase with the aid of endo-ß-(1 → 3)-galactanase released most (more than 98%, w/w) of the carbohydrate moieties as low-Mr fragments. These consisted of free L-Ara and Gal, and a series of ß-(1 → 6)-galactooligosaccharides with degree of polymerization (dp) up to at least 17, indicative of attachment of (1 → 6)-linked ß-galactosyl side chains of varying length along the (1 → 3)-linked ß-galactosyl backbone chains.

Development of nobiletin-methyl hesperidin amorphous solid dispersion: Novel application of methyl hesperidin as an excipient for hot-melt extrusion.

A novel amorphous solid dispersion (ASD) of poorly water-soluble nobiletin (Nob) with highly water-soluble methyl hesperidin (MeHes) was developed. Mixtures of Nob and excipients (MeHes, cellulose derivatives, and synthetic polymers) were processed by hot-melt extrusion (HME). Powder X-ray diffraction analysis proved that most of the HME products were fully amorphized. In dissolution studies, Nob-MeHes ASD showed a prominently higher Nob concentration than other HME products with polymeric excipients. Nob concentration upon dissolution of Nob-MeHes ASD was 400 and 7.5 times higher than that upon dissolution of crystalline Nob and a Nob-MeHes physical mixture, respectively. In addition, Nob-MeHes ASD showed good preservation stability for 6 months under an accelerated condition of 40 °C and 80% relative humidity. Permeation studies using a Caco-2 cell monolayer showed that Nob-MeHes ASD markedly increased the amount of Nob transported. In mice, the plasma Nob concentration and accumulated amount of Nob in various tissues drastically increased after administration of Nob-MeHes ASD. This is the first successful application of MeHes, with a relatively low glass-transition temperature, as an excipient for an ASD formulation prepared by hot-melt extrusion. The drastic improvement in Nob concentration with a small-molecule excipient may be an important finding.

Perilla extract improves frequent urination in spontaneously hypertensive rats with enhancement of the urothelial presence and anti-inflammatory effects.

OBJECTIVE: To investigate the effects of perilla extract on urinary symptoms in spontaneously hypertensive rats as a model of spontaneous overactive bladder. METHODS: Spontaneously hypertensive rats were randomly divided into two groups and fed either a control diet or a perilla extract-containing diet. Cystometry, gene expression and histological analyses were carried out to evaluate the effects of perilla extract after 2-week feeding of either the control or the perilla extract diet. The expression of inflammation-related genes in the human urothelial cell line HT-1376 and the normal human bladder epithelial cell was measured after the treatment with perillaldehyde, the main component of perilla extract, or perillic acid, the final metabolite of perillaldehyde. RESULTS: A significant 27% increase in the micturition interval and decreased expression of nerve growth factor, tumor necrosis factor-α, interleukin-1ß and transient receptor potential V1 were observed in the perilla group compared with the control group. The level of uroplakin 3A was 40% higher in the perilla group than in the control group. The urothelium in the control group was thin or defective, but it was almost completely intact in the perilla group. Perillaldehyde and perillic acid suppressed the induction of nerve growth factor and tumor necrosis factor-α by interleukin-1ß in HT-1376 and normal human bladder epithelial cells. CONCLUSIONS: The present findings suggest that perilla extract improves frequent urination, and this improvement seems to be mediated, at least in part, by enhancement of the urothelial presence and by the anti-inflammatory effects of perilla.

Triterpene alcohols and sterols from rice bran reduce postprandial hyperglycemia in rodents and humans.

SCOPE: Hyperglycemia is a major public health problem worldwide and there is increasing demand for prevention of postprandial hyperglycemia in diabetic, prediabetic, and healthy humans. METHODS AND RESULTS: We investigated whether rice bran and triterpene alcohol and sterol preparation (TASP) lowered hyperglycemia in mice and humans. Brown rice and white rice supplemented with TASP lowered the postprandial hyperglycemia in humans. TASP and its components (cycloartenol [CA], 24-methylene cycloartanol, ß-sitosterol, and campesterol) decreased postprandial hyperglycemia in C57BL/6J mice. Glucose transport into everted rat intestinal sacs and human HuTu80 cells transfected with sodium-glucose cotransporter-1 (SGLT1) was significantly reduced by the addition of CA. Intracellular localization analysis suggested that SGLT1 translocation to the apical plasma membrane was inhibited when the cells were treated with CA. CONCLUSIONS: We demonstrated for the first time that TASP from rice bran lowered postprandial hyperglycemia in mice and humans. The smaller increase in blood glucose following TASP consumption may be due to the CA-induced decrease in glucose absorption from the intestine, which may be related to decreased membrane translocation of SGLT1.

Triterpene alcohols and sterols from rice bran lower postprandial glucose-dependent insulinotropic polypeptide release and prevent diet-induced obesity in mice.

Obesity is now a worldwide health problem. Glucose-dependent insulinotropic polypeptide (GIP) is a gut hormone that is secreted following the ingestion of food and modulates energy metabolism. Previous studies reported that lowering diet-induced GIP secretion improved energy homeostasis in animals and humans, and attenuated diet-induced obesity in mice. Therefore, food-derived GIP regulators may be used in the development of foods that prevent obesity. Rice bran oil and its components are known to have beneficial effects on health. Therefore, the aim of the present study was to clarify the effects of the oil-soluble components of rice bran on postprandial GIP secretion and obesity in mice. Triterpene alcohols [cycloartenol (CA) and 24-methylene cycloartanol (24Me)], ß-sitosterol, and campesterol decreased the diet-induced secretion of GIP in C57BL/6J mice. Mice fed a high-fat diet supplemented with a triterpene alcohol and sterol preparation (TASP) from rice bran for 23 wk gained less weight than control mice. Indirect calorimetry revealed that fat utilization was higher in TASP-fed mice than in control mice. Fatty acid oxidation-related gene expression in the muscles of mice fed a TASP-supplemented diet was enhanced, whereas fatty acid synthesis-related gene expression in the liver was suppressed. The treatment of HepG2 cells with CA and 24Me decreased the gene expression of sterol regulatory element-binding protein (SREBP)-1c. In conclusion, we clarified for the first time that triterpene alcohols and sterols from rice bran prevented diet-induced obesity by increasing fatty acid oxidation in muscles and decreasing fatty acid synthesis in the liver through GIP-dependent and GIP-independent mechanisms.

Dietary milk fat globule membrane improves endurance capacity in mice.

Milk fat globule membrane (MFGM) comprises carbohydrates, membrane-specific proteins, glycoproteins, phospholipids, and sphingolipids. We evaluated the effects of MFGM consumption over a 12-wk period on endurance capacity and energy metabolism in BALB/c mice. Long-term MFGM intake combined with regular exercise improved endurance capacity, as evidenced by swimming time until fatigue, in a dose-dependent manner. The effect of dietary MFGM plus exercise was accompanied by higher oxygen consumption and lower respiratory quotient, as determined by indirect calorimetry. MFGM intake combined with exercise increased plasma levels of free fatty acids after swimming. After chronic intake of MFGM combined with exercise, the triglyceride content in the gastrocnemius muscle increased significantly. Mice given MFGM combined with exercise had higher mRNA levels of peroxisome proliferator-activated receptor-γ coactivator 1α (Pgc1α) and CPT-1b in the soleus muscle at rest, suggesting that increased lipid metabolism in skeletal muscle contributes, in part, to improved endurance capacity. MFGM treatment with cyclic equibiaxial stretch consisting of 10% elongation at 0.5 Hz with 1 h on and 5 h off increased the Pgc1α mRNA expression of differentiating C2C12 myoblasts in a dose-dependent manner. Supplementation with sphingomyelin increased endurance capacity in mice and Pgc1α mRNA expression in the soleus muscle in vivo and in differentiating myoblasts in vitro. These results indicate that dietary MFGM combined with exercise improves endurance performance via increased lipid metabolism and that sphingomyelin may be one of the components responsible for the beneficial effects of dietary MFGM.

Habitual exercise plus dietary supplementation with milk fat globule membrane improves muscle function deficits via neuromuscular development in senescence-accelerated mice.

We examined the effects of habitual exercise plus nutritional intervention through consumption of milk fat globule membrane (MFGM), a milk component, on aging-related deficits in muscle mass and function in senescence-accelerated P1 mice. Combining wheel-running and MFGM (MFGMEx) intake significantly attenuated age-related declines in quadriceps muscle mass (control: 318 ± 6 mg; MFGMEx: 356 ± 9 mg; P < 0.05) and in contractile force (1.4-fold and 1.5-fold higher in the soleus and extensor digitorum longus muscles, respectively). Microarray analysis of genes in the quadriceps muscle revealed that MFGMEx stimulated neuromuscular development; this was supported by significantly increased docking protein-7 (Dok-7) and myogenin mRNA expression. Treatment of differentiating myoblasts with MFGM-derived phospholipid or sphingolipid fractions plus mechanical stretching also significantly increased Dok-7 mRNA expression. These findings suggest that habitual exercise plus dietary MFGM improves muscle function deficits through neuromuscular development, and that phospholipid and sphingolipid in MFGM contribute to its physiological actions.

Identification of diacylglycerol acyltransferase inhibitors from Rosa centifolia petals.

Diacylglycerol acyltransferase (DGAT) catalyzes the final step of triacylglycerol (TAG) synthesis, and is considered as a potential target to control hypertriglyceridemia or other metabolic disorders. In this study, we found that the extract of rose petals suppressed TAG synthesis in cultured cells, and that the extract showed DGAT inhibitory action in a dose-dependent manner. Fractionation of the rose extract revealed that the DGAT inhibitory substances in the extract were ellagitannins; among them rugosin B, and D, and eusupinin A inhibited DGAT activity by 96, 82, and 84% respectively, at 10 µM. These substances did not inhibit the activities of other hepatic microsomal enzymes, glucose-6-phosphatase and HMG-CoA reductase, or pancreatic lipase, suggesting that ellagitannins inhibit DGAT preferentially. In an oral fat load test using mice, postprandial plasma TAG increase was suppressed by rose extract; TAG levels 2 h after the fat load were significantly lower in mice administered a fat emulsion containing rose extract than in control mice (446.3 ± 33.1 vs 345.3 ± 25.0 mg/dL, control vs rose extract group; P < 0.05). These results suggest that rose ellagitannins or rose extract could be beneficial in controlling lipid metabolism and used to improve metabolic disorders.