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1.
Syntheses of methyl 3-O--
-galactopyranosyl--
-mannopyranoside (10) and methyl 3-O--
-galactopyranosyl-2-O-(β-
-glucopyranosyluronic acid)--
-mannopyranoside (11) in good yield are described. Both 10 and 11 significantly inhibit antigen-antibody precipitation in the Klebsiella Type 10 immune system. The results provide more evidence for the structure (1) of the antigen from Klebsiella K-10 and its immunodominant grouping. 相似文献
2.
Three main saponins were isolated from the seeds of Albizzia lucida. Their structures were established by spectral analyses and chemical and enzymatic transformations as 3-O-[β-
-xylopyranosyl(1→2)--
-arabinopyranosyl (1→6)] [β-
-glucopyranosyl (1→2)] β-
-glucopyranosyl echinocystic acid; 3-O-[-
-arabinopyranosyl (1→6)][β-
-glucopyranosyl (1→2)]-β-
-glucopyranosyl echinocystic acid and 3-O-[β-
-xylopyranosyl (1→2)-β-
-fucopyranosyl (1→6)-2-acetamido-2-deoxy-β-
-glucopyranosyl echinocystic acid, characterized as its methyl ester. 相似文献
3.
Lubomír Kremnický Vladimír Mastihuba Gregory L. Ct 《Journal of Molecular Catalysis .B, Enzymatic》2004,30(5-6):229-239
Partially purified Trichoderma reesei RUT-C30 acetyl esterase preparation was found to catalyze acyl transfer reactions in organic solvents, mixtures of organic solvents with water and even in water. Using different acyl donors, the best results for acetyl transfer in water were obtained using vinyl acetate. As acetyl acceptors, a variety of hydroxyl bearing compounds in aqueous solutions were used. Degree of conversion and the number of newly formed acetates varied according to the acceptor used. Conversions over 50% were observed for the majority of several common monosaccharides, their methyl and deoxy derivatives and oligosaccharides. In several cases, the transesterification reaction exhibited strict regioselectivity, leading to only one acetyl derivative. Preparative potential of the transesterification in water was demonstrated by acetylation of methyl β-
-glucopyranoside, 4-nitrophenyl β-
-glucopyranoside and kojic acid, yielding 56.4% of methyl 3-O-acetyl β-
-glucopyranoside, 70.2% of 4-nitrophenyl 3-O-acetyl β-
-glucopyranoside and 30.9% of 7-O-acetyl-kojic acid as the only reaction products.
This enzymatically catalyzed transacetylation in water, which is applied to transformation of saccharides for the first time, opens a new area in chemoenzymatic synthesis. Its major advantages are simplicity, highly regioselective esterification of polar compounds, high yields, low enzyme consumption and elimination of the need to use toxic organic solvents. 相似文献
4.
Black CA Ucci JW Vorpagel JS Mauck MC Fenlon EE 《Bioorganic & medicinal chemistry letters》2002,12(24):3521-3523
A stereoselective synthesis of 3′-O-((R,R,R)-trimethylsilatranyl)thymidine (R,R,R-1) and synthesis of 3′-O-silatranylthymidine (5) via an improved silatranylation procedure using tetrakis(dimethylamino)silane are reported. Diastereomeric mixture 1 showed more activity than R,R,R-1 or 5 in a primary anticancer screen against breast, CNS, and lung cell lines; demonstrating the import of the configuration and presence, respectively, of the silatrane methyl groups for growth inhibition. 相似文献
5.
Three acylated flavonol diglucosides, kaempferol 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; quercetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; isorhamnetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside were isolated from the whole plant aqueous alcohol extract of Lotus polyphyllos. The known 3,7-di-O-glucosides of the aglycones kaempferol, quercetin and isorhamnetin were also characterized. All structures were established on the basis of chemical and spectral evidence. 相似文献
6.
Six new C21 steroidal glycosides, named curassavosides A–F (3–8), were obtained from the aerial parts of Asclepias curassavica (Asclepiadaceae), along with two known oxypregnanes, 12-O-benzoyldeacylmetaplexigenin (1) and 12-O-benzoylsarcostin (2). By spectroscopic methods, the structures of the six new compounds were determined as 12-O-benzoyldeacylmetaplexigenin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (3), 12-O-benzoylsarcostin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (4), sarcostin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (5), sarcostin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-digitoxopyranoside (6), 12-O-benzoyldeacylmetaplexigenin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (7), and 12-O-benzoylsarcostin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (8), respectively. All compounds (1–8) were tested for in vitro cytotoxicity; only compound 3 showed weak inhibitory activity against Raji and AGZY cell lines. 相似文献
7.
Manuel Alonso-Lopez Manuel Bernabe Alfonso Fernandez-Mayoralas Jesus Jimenez-Barbero Manuel Martin-Lomas Soledad Penades 《Carbohydrate research》1986,150(1):103-109
The reaction of benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-isopropylidene-β-lactoside with 1,11-ditosyloxy-3,6,9-trioxaundecane gave benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-isopropylidene-3,2′-O--(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (2, 47%). Acid hydrolysis of 2 and condensation of the product with 1,14-ditosyloxy-3,6,9,12-tetra-oxatetradecane afforded benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-(3,6,9,12-tetraoxa-tetradecane-1,14-diyl)-3,2′-O-(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (29%). Similarly, the reaction of benzyl 2,6,2′,4′,6′-penta-O-benzyl-β-lactoside with Ts[OCH2CH2]4OTs gave benzyl 2,6,2′,4′,6′-penta-O-benzyl-3,3′-O-(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (78%). 1H-N.m.r. spectroscopy has been used to study the formation of host-guest complexes with some of these macrocyclic compounds and benzyl ammonium thiocyanate. 相似文献
8.
β-Glycosides of 2-acetamido-2-deoxy-
-glucopyranose were synthesized, using either 7-methoxycarbonyl-3,6-dioxa-1-heptanol or 8-azido-3,6-dioxa-1-octanol. Selective β-lactosylation of 7-methoxycarbonyl-3,6-dioxaheptyl 2-acetamido-3-O-benzyl-2-deoxy-β-
-glucopyranoside with hepta-O-acetyl-lactosyl-trichloroacetimidate, followed by β-galactosylation of the secondary hydroxyl group with O-(2,3,4,6-tetra-O-acetyl--
-galactopyranosyl)trichloroacetimidate, catalytic hydrogenolysis, and O-deacetylation, gave 7-methoxycarbonyl-3,6-dioxaheptyl 2-acetamido-2-deoxy-4-O-β-
-galactopyranosyl-6-O-(4-O-β-
-galactopyranosyl-β-
-glucopyranosyl)β-
-glucopyranoside. Selective β-lactosylation of 8-azido-3,6-dioxaocytl 2-acetamido-3-O-benzyl-2-deoxy-β-
-glucopyranoside with hepta-O-acetyl-lactosyl bromide in the presence of silver triflate, followed by condensation with 2,3,4,6-tetra-O-acetyl--
-galactopyranosyl bromide in the presence of silver triflate, catalytic hdyrogenolysis, and O-deacetylation, gave 8-azido-3,6-dioxaoctyl 2-acetamido-2-deoxy-4-O-β-
-galactopyranosyl-6-O-(4-O-β-
-galactopyranosyl-β-
-glucopyranosyl)-β-
glucopyranoside. 相似文献
9.
Detlef Icheln Bärbel Gehrcke Yvonne Piprek Petra Mischnick Wilfried A. König Marco A. Dessoy Ademir F. Morel 《Carbohydrate research》1996,280(2):237-250
When 2,6-di-O-tert-butyldimethylsilylated cyclomalto-oligosaccharides (cyclodextrins) are treated with allyl or methyl iodide and NaH in dry tetrahydrofuran, O-2 → O-3 migration of the secondary 2-O-tert-butyldimethylsilyl groups occurs, leading to 2-O-alk(en)yl-3,6-di-O-tert-butyldimethylsilyl-cyclodextrin derivatives. The detection and identification of the reaction step during which migration occurred is described and possible mechanisms of migration are discussed. 相似文献
10.
Antonio C Santos Sérgio A Uyemura João L.C Lopes José N Bazon Fábio E Mingatto Carlos Curti 《Free radical biology & medicine》1998,24(9):1455-1461
The ability of eight structurally related naturally occurring flavonoids in inhibiting lipid peroxidation and mitochondrial membrane permeability transition (MMPT), as well as respiration and protein sulfhydryl oxidation in rat liver mitochondria, was evaluated. The flavonoids tested exhibited the following order of potency to inhibit ADP/Fe(II)-induced lipid peroxidation, estimated with the thiobarbituric acid assay: 3′-O-methyl-quercetin > quercetin > 3,5,7,3′,4′-penta-O-methyl-quercetin > 3,7,3′,4′-tetra-O-methyl-quercetin > pinobanksin > 7-O-methyl-pinocembrin > pinocembrin > 3-O-acyl-pinobanksin. MMPT was estimated by the extent of mitochondrial swelling induced by 10 μM CaCl2 plus 1.5 mM inorganic phosphate or 30 μM mefenamic acid. The most potent inhibitors of MMPT were quercetin, 7-O-methyl-pinocembrin, pinocembrin, and 3,5,7,3′,4′-penta-O-methyl-quercetin. The first two inhibited in parallel the oxidation of mitochondrial protein sulfhydryl involved in the MMPT mechanism. The most potent inhibitors of mitochondrial respiration were 7-O-methyl-pinocembrin, quercetin, and 3′-O-methyl-quercetin while the most potent uncouplers were pinocembrin and 3-O-acyl-pinobanksin. In contrast 3,7,3′,4′-tetra-O-methyl-quercetin and 3,5,7,3′,4′-penta-O-methyl-quercetin showed the lowest ability to affect mitochondrial respiration. We conclude that, in general, the flavonoids tested are able to inhibit lipid peroxidation on the mitochondrial membrane and/or MMPT. Multiple methylation of the hydroxyl substitutions, in addition to sustaining good anti-lipoperoxidant activity, reduces the effect of flavonoids on mitochondrial respiration, and therefore, increases the pharmacological potential of these compounds against pathological processes related to oxidative stress. 相似文献
11.
Pierluigi Gariboldi Francesca Pelizzoni Marco Tat Luisella Verotta Nadia El-Sebakhy Aya M. Asaad Rokia M. Abdallah Soad M. Toaima 《Phytochemistry》1995,40(6):1755-1760
Three new cycloartane glycosides, trigonoside I, II and III, and the known astragalosides I and II were isolated from the roots of Astragalus trigonus. The structures of the new glycosides were totally elucidated by high field (600 MHz) NMR analyses as cycloastragenol-6-O-β-xylopyranoside, cycloastragenol-3-O-[-l-arabinopyranosyl(1 → 2)-β-d-xylopyranosyl]-6-O-β- d-xylopyranoside and cycloastragenol-3-O-[-l-arabinopyranosyl(1 → 2)-β-d-(3-O-acetyl)-xylopyranosyl]-6-O-β-d-xylopyranoside. 相似文献
12.
Andr s Lipt k Lajos Szab J nos Ker kgy rt J nos Harangi P l N n si
Helmut Duddeck
《Carbohydrate research》1986,150(1):187-197The title tetrasacharide having the structure 3-O-Me-β-
-Xylp-(1→4)--
-Rhap-(1→4)--
-Rhap-(1→2)-
-Rhap was obtained by reaction of the -acetobromo derivative of 4-O-(3-O-methyl-β-
-xylopyranosyl)-
-rhamnopyranose and benzyl 3,4-di-O-benzyl-2-O-(2,3-O-isopropylidene--
-rhamnopyranosyl)--
-rhamnopyranoside, followed by removal of the protecting groups. The synthesised compounds were characterised on the basis of n.m.r. data. 相似文献
13.
Wieslaw Oleszek Anna Stochmal Piotr Karolewski Ana M. Simonet Francisco A. Macias Aldo Tava 《Biochemical Systematics and Ecology》2002,30(11):1011-1022
Flavonoids in needles of Scots pine planted in 1912–1914 in Poland from seeds originating from different parts of Europe, were isolated, chemically characterised and analysed by HPLC. It was shown that flavonoid profiles were similar in all tested populations and were different from those previously reported for Scots pine seedlings. They included taxifolin, taxifolin 3′-O-glucoside, quercetin as well as quercetin 3-O-glucoside and 3′-O-glucoside. The quercetin 3-O-glucoside could be found only in a trace amount in all samples and quercetin 3′-O-glucoside appeared in all samples regardless their origin. The relative concentration of taxifolin 3′-O-glucoside, quercetin, taxifolin and total flavonoids showed dependence on the origin of seeds; needles from high latitude populations contained smaller amounts of these compounds. Presented data clearly indicate that Scots pine contain glycosidases specific for glycosylation at C-3′ rather than at C-3. Besides, they indicate that long lasting influence of similar environmental factors is not able to change genetic regulatory systems responsible for flavonoid biosynthesis. 相似文献
14.
Extraction of the aerial parts of Dumasia truncata Sieb et Zucc. afforded two new triterpenoidal saponins, together with four known ones. The structures of the new compounds were elucidated by spectral analysis as 3-O--l-rhamnopyranosyl-(1 → 3)-β-d-glucuronopyranosy-28-O-β-d-glucopyransoyl hederagenin and 3-O-β-d-xylopyranosyl-(1 → 2)-[-l-rhamnopyranosyl(1 → 3)]-β-d-glucuronopyranosyl oleanic acid. 相似文献
15.
Wei Li Kazuo Koike Yoshihisa Asada Takafumi Yoshikawa Tamotsu Nikaido 《Journal of Molecular Catalysis .B, Enzymatic》2005,35(4-6):117-121
Panax ginseng root and cell cultures were shown to biotransform paeonol (1) into its 2-O-β-d-glucopyranoside (2). P. ginseng root cultures were also able to biotransform paeonol (1) into its 2-O-β-d-xylopyranoside (3), 2-O-β-d-glucopyranosyl(1 → 6)-β-d-glucopyranoside (4) and 2-O-β-d-xylopyranosyl(1 → 6)-β-d-glucopyranoside (5), and its demethylated derivate, 2′,4′-dihydroxyacetophenone (6). Compounds 3 and 4 are new glycosides. It is the first example that the administrated compound was converted into its xylopyranoside by plant biotransformation. 相似文献
16.
Stephen J. Bloor 《Phytochemistry》1999,50(8):1242-1399
The blue colour of the petals of the blue marguerite daisy, Felicia amelloides, has been found to arise from copigmentation between a novel malonylated delphinidin triglycoside, delphinidin 3-O-neohesperidoside 7-O- (6-O-malonyl-glucoside), and a new flavone C-glycoside, swertisin 2″-O-rhamnoside-4′-O-glucoside. Recombination, in vitro, of these two petal components at pH 6 recreates the blue petal colour. 相似文献
17.
Decendit A Waffo-Teguo P Richard T Krisa S Vercauteren J Monti JP Deffieux G Mérillon JM 《Phytochemistry》2002,60(8):795-798
Suspension cultures of Vitis vinifera were found to produce catechins and stilbenes. When cells were grown in a medium inducing polyphenol synthesis, (−)-epicatechin-3-O-gallate, dimeric procyanidin B-2 3′-O-gallate and two resveratrol diglucosides were isolated, together with a new natural compound that was identified as cis-resveratrol-3,4′-O-β-diglucoside by spectroscopical methods. 相似文献
18.
Yi Yang-Hua 《Phytochemistry》1991,30(12):4179-4181
A new triterpenoid, esculentagenin, and its glycoside, esculentoside M, were isolated from the roots of Phytolacca esculenta and characterized as 11-oxo-3-O-methyloleanata-12-en-2β,3β,23-trihydroxy-28-oic acid and 3-O-[β -
-glucopyranosyl (1→4)-β-
-Xylopyranosyl]-28-O-β-
-glucopyranosyl-11-oxo-30-methyloleanate-12-en-2β,3β,23-trihydroxy-28-oic acid by spectral and chemical evidence. 相似文献
19.
Two novel anthocyanins have been isolated from the stem of Allium victorialis. By means of chemical degradation and spectroscopy, especially homo- and hetero-nuclear two-dimensional NMR techniques, the structures were determined to be cyanidin 3-O-(3″,6″-O-dimalonyl-β-glucopyranoside) (76.6%) and cyanidin 3-O-(3″,O-malonyl-β-glucopyranoside) (13.8%). This is the first report of acylation of the 3-position in the sugar moiety of any anthocyanin. The stability of malonyl substitution in the 3″-position on glucose is higher than the corresponding 6″-malonylation. 相似文献