Sol-Gel Entrapment of Escherichia coli

Whole cell bacteria have been entrapped within sol-gel silica matrices in order to perform bio-catalytic experiments. Escherichia coli have been chosen as a model for sol-gel encapsulation. Transmission electron microscopy shows that bacteria are randomly dispersed within the silica matrix and that their cellular organization is preserved. The -galactosidase activity of entrapped E. coli was studied using p-NPG as a substrate. The formation of p-nitrophenol was followed by optical absorption. These experiments show that E. coli still exhibit noticeable enzymatic activity after encapsulation in wet gels. They follow the well known Michaelis-Menten kinetic law but their activity decreases in dried xerogels.     

On the Distribution of π-Electrons into Rings of Conjugated Hydrocarbons Containing a Linear Polyacene Fragment

Summary. A method for assessing the -electron contents (EC) of rings of benzenoid hydrocarbons, based on the examination of their Kekulé structures, was recently put forward by Balaban and Randi. We now show that all hexagons belonging to a linear polyacene fragment of a conjugated hydrocarbon (not necessarily benzenoid) have mutually equal EC-values.     

Triterpene Glycosides of Astragalus and Their Genins. LXI. Occurrence of Cycloartane 6-O-Monodesmosides

Cyclosiversigenin 6-O--L-rhamnopyranoside and 6-O--D-glucopyranoside were isolated fromAstragalus coluteocarpusBoiss. (Leguminosae) andAstragalus dissectusB. Fedtsch. et N. Ivanova, respectively. Cyclosiversigenin 5-O--L-rhamnopyranoside was shown to be an artifact forAstragalus coluteocarpus.Thus, the cyclosiversigenin 6-O--D-glucopyranoside that was isolated from certainAstragalusspecies is hypothesized also to be an artifact. Glycosylation of the 6 -hydroxyl group of cycloartanes by D-glucose and D-xylose, in contrast with other substituents, does not change the low-field position of the PMR signal of the 4-CH ₃ group (1.65 2.01 ppm) that is caused by the influence of deuteropyridine directly on the 6 -hydroxyl. Obviously one of the hydroxyls of the -D-glucopyranoside or -D-xylopyranoside residues has the same effect in this instance.     

VOLATILE COMPOUNDS FROM Haplophyllum myrtifolium

The volatile fractions of the petroleum ether extract and of the alkaloid extract ofHaplophyllum myrtifoliumBoiss., endemic to Turkey, were trapped by using the Solid Phase Micro Extraction (SPME) technique and analyzed by GC/MS. Forty-seven compounds were characterized from the petroleum ether extract of the aerial parts with -caryophyllene (14.6 %), decane (11.4 %), and -phellandrene (7.0 %) as the major components. Chavibetol (21.9 %), eugenol (19.1 %), methyleugenol (10.8 %), trans-linalool oxide (7.1 %) and -cyclocitral (6.0 %) were identified as the major components among the forty-two compounds characterized in the chloroform eluate of the alkaloid extract.     

Synthesis and sorption properties of new hybrid chelating sorbents with β-alanine functional groups

A series of -aminopropylsilylated sorbents was obtained from different oxide supports (silica gels, silica fillers, macroporous glasses, alumina) and by the direct synthesis (hydrolytic polycondensation of tetraalkoxysilanes with -aminopropyltriethoxysilane). The highest degree of immobilization was achieved for silicas, while the most convenient solvent was methanol. Sorbents with -alanine functional groups were obtained by the subsequent reaction with acrylic acid. The degree of -carboxyethylation was 1.3–1.9, and the highest content of functional groups (v_COOH = 3.23 mmol g^–1) was achieved for carboxyethylated xero gel synthesized by the copolycondensation of tetraethoxysilane with -aminopropyltriethoxysilane. The sorbents containing -alanine possess a higher selectivity of Cu²⁺ ion sorption than the initial -aminopropylsilylated sorbents.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2620–2625, December, 2004.     

Influence of organic modifier and temperature on the enantiomeric separation of γ-lactams by HPLC

Summary A high-performance liquid chromatographic method is reported for the resolution of the enantiomers of a series of fused -lactams (2,7-diaza-3-oxo[3.3.0]octan-6-ones) with probable anti-HIV and anticancer activity. Resolution was achieved on a Chiralcel^® OD column, cellulose tris-(3,5-dimethylphenyl carbamate) adsorbed on macroporous silica gel; mixtures ofn-hexane and isopropyl alcohol in different proportions were used as the mobile phase. The analysis was studied at different temperatures.     

Basic studies of the influence ofβ-cyclodextrin and 2-hydroxypropylβ-cyclodextrin on the photo-oxidation reaction of phenothiazine in inclusion complexes,using fluorescence detection

The photo-oxidation reaction of phenothiazine has been studied in the presence of-cyclodextrin (-CD) and 2-hydroxypropyl-cyclodextrin (HP -CD). The influence of these organized media on the formation of the oxidation photoproduct upon UV irradiation has been investigated. Phenothiazine forms an inclusion complex with the cyclodextrins. The stoichiometry and formation constant of the complex formed with 2-hydroxypropyl -CD have been calculated using the changes of the fluorescence emission signal and of the absorbance of the drug upon inclusion. An increase of the fluorescence intensity of the photogenerated product is attained when it becomes included inside the cyclodextrin cavity.     

Substituted 1,2-Thiazetidine 1,1-Dioxides. Synthesis and Properties of N-Alkylated and N-Acylated Derivatives of 1,2-Thiazetidine-3-acetic Acid 1,1-Dioxide

Summary. 1,2-Thiazetidine-3-acetic acid 1,1-dioxide was N-alkylated using bromoacetates, and N-acylated using either acyl chlorides, protected amino acid fluorides, or N-protected amino acid NCA, which seemed to be the most universal method. Most of the obtained -sultam peptides were sensitive against humidity, they hydrolyzed forming sulfonic acids, and reactions with amines resulted in sulfonamides. Reactions of N-acylated products showed that the sulfonyl group was faster attacked than the imide structure.     

Polymorphism of Inclusion Complexes and Unsolvated Hosts. IV. Dimorphism of the Acetone Host–Guest Complex of Dianilinegossypol. Structures of the α- and β-Phase Complexes

Crystal structures of the - and -phase inclusion complexes of dianilinegossypol with acetone obtained at 20° and 30 °C, respectively, have been determined by X-ray structure analysis. Crystal data of the -phase complex are: C₄₂H₄₀O₆N₂2C₃H₆O, orthorhombic, space group Pccn, a = 29.501(9), b = 10.866(2), c = 13.756(3) Å, V = 4409(1) ų, Z = 4, D _x = 1.18 g cm^-3. The structure has been refined to a final R value of 0.117 for 1401 observed reflections. The host–guest ratio for the -phase complex is the same (1 : 2) and the crystals are monoclinic, space group C2/c, a = 28.352(6), b = 11.836(2), c = 13.196(1) Å, = 93.05(1)°, V = 4422(2) Å3, Z = 4, D _x =1.18 g cm^-3. The structure has been refined to a final R value of 0.077 for 1414 observed reflections.In both phases molecules of dianilinegossypol form hydrogen-bondedribbons by O(4)–-HO(3) H-bonds. Phases are determined by the same structural motif. In the -phase complex the cages are in the form of prisms but in the -phase clathrate they undergo a modification by shrinking in two directions and widening in one. Molecules of acetone are hydrogen bonded to the host molecules via aO(1)–-HO(G) bond and are accommodated in cavities for both complexes, i.e. both phases are cryptate-type inclusion complexes.Supplementary data relevant to this publicationhave been deposited with the British Library,No. SUP 82227 (24 pages).     

Synthesis of Ethyl cis- and trans-4-Chloro-5-oxo-1,2-diphenylpyrrolidine-2-carboxylate

Ethyl cis- and trans-4-chloro-5-oxo-1,2-diphenylpyrrolidine-2-carboxylate have been synthesized by the cyclization of ethyl N-(,-dichloropropionyl)-N-phenyl--aminophenylacetate.     

Zur Chemie des „Dinaphthyldichinhydron”

Dinaphthyldiquinhydrone (4) first obtained byStenhouse andGroves ² reacts as well as 4,4-bi-(1,2-naphthoquinone)¹ with aniline and substituted anilines to give anilinoquinones2 a-h. However, yields of2 are considerable higher if4 is used. The IR-Spectrum of4 is very similar to that of 2,11-dihydroxy-3,10-perylenquinone, therefore we suggest for4 a the structure of a 3,3-dihydroxy-4,4-dioxo-1,1, 4,4-tetrahydro-1,1-binaphthylidene, at least in the solid state.

Herrn Prof. Dr.G. Zigeuner in traditionsverbundener Freundschaft zum 60. Geburtstag gewidmet.     

4,4′-Dipyridyl and 2,2′-dipyridyl complexes of rare-earth perchlorates

4,4-Dipyridyl and 2,2-dipyridyl complexes of rare-earth perchlorates of the formulaLn(4-dipy)₈(ClO₄)₃HClO₄ · 4H₂O (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 4-dipy=4,4-dipyridyl) andLn(2-dipy)₃(ClO₄)₃ · 6H₂O (Ln=Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 2-dipy = 2,2-dipyridyl) have been synthesized. The IR spectra of these compounds and other physical properties are discussed.

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4,4-Dipyridyl- und 2,2-Dipyridylkomplexe von Seltenerdmetallperchloraten

Zusammenfassung Es wurden 4,4-Dipyridylkomplexe des TypsLn(4-dipy)₈(ClO₄)₃HClO₄ · · 4 H₂O mitLn=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y und 2,2-Dipyridylkomplexe des TypsLn(2-dipy)₃(ClO₄)₃ · 6 H₂O mitLn=Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu und Y dargestellt. Die IR-Spektren und andere physikalische Eigenschaften werden diskutiert.

     

Encapsulation of Viable Aerobic Microorganisms in Silica Gels

The aim of this study was to develop techniques to sterilise the surface of silica gels containing encapsulated cells and the liquid broth they were immersed in, so that the observed metabolic activities could be unambiguously assigned to fully encapsulated cells. Gel surfaces were sterilised by UV-irradiation daily. The surfaces of the gels and the overlaying medium remained sterile for 20 days following irradiation, as demonstrated by the lack of visible surface growth and viable cells in the medium. We report the encapsulation of a viable, metabolically active, aerobic fungus Penicillium chrysogenum, and the aerobic Gram-positive bacterium Streptomyces rimosus in gels derived from aqueous silica sols. Carbohydrate consumption (catabolism) and antibiotic biosynthesis (penicillin or oxytetracycline) (anabolism) were monitored in both cultures, demonstrating that the encapsulated cells remained viable within the gel matrix. This demonstrates that the silica gels are sufficiently porous to sustain metabolic activities of aerobic cells, which require the diffusion of oxygen and other substrates within the gels nanopore network.     

Diastereoselectivity in theLewis acid mediated aldol reaction of chiral α, β-epoxyaldehydes with a ketene silyl acetal

Summary The Lewis acid mediated aldol reaction of chiral , -cis andtrans epoxyaldehydes1 and2 withtert-butyl ketene silyl acetal proceeds mainly withanti diastereofacial preference. The best results were obtained forcis epoxyaldehyde1 in the presence of catalytic amounts of BiCl₃·1.5 eq. ZnI₂ (anti:syn 13:1), whereas the poorest stereoselectivity was observed when an excess of LiClO₄ was used (anti:syn 1:1). The more stable epoxyaldehyde conformers were determined and the diastereofacial preference was found to be in agreement with a nucleophilic attack on the energetically more favoured conformers.

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Diastereoselektivität derLewis-Säure-katalysierten Aldolreaction zwischen chiralen , -Epoxyaldehyden und einem Ketensilylacetal

Zusammenfassung DieLewis-Säure-katalysierte Aldolreaktion der chiralen , -cis- und -trans-Epoxyaldehyde1 und2 mittert-Butylketensilylacetal verläuft stereoselektivanti. Die besten Ergebnisse wurden für dencis-Epoxyaldehyd1 in Gegenwart katalytischer Mengen BiCl3·1.5 eq. Znl₂ erhalten (anti:syn 13:1). Die geringste Stereoselektivität trat auf, wenn LiClO₄ im Überschuß eingesetzt wurde (anti:syn 1:1). Das beobachtete Verhalten steht mit einem nucleophilen Angriff am energetisch günstigeren Konformeren im Einklang.

     

Condensation of 1-Substituted 5-Aminopyrazoles with β-Dicarbonyl Compounds

Condensation of N-substituted 5-aminopyrazoles with -diketones occurs with the formation of pyrazolo[4,5-b]pyridines. Depending on the conditions, their reaction with -keto acids can give either 6-oxo- or 4-oxopyrazolo[4,5-b]pyridines.     

Reaction of dibenzylphosphine oxide with α,β-unsaturated O-methyloximes

The reaction of dibenzylphosphine oxide with O-methyloximes of some ,-unsaturated ketones results in the phosphorylation at the -carbon atom to form methoxyiminophosphine oxides, whereas the reaction of dibenzylphosphine oxide with O-methyloximes of ,-unsaturated aldehydes affords aminodihydrophosphole oxides.     

Monolithic silica columns with chemically bonded β-cyclodextrin as a stationary phase for enantiomer separations of chiral pharmaceuticals

An enantioselective silica rod type chiral stationary phase (CSP) is presented; a novel combination of the well known enantiomer separation properties of -cyclodextrin and the unique properties concerning the flow behavior of silica monoliths. Two different synthesis routes are described, and it was found that the in situ modification of a plain silica rod column turned out to be the best. The chromatographic behaviour of the -cyclodextrin silica rod was studied and compared with a very similar commercially available -cyclodextrin bonded particulate material (ChiraDex^®). Even if the amount of -cyclodextrin bound to the silica rod was only about half of the amount of -cyclodextrin bound to ChiraDex^® particles, good resolutions were achieved for a set of chiral test components like Chromakalin, Prominal, Oxazepam, Methadone and some other drugs. By taking advantage of the unique features of the silica rods relating to their flat H/u (Van Deemter) curves, fast enantiomer separations could be demonstrated.     

Substituted 1,2-Thiazetidine 1,1-Dioxides. Synthesis of (<Emphasis Type="Italic">RS</Emphasis>)- and (<Emphasis Type="Italic">S</Emphasis>)-1,2-Thiazetidine-3-acetic Acid 1,1-Dioxide and its Reactions with Amino Acids and Dipeptides

Summary. (RS)-2-tert-Butyldimethylsilyl-1,2-thiazetidine-3-acetic acid 1,1-dioxide prepared from (RS)-S-benzyl--homocysteine was condensed via DCC/NHS with various L-amino acid esters or dipeptide esters yielding N-silylated -sultam peptides. A -sultam active ester was isolated as an intermediate. Desilylation with TBAF in THF yielded stable N-unsubstituted products, and deprotection of the benzyl esters was achieved by catalytic hydrogenation. (S)-S-Benzyl--homocysteine was obtained by fractional crystallization of the brucine salt of the racemate and transformed into benzyl (S)-1,2-thiazetidine-3-acetate, which was on the other hand synthesized by an enantiospecific route from -benzyl Boc-L-aspartate. Some -sultam peptides were prepared from the (S)-enantiomer, and finally some -sultam peptides containing D-Ala units were obtained.     

Synthesis of some 5′-O-amino acid derivatives of uridine as potential inhibitors ofUDP-glucuronosyltransferase

Summary In an attempt to develop potential inhibitors ofUDP-glucuronosyltransferase, some 5-O-amino acid derivatives of uridine were synthesized. N-protectedL-amino acids were coupled at the 5-O-position of 2,3-O-isopropylideneuridine by esterification employing the method of symmetrical anhydrides in presence of 4-dimethylaminopyridine, 5-O-(N-benzyloxycarbonyl-O-tert.butyl-L-threonl)-23-O-isopropylideneuridine (1), 5-O-(N-tert.butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylideneuridine and (2), 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (3), and 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (4) were obtained in good yield after column chromatography on silica gel. The treatment of2 withTFA/CH₂Cl₂ (6:1) at room temperature for 30 min led to a selective removal of theBoc group without deblocking of the 2,3-O-isopropylidene group of uridine. Treatment of2 withTFA/H₂O (5:1) at room temperature for 1 h, however, released bothBoc and 2,3-isopropylidene groups. TheZ group of1 was deprotected by catalytic hydrogenolysis over 10% Pd/C/ammonium formate.

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Synthese von 5-O-Aminosäurederivaten des Uridins als potentielle Inhibitoren derUDP-Glukuronosyl-Transferase

Zusammenfassung In einem Versuch, potentielle Inhibitoren derUDP-Glukuronosyl-Transferase zu entwickeln, wurden einige 5-O-Aminosäurederivate des Uridins synthetisiert. N-GeschützteL-Aminosäuren wurden durch Veresterung mit der 5-O-Position des 2,3-isopropylidenuridins gekuppelt (Methode der symmetrischen Anhydride in der Gegenwart von 5-Dimethylaminopyridin). Solcherweise wurden 5-O-(N-Benzyloxycarbonyl-O-tert.butyl-L-threonly)-2,3-O-isopropylidenuridin (1), 5-O-(N-tert.Butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylidenuridin (2), 5-O-(N-tert.Butyloxycarbonyl-L-leucyl)-2,3-O-isopropylidenuridin (3) und 5-O-(N-tert.Butyloxycarbonyl-L-valyl)-2,3-O-isopropylidenuridine (4) nach Säulenchromatographie (Kieselgel) in guter Ausbeute hergestellt. Die Behandlung von2 mitTFA/CH₂Cl₂ (6:1) bei Zimmertemperatur (30 min) führte zu einer selektiven Abspaltung derBoc-Gruppe ohne Deblockierung der 2,3-O-Isopropylidengruppe des Uridins. Eine Behandlung von2 mitTFA/H₂O (5:1) bei Zimmertemperatur für 1 Stunde führte hingegen zur Abspaltung sowohl derBoc als auch der 2,3-O-Isopropylidengruppe. DieZ-Gruppe von1 wurde durch katalytische Hydrogenolyse auf 10% Pd/C/Ammoniumformiat abgespalten.

     

Binding forces in complexation ofp-alkylphenols withβ-cyclodextrin and methylatedβ-cyclodextrins

Fluorescence spectroscopy has been used to determine the binding constants (K) for inclusion complexes of six kinds ofp-Akyphenols with-cyclodextrin (-CDx), heptakis(2,6-di-O-methyl)--CDx (DMe--CDxg), and heptakis(2,3,6-tri-O-methyl)--CDx (TMe--CDx). The stability of the inclusion complex of each cyclodextrin increases with increasing alkyl chain length of thep-alkylphenol. TheK values decrease in the order of DMe--CDx,-CDx, and TMe--CDx for each guest. In complexation of 3-(p-hydroxyphenyl)-1-propanol (3) with-CDx as well as with DMe--CDx, negative enthalpy (H) and positive entropy changes (S) have been obtained, suggesting both van der Waals and hydrophobic interactions as binding forces. The inclusion of 3 by TMe--CDx, however, is an enthalpically favorable but entropically unfavorable process. The van der Waals interactions may be the main binding forces for complexing3 with TMe--CDx.