- Structural features and antioxidant activity of a new galactoglucan from edible mushroom Pleurotus djamor
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A new water soluble galactoglucan with apparent molecular weight ~1.61 × 105 Da, was isolated from the edible mushroom Pleurotus djamor by hot water extraction followed by purification through dialysis tubing cellulose membrane and sepharose 6B column chromatography. The sugar analysis showed the presence of glucose and galactose in a molar ratio of nearly 3:1 respectively. The structure of the repeating unit in the polysaccharide was determined through chemical and NMR experiments as:[Formula presented] In vitro antioxidant studies showed that the PDPS exhibited hydroxyl radical scavenging activity (EC50 = 1.681 ± 0.034 mg/mL), DPPH radical scavenging activity (EC50 = 3.83 ± 0.427 mg/mL), reducing power (EC50 = 4.258 ± 0.095 mg/mL), and ABTS radical quenching activity (EC50 = 0.816 ± 0.077 mg/mL). So, PDPS should be explored as a natural antioxidant.
- Maity, Gajendra Nath,Maity, Prasenjit,Khatua, Somanjana,Acharya, Krishnendu,Dalai, Sudipta,Mondal, Soumitra
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p. 743 - 749
(2020/12/07)
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- A novel low-molecular-mass pumpkin polysaccharide: Structural characterization, antioxidant activity, and hypoglycemic potential
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The novel natural low-molecular-mass polysaccharide (SLWPP-3) from pumpkin (Cucurbia moschata) was separated from the waste supernatant after macromolecular polysaccharide production and purified using a DEAE cellulose-52 column and gel-filtration chromatography. Chemical and instrumental studies revealed that SLWPP-3 with a molecular mass of 3.5 kDa was composed of rhamnose, glucose, arabinose, galactose and uronic acid with a weight ratio of 1: 1: 4: 6: 15, and primarily contained →3,6)-β-D-Galp-(1→, →4)-α-GalpA-(1→(OMe), →4)-α-GalpA-(1→, →2,4)-α-D-Rhap-(1→, →3)-β-D-Galp-(1→, →4)-α-D-Glcp, and →4)-β-D-Galp residues in the backbone. The branch chain passes were connected to the main chain through the O-4 atom of glucose and O-3 atom of arabinose. Physiologically, the ability of SLWPP-3 to inhibit carbohydrate-digesting enzymes and DPPH and ABTS radicals, as well as protect pancreatic β cells from oxidative damage by decreasing MDA levels and increasing SOD activities, was confirmed. The findings elucidated the structural types of pumpkin polysaccharides and revealed a potential adjuvant natural product with hypoglycemic effects.
- Huang, Linlin,Li, Fei,Li, Quanhong,Liang, Li,Wei, Yunlu,Yu, Guoyong
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- Isolation, purification and structural characterization of a water-soluble polysaccharide HM41 from Halenia elliptica D. Don
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A water-soluble polysaccharide, HM41, was obtained from Halenia elliptica D. Don by acidic ethanol fractionation and gel filtration. Its homogeneity was confirmed by chromatography using multiple systems. HM41 was composed of rhamnose (Rha), arabinose (Ara), xylose (Xyl), mannose (Man), galactose (Gal), glucose (Glc) with a molar ratio of 1.0:5.5:1.8:3.0:9.4:21. The average molecular weight of HM41 was approximately 1.17 × 104. Periodate oxidation, Smith degradation, methylation and GC, IR, NMR, XRD, GC-MS analysis were used for the structural analysis of HM41. Its main chain was composed mainly of β-(1 → 4)Gal, β-(1 → 4)Glc and β-(1 → 6)Glc. β-(1 → 4)Gal were substituted at 6-O and on average there were 14 branches among 23 main chain residues; (1 → 4)Glc had no branch; (1 → 6)Glc were substituted at 3-O and on average there were 9 branches among 14 main chain residues. The side chain was composed of (1 → 3,6)-Rha, (1 → 4)/(1 → 5)-Ara, (1 → 4)/(1 → 5)-Xyl, (1 → 4,6)-Man and (1 → 2)-Glc. The terminal residue was composed of Ara, Xyl, Man, Gal, and Glc. Then, we demonstrated that HM and HM41 had strong scavenging activities in vitro hydroxyl. Overall, HM and HM41 may have potential applications in the antioxidants for medical and food industry.
- Liu, Chun-Lan,Li, Yang,Xu, Gui-Yun,Li, Ya-Shuang
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p. 979 - 983
(2016/06/13)
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- Acyl transfer reactions of carbohydrates, alcohols, phenols, thiols and thiophenols under green reaction conditions
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Acyl transfer reactions of various carbohydrates, alcohols, phenols, thiols and thiophenols were achieved at room temperature in high yields and catalytic efficiency in the presence of methane sulfonic acid, a green organic acid, under solvent-free conditions over short time periods. The method is mild enough to allow acid labile substituents such as isopropylidene acetals and trityl ethers on the reacting substrates to be left completely unaffected. Esterification of free mono- and dicarboxylic acids such as acetic acid, cinnamic acid, sialic acid and tartaric acid with alcohols such as menthol, ethanol, methanol or propylene glycol has also been achieved efficiently at room temperature. A comparative study of the method with the silica-sulfuric acid is also reported.
- Giri, Santosh Kumar,Kartha, K. P. Ravindranathan
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p. 11687 - 11696
(2015/02/19)
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- Cu(ClO4)2·6H2O catalyzed solvent free per-O-acetylation and sequential one-pot conversions of sugars to thioglycosides
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The solvent free per-O-acetylation of various reducing and non-reducing sugars has been carried out using stoichiometric amounts of acetic anhydride and copper(ii) perchlorate hexahydrate as the catalyst. The reactions with various reducing monosaccharides have also been followed by a one-pot sequential conversion to the corresponding thioglycosides in high yields. This journal is
- Chatterjee, Debnath,Paul, Abhijit,Rajkamal,Yadav, Somnath
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p. 29669 - 29674
(2015/05/20)
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- I2/ionic liquid as a highly efficient catalyst for per-O-acetylation of sugar under microwave irradiation
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A practical and highly efficient approach was developed to synthesize peracetylated sugar derivatives using a recyclable iodine/PEG400-based ionic liquid catalyst (I2/IL). The peracetylated sugars were readily obtained in a few minutes in excellent yields (90%-99%, 13 examples) on a multi-gram scale (50.0 mmol) by the reaction of sugar and acetic anhydride under microwave irradiation in the absence of a volatile organic solvent. The desired product was easily obtained by simple extraction with toluene from the reaction mixture, and I2/ILs can be readily recovered and reused at least six times without obvious loss in the yield. When the scale of the per-O-acetylation reaction was increased to 50.0 mmol, the desired product was still obtained in 90% yield after five recycles.
- Xiong, Xingquan,Yi, Chao,Han, Qian,Shi, Lin,Li, Sizhong
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p. 237 - 243
(2015/09/28)
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- Isolation and characterization of a hyperbranched proteoglycan from Ganoderma Lucidum for anti-diabetes
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Presently, an efficient protein tyrosine phosphatase 1B (PTP1B) inhibitor, named FYGL-n, was isolatedfrom Ganoderma Lucidum and characterized for its structure and bioactivity. Structure and chain con-formation of FYGL-n based on both chemical and spectroscopic analysis showed that FYGL-n was ahyperbranched heteropolysaccharide bonded with protein via both serine and threonine residues by O-type glycoside, and showed a sphere observed by AFM. Specifically, monosaccharide compositionindicated that FYGL-n consisted of D-arabinose, D-galactose, L-rhamnose and D-glucose in a mole ratio of 0.08:0.21:0.24:0.47, with a molecular mass of 72.9 kDa. The analysis of amino acids in FYGL-n indicatedthat there were 16 common amino acids, among which aspartic acid, glycine, serine, alanine, glutamicacid and threonine were the dominant components. Also it was demonstrated that FYGL-n could inhibitthe PTP1B activity on a competitive mechanism in vitro.
- Pan, Deng,Wang, Linqiang,Chen, Congheng,Hu, Bingwen,Zhou, Ping
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supporting information
p. 106 - 114
(2015/02/19)
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- Characterization of the chemical diversity of glycosylated mycosporine-like amino acids in the terrestrial cyanobacterium Nostoc commune
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Mycosporine-like amino acids (MAAs) are UV-absorbing pigments, and structurally unique glycosylated MAAs are found in the terrestrial cyanobacterium Nostoc commune. In this study, we examined two genotypes of N. commune colonies with different water extract UV-absorption spectra. We found structurally distinct MAAs in each genotype. The water extract from genotype A showed a UV-absorbing spectrum with an absorption maximum at 335 nm. The extract contained the following compounds: 7-O-(β-arabinopyranosyl)-porphyra-334 (478 Da), pentose-bound shinorine (464 Da), hexose-bound porphyra-334 (508 Da) and porphyra-334 (346 Da). The water extract from genotype B showed a characteristic UV-absorbing spectrum with double absorption maxima at 312 and 340 nm. The extract contained hybrid MAAs (1050 Da and 880 Da) with two distinct chromophores of 3-aminocyclohexen-1-one and 1,3-diaminocyclohexen linked to 2-O-(β-xylopyranosyl)-β-galactopyranoside. A novel 273-Da MAA with an absorption maximum at 310 nm was also identified in genotype B. The MAA consisted of a 3-aminocyclohexen-1-one linked to a γ-aminobutyric acid chain. These MAAs had potent radical scavenging activities in vitro and the results confirmed that the MAAs have multiple roles as a UV protectant and an antioxidant relevant to anhydrobiosis in N. commune. The two genotypes of N. commune exclusively produced their own characteristic glycosylated MAAs, which supports that MAA composition could be a chemotaxonomic marker for the classification of N. commune.
- Nazifi, Ehsan,Wada, Naoki,Asano, Tomoya,Nishiuchi, Takumi,Iwamuro, Yoshiaki,Chinaka, Satoshi,Matsugo, Seiichi,Sakamoto, Toshio
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p. 154 - 168
(2015/02/18)
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- Tris(pentafluorophenyl)borane catalyzed acylation of alcohols, phenols, amines, and thiophenols under solvent-free condition
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The acylation of alcohols, phenols, amines, and thiophenols was accomplished with 0.5 mol % of tris(pentafluorophenyl)borane [B(C 6F5)3] at ambient temperature under solvent-free condition. Major advantages of this method include high yield, short reaction time, simple procedure, compatibility with sensitive protecting groups as well as other functional groups, absence of racemization of optical active compounds, and epimerization of sugars.
- Prajapti, Santosh Kumar,Nagarsenkar, Atulya,Babu, Bathini Nagendra
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p. 1784 - 1787
(2014/03/21)
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- Silica-supported boric acid catalyzed synthesis of dihydropyrimidin-2-ones, bis(indolyl)methanes, esters and amides
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Silica-supported boric acid (H3BO3-SiO2) has been established as a green, efficient and recyclable catalyst for the synthesis of dihydropyrimidin-2-ones, bis(indolyl)methanes, and acetylation of alcohols, phenols, amines and thiols under solvent free conditions. The main features of the present method include clean reaction, mild conditions, low loading of environment friendly catalyst and easy workup procedure. The catalyst can be recycled at least five times without any significant loss in activity.
- Kumar, Vishal,Singh, Chitra,Sharma, Upendra,Verma, Praveen K.,Singh, Bikram,Kumar, Neeraj
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- Combining clays and ultrasound irradiation for an o-acetylation reaction of N-glucopyranosyl and other molecules
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A convenient, efficient and fast acetylation combining clays and ultrasound irradiation is described. Some molecules from nature or synthetic source, i.e., D-glucose, glycerol, D-mannitol and 1,2,3-triazolic derivatives such as N-glucosyl sugars and 2-substituted 1,4-naphthoquinone structures were acetylated. This kind of chemistry may be classified as eco-friendly because the reactions take a short time and the catalyst is reusable.
- De Oliveira, Ronaldo N.,De Xavier, Augusto L.,Guimaraes, Bruna M.,Melo, Valentina N. E.,Valena, Wagner O.,Nascimento Do, Wilson S.,Da Costa, Pollyanna L. F.,Camara, Celso A.
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p. 2610 - 2614
(2015/02/18)
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- Structural characterization and anti-inflammatory activity of a linear β-d-glucan isolated from Pleurotus sajor-caju
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Glucans comprise an important class of polysaccharides present in basidiomycetes with potential biological activities. A (1 → 3)-β-d-glucan was isolated from Pleurotus sajor-caju via extraction with hot water followed by fractionation by freeze-thawing and finally by dimethyl sulfoxide extraction. The purified polysaccharide showed a 13C-NMR spectrum with six signals consisting of a linear glucan with a β-anomeric signal at 102.8 ppm and a signal at 86.1 ppm relative to O-3 substitution. The other signals at 76.2, 72.9, 68.3, and 60.8 ppm were attributed to C5, C2, C4, and C6, respectively. This structure was confirmed by methylation analysis, and HSQC studies. The β-d-glucan from P. sajor-caju presented an immunomodulatory activity on THP-1 macrophages, inhibited the inflammatory phase of nociception induced by formalin in mice, and reduced the number of total leukocytes and myeloperoxidase levels induced by LPS. Taken together, these results demonstrate that this β-d-glucan exhibits a significant anti-inflammatory activity.
- Silveira, Marcia L.L.,Smiderle, Fhernanda R.,Moraes, Carla Porto,Borato, Débora G.,Baggio, Cristiane H.,Ruthes, Andrea Caroline,Wisbeck, Elisabeth,Sassaki, Guilherme L.,Cipriani, Thales R.,Furlan, Sandra A.,Iacomini, Marcello
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p. 588 - 596
(2014/11/08)
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- Polyketide glycosides from bionectria ochroleuca inhibit candida albicans biofilm formation
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One of the challenges presented by Candida infections is that many of the isolates encountered in the clinic produce biofilms, which can decrease these pathogens' susceptibilities to standard-of-care antibiotic therapies. Inhibitors of fungal biofilm formation offer a potential solution to counteracting some of the problems associated with Candida infections. A screening campaign utilizing samples from our fungal extract library revealed that a Bionectria ochroleuca isolate cultured on Cheerios breakfast cereal produced metabolites that blocked the in vitro formation of Candida albicans biofilms. A scale-up culture of the fungus was undertaken using mycobags (also known as mushroom bags or spawn bags), which afforded four known [TMC-151s C-F (1-4)] and three new [bionectriols B-D (5-7)] polyketide glycosides. All seven metabolites exhibited potent biofilm inhibition against C. albicans SC5314, as well as exerted synergistic antifungal activities in combination with amphotericin B. In this report, we describe the structure determination of the new metabolites, as well as compare the secondary metabolome profiles of fungi grown in flasks and mycobags. These studies demonstrate that mycobags offer a useful alternative to flask-based cultures for the preparative production of fungal secondary metabolites.
- Wang, Bin,You, Jianlan,King, Jarrod B.,Cai, Shengxin,Park, Elizabeth,Powell, Douglas R.,Cichewicz, Robert H.
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p. 2273 - 2279
(2015/01/08)
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- Isolation and chemical characterization of a glucogalactomannan of the medicinal mushroom Cordyceps militaris
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Cordyceps militaris dried fruiting bodies were extracted with 5% KOH solution. The extract was purified by freeze-thawing treatment, and dialysis (100 kDa), giving rise to a homogeneous polysaccharide (Mw 23,000 Da). Its monosaccharide composition was mannose (56.7%), galactose (34.5%), and glucose (8.8%). The anomeric configurations were determined by their coupling constants. A complex polysaccharide was identified by NMR and methylation analysis. The HSQC spectrum showed signals at δ 107.7/5.06 and 106.1/5.14; 105.9/5.12 relative to β-D-Galf, and O-2-substituted β-D-Galf units, respectively. The sign at δ 104.4/5.21 corresponded to α-D-Galf. Other signals corresponded to α-D-Manp O-6- and O-2-substituted (δ 100.2/4.94; 100.5/5.27; 100.6/5.23; 100.7/5.16), and δ-D-Manp 2,6-di-O-substituted (from δ 99.3 to 99.9). The main linkages, confirmed by methylation analysis, showed the derivatives: 2,3,4-Me3-Manp (11.9%) and 3,4,6-Me3-Manp (28.6%). The branches were (1 → 6)-linked-α-D-Manp or (1 → 2)-linked-β-D-Galf, terminating with β-D-Galf, α-D-Galf, α-D-Galp, or α-D-Manp. 42.7% of the partially hydrolyzed product consisted of 3,4,6-Me3-Manp, suggesting a (1 → 2)-linked backbone.
- Smiderle, Fhernanda R.,Sassaki, Guilherme L.,Van Griensven, Leo J.L.D.,Iacomini, Marcello
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- 4-(N,N-dimethylamino)pyridine-embedded nanoporous conjugated polymer as a highly active heterogeneous organocatalyst
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We report herein for the first time the incorporation of a versatile organocatalyst, 4-(N,N-dimethylamino)pyridine (DMAP), into the network of a nanoporous conjugated polymer (NCP) by the "bottom-up" approach. The resulting DMAP-NCP material possesses highly concentrated and homogeneously distributed DMAP catalytic sites (2.02 mmol g-1). DMAP-NCP also exhibits enhanced stability and permanent porosity due to the strong covalent linkage and the rigidity of the "bottom-up" monomers. As a result, DMAP-NCP shows excellent catalytic activity in the acylation of alcohols with yields of 92-99 %. The DMAP-NCP catalyst could be easily recovered from the reaction mixture and reused in at least 14 consecutive cycles without measurable loss of activity. Moreover, the catalytic acylation reaction could be performed under neat and continuous-flow conditions for at least 536 h of continuous work with the same catalyst activity. Copyright
- Zhang, Yuan,Zhang, Yong,Sun, Ya Lei,Du, Xin,Shi, Jiao Yi,Wang, Wei,Wang, Wei David
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experimental part
p. 6328 - 6334
(2012/06/18)
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- Acremomannolipin A, the potential calcium signal modulator with a characteristic glycolipid structure from the filamentous fungus Acremonium strictum
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By the newly developed assay method, the glycolipid Acremomannolipin A (1) was isolated from a filamentous fungus Acremonium strictum as a potential calcium signal modulator. The structure of 1 elucidated on the basis of intensive spectroscopic analyses as well as its degradation studies is quite unique: the d-mannopyranose is connected to d-mannitol through a β-glycoside linkage; all the hydroxyls in the mannose are highly masked as peresters with aliphatic acids, and this moiety is made hydrophobic, whereas the mannitol part exhibits a highly hydrophilic property. The compound (1) showed the characteristic bioactivity property, enabling calcineurin deletion cells to grow in the presence of Cl-, which would be caused by calcium signal modulating. The activity was so potent as to exert the effect at a concentration of 200 nM.
- Sugiura, Reiko,Kita, Ayako,Tsutsui, Nozomi,Muraoka, Osamu,Hagihara, Kanako,Umeda, Nanae,Kunoh, Tatsuki,Takada, Hirofumi,Hirose, Dai
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p. 6735 - 6739
(2013/01/14)
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- Enumeration of hydroxyl groups of sugars and sugar alcohols by aqueous-based acetylation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
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RATIONALE The properties of carbohydrates are determined in part by the number and stereochemical arrangement of their hydroxyl groups. To facilitate their analysis, rapid methods are needed to identify and enumerate hydroxyl groups in sugars and polyalcohols, especially methods that are water-based. METHODS The present report details the results of an alternative method for identification and enumeration of hydroxyl groups in aqueous media. It employs vinyl acetate to selectively derivatize hydroxyl groups in analytes, followed by analysis of the reaction mixtures by matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF-MS). RESULTS The method has been applied to several single and multi-component mixtures of monosaccharides and polyalcohols. The O-acetylated products were analyzed without chromatographic separation or purification by MALDI-TOF-MS. The mass spectra revealed consecutive ion peaks that are separated by 42 mass units as a consequence of displacement of one hydroxyl hydrogen by one acetyl group. CONCLUSIONS A rapid and aqueous-based method is described to enumerate the hydroxyl groups in carbohydrates. The number of ion peaks due to derivatized products is determined by MALDI-TOF-MS, and corresponds to the number of free hydroxyl groups in the analyte. The method is applicable to both single and multi-component mixtures. Published 2011. This article is a US Government work and is in the public domain in the USA. Published 2012. This article is a US Government work and is in the public domain in the USA.
- Adeuya, Anthony,Price, Neil P.J.
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experimental part
p. 1372 - 1376
(2012/08/08)
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- H2SO4-SiO2: Highly efficient and reusable catalyst for per-O-acetylation of carbohydrates under solvent-free conditions
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Sulfuric acid immobilized on silica gel (H2SO 4-SiO2) was used as an efficient promoter for per-O-acetylation of carbohydrates with acetic anhydride under solvent-free conditions. The substrates include not only monosaccharides and disaccharides, but also glycosides. The catalyst is recyclable and stable at room temperature, and the reaction protocol is simple, is cost-effective, and gives good isolated yield with high purity. The large-scale reactions also proceeded conveniently and in high yields. Taylor & Francis Group, LLC.
- Zhang, Jianbo,Zhang, Bo,Zhou, Jiafen,Li, Juan,Shi, Chunjuan,Huang, Ting,Wang, Zhongfu,Tang, Jie
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experimental part
p. 165 - 177
(2012/01/19)
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- Extraction, purification, characterization and hypoglycemic activity of a polysaccharide isolated from the root of Ophiopogon japonicus
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In this research, a water-soluble polysaccharide (OJP1) extracted with hot water from the roots of Ophiopogon japonicus which is a traditional Chinese medicinal herb was precipitated with 95% ethanol and purified by DEAE-52 cellulose anion-exchange and Sephadex G-100 gel filtration chromatography. The high performance gel permeation chromatography (HPGPC) analysis showed that the average molecular weight (Mw) of OJP1 was 35.2 kDa. Monosaccharides analysis revealed that the OJP1 is composed of Ara, Glc, Gal with a relative molar ratio of 1:16:8. Pharmaceutical experiments showed OJP1 can significantly reduce blood glucose level, increase the insulin level and remediating destruction of pancreatic islets in STZ-induced diabetic rats compared with the diabetic control group. The study shows that OJP1 has an anti-diabetic effect on STZ-induced diabetic rats, and has potential use as an anti-diabetic agent. Copyright
- Chen, Xiaoming,Jin, Jing,Tang, Jia,Wang, Zhongfu,Wang, Junjun,Jin, Liqin,Lu, Jianxin
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experimental part
p. 749 - 754
(2011/06/27)
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- Chemical analysis of new water-soluble (1→6)-, (1→4)-α, β-glucan and water-insoluble (1→3)-, (1→4)-β-glucan (Calocyban) from alkaline extract of an edible mushroom, Calocybe indica (Dudh Chattu)
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Two different glucans (PS-I, water-soluble; and PS-II, water-insoluble) were isolated from the alkaline extract of fruit bodies of an edible mushroom Calocybe indica. On the basis of acid hydrolysis, methylation analysis, periodate oxidation, and NMR anal
- Mandal, Soumitra,Maity, Kankan K.,Bhunia, Sanjoy K.,Dey, Biswajit,Patra, Sukesh,Sikdar, Samir R.,Islam, Syed S.
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experimental part
p. 2657 - 2663
(2011/01/12)
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- Pregnane glycosides from Hoodia gordonii
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Hoodia gordonii is a 'weight loss' herb, which has gained popularity in the western countries as an appetite suppressant dietary supplement. Phytochemical study of its aerial parts led to isolation of seven pregnane glycosides (hoodigosides W-Z, hoodistan
- Shukla, Yatin J.,Pawar, Rahul S.,Ding, Yuanqing,Li, Xing-Cong,Ferreira, Daneel,Khan, Ikhlas A.
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experimental part
p. 675 - 683
(2010/02/17)
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- Structure and biological activity of maculansin A, a phytotoxin from the phytopathogenic fungus Leptosphaeria maculans
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During a search for elicitors and phytotoxins produced by virulent isolates of the phytopathogenic fungus Leptosphaeria maculans (Desm.) Ces. et de Not. [asexual stage Phoma lingam (Tode ex Fr.) Desm.], the selective phytotoxin maculansin A was isolated and its structure determined by analysis of spectroscopic data and chemical degradation. Maculansin A, a unique derivative of mannitol containing the unusual chromophore 2-isocyano-3-methyl-2-butenoyl, was isolated from potato dextrose cultures of L. maculans virulent on canola (Brassica napus L. cv. Westar). Surprisingly, maculansin A was more toxic to resistant plants (B. juncea L. cv. Cutlass, brown mustard) than to susceptible plants (canola). Maculansin A, however, did not elicit the production of phytoalexins either in resistant or susceptible plants. In addition, other maculansin type structures and the metabolite 2,4-dihydroxy-3,6-dimethylbenzaldehyde were isolated and the latter was found to be a strong inhibitor of root growth of both brown mustard and canola. Considering that L. maculans seems to be expanding its host range to infect brown mustard as well, maculansins could assist in chemotaxonomic studies to group the diverse isolates.
- Pedras, M. Soledade C.,Yu, Yang
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experimental part
p. 2966 - 2971
(2009/04/18)
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- Al(OTf)3 as a highly efficient catalyst for the rapid acetylation of alcohols, phenols and thiophenols under solvent-free conditions
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Aluminium triflate (0.01-0.1 mol %) was found to be an efficient catalyst for the acylation of alcohols, phenols, thiols and sugars with acetic anhydride in high yields under solvent-free conditions in a short reaction time at room temperature. Racemization of optically active alcohols and epimerization of sugars were not observed. The acylation efficacy of various acyl donors was also investigated.
- Kamal, Ahmed,Khan, M. Naseer A.,Reddy, K. Srinivasa,Srikanth,Krishnaji
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p. 3813 - 3818
(2008/02/06)
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- SO42-/SnO2: Efficient, chemoselective, and reusable catalyst for acylation of alcohols, phenols, and amines at room temperature
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SO42-/SnO2 was employed for the acylation of a variety of alcohols, phenols, and amines under solvent-free conditions at room temperature. This method showed preferential selectivity for acetylation of the amino group in the presence of a hydroxyl group. The reported method is simple, mild, and environmentally viable, using several other acid anhydrides at room temperature. Copyright Taylor & Francis Group, LLC.
- Satam, Jitendra R.,Gawande, Manoj B.,Deshpande, Sameer S.,Jayaram, Radha V.
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p. 3011 - 3020
(2008/02/12)
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- Facile catalyzed acylation of alcohols, phenols, amines and thiols based on ZrOCl2·8H2O and acetyl chloride in solution and in solvent-free conditions
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Acylation of heteroatoms (O, N and S) with acetyl chloride based on the use of a catalytic amount of the moisture stable, inexpensive ZrOCl 2?8H2O, proceeds efficiently producing the corresponding acylated products in excellent yields.
- Ghosh, Rina,Maiti, Swarupananda,Chakraborty, Arijit
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p. 147 - 151
(2007/10/03)
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- Prebiotic carbohydrate synthesis: Zinc-proline catalyzes direct aqueous aldol reactions of α-hydroxy aldehydes and ketones
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Zn-proline catalyzed aldolisation of glycoladehyde gave mainly tetroses whereas in the cross-aldolisation of glycoladehyde and rac-glyceraldehyde, pentoses accounted for 60% of the sugars formed with 20% of ribose. The Royal Society of Chemistry 2005.
- Kofoed, Jacob,Reymond, Jean-Louis,Darbre, Tamis
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p. 1850 - 1855
(2007/10/03)
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- Facile catalyzed acylation of heteroatoms using BiCl3 generated in situ from the procatalyst BiOCl and acetyl chloride
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Acylation of a variety of alcohols, phenols, aliphatic and aromatic amines, a thiol and a thiophenol proceeds efficiently using BiCl3 generated in situ from the procatalyst BiOCl and acetyl chloride in a solvent or under solventless conditions, furnishing the corresponding acylated derivatives in very good to excellent yields.
- Ghosh, Rina,Maiti, Swarupananda,Chakraborty, Arijit
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p. 6775 - 6778
(2007/10/03)
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- Adrenaline profiling of lipases and esterases with 1,2-diol and carbohydrate acetates
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The adrenaline test for enzymes is a general back-titration procedure to detect 1,2-diols, 1,2-aminoalcohols and α-hydroxyketones reaction products of enzyme catalysis by colorimetry. The method was used to profile a series of esterases and lipases for their esterolytic activity on a series of carbohydrate and polyol acetates. Substrates were prepared by peracetylation and used for parallel microtiter-plate analysis of enzyme activities. This method can be used to achieve a rapid and automated characterization of a set of enzymes during HTS screening.
- Wahler, Denis,Boujard, Olivier,Lefèvre, Fabrice,Reymond, Jean-Louis
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p. 703 - 710
(2007/10/03)
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- A new phenolic metabolite, involutone, isolated from the mushroom Paxillus involutus
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A new optically active metabolite, involutone, was found in methanol, ethanol, or n-butanol extracts of freshly collected Paxillus involutus. The structure of this compound was proved to be 5-(3,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-2-hydroxy-4-cyclopenten-1,3-dione on the basis of the spectral and chemical properties of involutone and its tetraacetyl derivative. In addition, a number of compounds of known structures such as linoleic and crotonic acids, mannitol, ergosterol, involutin, as well as methyl, ethyl, or n-butyl-β-D-glucopyranosides, and methyl, ethyl, or n-butyl linoleates, depending in both cases on the alcohol used in the extraction, were also isolated in a pure state from the mushroom.
- Antkowiak, Roza,Antkowiak, Wieslaw Z.,Banczyk, Izabela,Mikolajczyk, Lucyna
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p. 118 - 124
(2007/10/03)
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- Peracetylated 1,6-dibromo-D-glucitol as efficient precursor of 1,6-diiodo and some mono-, disubstituted and heterocyclic D-glucitol derivatives
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2,3,4,5-Tetra-O-acetyl-1,6-dibromo-1,6-dideoxy-D-glucitol (1a) obtained from D-glucitol was easily transformed into the 1,6-diiodo derivative in excellent yield (97%) by reaction with an excess of sodium iodide in refluxing butanone in 2 h. When the reaction time was prolonged to 24 h and the crude product was acetylated, 1,2,3,4,5-penta-O-acetyl-6-deoxy-6-iodo-D-glucitol and D-glucitol hexaacetate were isolated in 50 and 26% yields, respectively. The monodehalogenation then took place regioselectively at C-1. This regioselectivity allowed the synthesis of some mono- and disubstituted derivatives of D-glucitol. Thus, the peracetylated derivatives of D-glucitol, 6-bromo, 6-bromo-1-S-butyl, 6-bromo-1-S-octyl, 6-S-butyl, 6-S-butyl-1-S-octyl, 1-S-butyl, 1,6-di-S-octyl and 6-S-phenyl were synthesised in good to excellent yields. With S= as binucleophilic reagent, 1a gave mainly the thiepane derivative (75%) plus the 1-S-acetyl-2,6-anhydro-D-glucitol derivative as a by-product (10%).
- Halila, Sami,Benazza, Mohammed,Demailly, Gilles
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p. 177 - 182
(2007/10/03)
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- Lewis acid catalyzed acylation reactions: Scope and limitations
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Acylation of alcohols, thiols, and sugars were studied with a variety of Lewis acids, and it was found that Cu- and Sn(OTf)2 are very efficient in catalyzing the reaction under mild conditions. Among these two catalysts, Cu(OTf)2 was preferred because of its lower cost and relatively higher yield of the acylated product. The reaction was studied in several solvents, but CH2Cl2 was preferred. It was also observed that the present method is suitable for acylation of tertiary alcohols. Sugars were also acylated without any epimerization at the anomeric center. It is further shown here that this method is also suitable for selective acylation of primary or secondary alcohols over tertiary ones.
- Chandra, Kusum L,Saravanan,Singh, Rajesh K,Singh, Vinod K
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p. 1369 - 1374
(2007/10/03)
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- Regioselective benzylation of pentitols, tetritols, and some hexitols via their stannyl ether derivatives: Versatile synthesis of monobenzylalditols
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The xylitol, ribitol and D-arabinitol were transformed into their tributylstannyl ether derivatives by reaction with bis-tributyltin oxide [(nBu3Sn)2O I] and azeotropic removal of water. Subsequent benzyl etherification, using BnBr with solvent or under free solvent conditions, led regioselectively to primary mono-O-benzylalditol derivatives in satisfactory yields for a direct regioselective synthesis (~ 52%). This etherification when applied to tetritols and some hexitols exhibits similar behaviour. With pentitols, an analogous study carried out with the n-dibutyltin oxide [nBu2SnO (II)] as the activating reagent showed contrasting results as regards regioselectivity.
- Halila, Sami,Benazza, Mohammed,Demailly, Gilles
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p. 467 - 483
(2007/10/03)
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- Yttria-zirconia based Lewis acid: An efficient and chemoselective catalyst for acylation reactions
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Yttria-zirconia based strong Lewis acid efficiently catalyzes acylation of alcohols, amines and thiols under environmentally safe, heterogeneous reaction conditions with high selectivity and in excellent yields.
- Kumar,Pandey,Bodas,Dongare
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p. 206 - 209
(2007/10/03)
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- Impact of the central hydroxyl groups on the activity of symmetrical HIV-1 protease inhibitors derived from L-mannaric acid
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The influence of the central hydroxyl groups on the anti-viral activity of symmetrical HIV-1 protease inhibitors derived from L-mannaric acid has been examined. L-Iditol was synthesized and used as a chiral precursor for the synthesis of the corresponding inhibitor with inverted configuration at C-3 and C-4. Key intermediates were 3,4-O-isopropylidene-L-iditol and the activated L-idaric acid succinimidyI ester. The configurations of the central hydroxyl groups required for optimal inhibition of the HIV-1 protease were determined to be the C-3R and C-4R, i.e. the L-manno-configuration. Three C2-symmetric inhibitors were converted to their thiocarbonates and reduced to provide the corresponding hydroxyethyl transition-state mimics. Deletion of the C-4 hydroxyl group in these inhibitors gave no further improvement in the anti-viral activity. (C) 2000 Published by Elsevier Science Ltd.
- Wachtmeister, Johanna,Mühlman, Anna,Classon, Bj?rn,Kvarnstr?m, Ingemar,Hallberg, Anders,Samuelsson, Bertil
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p. 3219 - 3225
(2007/10/03)
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- Indium triflate: An efficient catalyst for acylation reactions
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Indium triflate is shown to be an extremely efficient catalyst for the acylation of alcohols and amines.
- Chauhan, Kamlesh K.,Frost, Christopher G.,Love, Ian,Waite, David
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p. 1743 - 1744
(2007/10/03)
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- Polyamides and polyesters containing 2,4:3,5-di-O-methylene-L-idaroyl residues
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Electrochemical oxidation of 2,4:3,5-di-O-methylene-D-gluconic acid in strong alkaline medium afforded a mixture of 2,4:3,5-di-O-methylene-D-glucaric acid 4 and 2,4:3,5-di-O-methylene-L-idaric acid 1 in a 1/8 ratio with a current efficiency of 53percent.Force-field calculations using Allinger's molecular mechanics program MM2p85 on 1 and 4 indicate that these cis-fused tetrahydro-dioxino-1,3-dioxin ring systems possess an O-inside conformation with a steric energy of 110.3 and 123.5 kJ*mol-1, respectively.Their conformation was confirmed by 400-MHz 1H- and 100-MHz 13C NMR measurements.A series of polycondensates were prepared by homogeneous solution polymerisation of 1 with an aromatic diol or aromatic diamine, which were analyzed by DSC and TGA.
- Tinnemans, A. H. A.,Budding, H. A.,Stein, F.,Venekamp, J. C.
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p. 181 - 186
(2007/10/02)
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- The Base-Catalysed Rearrangement of Dibromo Alditols via Epoxide Migration
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The reaction of 2,6-dibromo-2,6-dideoxy-D-mannitol (1) and -D-glucitol (12) with aqueous base has been studied.With potassium carbonate 1 forms epoxides which are subsequently hydrolysed to a mixture of D-mannitol and D-glucitol.The same treatment of 12 yields almost only D-glucitol.With aqueous potassium hydroxide both 1 and 12 undergo rearrangement through epoxide migration.Thus 1 is mainly converted into 2,5:3,4-dianhydro-L-altritol (10) whereas 12 yields 1,4:3,6-dianhydro-L-glucitol (18).The reactions were monitored using 13C NMR spectroscopy.
- Bock, Klaus,Castilla, Ines Maya,Lundt, Inge,Pedersen, Christian
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p. 264 - 268
(2007/10/02)
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- Structure of Brassicicolin A: A Novel Isocyanide Antibiotic from the Phylloplane Fungus Alternaria brassicicola
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Studies of the secondary metabolites produced in culture by the plant pathogenic phylloplane fungus Alternaria brassicicola (Schweinitz) Wiltshire (NRRL 1299 = ATCC 6650) have led to the isolation of brassicicolin A (6), a novel isocyanide antibiotic with potent in vitro activity against the gram-positive bacteria Bacillus subtilis and Staphylococcus aureus.Brassicicolin A is a fully acylated derivative of D-mannitol containing two D-α-hydroxyisovaleryl units, two acetyl groups, and two epimerized α-isocyanoisovaleryl units.The structure of brassicicolin A was assigned as 6 primarily trough chemical degradation studies and by NMR and mass spectral analysis of its deisocyanation product.This account represents the first report of the α-isocyanoisovaleryl group as a naturally occurring structural unit.
- Gloer, James B.,Poch, Gregory K.,Short, Diane M.,McCloskey, Deborah V.
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p. 3758 - 3761
(2007/10/02)
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- New Phenylethanoid Glycosides from Cistanche tubulosa (SCHRENK) HOOK. f. I.
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Four new phenylethanoid glycosides, tubulosides A (II), B (VI), C (VII) and D (VIII), have been isolated from Cistanche tubulosa (SCHRENK) HOOK. f. (Orobanchaceae), together with four known phenylethanoid glycosides, echinacoside (I), acteoside (III), acteoside isomer (IV) and 2'-acetylacteoside (V).The structures of II, VI, VII, and VIII were established on the basis of chemical evidence and spectral data.Compounds VII and VIII possess a triacetylrhamnosyl moiety as the terminal sugar.Keywords--Cistanche tubulosa; Orobanchaceae; parasitic plant; phenylethanoid glycoside; tubuloside A; tubuloside B; tubuloside C; tubuloside D
- Kobayashi, Hiromi,Oguchi, Hiroko,Takizawa, Nobuo,Miyase, Toshio,Ueno, Akira,el al.
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p. 3309 - 3314
(2007/10/02)
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- Structure of the Klebsiella type 10 capsular polysaccharide.
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The capsular polysaccharide from Klebsiella Type 10 was found to contain D-galactose, D-glucose, D-mannose, and D-glucuronic acid in the ratios 3:1:1:1. Acid hydrolysis of the polysaccharide gave one aldobiouronic acid, one aldotriouronic acid, one aldotetraouronic acid, and two neutral disaccharides the structures of which were established. The native and carboxyl-reduced polysaccharide have been subjected as appropriate to methylation analysis and Smith degradation. Degradation of the methylated polysaccharide with base established the identity of the sugar unit preceding the glucosyluronic acid residue. The anomeric configurations of the sugar residues were determined by oxidation of the acetylated native and carboxyl-reduced polysaccharides with chromium trioxide. Based on these studies, the hexasaccharide structure 1 has been assigned to the repeating unit of the K-10 polysaccharide.
- Sarkar,Roy
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p. 205 - 215
(2007/10/02)
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- Sesquiterpene Lactones from Ixeris tamagawaensis KITAM.
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Three new melampolide-type sesquiterpene lactones have been isolated from the methanol extract of Ixeris tamagawaensis KITAM. (Compositae) in addition to luteolin-7-glucoside, and the known sesquiterpene 8-desoxyurospermal A.The structure of the new compounds were elucidated from the spectral data and some chemical transformations.Keywords - Ixeris tamagawaensis; Compositae; sesquiterpene lactone; luteolin-7-glucoside; 8-desoxyurospermal A; ixerin A; ixerin B; ixerin C
- Asada, Hidehisa,Miyase, Toshio,Fukushima, Seigo
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p. 1724 - 1728
(2007/10/02)
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- TRITERPENE SAPONINS FROM Thalictrum minus. IV. THE STRUCTURE OF THALICOSIDE A
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The predominating saponin, which has been called thalicoside A, has been isolated from low meadow rue (Thalictrum minus).It has been established by chemical and spectral methods that thalicoside A is 3β,16β,22(S),29-tetrahydroxy-9,19-cyclo-20(S)-lanost-24-ene 3-O-β-D-galactopyranoside 29-O-β-D-glucopyranoside.
- Gromova, A. S.,Lutskii, V. I.,Semenov, A. A.,Denisenko, V. A.,Isakov, V. V.
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p. 197 - 203
(2007/10/02)
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- Synthesis of Saccharides and Related Polyhydroxylated Natural Products. 1. Simple Alditols
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A new approach to sugar synthesis is demonstrated through syntheses of tetritols, pentitols, and hexitols; titanium-catalyzed asymmetric epoxidation and a new selective opening reaction of 2,3-epoxy alcohols play essential roles.
- Katsuki, T.,Lee, A. W. M.,Ma, P.,Martin, V. S.,Masamune, S.,et al.
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p. 1373 - 1378
(2007/10/02)
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