The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Joanna Orejola - One of the best experts on this subject based on the ideXlab platform.
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nupharanin the first ellagitannin with 1 4 dehydrohexahydroxydiphenoyl α d glucopyranose from nuphar japonicum
Tetrahedron, 2020Co-Authors: Joanna Orejola, Yosuke Matsuo, Yoshinori Saito, Takashi TanakaAbstract:Abstract Nupharanin (1), the first ellagitannin with dehydrohexahydroxydiphenoyl esters at the 1,4-positions of α- d -glucose, was isolated from the fresh rhizome of Nuphar japonicum. Based on spectroscopic evidence, the structure was determined to be 1,4-(S)-dehydrohexahydroxydiphenoyl-2-galloyl-3,6-(R)-hexahydroxydiphenoyl-α- d -glucopyranose. The structure was supported by spectroscopic studies of acetonyl derivatives of 1 and its partial hydrolysate. In addition, unusual oxidative cleavage of the hydrated cyclohexenetrione ring of 1 was observed on moderate heating at 50 °C in pH 6 buffer.
Takashi Tanaka - One of the best experts on this subject based on the ideXlab platform.
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nupharanin the first ellagitannin with 1 4 dehydrohexahydroxydiphenoyl α d glucopyranose from nuphar japonicum
Tetrahedron, 2020Co-Authors: Joanna Orejola, Yosuke Matsuo, Yoshinori Saito, Takashi TanakaAbstract:Abstract Nupharanin (1), the first ellagitannin with dehydrohexahydroxydiphenoyl esters at the 1,4-positions of α- d -glucose, was isolated from the fresh rhizome of Nuphar japonicum. Based on spectroscopic evidence, the structure was determined to be 1,4-(S)-dehydrohexahydroxydiphenoyl-2-galloyl-3,6-(R)-hexahydroxydiphenoyl-α- d -glucopyranose. The structure was supported by spectroscopic studies of acetonyl derivatives of 1 and its partial hydrolysate. In addition, unusual oxidative cleavage of the hydrated cyclohexenetrione ring of 1 was observed on moderate heating at 50 °C in pH 6 buffer.
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revised structure of cercidinin a a novel ellagitannin having r hexahydroxydiphenoyl esters at the 3 4 positions of glucopyranose
Chemical & Pharmaceutical Bulletin, 2001Co-Authors: Takashi Tanaka, Makoto Ishimatsu, Gen-ichiro Nonaka, Itsuo Nishioka, Isao KounoAbstract:The structue of cercidinin A, an ellagitannin isolated from the bark of Cercidiphyllum japonicum, was revised to 1, 2, 6-tri-O-galloyl-3, 4-(R)-hexahydroxydipenoyl-β-D-glucose by two-dimensional NMR spectral analysis. Cercidinin A represents the first ellagitannin possessing a hexahydroxydiphenoyl group at the 3, 4-positions of a modified 4C1-glucopyranose core.
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uraemic toxin reduction a newly found effect of hydrolysable type tannin containing crude drug and gallotannin
Phytotherapy Research, 1995Co-Authors: Takako Yokozawa, Koji Fujioka, Hikokichi Oura, Takashi Tanaka, Gen-ichiro Nonaka, Itsuo NishiokaAbstract:The levels of urea nitrogen, creatinine, methylguanidine and guanidinosuccinic acid, which accumulate in blood in parallel with the progress of renal failure after adenine administration, were decreased significantly in rats given Galla Rhois, Moutan Cortex or Paeoniae Radix extract. Administration of Galla Rhois extract was found to be more effective than the other two crude drugs in decreasing the uraemic toxin parameters. A uraemic toxin-decreasing effect similar to that of crude drug was also obtained using 1,3,6-tri-O-galloyl-β-D-Glucopyranose and 1,2,3,4,6-penta-O-galloyl-β-D-Glucopyranose.
Kalevi Pihlaja - One of the best experts on this subject based on the ideXlab platform.
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Seasonal variation in the content of hydrolysable tannins in leaves of Betula pubescens.
Phytochemistry, 2001Co-Authors: Juha-pekka Salminen, Erkki Haukioja, Vladimir Ossipov, Kalevi PihlajaAbstract:The contents of 13 hydrolysable tannins in the leaves of white birch (Betula pubescens L.) trees were analysed at twelve stages throughout the growing season. All individual galloylglucoses, from 1-O-galloyl-beta-D-Glucopyranose to 1,2,3,4,6-penta-O-galloyl-beta-D-Glucopyranose, accumulated in young leaves, while ellagitannins showed significantly variable seasonal trends. The major ellagitannin during the whole growing season was pedunculagin while 2,3-(S)-HHDP-glucopyranose. the end product of the proposed ellagitannin pathway, accumulated in mature leaves. Relationships between the characteristics of seasonal variation in the contents of individual ellagitannins and their chemical structures were used to unravel the biogenesis of ellagitannins in birch leaves. Evidence of degradation of ellagitannins through hydrolysis during leaf growth and development is presented and implications for herbivory are discussed.
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high performance liquid chromatographic separation and identification of phenolic compounds from leaves of betula pubescens and betula pendula
Journal of Chromatography A, 1996Co-Authors: Vladimir Ossipov, Erkki Haukioja, Jyrki Loponen, K Nurmi, Kalevi PihlajaAbstract:Abstract The following major phenolics with non-flavonoid structure were identified from leaves of Betula pubescens (white birch) and Betula pendula (silver birch): 1-O- galloyl -β- d -(2-O- acetyl )- glucopyranose , 1-(4″-hydroxyphenyl)-3′-oxopropyl-β- d -glucopyranose, gallic, chlorogenic, neo-chlorogenic, cis- and trans-forms of 3- and 5-p-coumarolyloquinic acids. Chromatographic (analytical and preparative HPLC), chemical (hydrolysis) and spectroscopic (UV, 1H and 13C NMR, MS) techniques were applied for separation, isolation, purification and identification of these phenolics. Moreover, 33 low-molecular-mass phenolics were detected and quantitated and their occurrence was compared in leaves of white and silver birches.
Nobuji Nakatani - One of the best experts on this subject based on the ideXlab platform.
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novel trisaccharide fatty acid ester identified from the fruits of morinda citrifolia noni
Journal of Agricultural and Food Chemistry, 1999Co-Authors: Mingfu Wang, Hiroe Kikuzaki, Geetha Ghai, Robe T Rose, Katali Csisza, Charles D Oyd, Alika Maunakea, Sheri F T Fong, Nobuji NakataniAbstract:Two known glycosides and a novel trisaccharide fatty acid ester were isolated from the n-butanol-soluble fraction of the fruits of Morinda citrifolia (noni). Structure determination was carried out by spectral techniques such as MS, IR, NMR, and 2D-NMR. The novel trisaccharide fatty acid ester was elucidated as 2,6-di-O-(β-d-glucopyranosyl)-1-O-octanoyl-β-D-Glucopyranose. The known compounds were identified as rutin and asperulosidic acid. Keywords: Noni; Morinda citrifolia; trisaccharide fatty acid ester; 2,6-di-O-(β-d-glucopyranosyl-1-O-octanoyl-β-D-Glucopyranose; rutin; asperulosidic acid
Yong-ping Yang - One of the best experts on this subject based on the ideXlab platform.
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Insight into the Formation of Anhydrosugars in Glucose Pyrolysis: A Joint Computational and Experimental Investigation
2017Co-Authors: Xiao-yan Jiang, Xiao-chen Dong, Min-shu Cui, Chang-qing Dong, Yong-ping YangAbstract:Fast pyrolysis of glucose/cellulose will produce abundant 1,6-anhydro-β-D-Glucopyranose (known as levoglucosan, LG) as the predominant anhydrosugar product, together with certain amounts of other anhydrosugars, mainly including 1,6-anhydro-β-d-glucofuranose (AGF), 1,4:3,6-dianhydro-α-D-Glucopyranose (DGP), 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (APP), 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one (LAC). The formation mechanisms of the latter four anhydrosugar products are not well-known at present. Substantiated by analytical pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) experiments, quantum chemistry calculations are employed to give a deep insight into their formation mechanisms in this study. The anomeric effect of glucopyranose has a distinct effect to their formation. DGP is mainly derived from α-D-Glucopyranose which plays a vital role in the formation of 1,4-acetal ring. On the contrary, APP and LAC can merely derive from β-D-Glucopyranose due to the dehydration at 1-OH + 2-H site. APP is important but not necessary to form LAC, and their formation pathways also compete with each other. Moreover, AGF is not influenced by the anomeric effect of the two anomers, because its formation relies on the acyclic d-glucose
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the mechanism for the formation of levoglucosenone during pyrolysis of β d glucopyranose and cellobiose a density functional theory study
Journal of Analytical and Applied Pyrolysis, 2014Co-Authors: Yang Zhang, Chang-qing Dong, Yong-ping YangAbstract:Abstract Levoglucosenone (LGO) is a valuable anhydrosugar product from fast pyrolysis of cellulose/biomass, but its formation mechanism is still unclear at present. In this study, density functional theory (DFT) method was employed to examine the different LGO formation pathways from pyrolysis of both β- d -glucopyranose and cellobiose, and the most favorable pathways were clarified. The results corroborate the previous studies that levoglucosan (LG) is unlikely the essential intermediate to produce LGO. The most feasible LGO formation pathways from both β- d -glucopyranose and cellobiose include sequential 1,2-dehydration, six-membered hydrogen transfer and enol-keto tautomerization steps. Enol-keto tautomerization is the rate-determining steps for both reactions to form LGO.
