Search results
Search for "cell membrane" in Full Text gives 86 result(s) in Beilstein Journal of Organic Chemistry.
An easy α-glycosylation methodology for the synthesis and stereochemistry of mycoplasma α-glycolipid antigens
- Yoshihiro Nishida,
- Yuko Shingu,
- Yuan Mengfei,
- Kazuo Fukuda,
- Hirofumi Dohi,
- Sachie Matsuda and
- Kazuhiro Matsuda
Beilstein J. Org. Chem. 2012, 8, 629–639, doi:10.3762/bjoc.8.70
- the sugar primary (6-OH) position. The fatty acids at the glycerol moiety are saturated, namely palmitic acid (C16:0) and stearic acid (C18:0). GGPL-I has a structural feature analogous to 1,2-di-O-palmitoyl phosphatidylcholine (DPPC) as a ubiquitous cell membrane phospholipid. Apparently, GGPLs are
Graphical Abstract
Figure 1: Absolute chemical structures of M. fermentans α-glycolipid antigens, GGPL-I and GGPl-III (GGPL: Gly...
Scheme 1: An established synthetic pathway to α-glycosyl-sn-glycerols 4a and 5a. A reagent combination of CBr4...
Scheme 2: Syntheses of GGPL-I homologue I-a and its isomer I-b. Conditions: (a) K2CO3, CH3OH; (b) cesium palm...
Figure 2: 1H NMR spectra of I-a and I-b (500 MHz, 25 °C, CDCl3/CD3OD 10:1). The assignment of sn-glycerol met...
Figure 3: Distributions of gg, gt and tg-conformers in 3-substituted sn-glycerols at 11 mM in solutions of CD...
Figure 4: Distributions of gg, gt and tg-conformers in 1-substituted sn-glycerols. In these sn-isomers, Φ1 an...
Figure 5: A common conformational property of GGPL-I and DPPC. The tail lipid moiety favors two gauche-confor...
Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca
- Jeroen S. Dickschat,
- Hilke Bruns and
- Ramona Riclea
Beilstein J. Org. Chem. 2011, 7, 1697–1712, doi:10.3762/bjoc.7.200
- important building blocks of biological systems. They fulfill various physiological functions, such as cell-membrane assembly or, as highly reduced carbon compounds, energy storage, and are therefore found in every single living cell on earth. In bacteria the cell membranes are mainly formed from
Graphical Abstract
Scheme 1: Fatty acid biosynthesis.
Figure 1: Volatile methyl esters from bacteria.
Figure 2: Compounds found in the headspace extracts of M. aurantiaca.
Figure 3: Total ion chromatograms of the headspace extract from M. aurantiaca (A), and expansions of the tota...
Figure 4: FAMEs identified in the headspace extracts from M. aurantiaca.
Figure 5: Mass spectra of (A) methyl dodecanoate (83), (B) methyl 2-methyldodecanoate (10), (C) methyl 4-meth...
Scheme 2: McLafferty fragmentation of FAMEs.
Figure 6: The functional group increment FG(n)FAME, HP-5 MS.
Scheme 3: Synthesis of FAMEs identified from M. aurantiaca.
Scheme 4: Synthesis of the γ- and (ω−3)-methyl branched FAME 114.
Figure 7: Mass spectra of tentatively identified methyl 4,8-dimethyldodecanoate (115) and methyl 8-ethyl-4-me...
Coupled chemo(enzymatic) reactions in continuous flow
- Ruslan Yuryev,
- Simon Strompen and
- Andreas Liese
Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169
- molecules when whole cells are applied as biocatalysts. Instead, the cofactors are kept in the cytoplasm by the cell membrane, which functions as a natural and efficient diffusion barrier. Moreover, the enzymes are usually more stable in their native environment inside a living cell than they are in buffer
- stability. The multistep microbial biotransformations are also feasible for the continuous processes that do not require cofactor regeneration. Nöthe and coworkers developed a whole-cell membrane reactor operated in CSTR mode, with continuous product removal by ultrafiltration, for the microbial conversion
Graphical Abstract
Figure 1: Metabolic pathways in a living cell as an example of efficient coupled-reaction processes. A: Subst...
Figure 2: Four generations of biotransformations. I: Single-reaction processes; II: Single-reaction processes...
Scheme 1: Production of L-leucine (3) in a continuously operating enzyme membrane reactor (EMR). E1: L-Leucin...
Scheme 2: Production of D-mandelic acid (5) in a continuously operating enzyme membrane reactor. E1: D-(−)-Ma...
Scheme 3: Simultaneous synthesis of gluconic acid (9) and glutamic acid (8) in a continuously operated membra...
Scheme 4: Production of L-tert-leucine (11) in a continuously operated enzyme membrane reactor equipped with ...
Scheme 5: Continuous oxidation of lactose (12) to lactobionic acid (13) in a dynamic membrane-aerated reactor...
Scheme 6: Production of N-acetylneuraminic acid (17) in a continuously operated enzyme membrane reactor. E1: ...
Scheme 7: Chemo-enzymatic epoxidation of 1-methylcyclohexene (18) in a packed-bed reactor (PBR) containing No...
Scheme 8: Continuous production of (R)-1-phenylethyl propionate (24) by dynamic kinetic resolution of (rac)-1...
Scheme 9: Synthesis of D-xylulose (28) from D,L-serine (26) and D,L-glyceraldehyde (25) in a continuously ope...
Scheme 10: Continuous production of L-alanine (31) from fumarate (29) in a two-stage enzyme membrane reactor. ...
Scheme 11: Continuous synthesis of 1-phenyl-(1S,2S)-propanediol (35) in a cascade of two enzyme membrane react...
Scheme 12: Production of a dipeptide 39 in a cascade of two continuously operated membrane reactors. E1: Carbo...
Scheme 13: Continuous production of GDP-mannose (43) from mannose 1-phosphate (40) in a cascade of two enzyme ...
Scheme 14: Continuous solvent-free chemo-enzymatic synthesis of ethyl (S)-3-(benzylamino)butanoate (48) in a s...
Scheme 15: Continuous chemo-enzymatic synthesis of grossamide (52) in a cascade of packed-bed reactors. E: Per...
Scheme 16: Chemo-enzymatic synthesis of 2-aminophenoxazin-3-one (56) in a cascade of continuously operating pa...
Scheme 17: Continuous conversion of 3-phospho-D-glycerate (57) into D-ribulose 1,5-bisphosphate (58) in a casc...
Scheme 18: Continuous hydrolysis of 4-cyanopyridine (59) to isonicotinic acid (61) in a cascade of two packed-...
Scheme 19: Continuous fermentative production of ethanol (64) from hardwood lignocellulose (62) in a stirred-t...
Scheme 20: Production of hydrogen by anaerobic fermentation of glucose (7) using Clostridium acetobutylicum ce...
Scheme 21: Continuous production of (2R,5R)-hexanediol (67) in an enzyme membrane reactor containing whole cel...
Scheme 22: Synthesis of L-phenylalanine (69) in a continuously stirred tank reactor equipped with a hollow-fib...
Scheme 23: Continuous epoxidation of 1,7-octadiene (70) to (R)-7-epoxyoctene (72) by a strain of Pseudomonas o...
Scheme 24: Oxidation of styrene (73) to (S)-styrene oxide (74) in a continuously operated biofilm tube reactor...
Scheme 25: Reduction of estrone (75) to β-estradiol (76) by Saccharomyces cerevisiae in a cascade of two stirr...
Pyridinium based amphiphilic hydrogelators as potential antibacterial agents
- Sayanti Brahmachari,
- Sisir Debnath,
- Sounak Dutta and
- Prasanta Kumar Das
Beilstein J. Org. Chem. 2010, 6, 859–868, doi:10.3762/bjoc.6.101
- properties to amphiphilic molecules [28][29][30][31]. The cationic charge of the amphiphile plays an instrumental role in disrupting the innate defense mechanism of microorganisms by disrupting the microbial cell membrane [32][33]. Hence, it would be interesting to develop amphiphilic hydrogelators that have
- positively charged amphiphiles are presumably adsorbed on the negatively charged cell membrane of microbes due to electrostatic interaction. This interaction is also entropically favorable as huge numbers of counterions are released. Next, the hydrophobic chain penetrates the hydrophobic cell membrane by
Graphical Abstract
Figure 1: Structure of amphiphiles 1–5.
Scheme 1: Synthetic procedure of the amphiphiles.
Figure 2: Variation of the Tgel with concentration of amphiphiles 1 and 2.
Figure 3: (a, b) FESEM images of the dried gels of 1 and 2, respectively at their MGC. (c, d) Two- and three-...
Figure 4: Luminescence spectra of 2 in water (λex = 330 nm) at various concentrations and room temperature.
Figure 5: FTIR spectra of (a) 1 and (b) 2 in CHCl3 solution (dashed line) and in D2O at the gel state (solid ...
Figure 6: 2D-NOESY spectra of 2 (2%, w/v) in DMSO-d6 with 70% water.
Figure 7: XRD diagram of the dried gel of 2.
Figure 8: Schematic representation of the possible arrangement of molecules during hydrogelation of 2.
Figure 9: MTT assay based percent NIH3T3 cell viability as a function of concentration of amphiphile 2.
Molecular recognition of organic ammonium ions in solution using synthetic receptors
- Andreas Späth and
- Burkhard König
Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32
Graphical Abstract
Figure 1: Biologically important amines and quaternary ammonium salts: histamine (1), dopamine (2) and acetyl...
Figure 2: Crown ether 18-crown-6.
Figure 3: Conformations of 18-crown-6 (4) in solvents of different polarity.
Figure 4: Binding topologies of the ammonium ion depending on the crown ring size.
Figure 5: A “pseudorotaxane” structure consisting of 24-crown-8 and a secondary ammonium ion (5); R = Ph.
Figure 6: Typical examples of azacrown ethers, cryptands and related aza macrocycles.
Figure 7: Binding of ammonium to azacrown ethers and cryptands [111-113].
Figure 8: A 19-crown-6-ether with decalino blocking groups (11) and a thiazole-dibenzo-18-crown-6-ether (12).
Figure 9: 1,3-Bis(6-oxopyridazin-1-yl)propane derivatives 13 and 14 by Campayo et al.
Figure 10: Fluorescent azacrown-PET-sensors based on coumarin.
Figure 11: Two different pyridino-cryptands (17 and 18) compared to a pyridino-crown (19); chiral ammonium ion...
Figure 12: Pyridino-18-crown-6 ligand (21), a similar acridino-18-crown-6 ligand (22) and a structurally relat...
Figure 13: Ciral pyridine-azacrown ether receptors 24.
Figure 14: Chiral 15-crown-5 receptors 26 and an analogue 18-crown-6 ligand 27 derived from amino alcohols.
Figure 15: C2-symmetric chiral 18-crown-6 amino alcohol derivatives 28 and related macrocycles.
Figure 16: Macrocycles with diamide-diester groups (30).
Figure 17: C2-symmetric chiral aza-18-crown-6 ethers (31) with phenethylamine residues.
Figure 18: Chiral C-pivot p-methoxy-phenoxy-lariat ethers.
Figure 19: Chiral lariat crown ether 34.
Figure 20: Sucrose-based chiral crown ether receptors 36.
Figure 21: Permethylated fructooligosaccharide 37 showing induced-fit chiral recognition.
Figure 22: Biphenanthryl-18-crown-6 derivative 38.
Figure 23: Chiral lariat crown ethers derived from binol by Fuji et al.
Figure 24: Chiral phenolic crown ether 41 with “aryl chiral barriers” and guest amines.
Figure 25: Chiral bis-crown receptor 43 with a meso-ternaphthalene backbone.
Figure 26: Chromogenic pH-dependent bis-crown chemosensor 44 for diamines.
Figure 27: Triamine guests for binding to receptor 44.
Figure 28: Chiral bis-crown phenolphthalein chemosensors 46.
Figure 29: Crown ether amino acid 47.
Figure 30: Luminescent receptor 48 for bis-alkylammonium guests.
Figure 31: Luminescent CEAA (49a), a bis-CEAA receptor for amino acids (49b) and the structure of lysine bindi...
Figure 32: Luminescent CEAA tripeptide for binding small peptides.
Figure 33: Bis crown ether 51a self assembles co-operatively with C60-ammonium ion 51b.
Figure 34: Triptycene-based macrotricyclic dibenzo-[24]-crown-8 ether host 52 and guests.
Figure 35: Copper imido diacetic acid azacrown receptor 53a and the suggested His-Lys binding motif; a copper ...
Figure 36: Urea (54) and thiourea (55) benzo crown receptor for transport and extraction of amino acids.
Figure 37: Crown pyryliums ion receptors 56 for amino acids.
Figure 38: Ditopic sulfonamide bridged crown ether receptor 57.
Figure 39: Luminescent peptide receptor 58.
Figure 40: Luminescent receptor 59 for the detection of D-glucosamine hydrochloride in water/ethanol and lumin...
Figure 41: Guanidinium azacrown receptor 61 for simple amino acids and ditopic receptor 62 with crown ether an...
Figure 42: Chiral bicyclic guanidinium azacrown receptor 63 and similar receptor 64 for the enantioselective t...
Figure 43: Receptors for zwitterionic species based on luminescent CEAAs.
Figure 44: 1,10-Azacrown ethers with sugar podand arms and the anticancer agent busulfan.
Figure 45: Benzo-18-crown-6 modified β-cyclodextrin 69 and β-cyclodextrin functionalized with diaza-18-crown-6...
Figure 46: Receptors for colorimetric detection of primary and secondary ammonium ions.
Figure 47: Porphyrine-crown-receptors 72.
Figure 48: Porphyrin-crown ether conjugate 73 and fullerene-ammonium ion guest 74.
Figure 49: Calix[4]arene (75a), homooxocalix[4]arene (75b) and resorcin[4]arene (75c) compared (R = H, alkyl c...
Figure 50: Calix[4]arene and ammonium ion guest (R = H, alkyl, OAcyl etc.), possible binding sites; A: co-ordi...
Figure 51: Typical guests for studies with calixarenes and related molecules.
Figure 52: Lower rim modified p-tert-butylcalix[5]arenes 82.
Figure 53: The first example of a water soluble calixarene.
Figure 54: Sulfonated water soluble calix[n]arenes that bind ammonium ions.
Figure 55: Displacement assay for acetylcholine (3) with a sulfonato-calix[6]arene (84b).
Figure 56: Amino acid inclusion in p-sulfonatocalix[4]arene (84a).
Figure 57: Calixarene receptor family 86 with upper and lower rim functionalization.
Figure 58: Calix[6]arenes 87 with one carboxylic acid functionality.
Figure 59: Sulfonated calix[n]arenes with mono-substitution at the lower rim systematically studied on their r...
Figure 60: Cyclotetrachromotropylene host (91) and its binding to lysine (81c).
Figure 61: Calixarenes 92 and 93 with phosphonic acids groups.
Figure 62: Calix[4]arene tetraphosphonic acid (94a) and a double bridged analogue (94b).
Figure 63: Calix[4]arene tetraphosphonic acid ester (92c) for surface recognition experiments.
Figure 64: Calixarene receptors 95 with α-aminophosphonate groups.
Figure 65: A bridged homocalix[3]arene 95 and a distally bridged homocalix[4]crown 96.
Figure 66: Homocalix[3]arene ammonium ion receptor 97a and the Reichardt’s dye (97b) for colorimetric assays.
Figure 67: Chromogenic diazo-bridged calix[4]arene 98.
Figure 68: Calixarene receptor 99 by Huang et al.
Figure 69: Calixarenes 100 reported by Parisi et al.
Figure 70: Guest molecules for inclusion in calixarenes 100: DAP × 2 HCl (101a), APA (101b) and Lys-OMe × 2 HC...
Figure 71: Different N-linked peptido-calixarenes open and with glycol chain bridges.
Figure 72: (S)-1,1′-Bi-2-naphthol calixarene derivative 104 published by Kubo et al.
Figure 73: A chiral ammonium-ion receptor 105 based on the calix[4]arene skeleton.
Figure 74: R-/S-phenylalaninol functionalized calix[6]arenes 106a and 106b.
Figure 75: Capped homocalix[3]arene ammonium ion receptor 107.
Figure 76: Two C3 symmetric capped calix[6]arenes 108 and 109.
Figure 77: Phosphorous-containing rigidified calix[6]arene 110.
Figure 78: Calix[6]azacryptand 111.
Figure 79: Further substituted calix[6]azacryptands 112.
Figure 80: Resorcin[4]arene (75c) and the cavitands (113).
Figure 81: Tetrasulfonatomethylcalix[4]resorcinarene (114).
Figure 82: Resorcin[4]arenes (115a/b) and pyrogallo[4]arenes (115c, 116).
Figure 83: Displacement assay for acetylcholine (3) with tetracyanoresorcin[4]arene (117).
Figure 84: Tetramethoxy resorcinarene mono-crown-5 (118).
Figure 85: Components of a resorcinarene based displacement assay for ammonium ions.
Figure 86: Chiral basket resorcin[4]arenas 121.
Figure 87: Resorcinarenes with deeper cavitand structure (122).
Figure 88: Resorcinarene with partially open deeper cavitand structure (123).
Figure 89: Water-stabilized deep cavitands with partially structure (124, 125).
Figure 90: Charged cavitands 126 for tetralkylammonium ions.
Figure 91: Ditopic calix[4]arene receptor 127 capped with glycol chains.
Figure 92: A calix[5]arene dimer for diammonium salt recognition.
Figure 93: Calixarene parts 92c and 129 for the formation molecular capsules.
Figure 94: Encapsulation of a quaternary ammonium cation by two resorcin[4]arene molecules (NMe4+@[75c]2 × Cl−...
Figure 95: Encapsulation of a quaternary ammonium cation by six resorcin[4]arene molecules (NMe3D+@[130]6 × Cl−...
Figure 96: Structure and schematic of cucurbit[6]uril (CB[6], 131a).
Figure 97: Cyclohexanocucurbit[6]uril (CB′[6], 132) and the guest molecule spermine (133).
Figure 98: α,α,δ,δ-Tetramethylcucurbit[6]uril (134).
Figure 99: Structure of the cucurbituril-phthalhydrazide analogue 135.
Figure 100: Organic cavities for the displacement assay for amine differentiation.
Figure 101: Displacement assay methodology for diammonium- and related guests involving cucurbiturils and some ...
Figure 102: Nor-seco-Cucurbituril (±)-bis-ns-CB[6] (140) and guest molecules.
Figure 103: The cucurbit[6]uril based complexes 141 for chiral discrimination.
Figure 104: Cucurbit[7]uril (131c) and its ferrocene guests (142) opposed.
Figure 105: Cucurbit[7]uril (131c) guest inclusion and representative guests.
Figure 106: Cucurbit[7]uril (131c) binding to succinylcholine (145) and different bis-ammonium and bis-phosphon...
Figure 107: Paraquat-cucurbit[8]uril complex 149.
Figure 108: Gluconuril-based ammonium receptors 150.
Figure 109: Examples of clefts (151a), tweezers (151b, 151c, 151d) and clips (151e).
Figure 110: Kemp’s triacid (152a), on example of Rebek’s receptors (152b) and guests.
Figure 111: Amino acid receptor (154) by Rebek et al.
Figure 112: Hexagonal lattice designed hosts by Bell et al.
Figure 113: Bell’s amidinium receptor (156) and the amidinium ion (157).
Figure 114: Aromatic phosphonic acids.
Figure 115: Xylene phosphonates 159 and 160a/b for recognition of amines and amino alcohols.
Figure 116: Bisphosphonate recognition motif 161 for a colorimetric assay with alizarin complexone (163) for ca...
Figure 117: Bisphosphonate/phosphate clip 164 and bisphosphonate cleft 165.
Figure 118: N-Methylpyrazine 166a, N-methylnicotinamide iodide (166b) and NAD+ (166c).
Figure 119: Bisphosphate cavitands.
Figure 120: Bisphosphonate 167 of Schrader and Finocchiaro.
Figure 121: Tweezer 168 for noradrenaline (80b).
Figure 122: Different tripods and heparin (170).
Figure 123: Squaramide based receptors 172.
Figure 124: Cage like NH4+ receptor 173 of Kim et al.
Figure 125: Ammonium receptors 174 of Chin et al.
Figure 126: 2-Oxazolin-based ammonium receptors 175a–d and 176 by Ahn et al.
Figure 127: Racemic guest molecules 177.
Figure 128: Tripods based on a imidazole containing macrocycle (178) and the guest molecules employed in the st...
Figure 129: Ammonium ion receptor 180.
Figure 130: Tetraoxa[3.3.3.3]paracyclophanes 181 and a cyclophanic tetraester (182).
Figure 131: Peptidic bridged paraquat-cyclophane.
Figure 132: Shape-selective noradrenaline host.
Figure 133: Receptor 185 for binding of noradrenaline on surface layers from Schrader et al.
Figure 134: Tetraphosphonate receptor for binding of noradrenaline.
Figure 135: Tetraphosphonate 187 of Schrader and Finocchiaro.
Figure 136: Zinc-Porphyrin ammonium-ion receptors 188 and 189 of Mizutani et al.
Figure 137: Zinc porphyrin receptor 190.
Figure 138: Zinc porphyrin receptors 191 capable of amino acid binding.
Figure 139: Zinc-porphyrins with amino acid side chains for stereoinduction.
Figure 140: Bis-zinc-bis-porphyrin based on Tröger’s base 193.
Figure 141: BINAP-zinc-prophyrin derivative 194 and it’s guests.
Figure 142: Bisaryl-linked-zinc-porphyrin receptors.
Figure 143: Bis-zinc-porphyrin 199 for diamine recognition and guests.
Figure 144: Bis-zinc-porphyrin crown ether 201.
Figure 145: Bis-zinc-porphyrin 202 for stereodiscrimination (L = large substituent; S = small substituent).
Figure 146: Bis-zinc-porphyrin[3]rotaxane and its copper complex and guests.
Figure 147: Dien-bipyridyl ligand 206 for co-ordination of two metal atoms.
Figure 148: The ligand and corresponding tetradentate co-complex 207 serving as enantioselective receptor for a...
Figure 149: Bis(oxazoline)–copper(II) complex 208 for the recognition of amino acids in aqueous solution.
Figure 150: Zinc-salen-complexes 209 for the recognition tertiary amines.
Figure 151: Bis(oxazoline)–copper(II) 211 for the recognition of amino acids in aqueous solution.
Figure 152: Zn(II)-complex of a C2 terpyridine crown ether.
Figure 153: Displacement assay and receptor for aspartate over glutamate.
Figure 154: Chiral complex 214 for a colorimetric displacement assay for amino acids.
Figure 155: Metal complex receptor 215 with tripeptide side arms.
Figure 156: A sandwich complex 216 and its displaceable dye 217.
Figure 157: Lanthanide complexes 218–220 for amino acid recognition.
Figure 158: Nonactin (221), valinomycin (222) and vancomycin (223).
Figure 159: Monesin (224a) and a chiral analogue for enantiodiscrimination of ammonium guests (224b).
Figure 160: Chiral podands (226) compared to pentaglyme-dimethylether (225) and 18-crown-6 (4).
Figure 161: Lasalocid A (228).
Figure 162: Lasalocid derivatives (230) of Sessler et al.
Figure 163: The Coporphyrin I tetraanion (231).
Figure 164: Linear and cyclic peptides for ammonium ion recognition.
Figure 165: Cyclic and bicyclic depsipeptides for ammonium ion recognition.
Figure 166: α-Cyclodextrin (136a) and novocaine (236).
Figure 167: Helical diol receptor 237 by Reetz and Sostmann.
Figure 168: Ammonium binding spherand by Cram et al. (238a) and the cyclic[6]metaphenylacetylene 238b in compar...
Figure 169: Receptor for peptide backbone and ammonium binding (239).
Figure 170: Anion sensor principle with 3-hydroxy-2-naphthanilide of Jiang et al.
Figure 171: 7-bromo-3-hydroxy-N-(2-hydroxyphenyl)naphthalene 2-carboxamide (241) and its amine binding.
Figure 172: Naturally occurring catechins with affinity to quaternary ammonium ions.
Figure 173: Spiropyran (244) and merocyanine form (244a) of the amino acid receptors of Fuji et al.
Figure 174: Coumarin aldehyde (245) and its iminium species with amino acid bound (245a) by Glass et al.
Figure 175: Coumarin aldehyde appended with boronic acid.
Figure 176: Quinolone aldehyde dimers by Glass et al.
Figure 177: Chromogenic ammonium ion receptors with trifluoroacetophenone recognition motifs.
Figure 178: Chromogenic ammonium ion receptor with trifluoroacetophenone recognition motif bound on different m...
Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid
- Arne Homann,
- Riaz-ul Qamar,
- Sevnur Serim,
- Petra Dersch and
- Jürgen Seibel
Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24
- , functionalized carbohydrates both in vitro and in vivo [2][3]. Acetylated monosaccharides, for example 2-azidoacetylamino-2-deoxy-1,3,4,6-tetraacetyl-β-D-glucopyranoside (Ac4GlcNAz, 16), are believed to permeate the cell membrane by diffusion processes [4]. Recently, it was reported that neuraminic acid
Graphical Abstract
Scheme 1: The natural forms of sialic acids, human N-acetylneuraminic acid (Neu5Ac, 1) and mammalian N-glycol...
Scheme 2: Synthesis of N-(1-oxohex-5-ynyl)neuraminic acid (Neu5Hex 3).
Scheme 3: Metabolic pathway of Ac4GlcNAz and the genetic control of Neu5Ac 1 synthesis by feedback inhibition...
Scheme 4: Proposed metabolic pathway of Neu5Hex 3 based on known mechanisms of Neu5Gc 2 uptake [5]. TGN: trans-G...
Scheme 5: Labelling of alkynylated neuraminic acid by azido-fluorescein.
Figure 1: Top left: HEp-2 cells incorporated with Ac4GlcNAz 16, labelled with alkynylated TAMRA at 580 nm. Bo...
(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties
- José L. Jiménez Blanco,
- Fernando Ortega-Caballero,
- Carmen Ortiz Mellet and
- José M. García Fernández
Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20
- resistant to nucleases [91][92] and the positive charge may give rise to cell membrane permeability through electrostatic attraction with the negatively charged groups of the proteoglycans at the cell surface. Using this strategy, Bruice and co-workers synthesised ribonucleic guanidine (RNG) and
Graphical Abstract
Figure 1: Schematic representation of sugar aminoacids (SAAs) and (pseudo)amide oligosaccharide mimetics.
Figure 2: Natural SAAs structures and natural nucleosidic antibiotics.
Scheme 1: Synthetic route to the target amide-linked sialooligomers. (a) Fmoc-Cl, NaHCO3, H2O, dioxane, 0 °C....
Figure 3: The general structure of glycoamino acids and their corresponding oligomers.
Figure 4: Conformational analysis of the β(1→2)-amide-linked glucooligomer 9.
Figure 5: Short oligomeric chains of C-glycosyl D-arabino THF amino acid oligomers.
Figure 6: (A) Stereoview of the minimized structure of compound 16 (produced by a 500 ps simulation) that mos...
Figure 7: Structures of linear oxetane-β- and δ-SAA homo-oligomers 19–20.
Figure 8: 10-Membered ring H-bonds in compound 21 consistent with NMR and modelling investigations.
Figure 9: General structure of carbopeptoid-oligonucleotide conjugates.
Figure 10: Protected derivatives of 2,6-diamino-2,6-dideoxy-β-D-glucopyranosyl carboxylic acid 22 and 23.
Figure 11: Cyclic homo-oligomers containing glucopyranoid-SAAs.
Scheme 2: Strategy for solid-phase synthesis of cyclic trimers and tetramers containing pyranoid δ-SAAs.
Figure 12: Cyclic tetramers of L-rhamno- and D-gulo-configured oxetane-SAAs.
Figure 13: Aminoglycosidic antibiotics of the glycocinnamoylspermidine family.
Scheme 3: Synthesis of (thio)trehazoline, via triflate, from β-hydroxy(thio)urea.
Figure 14: Approaches to access pseudoamide-type oligosaccharide mimics.
Figure 15: Calystegine B2 analogues 38 and 39 with urea-linked disaccharide structure.
Figure 16: Rotameric equilibrium shift of 40 by formation of a bidentate hydrogen bond.
Figure 17: Nucleotide analogues with thiourea and S-methylisothiouronium linkers.
Scheme 4: Retrosynthetic approach to synthesize thiourea-linked glycooligomers.
Figure 18: Rotameric equilibria for β-(1→6)-thiourea-linked glucodimer 41.
Figure 19: Schematic representation of (a) cyclodextrin (CDs) and (b) cyclotrehalan (CTs) family members.
Scheme 5: Synthesis of guanidine-linked pseudodisaccharides via carbodiimide.
Figure 20: β(1→6)-Guanidine-linked pseudodi- and pseudotrisaccharides 47 and 48.
Scheme 6: Synthesis of N-benzylguanidine-linked CT2 50.
Figure 21: Structure of RNG and DNG.
Figure 22: Preparation of Fmoc-guanidinium derivatives.
Figure 23: Structures of the homo-oligomeric RNG derivatives 51–55.
Figure 24: Phosphoramidite building block 56.
Figure 25: Structures of DNGs 57–65.
Figure 26: Structure of the phosphoramidite building block 66.
Sordarin, an antifungal agent with a unique mode of action
- Huan Liang
Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31
- fungi by stabilizing the ribosome/EF2 complex. This mode of action is in contrast to typical antifungals, which target the cell membrane. This unusual bioactivity makes sordarin a promising candidate for the development of new fungicidal agents, and provided the motivation for extensive research. Three
- integrity of the cell membrane through binding of ergosterol or inhibition of its biosynthesis [2][7], sordarin acts on elongation factor 2 (EF2). This enzyme catalyzes the translocation of the ribosome along mRNA during elongation of the emerging polypeptide chain [8]. Sordarin inhibits this translocation
Graphical Abstract
Figure 1: Therapeutic antifungal agents.
Figure 2: Structure of sordarin (1) and sordaricin (2).
Scheme 1: Kato’s retrosynthetic plan.
Scheme 2: Synthesis of cyclopentadiene 13.
Scheme 3: Synthesis of sordaricin methyl ester.
Scheme 4: Mander’s retrosynthetic plan.
Scheme 5: Synthesis of iodo compound 27.
Scheme 6: Synthesis of sordaricin (2).
Scheme 7: Retrosynthesis of sordarin and sordaricin.
Scheme 8: Synthesis of ketone 43.
Scheme 9: Synthesis of β-keto ethyl ester 45.
Scheme 10: Synthesis of tetracyclic framework 52.
Scheme 11: Synthesis of sordaricin and sordarin.
Figure 3: Modifications of glycosyl part.
Scheme 12: Simplified model of sordarin.
Scheme 13: Synthesis of cyclopentane analog precursors.
Scheme 14: Synthesis of six cyclopentane analogs.
Scheme 15: Retrosynthetic plan of sordarin analog.
Scheme 16: Synthesis of sordarin analog 98.
Scheme 17: Synthesis of sordarin analog 103.
Trifluoromethyl ethers – synthesis and properties of an unusual substituent
- Frédéric R. Leroux,
- Baptiste Manteau,
- Jean-Pierre Vors and
- Sergiy Pazenok
Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13
- at the oxygen-adjacent position [71]. Conclusion In the life science field, single fluorine atoms, trifluoromethyl or trifluoromethoxy groups are used to tailor pKa values, to facilitate cell membrane penetration and to increase the metabolic stability of compounds. These features of fluorine
Graphical Abstract
Figure 1: OCF3-bearing pesticides.
Scheme 1: Preparation of trifluoromethyl ethers via a chlorination/fluorination sequence.
Scheme 2: Preparation of trifluoromethyl ethers via an in situ chlorination/fluorination sequence.
Scheme 3: Preparation of trifluoromethyl ethers via chlorothionoformates.
Scheme 4: Preparation of trifluoromethyl ethers via fluoroformates.
Scheme 5: Oxidative desulfurization-fluorination toward trifluoromethyl ethers.
Scheme 6: Mechanism of the oxidative desulfurization-fluorination.
Scheme 7: Umemoto's O-(trifluoromethyl)dibenzofuranium salts 4 as CF3-transfer agents.
Scheme 8: Togni's approach using hypervalent iodine compounds as CF3-transfer agents.
Scheme 9: TAS OCF3 as a nucleophilic OCF3-transfer agent.
Figure 2: Mesomeric structures of the OCF3-group.
Figure 3: Structures of 6 and 7.
Figure 4: Conformational preference of the trifluoromethoxy group on aryl rings.
Scheme 10: Nitration of trifluoromethoxy benzene.
Scheme 11: Synthesis and Nitration of N-Acetyl-(trifluoromethoxy)anilines.
Scheme 12: Bromine/lithium exchange of bromo(trifluoromethoxy)benzenes.
Scheme 13: Metalation of (trifluoromethoxy)benzene.
Scheme 14: Metalation of (trifluoromethoxy)naphthalenes.
Scheme 15: Competition between -CF3- and -OCF3 in Metalation reactions.
Scheme 16: Competition between -F- and -OCF3 in Metalation reactions.
Scheme 17: Metalation of trifluoromethoxyanisoles.
Figure 5: Direction of π-polarization depending on the substituent as described by Schlosser et al. [57].
Scheme 18: Metalation of Bromo(trifluoromethoxy)benzenes.
Scheme 19: Aryne formation from bromo(trifluoromethoxy)phenyllithiums and subsequent Diels-Alder cycloaddition...
Scheme 20: Metalation of (trifluoromethoxy)anilines.
Stereoselective synthesis of (2S,3S,4Z)-4-fluoro- 1,3-dihydroxy- 2-(octadecanoylamino)octadec- 4-ene, [(Z)-4-fluoroceramide], and its phase behavior at the air/water interface
- Gergana S. Nikolova and
- Günter Haufe
Beilstein J. Org. Chem. 2008, 4, No. 12, doi:10.3762/bjoc.4.12
- -position. While the primary OH group is functionalized with a carbohydrate, a phosphate, sulfate, etc. the 3-OH group is free for various interactions with other constituents of the cell membrane such as cholesterol or proteins [1][26]. The nature of these interactions among other factors depends on the
- configuration (2S,3S) of the products is controlled by the chiral auxiliary. In recent years several studies on cell membrane lipid models suggested that ceramide could act indirectly as a messenger by modulation of membrane properties. The membrane lipids (mostly sphingomyelin) together with cholesterol are
Graphical Abstract
Figure 1: Natural sphingosines 1a, 2a and synthesized fluorinated analogues 1b, 2b.
Scheme 1: Synthesis of 4-fluorosphingosine (2b); Reagents: i ClTi(OEt)3/Et3N, CH2Cl2, 13 h, 0 °C; ii 15% aq c...
Scheme 2: Mechanism of the aldol reaction.
Figure 2: Favorable conformations of the tert-butyl amino acid ester 7.
Figure 3: π–A Isotherms of ceramide (2a) and 4-fluoroceramide (2b) at 20 °C (80 cm2/min compression velocity)....
Figure 4: Cycles of compression and expansion for ceramide (2a) and 4-fluoroceramide (2b).
Colchitaxel, a coupled compound made from microtubule inhibitors colchicine and paclitaxel
- Karunananda Bombuwala,
- Thomas Kinstle,
- Vladimir Popik,
- Sonal O. Uppal,
- James B. Olesen,
- Jose Viña and
- Carol A. Heckman
Beilstein J. Org. Chem. 2006, 2, No. 13, doi:10.1186/1860-5397-2-13
- reactions are summarized in Scheme 2. Estimation of Partition Coefficients In order to estimate the extent to which colchitaxel may be able to permeate the cell membrane, logP values computed for the new compound were compared with those of the starting compounds. Its logP values were somewhat higher but
Graphical Abstract
Scheme 1: Reagents and conditions for synthesis of N-glutaryl-deacetylcolchicine. The reagents used at each s...
Scheme 2: Reagents and conditions for protection of paclitaxel and coupling to N-glutaryl-deacetylcolchicine ...
Figure 1: Microtubule arrangement as visualized by immunofluorescence localization of β-tubulin. Cells were t...
Figure 2: Projections of a VRO showing + ends localized by antibody against EB1 in a control cell. Cell was t...
Figure 3: Projections of a VRO showing + ends localized by antibody against EB1 in colchitaxel-treated cell. ...
Figure 4: Microtubule arrangement as visualized by immunofluorescence localization of β-tubulin. Cells were t...
