The use of 1-O-sulfonyl-d-mannopyranose derivatives in β-d-mannopyranoside synthesis

Several 1-O-sulfonyl derivatives of d-mannopyranose having a nonparticipating benzyl ether group at C-2 and ester functions at C-6 and C-4 were synthesized from the corresponding d-mannopyranosyl chloride derivatives with silver sulfonates in acetonitrile. The reaction of 1-O-sulfonyl-d-mannopyranose compounds with methanol in various solvents at room temperature gave high yields of glycosides with low degrees of stercoselectivity. On the other hand, 1-O-suffonyl-d-mannopyranose derivatives having an acyl participating-group at O-2 and benzyl ethers at C-3, C-4, and C-6 gave high yields and high stereoselectivity of α-d-mannopyranosides with primary and secondary alcohols in several solvents. Model studies were carried out to determine the best combination of 2-O-acyl group, solvent, time, temperature, and 1-O-sufonyl group to give high yields with high stereoselectivity. The method has been used to prepare in good yields more complex glycosides, including perbenzylated methy 2-O-(α-d-mannopyranosyl)-α-d-mannopyranoside.     

Identification by gas-liquid chromatography-mass spectrometry of 4-O-acetyl-9-O-lactyl-N-acetylneuraminic acid,a new sialic acid from horse submandibular gland

The novel sialic acid 4-O-acetyl-9-O-lactyl-N-acetylneuraminic acid has been identified as a constituent of horse submandibular gland glycoproteins in addition to the already know equine sialic acids, N-acetylneuraminic acid, 4-O-acetyl-N-acetylneuraminic acid, 9-O-acetyl-N-acetylneuraminic acid, 4,9-di-O-acetyl-N-acetylneuraminic acid, N-glycolylneuraminic acid, 4-O-acetyl-N-glycolylneuraminic acidand 9-O-acetyl-N-glycolylneuraminic acid. The structure has been established by combined gas-liquid chromatography-mass spectrometry.     

Synthesis of 4-O-glycosylated 1,5-anhydro-d-fructose and of 1,5-anhydro-d-tagatose from a common intermediate 2,3-O-isopropylidene-d-fructose

Four novel disaccharides of glycosylated 1,5-anhydro-d-ketoses have been prepared: 1,5-anhydro-4-O-β-d-glucopyranosyl-d-fructose, 1,5-anhydro-4-O-β-d-galactopyranosyl-d-fructose, 1,5-anhydro-4-O-β-d-glucopyranosyl-d-tagatose, and 1,5-anhydro-4-O-β-d-galactopyranosyl-d-tagatose. The common intermediate, 1,5-anhydro-2,3-O-isopropylidene-β-d-fructopyranose, was prepared from d-fructose and was converted into the d-tagatose derivative by oxidation followed by stereoselective reduction to the 4-epimer. The anhydroketoses thus prepared were glycosylated and deprotected to give the disaccharides.     

Some metabolites of Botrytis cinerea related to botcinolide

Four new botcinolide derivatives 4-O-methylbotcinolide, 3-O-acetyl-5-O-methylbotcinolide, 3-O-acetyl-2-epibotcinolide and 2-epibotcinolide have been isolated from the plant pathogen, Botrytis cinerea. Their structures have been established by extensive spectroscopic methods.     

Identification of N, O-diacetyl-, N-acetyl- and N-glycolylneuraminyl-(2 → 3)-lactose in rat urine

The structure of three neuraminyl-oligosaccharides isolated from rat urine-have been studied by chromatographic and mass spectrometric analyses of different hydrolysis and methylation products. The structures of the oligosaccharides were identifies as O-α-N-acetyl(O-acetyl)neuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose, O-α-N-acetylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose and O-α-N-glycolylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose.     

Flavonol tetraglycosides from the leaves of Prunus cerasus and P. Avium

Four new flavonol glycosides have been identified from fresh leaves and fruits of sweet and sour cherries (Prunus avium and P. cerasus) as minor flavonoids: quercetin 3-O-rutinosyl-7,3′-O-bisglucoside; two quercetin 3-O-rutinosyl-4′-di-O-glucosides; kaempferol 3-O-rutinosyl-4′-di-O-glucoside.     

Further flavonol glycosides from Anthyllis onobrychioides

The new triglycoside rhamnetin 3-O-β-d-galactopyranoside-3′,4′-di-O-β-d-glucopyranoside has been isolated from the aerial parts of Anthyllis onobrychioides. Two other new flavonol glycosides, rhamnazin 3-O-galactoside and rhamnazin 3-O-galactoside-4′-O-glucoside, were identified but not isolated as pure substances.     

Synthèse des méthyl-2,4,6-tridésoxy-4-trifluoroacétamido-l-hexopyranosides. Accès à de nouvelles anthracyclines

The four diastereoisomeric methyl 2,4,6-trideoxy-4-trifluoroacetamido-l-hexopyranosides have been synthesized. Coupling of the corresponding 1-O-acetyl-3-O-benzoyl-l-lyxo and 1-O-acetyl-3-O-p-nitrobenzoyl-l-arabino derivatives with daunomycinone in the presence of p-toluensulfonic acid as catalyst afforded two new anthracyclines.     

Flavonol glycosides in leaves of Spinacia oleracea

Besides spinatoside (3,6-dimethoxy-5,7,3′,4′-tetrahydroxyflavone 4′-O-β-D-glucopyranuronide), three new flavonol glycosides have now been isolated from the polar fractions of the methanolic extract of Spinacia oleracea. They have been identified as patuletin 3-O-β-D-glucopyranosyl-(1 → 6)-[β-D-apiofuranosyl-(1 → 2)]-β-D-glucopyranoside, patuletin 3-O-β-gentiobioside and spinacetin 3-O-β-gentiobioside, respectively.     

Synthesis of 3- and 2′-fucosyl-lactose and 3,2′-difucosyl-lactose from partially benzylated lactose derivatives

O-β-d-Galactopyranosyl-(1→4)-O-[α-l-fucopyranosyl-(1→3)]-d-glucose has been synthesised by reaction of benzyl 2,6-di-O-benzyl-4-O-(2,3,4,6-tetra-O-benzyl-β-d-galactopyranosyl)-β-d-glucopyranoside with 2,3,4-tri-O-benzyl-α-l-fucopyranosyl bromide in the presence of mercuric bromide, followed by hydrogenolysis. Benzylation of benzyl 3′,4′-O-isopropylidene-β-lactoside, via tributylstannylation, in the presence of tetrabutylammonium bromide or N-methylimidazole, gave benzyl 2,6-di-O-benzyl-4-O-(6-O-benzyl-3,4-O-isopropylidene-β-d-galactopyranosyl)-β-d-glucopyranoside (6). α-Fucosylation of 6 in the presence of tetraethylammonium bromide provided either benzyl 2,6-di-O-benzyl-4-O-[6-O-benzyl-3,4-O-isopropylidene-2-O-(2,3,4-tri-O-benzyl-α-l-fucopyransoyl)-β-d- galactopyranosyl]-β-d-glucopyranoside (13, 73%) or a mixture of 13 (42%) and benzyl 2,6-di-O-benzyl-4-O-[6-O-benzyl-3,4,-O-isopropylidene-2-O-(2,3,4-tri-O-benzyl-α-l-fucopyranosyl)-β-d- galactopyranosyl-3-O-(2,3,4-tri-O-benzyl-α-l-fucopyranosyl)-β-d-glucopyranoside (16, 34%). α-Fucosylation of 13 in the presence of mercuric bromide and 2,6-di-tert-butyl-4-methylpyridine gave 16 (73%). Hydrogenolysis and acid hydrolysis of 13 and 16 afforded O-α-l-fucopyranosyl-(1→2)-O-β-d-galactopyranosyl-(1→4)-d-glucose and O-α-l-fucopyranosyl-(1→2)-O-β-d-galactopyranosyl-(1→4)-O-[α-l-fucopyranosyl-(1→3)]-d-glucose, respectively.     

Biflavones from the leaves of Araucaria excelsa

Eight biflavones have been isolated from the leaf extracts of Araucaria excelsa. 7″-O-Methylamento-flavone, 7,7″-di-O-methylamentoflavone, 4′ or 4″', 7-di-O-methylcupressuflavone, 7,7″,4″'-tri-O-methyl agathisflavone and 7,4′,7″-tri-O-methylamentoflavone are new compounds and are being reported for the first time. The others are 7,7″-di-O-methylagathisflavone,7,4′,7″,4″'-tetra-O-methylamentoflavone and 7,4′,7″,4″'-tetra-O-methyl-cupressuflavone. Mass and NMR spectral studies are used for structural elucidation. In addition, the presence of several other biflavones has been indicated by TLC examination of methylated products.     

Synthesis and antibacterial activity of a series of novel 9-O-acetyl- 4′-substituted 16-membered macrolides derived from josamycin

A series of novel 9-O-acetyl-4′-substituted 16-membered macrolides derived from josamycin has been designed and synthesized by cleavage of the mycarose of josamycin and subsequent modification of the 4′-hydroxyl group. These derivatives were evaluated for their in vitro antibacterial activities against a panel of Staphylococcus aureus and Staphylococcus epidermidis. 15 (4′-O-(3-Phenylpropanoyl)-9-O-acetyl-desmycarosyl josamycin) and 16 (4′-O-butanoyl-9-O-acetyl-desmycarosyl josamycin) exhibited comparable activities to josamycin against S. aureus (MSSA) and S. epidermidis (MSSE).     

Isolation from a softwood xylan of oligosaccharides containing two 4-O-methyl-d-glucuronic acid residues

Partial hydrolysis of a larch arabino(4-O-methylglucurono)xylan afforded two series of oligouronides composed of 4-O-methyl- d-glucuronic acid and d-xylose residues. The first series included aldouronic acids up to the aldopentaouronic acid. Methylation analysis indicated that the aldopentao- and aldotetrao-uronic acids were mixtures of isomers. One aldotetraouronic acid was isolated and identified as O-β-d-Xylp-(1 → 4)-O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-d-Xyl. The two isomeric aldotriouronic acids were separated from each other. The acids of the second series, which were composed of two uronic acids and 2-4 d-xylose residues, were identified as follows: O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-d-Xyl, O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-β-d -Xylp-(1 → 4)-D-Xyl, O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-(4-O-Mec-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-D-Xyl, and O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-D-Xyl. The first three compounds were new acidic oligosaccharides. The 4-O-methyl-d-glucuronic acid in the second series was present in a larger proportion than in the first series, indicating that a large proportion of the uronic acid side-chains were located on two contiguous D-xylose residues in the backbone of the softwood xylan.     

Three flavonoid glycosides containing acetylated allose from stachys recta

By means of ¹³C and ¹H NMR spectroscopy three flavone glycosides, obtained from Stachys recta, were identified as 7-O-(2″-O-6″′-O-acetyl-β-D-allopyranosyl-β-D-glucopyranosides) of 4′-O-methylisoscutellarein, isoscutellarein and 3′-hydroxy-4′-O-methylisoscutellarein. The latter two compounds are isolated for the first time. Only mannose and glucose have been reported previously as sugar components of flavonoids of the genus Stachys.     

Flavonoid variation in the liverwort Conocephalum conicum: Evidence for geographic races

The flavonoids of 2 samples of Conocephalum conicum gametophyte tissue have been studied, one from U.S.A. and the other from Germany. Common to both samples were vicenin-2, lucenin-2, the 7-O-glucuronides of apigenin, chrysoeriol and luteolin and the previously unknown 7-O-glucuronide 4′-O-rhamnosides of apigenin, chrysoeriol and luteolin. Additionally the German sample contained the 7,4′-di-O-glucuronides of apigenin and luteolin and a new compound, apigenin 7-O-diglucuronide 4′-O-glucuronide. The North American sample contained, additionally, luteolin 7,3′-di-O-glucuronide, luteolin 7-O-glucuronide 3′,4′-di-O-rhamnoside (a new triglycoside) and 2 further derivatives of luteolin 7-O-glucuronide. Evidence is presented for the existence of geographic faces of C. conicum and for the qualitative invariability of the flavonoid patterns with changing season or environment.     

A synthesis of psi-cytidine

2-O-Benzoyl-3,6-di-O-benzyl-4-O-(chloroacetyl)-, 4-O-acetyl-2-O-benzoyl-3,6-di-O-benzyl-, and 2-O-benzoyl-3,4,6-tri-O-benzyl-α-d-galactopyranosyl chloride were converted into the corresponding 2,2,2-trifluoroethanesulfonates, and these were treated with allyl 2-O-benzoyl-3,6-di-O-benzyl-α-d-galactopyranoside, to give allyl 2-O-benzoyl-4-O-[2-O-benzoyl-3,6-di-O-benzyl-4-O-(chloroacetyl)-β-d-galactopyranosyl]-3,6-di-O-benzyl- α-d-galactopyranoside (26; 41% yield), allyl 4-O-(4-O-acetyl-2-O-benzoyl-3,6-di-O-benzyl-β-d-galactopyranosyl)-2-O-benzoyl-3,6-di-O-benzyl- α-d-galactopyranoside (27; 62% yield), and allyl 2-O-benzoyl-4-O-(2-O-benzoyl-3,4,6-tri-O-benzyl-β-d-galactopyranosyl)-3,6-di-O-benzyl-α-d-galactopyranoside (28; 65% yield). All disaccharides were free from their α anomers. Disaccharides 26 and 27 were found to be base-sensitive, and were de-esterified by KCN in aqueous ethanol, and debenzylated with H₂-Pd. Attempts to produce (1→4)-β-d-galactopyranosides from the coupling of a number of fully esterified d-galactopyranosyl sulfonates to allyl 2,3,6-tri-O-benzoyl-α-d-galactopyranoside were unsuccessful.     

Biotransformation of naringin and naringenin by cultured Eucalyptus perriniana cells

The biotransformation of naringin and naringenin was investigated using cultured cells of Eucalyptus perriniana. Naringin (1) was converted into naringenin 7-O-β-d-glucopyranoside (2, 15%), naringenin (3, 1%), naringenin 5,7-O-β-d-diglucopyranoside (4, 15%), naringenin 4′,7-O-β-d-diglucopyranoside (5, 26%), naringenin 7-O-[6-O-(β-d-glucopyranosyl)]-β-d-glucopyranoside (6, β-gentiobioside, 5%), naringenin 7-O-[6-O-(α-l-rhamnopyranosyl)]-β-d-glucopyranoside (7, β-rutinoside, 3%), and 7-O-β-d-gentiobiosyl-4′-O-β-d-glucopyranosylnaringenin (8, 1%) by cultured cells of E. perriniana. On the other hand, 2 (14%), 4 (7%), 5 (13%), 6 (2%), 7 (1%), naringenin 4′-O-β-d-glucopyranoside (9, 4%), naringenin 5-O-β-d-glucopyranoside (10, 2%), and naringenin 4′,5-O-β-d-diglucopyranoside (11, 5%) were isolated from cultured E. perriniana cells, that had been treated with naringenin (3). Products, 7-O-β-d-gentiobiosyl-4′-O-β-d-glucopyranosylnaringenin (8) and naringenin 4′,5-O-β-d-diglucopyranoside (11), were hitherto unknown.     

Flavonoids and the chemotaxonomy of three Sophora species

Sophora microphylla, S. prostrata and S. tetraptera are distinguishable from one another by their leaf flavonoids. S. microphylla is distinguished by the present of rhamnosylvitexin and rhamnosylisovitexin and S. tetraptera by the presence of apigenin-7-O-rhamnosylglucoside-4′-O-glucoside and the 7-O-glucosides of apigenin, 7,4′-dihydroxyflavone, luteolin and 7,3′,4′-trihydroxyflavone. Sophora prostrata lacks all these flavonoids, but has several pigments which are common to all three species.     

Synthesis of nonreducing-sugar subunit analogs of bacterial lipid a carrying an amide-group (3R)-3-acyloxytetradecanoyl group

Two types of optically active, 4-O-phosphono-d-glucosamine derivatives related to the nonreducing-sugar subunit of bacterial lipid A, one being 2-[(3R)-3-acyloxytetradecanamido]-2-deoxy-4-O-phosphono-3-O-tetradecanoyl-d-glucose (GLA-27 type; GLA-57 and GLA-58), and the other 2-[(3R)-3-acyloxytetradecanamido]-2-deoxy-3-O-[(3R)-3-hydroxytetradecanoyl]-4-O-phosphono-d-glucose (GLA-59 type; GLA-61 and GLA-62), have been synthesized. The amino group of benzyl 2-amino-2-deoxy-4,6-O-isopropylidene-β-d-glucopyranoside was first acylated with the (3R)-3-dodecanoyloxytetradecanoyl or (3R)-3-hexadecanoyloxytetradecanoyl group, and then the remaining hydroxyl group was esterified with the tetradecanoyl or (3R)-3-(benzyloxymethoxy)tetradecanoyl group, respectively. The resulting protected intermediates were each converted, by the sequence of O-deisopropylidenation, 6-O-trityltion, and 4-O-phosphorylation, into the desired compounds.     

Synthesis of oleanolic acid saponins mimicking components of Chinese folk medicine Di Wu

3,28-Di-O-rhamnosylated oleanolic acid saponins, mimicking components of Chinese folk medicine Di Wu, have been designed and synthesized. One-pot glycosylation and ‘inverse procedure’ technologies have been applied thus significantly simplifying the preparation of desired saponins. The cytotoxic activity of compounds 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-xylopyranosyl]oleanolic acid 28-O-[α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl] ester (3), 3-O-[α-l-rhamnopyranosyl]oleanolic acid 28-O-[α-l-rhamnopyranosyl- (1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl] ester (4), 3-O-[α-l-rhamnopyranosyl]oleanolic acid 28-O-[α-l-rhamnopyranosyl] ester (5), and 3-O-[α-l-rhamnopyranosyl]oleanolic acid 28-O-[6-O-(α-l-rhamnopyranosyl)hexyl] ester (6) was preliminarily evaluated against HL-60 human promyelocytic leukemia cells. The natural saponin 3 and designed saponin 4 exhibited comparable moderate cytotoxic activity under our testing conditions.