Structural studies of seven homoisoflavonoids, six thiohomoisoflavonoids, and four structurally related compounds

¹H and ¹³C NMR chemical shifts have been determined and assigned based on PFG ¹H, ¹³C HMQC, and HMBC experiments for 3-(4′-X-benzyl)-4-chromenones (Ia, X = CN and Ib, X = NO₂), 3-(4′-X-benzyl)-4-thiochromenones (IIa, X = Cl and IIb, X = Br), (E)-3-(4′-X-benzylidene)-4-chromanones (IIIa–IIIe, X = OCH₃, CH₃, Cl, N(CH₃)₂, Br), (Z)-3-(4′-X-benzylidene)4-thiochromanones (IVa–IVd, X = Cl, Br, F, OCH₃), 2-benzyl-1,2,3,4-tetrahydro-1-naphthol (V), 2-benzyl- and (E)-2-benzylidene-1-tetralones (VI and VII), and (E)-2-benzylidene-1-benzosuberol (VIII). The crystal structures have been determined for the following seven compounds: derivatives of 4-chromanones (IIIa–IIId), 1-tetrahydronaphtol (V), and 1-tetralones (VI and VII). The molecular features and intermolecular interactions in crystal state have been discussed.     

Kinetic study of gas-phase reactions of pinonaldehyde and structurally related compounds

Rate constants for the reactions of OH, NO₃, and O₃ with pinonaldehyde and the structurally related compounds 3-methylbutanal, 3-methylbutan-2-one, cyclobutyl-methylketone, and 2,2,3-trimethyl-cyclobutyl-1-ethanone have been measured at 300±5 K using on-line Fourier transform infrared spectroscopy. The rate constants obtained for the reactions with pinonaldehyde were: k_OH=(9.1±1.8)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹, k_NO3=(5.4±1.8)×10⁻¹⁴ cm³ molecule⁻¹ s⁻¹, and k_O3=(8.9±1.4)×10⁻²⁰ cm³ molecule⁻¹ s⁻¹. The results obtained indicate a chemical lifetime of pinonaldehyde in the troposphere of about two hours under typical daytime conditions, [OH]=1.6×10⁶ molecule cm⁻³. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 527–533, 1997.     

Quantitative high-perormance liquid chromatographic analysis of nitroxoline and structurally related compounds

Summary Nitroxoline (8-hydroxy-5-nitroquinoline) and the structural related compounds 8-hydroxyquine, 8-hydroxy-5,7-dinitroquinoline, and 8-hydroxy-5-nitrosoquinoline have been investigated by reversed-phase high-performance liquid chromatography on C₁₈/ODS. Complete separation and symmetric, peaks were obtained by use of THF-methanol-water, 3∶3∶4, containing 10 mmol L⁻¹ disodium ethylenediamine tetraacetic acid (EDTA) and 10 mmol L⁻¹ citric acid in the water, as mobile phase. The pH and the concentration of EDTA in the mobile phase were found to be critical for eliminating tailing and for full separation. The calibration plot was linear for concentrations between 3.0 and 300 μg mL⁻¹; the regression coefficient was 0.99996. Assay of the nitroxoline standard showed that recovery was from 99.3 to 102%, with a mean standard deviation for nitroxoline of 0.9%. The method is suitable for quality control of nitroxoline.     

Bioactive compounds from Selaginella involven Spring that protect PC-12 cells

Two new compounds named as 3b 12 16-trihydroxy-6 8 11 13-abietatrien（1） （8R 80S）-4 40 8-trihydroxyl-3 30-dimethoxyl-90-lignanolide（2） and a new natural product 4 40-dihydroxyl-3 30 5 50-dimethoxyldiphenyl diketone（3） were isolated from the whole herbs of Selaginella involven Spring.The structures were elucidated by spectroscopic analyses including UV,IR,1D,2D NMR and MS methods.Additionally,these three compounds exhibited potent protective effect against the injury of PC-12 cells induced by hypoxia/reoxygenation.     

Preparation of99mTc complexes with compounds structurally related to ethylene diamine tetraacetic acid

The preparation of^99mTc-Sn-DOTA,^99mTc-Sn-DDDTA and^99mTc-Sn-DHDTA is described. The labelling efficiency of all samples was checked by paper chromatography, thin layer chromatography and paper electrophoresis. Preliminary results of the biodistribution studies performed in white rats are given.     

Inclusion complexes of fusidic acid and three structurally related compounds with cyclodextrins

The inclusion complexes between fusidate, 3-keto fusidate, 11-keto fusidate and 11-deoxy fusidate and α-, β-, and γ-cyclodextrin (CD) were studied using capillary electrophoresis. By monitoring the changes in mobility of the negatively charged compounds in the presence of varying amount of CD the stability constants of the complexes formed could be obtained. In the case of α- and β-CD the obtained results could be modelled to a simple model assuming 1:1 stoichiometry, revealing, not surprisingly, that β-CD formed a stronger complex compared to α-CD. A model assuming 1:2 (fusidate:CD) stoichiometry could be fitted to the data obtained with γ-CD. The results showed that the different fusidanes formed very strong 1:1 complexes with γ-CD as well as a quite weak 1:2 complex. 3-keto-, 11-keto- and 11-deoxy-fusidate formed stronger complexes compared to fusidate, probably due to an decrease in hydrophilicity caused by the reduced number of hydroxyl groups. The complex between γ-CD and fusidate was studied by use of 2D-NMR spectroscopy. The results showed that most of the hydrogen atoms of fusidate show interactions with the hydrogen atoms in the cavity of γ-CD. The interaction pattern suggests that fusidate may be fully embedded in the cavity of γ-CD. No interactions between fusidate and the hydrogen atoms situated at the outside of the CD were found.     

Syntheses of some indazoles structurally related to equilenin

This study reports the complete synthesis and characterization of the 15, 16-diazaequilenin derivative 10,11-dihydro-3H-naphth[1,2-g]indazol-7-ol ( 2b ) as well as the methyl ether 2a of the above compound and the novel “model” compound 4,5-dihydro-1H-benz[g]indazol-7-ol ( 3b ). Indazoles 2a and 3a have demonstrated in vitro activity against a variety of microorganisms.     

Thiophene, furans, and related aromatic compounds from Eupatorium heterophyllum

A thiophene, two furans, a dihydro furan, and two acetylenic benzene derivatives were isolated from the roots of Eupatorium heterophyllum collected in China. Structures were established on the basis of spectroscopic analyses as well as chemical transformations.     

Relationship between kováts retention indices and molecular connectivity indices of tetralones, coumarins and structurally related compounds

A study was undertaken to test the ability of several molecular connectivity indices to predict the retention indices (I) of tetralones, coumarins and structurally related compounds determined on OV-17 and Apiezon L as stationary phases. The regression analyses with I_OV-17 showed that a two-variable linear regression equation with ²χ and ⁴χ^v_pc gives the best correlation coefficient, suggesting that retention depends basically on branching and the presence and number of adjacent atoms, and secondarily on unsaturations and the number and orientation of substituents. I_ApL gives the best correlation with a two-variable linear regression equation with ¹χ and ³χ^v_p indicating that on this stationary phase retention depends basically on the presence and number of adjacent atoms, and secondarily on unsaturation, branching of adjacent atoms and the presence of heteroaroms. ΔI (ΔI = I_OV-17 - I_ApL), according to the different polarities of both phases, considered to be a measure of the polar forces in retention, does not give a good correlation.     

Adaptation of cyanobacteria to UV-B stress correlated with oxidative stress and oxidative damage

Cyanobacteria must cope with the negative effects of ultraviolet B (280-315 nm) (UV-B) stress caused by their obligatory light requirement for photosynthesis. The adaptation of the cyanobacterium Anabaena sp. to moderate UV-B radiation has been observed after 2 weeks of irradiation, as indicated by decreased oxidative stress, decreased damage, recovered photosynthetic efficiency and increased survival. Oxidative stress in the form of UV-B-induced production of reactive oxygen species was measured in vivo with the oxidative stress-sensitive probe 2',7'-dichlorodihydrofluorescein diacetate. Photooxidative damage by UV-B radiation, including lipid peroxidation and DNA strand breakage, was determined by a modified method using thiobarbituric acid reactive substances and fluorometric analysis of DNA unwinding. Photosynthetic quantum yield was determined by pulse amplitude-modulated fluorometry. The results suggest that moderate UV-B radiation results in an evident oxidative stress, enhanced lipid peroxidation, increased DNA strand breaks, elevated chlorophyll bleaching as well as decreased photosynthetic efficiency and survival during the initial exposure. However, DNA strand breaks, photosynthetic parameters and chlorophyll bleaching returned to their unirradiated levels after 4-7 days of irradiation. Oxidative stress and lipid peroxidation appeared to respond later because decreases were observed after 7 days of radiation. The survival curve against irradiation time exhibited a close relationship with the changes in photosynthetic quantum yield and DNA damage, with little mortality after 4 days. Growth inhibition by UV-B radiation was observed during the first 7 days of radiation, whereas normal growth resumed even under UV-B stress thereafter. An efficient defense system was assumed to come into play to repair photosynthetic and DNA damage and induce the de novo synthesis of UV-sensitive proteins and lipids, allowing the organisms to adapt to UV-B stress successfully and survive as well as grow. No induction of mycosporine-like amino acids (MAA) was observed during the adaptation of Anabaena sp. to UV-B stress in our work. The adaptation of the cyanobacterium correlated with and could be caused by the oxidative stress and oxidative damage.     

Maristentorin, a novel pigment from the positively phototactic marine ciliate Maristentor dinoferus, is structurally related to hypericin and stentorin

The photoreceptor pigment of the heterotrich ciliate, Maristentor dinoferus, has been characterized. It is structurally similar to those of Stentor coeruleus and Blepharisma japonicum but differs significantly in that it bears no aromatic hydrogens. The structure of the pigment, maristentorin, is based upon the hypericin skeleton, and its spectra are nearly identical to those of hypericin but shifted toward the red. Within experimental error, its fluorescence lifetime is identical to that of hypericin, approximately 5.5 ns in dimethylsulfoxide. It is remarkable that while the pigments are structurally similar in S. coeruleus and M. dinoferus, in the former there is an abrupt photophobic response, whereas in the latter there is a slow response toward light. The roles of the hypericin-like pigments in the heterotrich ciliates are discussed as potentially analogous in Maristentor.     

Synthesis of biotinylated pentasaccharide structurally related to a fragment of glucomannan from Candida utilis

Russian Chemical Bulletin - The polysaccharide mannan is the main surface antigen of the cell wall of Candida fungi, playing an important role in the pathogenesis of diseases caused by these...     

Thermal behaviour of the monoclinic allotropesγ-sulfur andα-selenium and some structurally related sulfur-selenium compounds

The thermal behaviour of-sulfur, monoclinic-Se, S₆Se₂, S₅Se₃, S₄Se₄ and S₃Se₅, has been studied by hot-stage microscopy and differential scanning calorimetry. X-ray diffraction results show that S₆Se₂ and S₅Se₃ are isostructural with S, but S₄Se₄ and S₃Se₅ are isostructural with monoclinic-Se. The melting of S, is accompanied by rapid crystallization of S, which often occurs almost simultaneously with melting. The melting of S₆Se₂, S₅Se₃, S₄S₄ and S₃Se₅ is irreversible as the compounds decompose on melting. For monoclinic-Se no phase transformation to monoclinic Se was observed at 110–120°, but it changes to hexagonal-Se when the temperature is over 120°.

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Zusammenfassung Das thermische Verhalten von -Schwefel, monoklinem-Se, S₆Se₂, S₅Se₃, S₄Se₄ und S₃Se₅ wurde mittels Heißphasenmikroskopie und Differential Scanning-Kalorimetrie untersucht. Röntgendiffraktionsergebnisse zeigen, daß S₆Se₂ und S₅Se₃ mit S isostrukturell sind, doch sind S₄Se₄ und S₃Se₅ mit monoklinem-Se isostrukturell. Das Schmelzen von S wird von der schnellen Kristallisation von S begleitet, welche oft beinahe simultan mit dem Schmelzen verläuft. Das Schmelzen von S₆Se₂, S₅Se₃, S₄Se₄ und S₃Se₅ ist irreversibel, da die Verbindungen während des Schmelzens zersetzt werden. Bei monoklinem-Se wurde zwischen 110 und 120° keine Phasentransformation zu monoklinem -Se beobachtet, doch wird ersteres bei Temperaturen über 120° in hexagonales-Se umgewandelt.

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Résumé On a étudié le comportement thermique du soufre, du sélénium monoclinique, de S₆Se₂, S₅Se₃, S₄Se₄ et de S₃Se₅ par microscopie avec platine chauffante et par analyse calorimétrique différentielle (DSC). Les résultats de la diffraction des rayons X montrent que S₆Se₂ et S₅Se₃ sont isostructuraux avec S, tandis que S₄Se₄ et S₃Se₅sont isostructuraux avec Se monoclinique. La fusion de S s'accompagne d'une cristallisation rapide de S qui a souvent lieu presque simultanément avec la fusion. La fusion de S₆Se₂, S₅Se₃, S₄Se₄ et S₃Se₅ est irréversible car ces composés se décomposent lors de la fusion. On n'a pas observé la transformation de phase Se Se entre 100 et 120° mais la transformation en Se hexagonal au-dessus de 120°.

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-, -Se, S₆Se₂, S₅Se₃, S₄Se₄, S₃Se₅ . , S₆Se₂ S₅Se₃ Sy, S4Se4 S3Se6 -Se. S S, . S₆Se₂, S₅Se₃ S₄Se₄ S₃Se₅ , . 110–120; a-Se -Se, 120° -Se.

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Financial aid from the Neste Oy Foundation (to R. L.) is gratefully acknowledged.     

Inositolphosphoglycan mediators structurally related to glycosyl phosphatidylinositol anchors: synthesis, structure and biological activity

The preparation of the pseudopentasaccharide 1a, an inositol-phosphoglycan (IPG) that contains the conserved linear structure of glycosyl phosphatidylinositol anchors (GPI anchors), was carried out by using a highly convergent 2+3-block synthesis approach which involves imidate and sulfoxide glycosylation reactions. The preferred solution conformation of this structure was determined by using NMR spectroscopy and molecular dynamics simulations prior to carrying out quantitative structure--activity relationship studies in connection with the insulin signalling process. The ability of 1a to stimulate lipogenesis in rat adipocytes as well as to inhibit cAMP dependent protein kinase and to activate pyruvate dehydrogenase phosphatase was investigated. Compound 1a did not show any significant activity, which may be taken as a strong indication that the GPI anchors are not the precursors of the IPG mediators.     

Preparation of99mTc complexes with compounds structurally related to (4r)-1,3-thiazolidine-4-carboxylic acid

The preparation of^99mTc-Sn-complexes with derivatives of (4R)-1,3-thiazolidine-4-carboxylic acid is described. The labeling efficiency of all labeled compounds was checked by paper chromatography, thin layer chromatography and paper electrophoresis. Preliminary results of the biodistribution studies performed in mice are given. The proposed structure of the^99mTc-labled monocomplexes is also discussed.     

Pyran,its analogs,and related compounds

The effect of amines (benzylamine, N,N-dimethylethylenediamine, and ethylenediamine) on the tert-butyl ester (I) and tert-butyl amide (II) of chromone-2-carboxylic acid was studied. In contrast to the sterically unhindered derivatives of chromone-2-carboxylic acid, I and II do not undergo amidation or transamidation by reaction with the amines but are converted directly to pyran-ring-opening products. In the case of ethylenediamine, further intramolecular cyclization also occurs to form 5-(o-hydroxyphenyl)-7-carboxy-1,4-diaza-4,6-cycloheptadiene derivatives (VII and IX).See [6] for communication XXXVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 17–21, January, 1971.