Contribution à la phytochimie du genre Gentiana. XXII. Identification de nouveaux O-glucosides de la mangiférine dans Gentiana asclepiadeaL.

Phytochemistry of genus Gentiana. XXII. Identification of new O-glucosides of mangiferin in Gentiana asclepiadea L. Two new O-glucosides of mangiferin (mangiferin-7-O-β-D -glucoside ( 1 ) and mangiferin-6-O-β-D -glucoside ( 2 )) have been isolated from the leaves of Gentiana asclepiadea L . This is the first full structure elucidation of naturally occurring O-glucosides of C-glucosylxanthones. The known C-glucosylflavone, saponarin ( 5 ) was also identified.     

Contribution à la phytochimie du genre Gentiana XXI; Les cinnamoyl-C-glucosylflavones et leurs O-glucosides dans Gentiana punctataL.

Phytochemistry of genus Gentiana XXI: The cinnamoyl-C-glucosylflavones and their O-glucosides in Gentiana punctata L . Three new ( 1 – 3 ) and three previously identified ( 4 – 6 ) cinnamoyl-C-glucosyl-flavones have been isolated from the leaves of Gentiana punctata L . The structures of the new compounds were established as: trans-cafeoyl-2″-iso-orientin-4′-O-β-D -glucoside ( 1 ), trans-feruloyl-2″-isovitexin-4′-O-β-D -glucoside ( 2 ) and trans-feruloyl-2″-isovitexin ( 3 ). Isoscoparine ( 8 ) and O-β-D -glucosyl-2″-iso-orientin ( 7 ) were also isolated and identified.     

Phytochemistry of genus Gentiana, XX. Identification of new di-O-glucosides of C-glucosylflavones in Gentiana asclepiadea l (author's transl)

Phytochemistry of genus Gentiana, XX. Identification of new di-O-glucosides of C-glucosylflavones in Gentiana asclepiadea L. Two new O-glucosides of C-glucoside flavonic compounds [isoorientin-2″,4′-di-O-β-D -glucoside ( 1 ) and isovitexin-2″-4′-O-β-D -glucoside ( 2 )] have been isolated from leaves of Gentiana asclepiadea L . This is the first case of di-O-glucosides of C-glucoside flavones occurring in nature.     

Contribution à la phytochimie du genre Gentiana. XXV. Etude des composés flavoniques et xanthoniques dans les feuilles de Gentiana X marcailhouana RY. Nouveaux cinnamoyl-C-glucosides flavoniques

Phytochemistry of genus Gentiana XXV: Study of the flavonic and xanthonic compounds in leaves of Gentiana X marcailhouana RY . New cinnamoyl-C-glucosyl-flavones Nine flavonic compounds: isoorientin ( 1 ), isovitexin ( 2 ), isoorientin-4′-O-β-D -glucoside ( 3 ), isovitexin-4′-O-β-D -glucoside ( 4 ), luteolin-7-O-β-D -glucoside ( 5 ), trans-cafeoyl-2′′-isoorientin ( 6 ), trans-feruloyl-2′′-isoorientin ( 7 ), trans-p-coumaroyl-2′′-isoorientin ( 8 ), p-O-β-D -glucosyl-trans-cafeoyl-2′′-isoorientin ( 9 ) and three xanthones: gentioside ( 10 ), isogentisine ( 11 ), mangiferin ( 12 ), have been identified from leaves of Gentiana X marcailhouana RY . Compounds 8 and 9 were described for the first time. The cyclitol L -(+)-bornesitol ( 13 ) has been also isolated.     

Die Herzglykoside des Pfeilgiftes von Lophopetalum toxicum LOHER. 13. Mitteilung über Celastraceen-Inhaltsstoffe

The Heart Glycosides of the Arrow Poison of Lophopetalum toxicum LOHER From the cytotoxic and positive inotropic acting bark extract of the Philippinan Lophopetalum toxicum eight heart glycosides have been isolated and their structures have been elucidated mainly by field-desorption-MS- and ¹- and ¹³C-NMR spectroscopy. Besides the known k-Strophanthidin ( 1 ), Antiarigenin ( 6 ) and β-Antiarin (Antiarigenin-3-β-O-α-L -rhamnoside, 10 ) the following mono- and diglycosides could be identified: strophanthidin-3-β-O-α-6-desoxy-D -allopyranoside (strophalloside, 2 ), strophanthidin-3-β-O-β-6-desoxy-D -glucopyranoside (= Strophanthidin chinovoside, 3 ), strophanthidin-3-β-O[-4Oβ-D -allopyranosyl-β-6-desoxy-D -allopyranoside] ( 4 ), strophanthidin-3-β-O-[3-O-β-D -glucopyranosyl-β-6-desoxy-D -talopyranoside] ( 5 ), antiarigenin-3-β-O-[3-O-β-D -gulopyranosyl-β-6-desoxy-D -talopyranoside] ( 7 ), antiarigenin-3-β-O-[4O-β-D -allopyranosyl-β-6-desoxy-D -allopyranoside] ( 8 ), and antiarigenin-3-β-O-β-6-desoxy-D -allopyranoside (antiallosid) ( 9 ). The structure of strophanthidinchinovoside ( 3 ) could be confirmed by synthesis.     

New Triterpene Saponins from Herniaria glabra

Three new saponins 1–3 were isolated from Herniaria glabra by means of prep. HPLC and TLC. The structures were established mainly by a combination of 2D-NMR techniques (COSY, TOCSY, ROESY, HMQC, and HMBC) as O-α-L -rhamnopyranosyl-(1→4)-O-β-D -glucopyranosyl-(1-→6)-O-[β-D -glucopyranosyl-(1→2)]-β-D -glucopyranosyl medicagen-28-ate (herniaria saponin 4; 1 ), O-β-D -glucopyranosyl-(1→3)-O-α-L -rhamnopyranosyl-(1→2)-O-[β-(3R)-D -apiofuranosyl-(1→3)]-β-D -4-O-acetylfucopyranosyl 3-O-(β-D -glucuronopyranosyl)-16α-hydroxymedicagen-28-ate (herniaria saponin 5; 2 ), and O-α-L -rhamnopyranosyl-(1→4)-O-β-D -glucopyranosyl-(1→6)-O-[β-D -6-O-acetylglucopyra nosyl-(1→2)]-β-D -glucopyranosyl medicagen-28-ate (herniaria saponin 6; 3 ).     

Characterization of flavonoid glycosides from rapeseed bee pollen using a combination of chromatography,spectrometry and nuclear magnetic resonance with a step-wise separation strategy

To identify the structures of flavonoid glycosides in bee pollen collected from rapeseed plants (Brassica napus L.), we utilised an approach that combined liquid chromatography–diode array detector–electrospray ionization–mass spectrometry (LC–DAD–ESI–MS) and nuclear magnetic resonance (NMR) technology with a step-wise separation strategy. We identified four constituents of high purity in rape bee pollen samples: (1) quercetin-3-O-β-D-glucosyl-(2→l)-β-glucoside, (2) kaempferol-3, 4′-di-O-β-D-glucoside, (3) 5, 7, 4′-trihydroxy-3′-methoxyflavone-3-O-β-D-sophoroside and (4) kaempferol-3-O-β-D-glucosyl-(2→l)-β-D-glucoside. This study will also provide useful reference standards for qualification and quantification of four flavonoid glycosides in natural products.     

Preparative isolation and purification of anthocyanins from purple sweet potato by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) was applied to the preparative isolation and purification of peonidin 3-O-(6-O-(E)-caffeoyl-2-O-β-D -glucopyranosyl-β-D -glucopyranoside)-5-O-β-D -glucoside ( 1 ), cyanidin 3-O-(6-O-p-coumaroyl)-β-D -glucopyranoside ( 2 ), peonidin 3-O-(2-O-(6-O-(E)-caffeoyl-β-D -glucopyranosyl)-6-O-(E)-caffeoyl-β-D -glucopyranoside)-5-O-β-D -glucopyranoside ( 3 ), peonidin 3-O-(2-O-(6-O-(E)-feruloyl-β-D -glucopyranosyl)-6-O-(E)-caffeoyl-β-D -glucopyranoside)-5-O-β-D -glucopyranoside ( 4 ) from purple sweet potato. Separation of crude extracts (200 mg) from the roots of purple sweet potato using methyl tert-butyl ether/n-butanol/acetonitrile/water/trifluoroacetic acid (1:4:1:5:0.01, v/v) as the two-phase solvent system yielded 1 (15 mg), 2 (7 mg), 3 (10 mg), and 4 (12 mg). The purities of 1 – 4 were 95.5%, 95.0%, 97.8%, and 96.3%, respectively, as determined by HPLC. Compound 2 was isolated from purple sweet potato for the first time. The chemical structures of these components were identified by ¹H NMR, ¹³C NMR and ESI-MSⁿ.     

Isolierung und Strukturaufklärung von Neapolitanose (O-β-D-Glucopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→6)]-(D-glucose), einem neuen Trisaccharid aus den Stempeln von Gartenkrokussen (Crocus neapolitanus var.)

Isolation and Structure Elucidation of Neapolitanose (O-β-D -Glucopyranosyl-(1→2)-O-[β-D -glucopyranosyl-(1→6)]-D -glucose), New Trisaccharide from the Stigmas of Garden Crocusses (Crocus neapolitanus var.) From the stigmas of Crocus neapolitanus var. ‘Blue Bird’ two new crocetin glycosyl esters were isolated. They contained a hitherto unknown trisaccharide. For the structure elucidation a homonuclear 2D-¹H-NMR-shift-correlation experiment was carried out with the peracetate of the isolated trisaccharide. This experiment revealed that the carbohydrate is O-β-D -glucopyranosyl-(1→2)-O-[β-D -glucopyranosyl-(1→6))]-D -glucose, for which we suggest the name ‘neapolitanose’. The two new C₂₀-carotenoids from Crocus neapolitanus are crocetin (β-gentiobiosyl) (β-neapolitanosyl) ester ( 4 ) and crocetin di(β-neapolitanosyl) ester ( 5 ).     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphin/Azodicarbonsäure-diäthylester. 3. Mitteilung [1]

Structural Modification on Partially Silylated Carbohydrates by Means of Triphenylphosphine/Diethyl Azodicarboxylate Reaction of methyl 2, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1a ) with triphenylphosphine (TPP)/diethyl azodicarboxylate (DEAD) and Ph₃P · HBr or methyl iodide yields methyl 3-bromo-2, 6-bis-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 3a ) and the corresponding 3-deoxy-3-iodo-alloside 3c (Scheme 1). By a similar way methyl 2, 6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2a ) can be converted to the 4-bromo-4-deoxy-galactoside 4a and the 4-deoxy-4-iodo-galactoside 4b . In the absence of an external nucleophile the sugar derivatives 1a and 2a react with TPP/DEAD to form the 3,4-anhydro-α- or -β-D -galactosides 5 and 6a , respectively, while methyl 4, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1b ) yields methyl 2,3-anhydro-4, 6-bis-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 7a , s. Scheme 2). Even the monosilylated sugar methyl 6-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2b ) can be transformed to methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 8 ; 56%) and 3,4-anhydro-α-D -alloside 9 (23%, s. Scheme 3). Reaction of 1c with TPP/DEAD/HN₃ leads to methyl 3-azido-6-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 10 ). The epoxides 7 and 8 were converted with NaN₃/NH₄Cl to the 2-azido-2-deoxy-altrosides 11 and 13 , respectively, and the 3-azido-3-deoxy-glucosides 12 and 14 , respectively (Scheme 4 and 5). Reaction of 7 and 8 with TPP/DEAD/HN₃ or p-nitrobenzoic acid afforded methyl 2,3-anhydro-4-azido-6-O-(t-butyldimethylsilyl)-4-deoxy-α- and -β-D -gulopyranoside ( 15 and 17 ), respectively, or methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-4-O-(p-nitrobenzoyl)-α- and -β-D -gulopyranoside ( 16 and 18 ), respectively, without any opening of the oxirane ring (s. Scheme 6). - The 2-acetamido-2-deoxy-glucosides 19a and 20a react with TPP/DEAD alone to form the corresponding methyl 2-acetamido-3,4-anhydro-6-O-(t-butyldimethylsilyl)-2-deoxy-galactopyranosides ( 21 and 22 ) in a yield of 80 and 85%, respectively (Scheme 7). With TPP/DEAD/HN₃ 20a is transformed to methyl 2-acetamido-3-azido-6-O-(t-butyldimethylsilyl)-2,3-didesoxy-β-D -allopyranoside ( 25 , Scheme 8). By this way methyl 2-acetamido-3,6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 19b ) yields methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-α-D -galactopyranoside ( 23 ; 16%) and the isomerized product methyl 2-acetamido-4,6-bis-O-(t-butyldimethylsilyl)-2-deoxy-α-D -glucopyranoside ( 19d ; 45%). Under the same conditions the disilylated methyl 2-acetamido-2-deoxy-glucoside 20b leads to methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-β-D -galactopyranoside ( 24 ). - All Structures were assigned by ¹H-NMR. analysis of the corresponding acetates.     

Roripanoside,a New Kaempferol Rhamnoside from Rorippa Indica (L.) Hiern

Extracts of the whole herb of Rorippa indica contain benzoic acid, ferulic acid, vanillic acid, gallic acid, glucosyl sinapinate, β-sitosteroyl-3-O-β-glucoside, quercetin-7-O-rhamnoside, kaempferol, kaempferol-3-O-β-glucoside, ?7-O-β-glucoside, ?7-O-rhamnoside, ?3-O-arabinoside, and ?3-O-glucosyl-7-O-rhamnoside together with a new compound, roripanoside. The new compound was elucidated as kampferol-7-O-(6″′-O-caffeoyl)glucosyl (1 → 4) rhamnoside on the basis of spectral and chemical evidence.     

Anatoliosides: Five Novel Acyclic Monoterpene Glylcosides from Viburnum orientale

Five new acyclic monoterpene glycosides 1 – 5 were isolated from the leaves of Viburnum orientale (Caprifoliaceae). Anatolioside ( 1 ) is a monoterpene diglycoside and its structure was elucidated as linalo-6-yl 2′-O-(α-L -rhamnopyranosyl)β-D -glucopyranoside (arbitrary numbering of linalool moiety). Compounds 2 – 5 are all derivatives of 1 , containing additional monoterpene and sugar units, connected by ester and glycoside bonds. Their structures were established as linalo-6-yl O-[(2E,6R)-6-hydroxy-2, 6-dimethylocta-2,7-dienoyl]-(1? → 4″)-O-α-L -rhamnopyranosyl-(1″? → 2″″)-β-D -glucopyranoside ( = anatolioside A; 2 ), linalo-6-yl O-β-D -glucopyranosyl-(1? → 6?)-O-[(2E,6R)-6-hydroxy-2,6-dimethylocta-2,7-dienoyl]-(1? → 4″)-O-α-L -rhamnopyranosyl-(1″ → 2′)–β-D -glucopyranoside ( = anatolioside B; 3 ), linalo-6-yl O-β-D ribo-hexopyranos-3-ulosyl-(1′? → 6?)-O-[(2E,6R)-6-hydroxy-2,6-dimethylocta-2,7-dienoyl]-(1? → 4″)-O-α-L -rhamnopyranosyl-(1″ → 2′)-β-D -glucopyranoside ( = anatolioside C; 4 ) and linalo-6-yl O-[(2E, 6R)-6-hydroxy-2,6-dimethylocta-2,7-dienoyl]-(1″? → 2″″)-O-β-D -glucopyranosly-(1″″ → 6?)-O-[(2E,6R)-6-hydroxy-2,6-dimethylocta-2,7-dienoyl]-(1? → 4″)-O-α-L -rhamnopyranosyl(1″ → 2′)-β-D -glucopyranoside ( = anatolioside D ; 5 ). The structure determinations were based on spectroscopic and chemical methods (acid and alkaline hydrolysis, acetylation and methylation).     

C-Glycoside Analogues of N4-(2-Acetamido-2-deoxy-β-D-glucopyranosyl)-L-asparagine: Synthesis and conformational analysis of a cyclic C-glycopeptide

The synthesis of C-glycosidic analogues 15–22 of N⁴-(2-acetamido-2-deoxy-β-D -glucopyranosyl)-L -asparagine (Asn(N⁴GlcNAc)) possessing a reversed amide bond as an isosteric replacement of the N-glycosidic linkage is presented. The peptide cyclo(-D -Pro-Phe-Ala-CGaa-Phe-Phe-) (CGaa = C-glycosylated amino acid; 24 ) was prepared to demonstrate that 3-[(3-acetamido-2,6-anhydro-4,5,7-tri-O-benzyl-3-deoxy-β-D -glycero-D -guloheptonoyl)amino]-2-[(9H-fluoren-9-yloxycarbonyl)amino]propanoic acid ( 22 ) can be used in solid-phase peptide synthesis. The conformation of 24 was determined by NMR and molecular-dynamics (MD) techniques. Evidence is provided that the CGaa side chain interacts with the peptide backbone. The different C-glycosylated amino acids 15–21 were prepared by coupling 3-acetamido-2,6-anhydro-4,5,7-tri-O-benzyl-3-deoxy-β-D -glycero-D -gulo-heptonic acid ( 4 ) with diamino-acid derivatives 8–14 in 83–96% yield. The synthesis of 4 was performed from 2-(acetamido-3,4,6-tri-O-benzyl-2-deoxy-β-D -glucopyranosyl) tributylstannane ( 2 ) by treatment with BuLi and CO₂ in 83% yield. Similarly, propyl isocyanat yielded the glycoheptonamide 7 in 52% from 2 . Compound 2 was obtained from 2-acetamido-3,4,6-tri-O-benzyl-2-deoxy-D -glucopyranose ( 1 ) by chlorination and addition of tributyltinlithium in 74% yield. A procedure for a multigram-scale synthesis of 1 is given.     

Desoxy-nitrozucker 14. Mitteilung 1-C-Nitroglycale. Herstellung und Umsetzung mit einigen Stickstoff-Nucleophilen

1-C-Nitroglycals. Preparation and Reaction with Some Nitrogen Nucleophiles Acetylation of the 1-deoxy-1-nitromannopyranoses 2 and 6 was accompagnied by spontanous β-elimination to give the 1-C-nitroglucals 3 and 7 , respectively, while acetylation of the gluco- and galacto-configurated 1-deoxy-1-nitropyranoses 8 and 14 gave the acetates 9 and 15 , respectively (Scheme 1). The acetylation of the ribo- and arabino-configurated 1-deoxy-1-nitrofuranoses 19 and 21 also occurred without β-elimination to give the acetates 20 and 22 , respectively (Scheme 2). Mild base treatment of the previously described O-acetylnitro-β-D -glucose 4 , the O-acetylnitro-β-D -pyranoses 9 and 15 , and the O-acetylnitro-β-D -furanoses 17 , 20 , and 22 gave the 1-C-nitroglycals 3 , 10 , 16 , 18 and 23 , respectively (Scheme 1 and 2). The previously obtained 1-C-nitroglucal 3 was deacetylated by treatment with MeOH in the presence of KCN or sodium m-nitrophenolate to give the free nitroglucal 5 . Deacetylation of the benzylidene protected 1-C-nitroglucal 10 (MeOH, NaOMe) gave the 4,6-O-benzylidene-1-C-nitroglucal 11 and traces of the 2-O-methyl-1-C-nitromannoses 12 and 13 . The UV, IR, ¹H-NMR and ¹³C-NMR spectra of the 1-C-nitroglycals are discussed. In solution, the 1-C-nitroglycals 1 , 5 , 7 , 10 , 11 , and 16 adopt approximately a ⁴H_5? and 3 a flattened ⁴H₅ conformation. The structure of 5 was established by X-ray analysis. In the solid state, 5 adopts a sofa conformation, which is stabilized by an intramolecular H-bond. The β-addition of NH₃ to the 1-C-nitroglucals 7 and 10 was followed by an O→ N acetyl migration to give exclusively anomeric pairs of the N-acetyl-1-nitromannosamine derivatives 24 / 25 and 26/27 , respectively (Scheme 3). The β-addition of methylamine, octadecylamine, and tryptamine to the 1-C-nitroglucal 11 also stereoelectronically controlled and gave the crystalline N-alkyl-1-nitromannosamines 28 , 29 , and 30 , respectively. The stereoelectronically controlled β-addition of NH₃ to the 1-C-nitrogalactal 16 , followed by acetylation, yielded exclusively the talosamine derivative 31 , while the reversible β-addition of azide ions to 16 gave the anomeric 2-azido-1-nitrogalactoses 32 and 33 . The β-addition of azide ions to the 1-C-nitroglucal 1 led to the 2-azido-1-nitromannose 34 . In the presence of excess formaldehyde, this addition was followed by a Henry reaction. Chromatography of the crude product was accompagnied by solvolytic removal of the NO₂ group to give the 3-azidomannoheptulose 35 in high yields (Scheme 4).     

Molluscicidal Saponins from Talinum tenuissimum DINTER

Two new saponins, β-D -glucopyranosyl 3-O[O-βD -xylopyranosyl-(1→3)-O-(β-D -glucopyranosyluronic acid)]oleanolate ( 1 ) and 3-O-[O-β-D -xylopyranosyl-(1→3)-O-(β-D-glucopyranosyluronic acid)]oleanolic acid ( 2 ), have been isolated from the tubers of Talinum tenuissimum. The structures have been established mainly by ¹³C-NMR and FAB-MS. The monodesmosidic saponin 2 exhibits very strong molluscicidal activity against the schistosomiasis-transmitting snail Biomphalaria glabrata.     

Synthesis and Biological Evaluation of 2-(2-Deoxy-β-D-ribofuranosyl)pyridine-4-carboxamide

A new protected 2-deoxy-D -ribose derivative, 5-O-[(tert-butyl)diphenylsilyl]-2-deoxy-3,4-O- isopropylidene-aldehydo-D -ribose ( 5 ), was synthesized starting from 2-deoxy-D -ribose. This compound was coupled with 2-lithio-4-(4,5-dihydro-4,4-dimethyloxazol-2-yl)pyridine giving a D /L -glycero-mixture 7 of 5-O-[(tert-butyl)diphenylsilyl]-2-deoxy-1-C-[4-(4,5 -dihydro-4,4-dimethyloxazol-2-yl)pyridin-2-yl]-3,4-O-isopropylidene- D -erythro-pentitol. The mixture 7 was 1-O-mesylated with methanesulfonyl chloride and subsequently treated with CF₃COOH/H₂O and ammonia to afford the α/β-D -anomers 10 of 2-(2-deoxy-D -ribofuranosyl)pyridine-4-carboxamide. Both anomers were purified and separated by HPLC and identified by NMR and DCI-MS. Anomer β-D - 10 was evaluated against a series of tumor-cell lines and a variety of viral strains. No antitumor or antiviral activity was observed.     

Carotinoid-Glycosylester 4. Mitteilung. Synthese von 8′-Apo-β-carotin-8′-säure-(β-D-glucosyl)ester und Vitamin-A-säure-(β-D-glucosyl)ester

Carotenoid Glycosyl Esters Synthesis of β-D -Glucosyl 8′-Apo-β-carotene-8′-oate and β-D -Glucosyl Vitamin-A-oate (β-D -Glucosyl Retionate) β-D -glucosyl 8′-apo-β-carotene-8′-oate (III) and β-D -glucosyl vitamin-A-oate (VI) were regio- and stereoselectively synthesized in high yields from the N-acylimidazoles I and IV, respectively, or from the N-acyltriazoles II and V, respectively, and unprotected β-D -glucose, according to the method described for the synthesis of di(β-D -glucosyl) 8,8′-diapo-carotene-8,8′-dioate [1]. It seems that this method can generally be applied for the synthesis of β-D -glucosyl esters of polyene carboxylic acids.     

Synthesis of 5-Methyluridine and Its 5′-Mercapto-, 2-Amino-, and 4′,5′-Unsaturated Analogues

The stereospecific cis-hydroxylation of 1-(2,3-dideoxy-β-D -glyceropent-2-enofuranosyl)thymine (1) into 1-β-D -ribofuranosylthymine (2) by osmium tetroxide is described. Treatment of 2′,3′-O, O-isopropylidene-5-methyl-2,5′-anhydrouridine (8) with hydrogen sulfide or methanolic ammonia afforded 5′-deoxy-2′,3′-O, O-isopropylidene-5′-mercapto-5-methyluridine (9) and 2′,3′-O, O-isopropylidene-5-methyl-isocytidine (10) , respectively. The action of ethanolic potassium hydroxide on 5′-deoxy-5′-iodo-2′,3′-O, O-isopropylidene-5-methyluridine (7) gave rise to the corresponding 1-(5-deoxy-β-D -erythropent-4-enofuranosyl)5-methyluracil (13) and 2-O-ethyl-5-methyluridine (14) . The hydrogenation of 2 and its 2′,3′-O, O-isopropylidene derivative 4 over 5% Rh/Al₂O₃ as catalyst generated diastereoisomers of the corresponding 5-methyl-5,6-dihydrouridine ( 17 and 18 ).     

Synthesis of Xanthone-O-Glycosides. II.. Synthesis of 1-O-β-glycosides

Several naturally occurring xanthone-1-O-glycosides have been synthesized in order to study monoamine oxidase (MAO) inhibition structure-activity relationships. The syntheses also confirmed the structures as 1-β-D -glucosyloxy-3-hydroxy-5-methoxyxanthone (Canscora decussata SCHULT .), 1-O-β-primeverosyl-3, 7, 8-trimethoxyxanthone (decussatin-1-O-primeveroside, Gentiana verna L .) and 1-O-β-primeverosyl-3, 8-dimethoxy-7-hydroxyxanthone (gentiacaulein-1-O-β-primeveroside, Gentiana verna L .).     

A new alkylbenzoquinone from Embelia rowlandii Gilg. (Myrsinaceae)

A new alkylbenzoquinone named embeliquinone (1) together with five known compounds, lupeol (2), 3-O-[6′-O-palmitoyl-β-d-glucosyl]-spinasta-7,22(23)-diene (3), quercetin (4), (2S,3S,4R,8E)-2-[(2′R)-2′-hydroxy-heneicosanoylamino]-heneicosane-1,3,4-triol-8-ene (5), and β-sitosterol-3-O-β-d-glucopyranoside (6) were isolated from the MeOH leaf extract of Embelia rowlandii by using repeated open column chromatography techniques. The structure of the new compound was characterized by analyses of 1D- and 2D-NMR, and MS data. Embeliquinone (1) had moderate anti-cell proliferation activity against A549 cell line with the IC₅₀ value of 21.8 μM. In addition, 1 exhibited weak antibacterial activities against Klebsiella pneumoniae and Staphylococcus aureus with an MIC value of 206.0 μM in both cases.