Membrane-associated prostaglandin E synthase-1 is upregulated by proinflammatory cytokines in chondrocytes from patients with osteoarthritis

Prostaglandin E synthase (PGES) including isoenzymes of membrane-associated PGES (mPGES)-1, mPGES-2, and cytosolic PGES (cPGES) is the recently identified terminal enzyme of the arachidonic acid cascade. PGES converts prostaglandin (PG)H(2 )to PGE(2 )downstream of cyclooxygenase (COX). We investigated the expression of PGES isoenzyme in articular chondrocytes from patients with osteoarthritis (OA). Chondrocytes were treated with various cytokines and the expression of PGES isoenzyme mRNA was analyzed by the reverse transcription–polymerase chain reaction and Northern blotting, whereas Western blotting was performed for protein expression. The subcellular localization of mPGES-1 was determined by immunofluorescent microscopy. Conversion of arachidonic acid or PGH(2 )to PGE(2 )was measured by enzyme-linked immunosorbent assay. Finally, the expression of mPGES-1 protein in OA articular cartilage was assessed by immunohistochemistry. Expression of mPGES-1 mRNA in chondrocytes was significantly induced by interleukin (IL)-1β or tumor necrosis factor (TNF)-α, whereas other cytokines, such as IL-4, IL-6, IL-8, IL-10, and interferon-γ, had no effect. COX-2 was also induced under the same conditions, although its pattern of expression was different. Expression of cPGES, mPGES-2, and COX-1 mRNA was not affected by IL-1β or TNF-α. The subcellular localization of mPGES-1 and COX-2 almost overlapped in the perinuclear region. In comparison with 6-keto-PGF(1α )and thromboxane B(2), the production of PGE(2 )was greater after chondrocytes were stimulated by IL-1β or TNF-α. Conversion of PGH(2 )to PGE(2 )(PGES activity) was significantly increased in the lysate from IL-1β-stimulated chondrocytes and it was inhibited by MK-886, which has an inhibitory effect on mPGES-1 activity. Chondrocytes in articular cartilage from patients with OA showed positive immunostaining for mPGES-1. These results suggest that mPGES-1 might be important in the pathogenesis of OA. It might also be a potential new target for therapeutic strategies that specifically modulate PGE(2 )synthesis in patients with OA

Analysis of minor vitamin E homologues in natural products

Fruits and seeds are naturally rich in antioxidants, which provide protection against UV light and oxygen. Vitamin E is a typical antioxidant, and offers radical scavenging activity to prevent the oxidation of the polyunsaturated fatty acids in cell membranes, contribute to homeostasis, and support the biological functions of animals and plants. Tocopherol and tocotrienol are forms of vitamin E widely found in natural products. In addition, recent studies have demonstrated the existence of minor homologues, namely tocomonoenol and tocodienol. The characteristic physiological functions of vitamin E homologues are dependent on their structure. Consequently, the nutritional functionality of the minor homologues has attracted much research interest, which relies on highly accurate analytical methods. This review aimed to summarize the literature concerning the diversity of tocomonoenol and tocodienol, as well as reports on the various methods for their analysis and detection in different sample matrices. This paper is expected to contribute to future exploratory research and the functional evaluation of minor homologues

Nutraceutical characteristics of the brown seaweed carotenoid fucoxanthin

Fucoxanthin (Fx), a major carotenoid found in brown seaweed, is known to show a unique and wide variety of biological activities. Upon absorption, Fx is metabolized to fucoxanthinol and amarouciaxanthin, and these metabolites mainly accumulate in visceral white adipose tissue (WAT). As seen in other carotenoids, Fx can quench singlet oxygen and scavenge a wide range of free radicals. The antioxidant activity is related to the neuroprotective, photoprotective, and hepatoprotective effects of Fx. Fx is also reported to show anti-cancer activity through the regulation of several biomolecules and signaling pathways that are involved in either cell cycle arrest, apoptosis, or metastasis suppression. Among the biological activities of Fx, anti-obesity is the most well-studied and most promising effect. This effect is primarily based on the upregulation of thermogenesis by uncoupling protein 1 expression and the increase in the metabolic rate induced by mitochondrial activation. In addition, Fx shows anti-diabetic effects by improving insulin resistance and promoting glucose utilization in skeletal muscle

Potent inhibitory effect of trans9, trans11 isomer of conjugated linoleic acid on the growth of human colon cancer cells

This study compared the growth inhibitory effects of pure conjugated linoleic acid (CLA) isomers [cis(c)9,c11-CLA, c9,trans(t)11-CLA, t9,t11-CLA, and t10,c12-CLA] on human colon cancer cell lines (Caco-2, HT-29 and DLD-1). When Caco-2 cells were incubated up to 72 h with 200 μM, each isomer, even in the presence of 10% fetal bovine serum (FBS), cell proliferation was inhibited by all CLA isomers in a time-dependent manner. The strongest inhibitory effect was shown by t9,t11-CLA, followed by t10,c12-CLA, c9,c11-CLA and c9,t11-CLA, respectively. The strongest effect of t9,t11-CLA was also observed in other colon cancer cell lines (HT-29 and DLD-1). The order of the inhibitory effect of CLA isomer was confirmed in the presence of 1% FBS. CLA isomers supplemented in the culture medium were readily incorporated into the cellular lipids of Caco-2 and changed their fatty acid composition. The CLA contents in cellular lipids were 26.2±2.7% for t9,t11-CLA, 35.9±0.3% for c9,t11-CLA and 46.3±0.8% for t10,c12-CLA, respectively. DNA fragmentation was clearly recognized in Caco-2 cells treated with t9,t11-CLA. This apoptotic effect of t9,t11-CLA was dose- and time-dependent. DNA fragmentation was also induced by 9c,11t-CLA and t10,c12-CLA. However, fragmentation levels with both isomers were much lower than that with t9,t11-CLA. t9t11-CLA treatment of Caco-2 cells decreased Bcl-2 levels in association with apoptosis, whereas Bax levels remained unchanged. These results suggest that decreased expression of Bcl-2 by t9t11-CLA might increase the sensitivity of cells to lipid peroxidation and to programmed cell death, apoptosis

Effects of dietary fucoxanthin on cholesterol metabolism in diabetic/obese KK-<it>A</it>^<it>y</it> mice

<p>Abstract</p> <p>Background</p> <p>Fucoxanthin is a xanthophyll present in brown seaweeds and has several beneficial effects, including anti-obesity and anti-diabetic effects. However, we and another group previously observed that fucoxanthin increases serum cholesterol levels in rodents. Cholesterol is an important component of cell membranes and biosynthesis of bile acids. Serum cholesterol levels are also closely associated with atherosclerosis. Therefore, we sought to identify the mechanism underlying the increase in serum cholesterol levels by fucoxanthin.</p> <p>Methods</p> <p>Diabetic/obese KK-<it>A</it>^<it>y</it> mice were fed a diet containing 0.2% fucoxanthin for 4 weeks. The mice were sacrificed, and total blood samples were collected for the measurement of serum total cholesterol, HDL-cholesterol and non-HDL-cholesterol levels. Cholesterol content in tissues was also analyzed. Real-time PCR and Western blotting were performed to determine hepatic mRNA and protein expression of genes involved in cholesterol metabolism, respectively.</p> <p>Results</p> <p>Dietary fucoxanthin significantly increased serum HDL and non-HDL cholesterol levels, and reduced hepatic cholesterol content. In liver, the expression of SREBP1, SREBP2 and their target genes involved in cholesterol biosynthesis significantly increased and tended to increase in the fucoxanthin-fed mice, respectively. In contrast, hepatic levels of LDLR and SR-B1 proteins which is important factors for LDL-cholesterol and HDL-cholesterol uptake in the liver from serum, decreased to 60% and 80% in the fucoxanthin-fed mice, respectively, compared with the control mice. Further, we found that dietary fucoxanthin significantly increased the mRNA expression of proprotein convertase subtilisin/kexin type 9 (PCSK9), which enhances intracellular degradation of LDLR in lysosomes.</p> <p>Conclusions</p> <p>Fucoxanthin increased HDL-cholesterol and non-HDL-cholesterol levels in KK-<it>A</it>^<it>y</it> mice by inducing SREBP expression and reduced cholesterol uptake in the liver via down-regulation of LDLR and SR-B1, resulted in increased serum cholesterol in the mice.</p

Methane Activation through Single-Electron Transfer from Water Molecules to the Surface States of Semiconductor Photocatalysts

Photocatalytic transformation of methane to ethane and hydrogen (2CH4 → C2H6 + H2) is enhanced over metallic cocatalyst-loaded Ga2O3 particles under gas-flow conditions with water vapor. We examined the photocatalytic activity of oxide materials (Ga2O3, NaTaO3:La, SrTiO3:Al, and AgTaO3) loaded with Pd or Rh–Cr oxides, which are hydrogen-evolving cocatalysts. Electron spin resonance analysis revealed that the hydroxyl radical (•OH) generated through the single-electron oxidation of water is the active species for methane activation to produce C2H6 and carbon dioxide over Pd/Ga2O3 and Pd/NaTaO3:La photocatalysts. In contrast, the photocatalysts active for water vapor splitting rather than methane transformation generate a surface peroxyl radical (superoxo) moiety as an intermediate of oxygen evolution. For methane activation, the ionization potentials (valence band maximum and midgap surface states) of the photocatalysts should be sufficiently high to promote single-electron transfer from the water to generate •OH since methane exhibits high oxidation potential. This study unravels the crucial role of surface energy levels of photocatalysts for the activation of methane with water vapor

Effective extraction of carotenoids from brown seaweeds and vegetable leaves with edible oils

Factors affecting carotenoid extraction with edible oils were examined using edible brown seaweed, Sargassum horneri, as main sample. The results indicate that drying was essential to extract fucoxanthin (Fx) from S. horneri and physical (boiling) and chemical (acid/alkali) pretreatment of the wet sample increased the extraction rate of Fx. Additionally, more Fx was found from the dried S. horneri powder with a smaller particle size. The extraction rate of Fx is affected by the extraction temperature and time, showing that the effective extraction would be obtained at 50 °C within 12 hr extraction. Among the oils used, short-chain (C4 and C6) triacylglycerol (TAG) (SCT) and medium-chain (C8) TAG (MCT) could extract more Fx from S. horneri and more β-carotene and lutein from spinach and olive leaves. The relatively lower viscosity of SCT and MCT would be the most likely reason for the higher extraction rates of both TAGs

The Effect of n-3 PUFA Binding Phosphatidylglycerol on Metabolic Syndrome-Related Parameters and n-3 PUFA Accretion in Diabetic/Obese KK-A(y) Mice

n-3 Polyunsaturated fatty acid binding phospholipids (n-3 PUFA-PLs) are known to be potent carriers of n-3 PUFAs and provide health benefits. We previously prepared n-3 PUFA binding phosphatidylglycerol (n-3 PUFA-PG) by phospholipase D-mediated transphosphatidylation. Because PG has excellent emulsifiability, n-3 PUFA-PG is expected to work as a functional molecule with properties of both PG and n-3 PUFAs. In the present study, the health benefits and tissue accretion of dietary n-3 PUFA-PG were examined in diabetic/obese KK-A(y) mice. After a feeding duration over 30 days, n-3 PUFA-PG significantly reduced the total and non-HDL cholesterols in the serum of diabetic/obese KK-A(y) mice. In the mice fed n-3 PUFA-PG, but not n-3 PUFA-TAG, hepatic lipid content was markedly alleviated depending on the neutral lipid reduction compared with the SoyPC-fed mice. Further, the n-3 PUFA-PG diet increased eicosapentaenoic acid and docosahexaenoic acid (DHA) and reduced arachidonic acid in the small intestine, liver, perirenal white adipose tissue, and brain, and the ratio of the n-6 PUFAs to n-3 PUFAs in those tissues became lower compared to the SoyPC-fed mice. Especially, the DHA level was more significantly elevated in the brains of n-3 PUFA-PG-fed mice compared to the SoyPC-fed mice, whereas n-3 PUFA-TAG did not significantly alter DHA in the brain. The present results indicate that n-3 PUFA-PG is a functional lipid for reducing serum and liver lipids and is able to supply n-3 PUFAs to KK-A(y) mice

Seco-type beta-Apocarotenoid Generated by beta-Carotene Oxidation Exerts Anti-inflammatory Effects against Activated Macrophages

beta-Apocarotenoids are the cleavage products of beta-carotene. They are found in plants, carotenoid-containing foods, and animal tissues. However, limited information is available regarding the health benefits of beta-apocarotenoids. Here, we prepared seco-type beta-apocarotenoids through the chemical oxidation of beta-carotene and investigated their anti-inflammatory effects against activated macrophages. Oxidation of beta-carotene with potassium permanganate produced seco-beta-apo-8'-carotenal, in which one end-group formed an "open" beta-ring and the other was cleaved at the C-7',8' position. In lipopolysaccharide-stimulated murine macrophage-like RAW264.7 cells, seco-beta-apo-8'-carotenal inhibited the secretion and mRNA expression of inflammatory mediators such as nitric oxide, interleukin (IL)-6 and IL-1 beta, and monocyte chemoattractant protein-1. Furthermore, seco-beta-apo-8'-carotenal suppressed phosphorylation of c-Jun N-terminal kinase and the inhibitor of nuclear factor (NF)-kappa B as well as the nuclear accumulation of NF-kappa B p65. Notably, since seco-beta-apo-8'-carotenal exhibited remarkable anti-inflammatory activity compared with beta-apo-8'-carotenal, its anti-inflammatory action could depend on the opened beta-ring structure. These results suggest that seco-beta-apo-8'-carotenal has high potential for the prevention of inflammation-related diseases