Takashi Maoka

MassBank: a public repository for sharing mass spectral data for life sciences.

MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron-ionization mass spectrometry (EI-MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)-MS(n) data of 2337 authentic compounds of metabolites, 11 545 EI-MS and 834 other-MS data of 10,286 volatile natural and synthetic compounds, and 3045 ESI-MS(2) data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI-MS(2) data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass-to-charge ratio are optimized to the ESI-MS(2) data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI-MS(2) data on an identical compound under different collision-induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21-23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data.

Carotenoids in Marine Animals

Marine animals contain various carotenoids that show structural diversity. These marine animals accumulate carotenoids from foods such as algae and other animals and modify them through metabolic reactions. Many of the carotenoids present in marine animals are metabolites of β-carotene, fucoxanthin, peridinin, diatoxanthin, alloxanthin, and astaxanthin, etc. Carotenoids found in these animals provide the food chain as well as metabolic pathways. In the present review, I will describe marine animal carotenoids from natural product chemistry, metabolism, food chain, and chemosystematic viewpoints, and also describe new structural carotenoids isolated from marine animals over the last decade.

Astaxanthin Protects Mesangial Cells From Hyperglycemia-Induced Oxidative Signaling

Astaxanthin (ASX) is a carotenoid that has potent protective effects on diabetic nephropathy in mice model of type 2 diabetes. In this study, we investigated the protective mechanism of ASX on the progression of diabetic nephropathy using an in vitro model of hyperglycemia, focusing on mesangial cells. Normal human mesangial cells (NHMCs) were cultured in the medium containing normal (5 mM) or high (25 mM) concentrations of D‐glucose. Reactive oxygen species (ROS) production, the activation of nuclear transcription factors such as nuclear factor kappa B (NFκB) and activator protein‐1 (AP‐1), and the expression/production of transforming growth factor‐beta 1 (TGFβ1) and monocyte chemoattractant protein‐1 (MCP‐1) were evaluated in the presence or absence of ASX. High glucose (HG) exposure induced significant ROS production in mitochondria of NHMCs, which resulted in the activation of transcription factors, and subsequent expression/production of cytokines that plays an important role in the mesangial expansion, an important event in the pathogenesis of diabetic nephropathy. ASX significantly suppressed HG‐induced ROS production, the activation of transcription factors, and cytokine expression/production by NHMCs. In addition, ASX accumulated in the mitochondria of NHMCs and reduced the production of ROS‐modified proteins in mitochondria. ASX may prevent the progression of diabetic nephropathy mainly through ROS scavenging effect in mitochondria of mesangial cells and thus is expected to be very useful for the prevention of diabetic nephropathy. J. Cell. Biochem. 103: 1925–1937, 2007.

Analysis of Carotenoid Composition in Petals of Calendula (Calendula officinalis L.)

Nineteen carotenoids were identified in extracts of petals of orange- and yellow-flowered cultivars of calendula (Calendula officinalis L.). Ten carotenoids were unique to orange-flowered cultivars. The UV–vis absorption maxima of these ten carotenoids were at longer wavelengths than that of flavoxanthin, the main carotenoid of calendula petals, and it is clear that these carotenoids are responsible for the orange color of the petals. Six carotenoids had a cis structure at C-5 (C-5′), and it is conceivable that these (5Z)-carotenoids are enzymatically isomerized at C-5 in a pathway that diverges from the main carotenoid biosynthesis pathway. Among them, (5Z,9Z)-lycopene (1), (5Z,9Z,5′Z,9′Z)-lycopene (3), (5′Z)-γ-carotene (4), and (5′Z,9′Z)-rubixanthin (5) has never before been identified. Additionally, (5Z,9Z,5′Z)-lycopene (2) has been reported only as a synthesized compound.

Hydroxybenzoic acids from Boreava orientalis

A new guaiacylglycerol ether, threo-guaiacylglycerol-8′-vanillic acid ether, pyrocatechuic acid, pyrocatechuic acid 3-O-β-d-glucoside, gentisic acid, gentisic acid 5-O-β-d-glucoside, vanillic acid and vanillic acid 4-O-β-d-glucoside were identified from fruits of Boreava orientalis. Structural elucidation was carried out on the basis of UV, mass, 1H and 13C NMR spectral data, including 2D shift-correlation and selective INEPT experiments.

The distribution and accumulation of fucoxanthin and its metabolites after oral administration in mice.

The pharmacokinetics of dietary fucoxanthin, one of the xanthophylls in brown sea algae, is little understood. In the present study, mice were orally administered fucoxanthin, and the distribution and accumulation of fucoxanthin and its metabolites fucoxanthinol and amarouciaxanthin A were measured in the plasma, erythrocytes, liver, lung, kidney, heart, spleen and adipose tissue. In a single oral administration of 160 nmol fucoxanthin, fucoxanthinol and amarouciaxanthin A were detectable in all specimens tested in the present study, but fucoxanthin was not. The time at maximum concentration (Tmax) of these metabolites in adipose tissue was 24 h, while the Tmax in the others was 4 h. The area under the curve to infinity (AUCinfinity) of fucoxanthinol in the liver was the highest value (4680 nmol/g x h) among the tissues tested in the present study, while the AUCinfinity of amarouciaxanthin A in adipose tissue was the highest value (4630 nmol/g x h). In daily oral administration of 160 nmol fucoxanthin for 1 week, fucoxanthin was also detectable in the tissues even at a low concentration. The amount of fucoxanthinol was 123 nmol/g in the heart and 85.2 nmol/g in the liver. Amarouciaxanthin A in the adipose tissue was distributed at a concentration of 97.5 nmol/g. These results demonstrate that dietary fucoxanthin accumulates in the heart and liver as fucoxanthinol and in adipose tissue as amarouciaxanthin A.

Modifying effects of carotenoids on superoxide and nitric oxide generation from stimulated leukocytes

Excessive and prolonged generation of superoxide (O2-) and nitric oxide (NO) from inflammatory leukocytes is associated with several lifestyle-related diseases, including cancer. In the present study, we screened 19 natural carotenoids for their modifying effects on O2- and NO generation from differentiated human promyelocytic HL-60 cells and mouse macrophage RAW 264.7 cells, respectively. Of the carotenoids tested, halocynthiaxanthin, isolated from oysters, showed the highest suppressive effect on the generation of both free radicals. The inhibitory potencies of certain carotenoids on radical generation markedly exceeded that of beta-carotene. In addition, some important structural moieties regulating radical generation suppression are discussed.

Structure of β-Glucan Oligomer from Laminarin and Its Effect on Human Monocytes to Inhibit the Proliferation of U937 Cells

We analyzed the human monocyte-stimulating ability of laminarin from Eisenia bicyclis, lichenan from Cetraria islandica, and their oligomers depolymerized with endo-1,3-β-glucanase from Arthrobacter sp. The respective β-glucan oligomers with different degrees of polymerization (DP) were fractionated from hydrolytic products of laminarin and lichenan using gel-filtration chromatography. The monocyte-conditioned medium pre-cultured in the presence of a fraction of β-glucan oligomer (DP≥8) from laminarin exhibited inhibitory activity against the proliferation of human myeloid leukemia U937 cells, while those pre-cultured with other β-glucan oligomers and the original laminarin and lichenan showed little or no activity. NMR analysis indicated that the β-glucan oligomer (DP≥8) has an average DP value of 13, and its ratio of β-1,3- to β-1,6-linkages in glucopyranose units was estimated to be 1.3:1. These results indicate that the β-1,3-glucan oligomer with a higher content of β-1,6-linkage stimulates monocytes to inhibit the proliferation of U937 cells.

The cyanobacterium Gloeobacter violaceus PCC 7421 uses bacterial-type phytoene desaturase in carotenoid biosynthesis

Carotenoid composition and its biosynthetic pathway in the cyanobacterium Gloeobacter violaceus PCC 7421 were investigated. β‐Carotene and (2S,2′S)‐oscillol 2,2′‐di(α‐l‐fucoside), and echinenone were major and minor carotenoids, respectively. We identified two unique genes for carotenoid biosynthesis using in vivo functional complementation experiments. In Gloeobacter, a bacterial‐type phytoene desaturase (CrtI), rather than plant‐type desaturases (CrtP and CrtQ), produced lycopene. This is the first demonstration of an oxygenic photosynthetic organism utilizing bacterial‐type phytoene desaturase. We also revealed that echinenone synthesis is catalyzed by CrtW rather than CrtO. These findings indicated that Gloeobacter retains ancestral properties of carotenoid biosynthesis.

Detailed biosynthetic pathway to decaprenoxanthin diglucoside in Corynebacterium glutamicum and identification of novel intermediates

Abstract. Carotenogenic mutants of Corynebacterium glutamicum were analyzed for their carotenoid content. Mutant MV10 accumulated the same carotenoids as the wild-type, decaprenoxanthin, decaprenoxanthin monoglucoside, and (2R,6R,2′R,6′R)-decaprenoxanthin di-(β-D)-glucoside, but in three-fold higher amounts. In addition, decaprenoxanthin diglucoside fatty acid esters and the intermediates nonaprene, 2-(3-methyl-2-butenyl)-ε,ψ-carotene, and sarcinene, 2,2′-bis(3-methyl-2-butenyl)-ε,ε-carotene were identified as minor carotenoids. The pink mutants MV40 and MV60 synthesized only lycopene. From another pink mutant, MV70, novel C50-carotenoids were isolated. By NMR and mass spectroscopy, nonaflavuxanthin, 2-(4-hydroxy-3-methyl-2-butenyl)-1,16-didehydro-1,2-dihydro-ψ,ψ-carotene, and flavuxanthin, 2,2′-bis(4-hydroxy-3-methyl-2-butenyl)-1,16,1′,16′-tetradehydro-1,2,1′,2′-tetrahydro-ψ,ψ-carotene, were identified. The identification of these intermediates revealed the detailed pathway for the formation of decaprenoxanthin derivatives in Corynebacterium glutamicum.