Genotoxicity of 2-alkylcyclobutanones, markers for an irradiation treatment in fat-containing food—Part I: cyto- and genotoxic potential of 2-tetradecylcyclobutanone

Previous experiments had indicated a slight genotoxic potential both in rat and in human colon cells of a sample of 2-dodecylcyclobutanone, a compound formed by irradiation of food containing palmitic acid in its triglycerides. Up to date, there is no evidence that 2-alkylcyclobutanones occur in non-irradiated foodstuffs, consequently it is prudent to test several members of the class of 2-alkylcyclobutanones which are produced by treatment of fat-containing food with ionising radiation. In this work, 2-tetradecylcyclobutanone (derived from stearic acid) has been tested for its cytotoxic and genotoxic potential. Human colon tumor cell lines, i.e. HT 29 and HT 29 clone 19A, were employed as models for in vitro experiments for cytotoxicity and genotoxicity tests. Cytotoxicity was measured by tetrazolium salt reduction assays (MTT and WST-1) and genotoxicity by determining DNA damage using the Comet Assay. Neither cytotoxic nor genotoxic effects were induced by 2-TCB in HT 29 or HT 29 cl 19A cells at an incubation time of 30 min at 37°C, not even at the highest concentration (400 μM) tested. After prolonged incubation times (1–2 days) at higher concentrations (>50 μM) cytotoxicity did, however, appear. Studies on other 2-alkylcyclobutanones are in progress.     

An inverse gas chromatography study of the adsorption of organics on nickel- and copper-hexacyanoferrates at zero surface coverage

The surface properties of Ni and Cu hexacyanoferrates were investigated by the inverse gas chromatography method. Retentions of 10 organic compounds were measured at zero surface coverage in the temperature range 80 to 95 degrees C. The gas/solid partition coefficients and the related thermodynamic data of adsorption (standard free energy change, standard state enthalpies, and entropy changes) also at zero surface coverage were determined. The dispersive component of free surface energy of both hexacyanoferrates, at investigated temperatures, was calculated. The surface acid/base properties were also evaluated using polar adsorbates and the results obtained indicate that nickel hexacyanoferrate is more acidic than copper hexacyanoferrate.     

Heterobi‐ and ‐trinuclear Complexes with an Amino(ethynyl)carbene as Bridging Ligand

The sequential reaction of the amino(trimethylsilyl)carbene complex [(CO)₅W=C(NH₂)C≡CSiMe₃] ( 1 ) with nBuLi and [I‐Fe(CO)₂Cp] affords the C(carbene)‐N bridged heterobinuclear complex [(CO)₅W=C{NHFe(CO)₂Cp}C≡CSiMe₃] ( 2 ). Desilylation of 1 is achieved by treatment with KF in THF/MeOH. From the reaction of the resulting complex [(CO)₅W=C(NH₂)C≡CH] ( 3 ) with nBuLi and [I‐Fe(CO)₂Cp] two binuclear WFe compounds in a ratio of approximately 1:1 are obtained: the C(carbene)‐C≡C bridged complex 4 and the C(carbene)‐N bridged complex 5 . Repetition of the deprotonation/metallation sequence yields the trinuclear WFe₂ complex 6 . One Fe(CO)₂Cp fragment in 6 is bonded to the amino group and the other one to the terminal carbon atom of the ethynyl substituent. The analogous reaction of 3 with nBuLi and [Br‐Ni(PMe₂Ph)₂Mes] gives a ca. 1:1 mixture of two heterobinuclear complexes ( 7 and 8 ). Complex 7 is bridged by the C(carbene)‐C≡C and complex 8 by the C(carbene)‐N fragment. Subsequent reaction of 7 with BuLi and [Br‐Ni(PMe₂Ph)₂Mes] finally affords the trinuclear WNi₂ complex 9 related to 6 . The solid‐state structure of 2 is established by an X‐ray diffraction analysis. The spectroscopic data of the bi‐ and trinuclear complexes indicate electronic communication between the metal centers through the bridging group.     

Aza-2-dienes-1,3. Partie 5. Préparation de N-aminoimidazoles, 3H-pyrroles,triazolo[1,2,4][1,5-a]pyrazines et imidazo[1,2-a]pyrazines

2-Aza-1,3-dienes. Access to N-Aminoimidazoles, 3H-Pyrroles, [1,2,4]Triazolo[1,5-a]pyrazines, or Imidazo[1,2-a]pyrazines Nucleophilic attack of 5-(dialkylamino)-2-aza-1,3-diene-1,1-dicarbonitriles (or their 1-methoxycarbonyl analogous) by hydrazines or hydrazdes gives substituted N-aminoimidazoles, [1,2,4]triazolo-[1,5-a]pyrazines, or α-dihydrazino derivatives. With α-amino esters (or analogous), imidazo[1,2-a]pyrazines are produced. Addtion of cyanide anions occurs also with formation of substituted 3H-pyrroles. Structures and rationalisation of this nucleophilic attack are discussed.     

Substituenteneffekte in den13C-NMR-Spektren von diastereomeren Chalkondihalogeniden, 10. Mitt.: Erste Synthese und Konfigurationsbestimmung vonthreo-Chalkonbromhydrinen

Summary The first synthesis ofthreo chalcone bromohydrins was realized by reaction oftrans chalcone epoxides with SnBr₄ in molar ratios from 1:1 to 2:1. The compounds were obtained in high yields and isomeric purity. Their configuration was determined asthreo by different methods based on¹³C-NMR shifts of C- and C- atoms.

     

Synthesis of 1-functionalized-6-hydroxy-4-methyl and 6,11-dihydroxy-4-methylnaphtho[2,3-g]isoquinoline-5,12-quinones

Using 2-methoxy- and 2,5-dimethoxyacetophenones 8a and 8b as starting materials, 1-chloro-4-methylisoquinoline-5,8-quinone ( 6 ) and its 6-bromo derivative 7 were obtained via multistep sequences. Whereas Diels-Alder condensation of the former compound with homophthalic anhydride ( 22 ) led to a mixture of the two possible isomers: 1-chloro-11-hydroxy-4-methylnaphtho[2,3-g]isoquinoline-5,12-quinone ( 23 ) and 1-chloro-6-hydroxy-4-methylnaphtho[2,3-g]isoquinoline-5,12-quinone ( 24 ), this last tetracyclic chloroquinone was specifically obtained from 6-bromo-1-chloro-4-methylisoquinoline-5,8-quinone ( 7 ) and homophthalic anhydride. The 6,11-dihydroxy derivative was then prepared by ammonium nitrate oxidation or photochemically by cycloaddition of benzocyclobutenedione ( 28 ) and 1-chloro-4-methylisoquinoline-5,8-quinone ( 6 ). Chloro compounds were easily substituted by diamines to provide corresponding 1-amino substituted hydroxy tetracyclic quinones.     

Biomimetic formation of 5,6-dihydroflavopereirine from 4,21-dehydrogeissoschizine

Indole alkaloids lacking the three carbon unit at C-15 such as deplancheine $\text{7}$ and flavopereirine $\text{8}$ can be biogenetically related to 4,21-dehydrogeissoschizine $\text{3}$. A biomimetic transformation of $\text{3}$ into 5,6-dihydroflavopereirine $\text{5}$ supports this proposal.     

Chemical Interactions by Low-Energy Electron-Induced X-Ray Emission Spectroscopy, LEXES

 The possibilities presented by low-energy electron-induced X-ray emission spectroscopy to study chemical interactions in solids are discussed. Examples of change observed for the emissions between core levels as a function of the chemical environment of the emitting atoms are given. By comparing the partial densities of the valence states associated to each type of atoms in the compound, it is shown that the strength of the metal-ligand interactions can be obtained. Information on the charge densities around each type of atoms can be deduced. Application to the study of the interactions at the atomic scale to solid–solid interfaces is presented.     

Preparation of ethyl 5(s),6-epoxy-3(r)-(methoxymethoxy)hexanoate: a key chiral intermediate for mevinolin and compactin.

The synthesis of Ethyl 5(S),6-Epoxy-3(R)-(methoxymethoxy)hexanoate, a key chiral synthon for the β-hydroxy-δ-lactone portion of Mevinolin and Compactin, $\text{via}$ a regiospecific ring opening of a tetrahydrofuran derivative by dimethylboron bromide, is described.     

Molecular simulation of the adsorption and structure of benzene confined in mesoporous silicas

Grand Canonical Monte Carlo simulations are used to study the adsorption of benzene at 298 K in an atomistic cylindrical silica nanopore of a diameter 3.6 nm. The adsorption involves a transition from a partially filled pore (a two layers thick film at the pore surface) to a completely filled pore configuration. Strong layering of the benzene molecules at the pore surface is observed. It is found that the layering decays as the distance to the pore surface increases. The position of the peaks for the density of the C, H atoms and the center of mass of the molecules shows that benzene molecules prefer an orientation in which their ring is perpendicular to the pore surface. This result is corroborated by calculating orientational order parameters and examining the distribution of the distances between the H and C atoms of the benzene molecules and the H and O atoms of the silica substrate.