Rapid determination of90Sr by Compton suppression gamma-ray spectrometry

This work presents a low-level background gamma spectrometry system capable of achieving rapid determination of⁹⁰Sr without chemical separation, in a soil sample when the⁹⁰Sr to -ray emitting nuclide concentration ratio exceeds 10. The system consists of a highly efficient HPGe central detector operated in coincidence or anticoincidence with a NaI(Tl) guard detector and a NaI(Tl) backscatter detector. Experimental results indicate that the bremstrahlung radiation from a pure -emitter can be distinguished with respect to the differences in normal and coincidence spectra. The⁹⁰Sr activity can be directly detemined in the sample in less than 1 hour with a minimum detectable concentration (MDC) estimated at 0.002 Bq·g^–1 for a sample containing no appreciable -ray nuclides or other high energy, -emitting nuclides. In actual measurement, a 0.06 Bq·g^–1 MDC for contaminated soils is achieved.     

90Sr in lake sediments

For a better understanding of the behaviour of⁹⁰Sr in aquatic systems, this -emitter has been determined in the different layers of a lake sediment core which has been previously dated using the well established²¹⁰Pb dating method. For this, a radiochemical technique has been developed for the isolation of strontium from the sediment samples and for its activity measurement with a low-level gas-flow proportional counter. A conservative behaviour of⁹⁰Sr in the water column remaining dissolved in the water body, can be inferred from the data obtained. Consequently, a possible⁹⁰Sr transport pathway through the outflowing waters of the lake can be deduced.     

Complexation of the Non-steroidal Anti-inflammatory Drug Loxoprofen with Modified and Unmodified β-Cyclodextrins

The inclusion complex of the anti-inflammatory drug, loxoprofen, with -cyclodextrin-(CD), sulfated -CD, and glycerol ether -CD was studied by UV-VIS absorption and ¹H-NMR spectroscopy in solution. The inclusion complex of loxoprofen with -CDs was prepared by freeze-drying, and then characterized in the solid state by thermal analysis, X-ray diffraction, FT-IR and FT-Raman spectroscopy, and scanning electron microscopy (SEM). Furthermore, a physical mixture of loxoprofen/-CD (1/1, mol-%) in the solid state was also characterized. The solubility of the loxoprofen increased on addition of -CDs. The solubility enhancement of the loxoprofen with -CDs is in the following order: glycerol ether -CD > sulfated -CD > -CD.     

Application of the MIMS Technique to Study the Stability Constants of Small Organic Guest Molecules into Cyclodextrin Hosts in Aqueous Medium

In this work the potential of MIMS (Membrane Introduction Mass Spectrometry) for studying the inclusion of small organic guest molecules into cyclodextrin hosts in aqueous medium was investigated. MIMS profiles showed that the inclusion of benzene in cyclodextrins is favored in the following order: -CD HO-propyl--CD> -CD> -CD with equilibrium constants of K -CD = 404; K_HO-propyl-CD = 395, K _-CD = 335 and K _-CD = 210 M^-1 at 25 °C. Kinetic experiments suggested that under the conditions employed the inclusion process has a pseudo first-order dependence on the guest benzene concentration with the following order: -CD > -CD HO-propyl--CD> -CD. MIMS inclusion profiles of chlorobenzene and toluene showed that the presence of substituents in benzene makes the inclusion in -CD more difficult. Experiments with ferrocene--CD have also been carried out, showing that the complex rapidly dissociates in water and the resulting free -CD can complex with benzene present in the solution.     

Structure of psolusoside B — A nonholostane triterpene glycoside of the holothurian genus Psolus

The structure of psolusoside B — a minor triterpene oligoglycoside from the holothurianPsolus fabricii and the main glycoside fromPsolus sp. has been determined by the methods of partial acid hydrolysis, methylation,¹³C NMR, and FAB mass spectrometry as 20S-acetoxy-3-{2-O-[O--D-glucopyranosyl-(1 4)-O--D-glucopyranosyl]-4-O-(6-O-sulfato--D-glucopyranosyl)--D-xylo-pyranosyloxy}holosta-7,25-diene-18,16-carbolactone. 3-[O-(3-O-Methyl-6-O-sulfato--D-glucopyranosyl)-(1 3)-O-(6-O-sulfato--D-glucopyranosyl)-(1 4)-O--D-quinovopyranosyl-(12)--D-xylopyranosyloxy]holosta-9(11),25-dien-16-one (psolusoside A), known previously forPsolus fabricii, has been identified in a holothurian —Psolus sp. — from Kraternaya Bay (island of Ushishir).Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 361–368, May–June, 1989.     

Improvement of Solubility and Dissolution of 19-Norprogesterone via Inclusion Complexation

In an effort to modify the solubility and dissolution rate of the contraceptive steroid, 19-norprogesterone in order to improve its bioavailability, the cyclodextrin complexation approach was chosen. In solution, the complex formation with -cyclodextrin (-CD), hydroxyethyl -cyclodextrin (HE--CD) and hydroxypropyl -cyclodextrin (HP--CD) was confirmed by using solubility, UV, IR and ¹H-NMR spectrophotometric techniques. The phase solubility diagrams were categorized as A_L-type. The complexing affinity of the CDs investigated were ranked as follows: -CD > HP--CD > HE--CD. The complexation thermodynamic parameters were obtained from the temperature dependence of the dissociation constants. In the solid state, differential scanning calorimetery (DSC) and optical microscopy methods were utilized to characterize the complexes. Dissolution studies showed that such molecularly encapsulated forms offered a marked improvement in the dissolution rate compared to the parent drug.     

Synthesis of 2β, 3β, 14α-trihydroxy-Δ4,7-6-ketosteroids and their derivatives

A scheme using -sitosterol as an example for synthesizing 2, 3, 14-trihydroxy-^4,7-6-ketosteroids and their derivatives from 3-hydroxy-⁵-steroids was developed.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, 220141, Belarus, Minsk, ul, akad. Kuprevicha, 5/2. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 244–248, May–June, 2000.     

Solubility Study of Nimodipine Inclusion Complexation with α- and β-Cyclodextrin and some Substituted Cyclodextrins

The solubility of nimodipine was measured in aqueous solutions of the following cyclodextrins: -cyclodextrin (-CD), hydroxypropyl--CD (HP--CD), -cyclodextrin (-CD), random substituted methyl--CD (M--CD), three hydroxypropyl--CDs (HP--CD) with mutually different average degree of substitution, and hydroxypropyl--cyclodextrin (HP--CD). From the determined linear solubility diagrams the values of the binding constant K₁₁ of the inclusion complexes of nimodipine with the respective CDs were evaluated. The -CDs efficiently solubilized sparingly soluble nimodipine, the highest value of K₁₁ was found for M--CD (1680 M^-1), followed by -CD (550 M^-1) and HP--CDs, where the higher degree of substitution lowered K₁₁. Only slight solubilization of nimodipine was observed in the solutions of the -CDs and HP--CD.     

Mass spectrometric study of monoalkyl-substituted thiacyclanes

Monosubstituted - and -alkylthiophans and -, -, and -alkylthiacyclohexanes were subjected to a comparative mass spectrometric study. The stability of the M⁺ ion increases on passing from - to -alkylthiophans and from - to - and -alkylthiacyclohexanes. In the case of -alkylthiophans and - and -alkylthia-cyclohexanes the principal process is associated with ejection of the substituent as a whole, whereas a portion of the alkyl substituent, with retention of one CH₂ group in the composition of the charged fragment, is eliminated from the molecular ions of -alkylthiophans and -alkylthiacyclohexanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–181, February, 1978.     

Three-component complexes of cyclodextrins. Exciplex formation in cyclodextrin cavity

The fluorescence quenching of naphthalene, 1-methylnaphthalene, and acenaphthene by trimethylamine (TMA) was studied in aqueous -cyclodextrin (-CD) solutions to know the structural requirements for guest molecules to form three-component complexes. The apparent rates for the fluorescence quenching of the naphthalene derivatives by TMA markedly increased in the presence of -CD. The fluorescence quenching of 1-methylnaphthalene and acenaphthene by TMA was accelerated by -CD more efficently than that of naphthalene. These results suggest the structures of the three-component complexes as the arene-capped -CD including TMA in its cavity.     

Rearrangement ofα -trifluoromethyl-β-dialkylamino-β-fluoroacrylic acid N.N-dialkylamides

Conclusions When heated in the presence of a catalytic amount of BF₃ etherate,-trifluoromethyl--diethylamino--fluoroacrylic acid N, N-dimethylamide is reversibly isomerized to-trifluoromethyl--dimethylamino--fluoroacrylic acid N, N-diethylamide. The methyl esters of-trifluoromethyl--diethylammo--fluoroacrylic acid and-trifluoromethyl--phenoxy--fluoroacrylic acid N,N-dimethylamide are not isomerized under the same conditions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No.1, pp.137–141, January, 1976.     

1-Aryl-6-azauracile, 5. Mitt.: Die Synthese von 1-(β-Pyridyl)-6-azauracil-5-carbonsäure und einiger ihrer Derivate

Zusammenfassung Analog wie in vorherigen Mitteilungen^1–4 wurden -Pyridyl-hydrazono-cyanacetylcarbamidsäureäthylester (1), 1-(-Pyridyl)-5-cyan-6-azauracil (2), 1-(-Pyridyl)-6-azauracil-5-carbonsäure (3), deren Thioamid (4), und Amidoxim (5), welches in 1-(-Pyridyl)-5-[5-methyl-1,2,4-oxdiazolyl(3)]-6-azauracil (6) überge-führt wurde, hergestellt.

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-Pyridylhydrazono-cyanacetylcarbamic acid ethyl ester (1), l-(-pyridyl)-5-cyano-6-azauracil (2), 1-(-pyridyl)-6-azauracil-5-carboxylic acid (3), its thioamide (4) and amidoxime (5) were prepared as described in preceding communications. (5) was converted into l-(-pyridyl)-5-[5-methyl-1,2,4-oxdiazolyl(3)]-6-azauracil (6).

     

Comparative study on inclusion complexations of antiinflammatory drug flurbiprofen with β-cyclodextrin and methylated β-cyclodextrins

Abstruct Some physicochemical properties of methylated -cyclodextrins, i.e., heptakis(2,6-di-O-methyl)--cyclodextrin (DM--CyD) and heptakis(2,3,6-tri-O-methyl)--cyclodextrin (TM--CyD) were compared with those of natural -cyclodextrin (-CyD). Inclusion behaviors of -CyD and methylated -CyDs in water and in solid state were studied by solubility analysis, spectroscopies (UV, CD,¹³C-NMR and IR), X-ray diffractometry and thermal analysis, using an antiinflammatory drug flurbiprofen (FP) as a guest molecule. The spectral data suggest that the inclusion mode of FP-TM--CyD is somewhat different from those of FP--CyD and FP-DM--CyD. The solid complexes of FP with - and methylated -CyDs were obtained in molar ratio of 11, and their dissolution behavior and release from suppository base were examined. The data are presented suggesting that DM--CyD is particularly useful for improving the pharmaceutical properties of FP in various dosage forms.     

Cardenolides of the seeds ofCoronilla glauca and ofC. scorpioides. New glycosides alloglaucoside and scorpiosidol

Two new glycosides have been isolated from the seeds ofCoronilla glauca L. and C. scorpioides Koch: 3-(0-D-glucopyranosyloxy)-14. 15-dihydroxy-19-oxo-5-card-20(22)-enolide (alloglaucoside) and 3-(-D-gluco-ucofuranosyloxy)-5,14,19-trihydroxy-5-card-20(22)-enolide (scorpiosidol), together with a glycoside previously unknown for theCoronilla genus — 3-(-D-glucopyranosylo)g)-14-hydroxy-5-card-20(22)-enolide (desglucouzarin) and known aglycons (corotoxigenin, alloglaucotoxigenin, coroglaucigenin) and glycosides (glucocorotoxigenin, coronillobioside, glucocoroglaucigenin, coronillobiosidol and scorpioside).Ukraine Pharmaceutical Academy, Kharkov–2. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 372–376, May–June, 1996. Original article submitted August 14, 1995.     

Lithium intercalation in layer structured compound β-ZrNCl

A layer structured crystal -ZrNCl forms a lithium intercalation compound Li_xZrNCl. The upper limit for x determined on the compound prepared by the n-butyl lithium technique is 0.29. In the electrochemical process, a pressed -ZrNCl cathode is further reduced up to x=11.25 at potentials as low as 0.80.6 V relative to Li/Li⁺. The lithium intercalate swells in various polar solvents, increasing the basal spacing. However, in contrast to the salt-like intercalates of transition metal chalcogenides and FeOCl, the lithium intercalated -ZrNCl does not form hydration phases, but reacts with water, evolving hydrogen. These results can be interpreted in terms of the formation of an alloy-like intercalate like the alkali intercalates of graphite. On intercalation, -ZrNCl is changed from pale yellow-green to black in color, and the electrical conductivity increases by a factor of 10⁶.     

NMR Spectral Assignment of Per-substituted Key-Intermediates of β-Cyclodextrin and Implications in the Structures of the Derivatives

The compounds, 6-per-O-(t-butyldimethylsilyl)--cyclodextrin(1), 2,3-per-O-benzyl-6-per-O-(t-butyldimethylsilyl)--cyclodextrin(2), 2,3-per-O-benzyl--cyclodextrin (3),2,3,6-per-O-benzyl--cyclodextrin (4),2,3,6-per-O-benzoyl--cyclodextrin (5), are used as keyintermediates in the synthesis of selectively substituted -CD derivatives. Simple and assignable ¹H and ¹³C NMR spectra (chemical shifts and coupling constants) were obtained for compounds1–4 indicating C₇ symmetry, ⁴C₁ glucose conformation and major arrangement of H6, H6' atoms at the primary side. The derivative 5, however, gave very broad peaksat room temperature. The peaks could partially be assigned at 270 K, but the broadening was still present at 220 K. This implies that there exist several conformers of similar energyand C₁ symmetry that continuously interchange, since there is not a single type of stabilizing interaction thatpredominates. We attributed this phenomenon to the presence of the carbonyl group, which probablydisfavors - stacking and induces random arrangements of the aromatic rings.     

Steroids of the spirostan and furostan series from nolina microcarpa III. Structure of nolinofurosides G and H

Two new glycosides which have been called nolinofurosides G(I) and H(III), have been isolated from the leaves ofNolina microcarpa. Nolinofuroside G is the sodium salt of 26--D-glucofuranosyloxy-(25S)-furost-5,20(22)-diene-1, 3-diol 1-sulfate, and nolinofuroside H is the sodium salt of 1--D-fucopyranosyloxy-26--D-glucopyranosyloxy-(25S)-furost-5,20(22)-dinen-1-3-ol 3-sulfate.M. V. Frunze Simferopol' State University. Institute of the Chemistry of Plant Substances, Uzbek. Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 801–806, November–December, 1991.     

The GC separation of C2-naphthalene isomers using cyclodextrins and crown ethers

Summary The twelve structural C₂ isomers of naphthalene are resolved on a single capillary column using , , or cyclodextrin as the stationary phase. A change in elution order is seen upon going from to and then cyclodextrin which can be related to the size of the cyclodextrin cavity and the stereochemical fit of the isomer. A crown-ether column and a liquid-crystal column were found to be unable to separate all of the isomers.     

Influence of additives on the structure and properties of polymers

Investigations into the transformation of hexagonal into monoclinic modification in isotactic polypropylene (iPP) were carried out. The hexagonal phase () was obtained by crystallization from a melt of iPP samples containing small molecular compounds (additives). A decline in the amount of-modification and changes of dimensions of ordering areas, perpendicular to the chain axes of iPP, was analysed at various temperatures and times of heating.The interdependence between the structure of additives and the amount of-phase occurring and also the stability of this modification during thermal treatment was observed.Obtained results indicated that only some additives play the role of moderating agents for the phase transition process.A preliminary report of this work has been presented at XIII Congress of the International Union of Crystallography (9–18 August 1984).     

Alkyl capped carbonates ofβ-cyclodextrin

The synthesis is described of alkyl capped carbonates of-cyclodextrin, obtained from diols activated with carbonyldiimidazole. The reaction preferentially gave monocapped derivatives which were characterized by HPLC, TLC, FT-IR and¹³C-NMR. These compounds are stable at pH <7, and methyl orange was found to form stronger inclusion compounds with capped-cyclodextrin than with the parent-cyclodextrin. Paramagnetic Gd(III) complexes were also studied, but they were found to be included into capped-cyclodextrin as well as into-cyclodextrin.Part of this work was presented at the 7th International Symposium on Cyclodextrins, 1994, Tokyo, April 25–28, Book of Abstract, page 54.