Biomedical subjects

Tatsuya Sugawara

Publications and source records attributed to Tatsuya Sugawara.

11 recordsLinked to original sources

PubMed2006

Antiangiogenic activity of brown algae fucoxanthin and its deacetylated product, fucoxanthinol.

The antiangiogenic effects of fucoxanthin and a deacetylated product, fucoxanthinol, were examined. Fucoxanthin significantly suppressed HUVEC proliferation and tube formation at more than 10 microM, but it had no significant effect on HUVEC chemotaxis. The formation of blood vessel-like structures from CD31-positive cells was evaluated using embryonic stem cell-derived embryoid bodies. Fucoxanthin effectively suppressed the development of these structures at 10-20 microM, suggesting that it could suppress differentiation of endothelial progenitor cells into endothelial cells involving new blood vessel formation. Fucoxanthin and fucoxanthinol suppressed microvessel outgrowth in an ex vivo angiogenesis assay using a rat aortic ring, in a dose-dependent manner. These results imply that fucoxanthin having antiangiogenic activity might be useful in preventing angiogenesis-related diseases.

Angiogenesis Inhibitors↗

PubMed2006

Isolation of sphingoid bases of sea cucumber cerebrosides and their cytotoxicity against human colon cancer cells.

Sea cucumber is a health-beneficial food, and contains a variety of physiologically active substances including glycosphingolipids. We show here the sphingoid base composition of cerebrosides prepared from sea cucumber and the cytotoxicity against human colon cancer cell lines. The composition of sphingoid bases prepared from sea cucumber was different from that of mammals, and the major constituents estimated from mass spectra had a branched C17-19 alkyl chain with 1-3 double bonds. The viability of DLD-1, WiDr and Caco-2 cells treated with sea cucumber sphingoid bases was reduced in a dose-dependent manner and was similar to that of cells treated with sphingosine. The sphingoid bases induced such a morphological change as condensed chromatin fragments and increased the caspase-3 activity, indicating that the sphingoid bases reduced the cell viability by causing apoptosis in these cells. Sphingolipids of sea cucumber might therefore serve as bioactive dietary components to suppress colon cancer.

Animals↗

PubMed2006

Trans geometric isomers of EPA decrease LXRalpha-induced cellular triacylglycerol via suppression of SREBP-1c and PGC-1beta.

Dietary mono- or di-trans fatty acids with chain lengths of 18-22 increase the risk of cardiovascular diseases because they increase LDL cholesterol and decrease HDL cholesterol in the plasma. However, the effects of trans isomers of PUFAs on lipid metabolism remain unknown. Dietary PUFAs, especially eicosapentaenoic acid (EPA) in marine oils, improve serum lipid profiles by suppressing liver X receptor alpha (LXRalpha) activity in the liver. In this study, we compared the effects of trans geometric isomers of eicosapentaenoic acid (TEPA) on triacylglycerol synthesis induced by a synthetic LXRalpha agonist (T0901317) with the effects of EPA in HepG2 cells. TEPA significantly decreased the amount of cellular triacylglycerol and the expression of mRNAs encoding fatty acid synthase, stearoyl-CoA desaturase-1, and glycerol-3-phosphate acyltransferase induced by T0901317 compared with EPA. However, there was no significant difference between the suppressive effect of TEPA or EPA on the expression of sterol-regulatory element binding protein-1c (SREBP-1c) induced by T0901317. We found that TEPA, but not EPA, decreased the mRNA expression of peroxisome proliferator-activated receptor gamma coactivator 1beta (PGC-1beta), which is a coactivator of both LXRalpha and SREBP-1. These results suggest that the hypolipidemic effect of TEPA can be attributed to a decrease not only in SREBP-1 but also in PGC-1beta expression.

Base Sequence↗

PubMed2005

Effects of middle molecular weight fucoidans on in vitro and ex vivo angiogenesis of endothelial cells.

Native fucoidan, sulfated L-fucose polymer isolated from marine brown algae, has diverse biological activities including anticoagulant, anti-angiogenic and anti-tumor effects. Its anti-angiogenic effect is of interest and the mechanisms have been studied. However, recently, proangiogenic effect of low molecular weight (LMW) fucoidans has been demonstrated. To clarify the opposite effects of fucoidan and LMW fucoidans, it is necessary to address the relationship between the molecular size and the effect on angiogenesis. In this study, the effects of middle molecular weight (MMW) fucoidans (15-30 kDa) on human umbilical vein endothelial cell functions were examined. Fucoidan (30 kDa) had similar effects to native fucoidan; inhibition of HUVEC tube formation and angiogenesis in an ex vivo model, although their effects were weaker than native fucoidan. On the other hand, 15-20 kDa fucoidan enhanced HUVEC migration, but did not inhibit HUVEC tube formation. Thus, 15-20 kDa fucoidan would have proangiogenic effect on angiogenesis. These results elucidate that 20-30 kDa would be a critical point to characterize the role of fucoidans on angiogenesis.

Animals↗

PubMed2004

Ozonation of cholesterol in the presence of ethanol: identification of a cytotoxic ethoxyhydroperoxide molecule.

Cholesterol ozonation was carried out in ethanol-containing aqueous or nonaqueous solvent, and the ozonized products were analyzed by chemiluminescence detection-HPLC with on-line electrospray MS (HPLC-CL-MS) and characterized on the basis of NMR and FABMS. After the ozonolysis of cholesterol in water/ethanol (aqueous system) as well as in chloroform/ethanol (nonaqueous system), a unique ethoxyhydroperoxide molecule (7alpha-ethoxy-3beta-hydroxy-5alpha-B-homo-6-oxacholestane-5-hydroperoxide, termed "7alpha-ethoxy-5-OOH") appeared as main ozonation product. In addition to structural analysis, we confirmed the remarkable cytotoxicity of 7alpha-ethoxy-5-OOH toward human lung adenocarcinoma A549 cells and found that its cytotoxicity is superior to that of the commonly known autoxidized cholesterol (3beta-hydroxycholest-5-ene-7-one). Hence, 7alpha-ethoxy-5-OOH is a toxic molecule of primary importance, arising during cholesterol ozonation in the presence of ethanol.

Cell Line, Tumor↗

PubMed2004

Biotransformation of fucoxanthinol into amarouciaxanthin A in mice and HepG2 cells: formation and cytotoxicity of fucoxanthin metabolites.

Fucoxanthin, a major carotenoid in edible brown algae, potentially inhibits the proliferation of human prostate cancer cells via apoptosis induction. However, it has been postulated that dietary fucoxanthin is hydrolyzed into fucoxanthinol in the gastrointestinal tract before absorption in the intestine. In the present study, we investigated the further biotransformation of orally administered fucoxanthin and estimated the cytotoxicity of fucoxanthin metabolites on PC-3 human prostate cancer cells. After the oral administration of fucoxanthin in mice, two metabolites, fucoxanthinol and an unknown metabolite, were found in the plasma and liver. The unknown metabolite was isolated from the incubation mixture of fucoxanthinol and mouse liver preparation (10,000 g supernatant of homogenates), and a series of instrumental analyses identified it as amarouciaxanthin A [(3S,5R,6'S)-3,5,6'-trihydroxy-6,7-didehydro-5,6,7',8'-tetrahydro-beta,epsilon-carotene-3',8'-dione]. The conversion of fucoxanthinol into amarouciaxanthin A was predominantly shown in liver microsomes. This dehydrogenation/isomerization of the 5,6-epoxy-3-hydroxy-5,6-dihydro-beta end group of fucoxanthinol into the 6'-hydroxy-3'-oxo-epsilon end group of amarouciaxanthin A required NAD(P)+ as a cofactor, and the optimal pH for the conversion was 9.5 to 10.0. Fucoxanthinol supplemented to culture medium via HepG2 cells was also converted into amarouciaxanthin A. The 50% inhibitory concentrations on the proliferation of PC-3 human prostate cancer cells were 3.0, 2.0, and 4.6 microM for fucoxanthin, fucoxanthinol, and amarouciaxanthin A, respectively. To our knowledge, this is the first report on the enzymatic dehydrogenation of a 3-hydroxyl end group of xanthophylls in mammals.

Administration, Oral↗

PubMed2004

Efflux of sphingoid bases by P-glycoprotein in human intestinal Caco-2 cells.

The aim of this study was to determine whether sphingoid bases that originated from various dietary sources, such as mammals, plants, and fungi, are substrates for P-glycoprotein in differentiated Caco-2 cells, which are used as a model of intestinal epithelial cells. In Caco-2 cells, the uptake of sphingosine, the most common sphingoid base found in mammals, was significantly higher at physiological temperatures than those of cis/trans-8-sphingenine, trans-4, cis/trans-8-sphingadienine, 9-methyl-trans-4, trans-8-sphingadienine, or sphinganine. Verapamil, a potent P-glycoprotein inhibitor, increased the cellular accumulation of sphingoid bases, except for sphingosine, in a dose-dependent manner. Incubation with 1 microM digoxin for 48 h caused up-regulation of multidrug-resistance (MDR)1 mRNA and decreased the accumulation of sphingoid bases in Caco-2 cells, except for sphingosine. Thus P-glycoprotein probably contributes to the selective absorption of sphingosine from dietary sphingolipids in the digestive tract.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2003

Phospholipids affect the intestinal absorption of carotenoids in mice.

Previously, we have shown that uptake of carotenoids solubilized with mixed micelles by human intestinal Caco-2 cells is enhanced by lysophosphatidylcholine (lysoPC) and suppressed by PC. This study determined the effect of PC and lysoPC in mixed micelles on the accumulation of beta-carotene and lutein in mice in order to elucidate the roles of micellar phospholipid in the intestinal uptake of carotenoids in vivo. Mixed micelles were composed of 2.5 mM monooleoylglycerol, 7.5 mM oleic acid, 12 mM sodium taurocholate, 200 microM carotenoid, and 3 mM phospholipid in PBS. The mice were fed single doses of beta-carotene or lutein solubilized in PC (PC group), lysoPC (LPC group), and no phospholipid (NoPL group) micelles. The beta-carotene responses in the plasma and liver of the PC group were markedly lower than those of the other two groups, whereas no differences were noticed between the LPC and NoPL groups. The average level of lutein in the plasma of the PC group after administration was significantly (P < 0.05) lower than those of the other groups. Moreover, the average level of lutein in the liver was significantly (P < 0.05) different among the groups in the order of LPC > NoPL > PC. Thus, the results clearly indicate that PC suppressed the accumulation of beta-carotene and lutein in plasma and liver and that lysoPC enhanced the accumulation of lutein in liver. These results suggest that the hydrolysis of PC to lysoPC plays an important role in the intestinal uptake of carotenoids solubilized in mixed micelles.

Animals↗

PubMed2003

Digestion of maize sphingolipids in rats and uptake of sphingadienine by Caco-2 cells.

We investigated the digestion of cerebrosides of plant origin prepared from maize, focusing especially on the digestive fates of trans-4, cis-8- and trans-4, trans-8-sphingadienine, which are common in higher plants. In the small intestinal mucosa and cecal contents of rats, the cerebrosidase activity at pH 5.2 toward the glucosyl linkage in maize cerebrosides (glucosylceramides) was similar to that in cerebrosides of mammalian origin. Similarly, the ceramidase activity toward the amide linkage in ceramides prepared from maize cerebrosides at pH 7.0 was the same as that toward ceramides of mammalian origin. In addition, maize cerebrosides were hydrolyzed to ceramide and free sphingoid bases in the digestive tract of rats after oral administration. To further evaluate the uptake by enterocytes of 4,8-sphingadienine, we used differentiated Caco-2 cells, derived from human colonic carcinoma, as a model of intestinal epithelial cells. The accumulation of sphingoid bases in Caco-2 cells incubated with each isomer of sphingadienine was lower than that after incubation with sphingosine (P < 0.05). Verapamil, a P-glycoprotein inhibitor, increased the accumulation of each sphingadienine but not of sphingosine, suggesting that the efflux of sphingadienine of plant origin, but not sphingosine of mammalian origin, was affected by P-glycoprotein. The digestibility of maize cerebrosides appears similar to that of cerebrosides of mammalian origin, but the metabolic fate of sphingoid bases of plant origin within enterocytes differs from that of sphingosine. Isomers of 4,8-sphingadienine degraded from dietary plant cerebrosides appear to be poorly absorbed from the digestive tract.

Animals↗

PubMed2002

Brown algae fucoxanthin is hydrolyzed to fucoxanthinol during absorption by Caco-2 human intestinal cells and mice.

The metabolic fate in mammals of dietary fucoxanthin, a major carotenoid in brown algae, is not known. We investigated the absorption and metabolism of fucoxanthin in differentiated Caco-2 human intestinal cells, a useful model for studying the absorption of dietary compounds by intestinal cells. Fucoxanthin was taken up by Caco-2 cells incubated with micellar fucoxanthin composed of 1 micromol/L fucoxanthin, 2 mmol/L sodium taurocholate, 100 micromol/L monoacylglycerol, 33.3 micromol/L fatty acids and 50 micromol/L lysophosphatidylcholine. Fucoxanthinol, the deacetylated product of fucoxanthin, was also found in both medium and cells, with its level increasing significantly in a time-dependent manner. No conjugated forms of fucoxanthin and fucoxanthinol were found in either medium or cells. In the animal study, fucoxanthinol (10.4 +/- 5.3 nmol/L plasma, n = 4) was detected in plasma of mice 1 h after intubation of 40 nmol fucoxanthin. These results indicate that dietary fucoxanthin is incorporated as fucoxanthinol, the deacetylated form, from the digestive tract into the blood circulation system in mammals.

Animals↗

PubMed2002

Apoptosis induction by wheat-flour sphingoid bases in DLD-1 human colon cancer cells.

The apoptotic effects of plant sphingoid bases prepared from wheat-flour cerebroside on human colorectal cancer DLD-1 cells were examined. The viability of DLD-1 cells treated with such plant sphingoid bases was reduced in a dose-dependent manner and was similar to that of cells treated with sphingosine. Morphological changes such as condensed chromatin fragments were found, so those sphingoid bases reduced cell viability through causing apoptosis in these cells.

Antineoplastic Agents, Phytogenic↗