Microbial transformation of mestranol by Cunninghamella elegans

The microbial transformation of an oral contraceptive, mestranol (1) by Cunninghamella elegans yielded two hydroxylated metabolites, 6beta-hydroxymestranol (2) and 6beta,12beta-dihydroxymestranol (3). Metabolite 3 was found to be a new compound. These metabolites were structurally characterized on the basis of spectroscopic techniques.     

Isolation of onosmins A and B, lipoxygenase inhibitors from Onosma hispida

Onosmins A (1) and B (2), lipoxygenase inhibitors, have been isolated from Onosma hispida. Their structures were established as 2-[(4-methylbenzyl)amino]benzoic acid (1) and methyl 2-[(4-methylbenzyl)amino]benzoate (2) through spectroscopic studies, including 2D-NMR. The known compounds apigenin (3), 6,4'-dimethoxy-3,5,7-trihydroxyflavone (4), 6,7-dimethoxy-3,5,4'-trihydroxyflavone (5) and apigenin 7-O-beta-D-glucoside (6) are also reported for the first time from this species. Compounds (1) and (2) inhibited lipoxygenase (LOX, EC 1.13.11.12) enzyme in a concentration-dependent fashion with IC50 values of 24.0 and 36.2 microM, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that the nature of inhibition was purely a non-competitive type, with K(i) values 22.0 microM and 31.1, respectively.     

Lipoxygenase inhibiting constituents from Indigofera hetrantha

A lignan and two acylphloroglucinols have been isolated from the ethyl acetate soluble fraction of the whole plant of Indigofera hetrantha. Their structures have been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. Compounds 1-3 displayed promising inhibitory potential against enzyme lipoxygenase in concentration-dependent manner.     

Tyrosinase-inhibitory long-chain esters from Amberboa ramosa

Long-chain esters 1 and 2 have been isolated from the chloroform-soluble fraction of Amberboa ramosa and their structures assigned to be methyl 2beta(2S)-hydroxyl-7(E)-tritriacontenoate (1) and methyl 2beta(2S)-O-beta-D-galactopyranosyl-7(E)-tetratriacontenoate (2). In addition, tricontane (3) and apigenin (4) are also reported for the first time from this species. The structures were assigned on the basis of 1D and 2D NMR techniques. Compounds 1 and 2 showed strong to moderate inhibitory activity against tyrosinase.     

Gas chromatographic-mass spectrometric analysis of essential oils from Pimpinella aurea, Pimpinella corymbosa, Pimpinella peregrina and Pimpinella puberula gathered from Eastern and Southern Turkey

Essential oils from fruits, stems and leaves and roots of Pimpinella aurea DC., P. corymbosa Boiss., P. peregrina L. were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques. Fruits and aerial parts of P. puberula (DC.) Boiss were also evaluated. A total of 140 different compounds were identified, and significant qualitative and quantitative differences were observed among the samples. In fact, the main constituents of each species were different and only the oils extracted from roots shared the same principal compound, epoxy pseudoisoeugenyl-2-methyl butyrate (26.8-42.8%). The other fractions were dominated by different sesquiterpene compounds although in three of them, P. aurea stem and leaves, P. puberula fruits and P. puberula stems and leaves, monoterpene constituents also appear as main ones.     

Nitrosoarene-CuI complexes are intermediates in copper-catalyzed allylic amination

Reactions of nitrosobenzene and N,N'-diethyl-4-nitrosoaniline with [Cu(CH3CN)4]PF6 produce novel homoleptic Cu(I)-nitrosoarene complexes, [Cu(ArNO)3]PF6, 1 (Ar = Ph) and 2 (Ar = 4-Et2NC6H4NO). The X-ray structure of 2 reveals that the copper is coordinated in a severely distorted trigonal planar geometry to the N-atom of the nitrosoarene ligand. Reactions of the PhNO complex 1 with olefins and an olefin/diene mixture provide evidence for its role as an intermediate and possibly the active nitrogen transfer agent in the Cu-catalyzed allylic amination of olefins by aryl hydroxylamines.     

Practical synthesis of an amphiphilic, non-ionic poly(para-phenyleneethynylene) derivative with a remarkable quantum yield in water

Aggregation of poly(para-phenyleneethynylene)s is efficiently suppressed by introduction of branched oligoethyleneglycol side chains rendering the polymer backbone, which is readily obtained using an A2 + BB' polycondensation protocol, soluble and highly emissive in aqueous environments.     

On the maximal difference between an element and its inverse in residue rings

We investigate the distribution of where

Exponential sums provide a natural tool for obtaining upper bounds on this quantity. Here we use results about the distribution of integers with a divisor in a given interval to obtain lower bounds on . We also present some heuristic arguments showing that these lower bounds are probably tight, and thus our technique can be a more appropriate tool to study than a more traditional way using exponential sums.

     

The acidities of arylazoformaldoximes. Electronic transmission of substitutent effects through the azo group

A series of para- and meta-substituted phenylazoformaldoximes have been prepared and their acidities determined spectrophotometrically at 25.0±0.1°C and μ of 0.10 in ethanol-water mixtures containing 1, 50 and 80 vol. % ethanol. The pK_a. data obtained were linearly correlated with the Hammett substituent constant, σ_x. The variation with solvent of the reaction constant, ?, was linear function of the solvent activity function, Y_. The ? value for the series studied in 99 vol. % water has been compared with that reported for the ionization of α-benzaldoximes. The results show that the azo bond transmits electronic effects approximately 1.5 times better than the ethylenic bond.     

Characterizations of Schauder decompositions in Banach spaces

Acta Mathematica Hungarica -