Nuclear magnetic resonance of benzobisheterocyclic compounds

The nuclear magnetic resonance spectra of forty-nine benzobisheterocyclic compounds, containing various heterocycles, were determined. The observed spectral data made possible the elucidation of the structure and also clarified the influences of the heterocyclic substituents and of heterocyclic rings on chemical shift values of the aromatic protons.     

Scalar conservation laws with moving constraints arising in traffic flow modeling: An existence result

We consider a strongly coupled PDE–ODE system that describes the influence of a slow and large vehicle on road traffic. The model consists of a scalar conservation law accounting for the main traffic evolution, while the trajectory of the slower vehicle is given by an ODE depending on the downstream traffic density. The moving constraint is expressed by an inequality on the flux, which models the bottleneck created in the road by the presence of the slower vehicle. We prove the existence of solutions to the Cauchy problem for initial data of bounded variation.     

Seasonal and biological variations of Epidendrum mosenii: quantification of 24-methylenecycloartanol using gas chromatography

Epidendrum mosenii is a Brazilian medicinal plant, traditionally used to treat infective and dolorous processes. The present article reports a comparative study of the chemical and pharmacological aspects of different parts and seasons of this plant. The results demonstrate that 24-methylenecycloartanol (1), one of the main active principles present in this plant, is located practically in all the parts and during all seasons, but it is much more concentrated in the stems when collected in spring and summer. The pharmacological results indicate that dichloromethane extracts collected in spring and summer were the most active when evaluated against the writhing test in mice, being several times more potent than some reference drugs used as comparison. Together, the results strongly suggest that the antinociceptive effect of E. mosenii is related, at least in part, to the presence of compound 1, and this finding could be useful for quality control of phytopreparations based on this plant.     

Traffic flow optimization on roundabouts

The aim of this article is to propose an optimization strategy for traffic flowon roundabouts using amacroscopic approach. The roundabout is modeled as a sequence of 2 × 2 junctions with one main lane and secondary incoming and outgoing roads. We consider two cost functionals: the total travel time and the total waiting time, which give an estimate of the time spent by drivers on the network section. These cost functionals areminimized with respect to the right ofway parameter of the incoming roads. For each cost functional, the analytical expression is given for each junction. We then solve numerically the optimization problem and show some numerical results. Copyright © 2014 John Wiley & Sons, Ltd.     

Antioxidant capacity of flavonoids and a new arylphenol of the resinous exudate from Heliotropium sinuatum

From the resinous exudate of Heliotropium sinuatum (family Boraginaceae), a new compound: 4-(3',5'-dihydroxynonadecyl)phenol 1, together with eight previously described flavonoids, were isolated and their antioxidant activities were assessed by quenching measurements with ABTS and DPPH cation radicals.     

Synthesis and molecular modelling studies of resorcin[4]arene-capped porphyrins

Three new resorcin[4]arene-capped porphyrins (3, 5 and 7) different in the porphyrin skeleton, in the linking arms and in the cavity dimensions, have been synthesised. Molecular modelling calculations explored the conformations and the cavity size of the three compounds and showed that their hydrophobic pockets can accommodate one molecule of water or methane (3 and 5), or benzene (7) without any distortion. Notably, the capped porphyrin 5 was able to inhibit the oxidation of Co(II) to Co(III), whereas compound 7 did it only partially.     

Chiral recognition by resorcin[4]arene receptors: intrinsic kinetics and dynamics

Molecular recognition of representative amino acids (A) by a chiral amido[4]resorcinarene receptor (1(L)) was investigated in the gas phase by ESI-FT-ICR mass spectrometry. The ligand displacement reaction between noncovalent diastereomeric [1(L).H.A](+) complexes and the 2-aminobutane enantiomers (B) exhibits a distinct enantioselectivity with regard to both the leaving amino acid A and the amine reactant B. The emerging selectivity picture, discussed in the light of molecular mechanics and molecular dynamics calculations, points to chiral recognition by 1(L), as determined by the effects of the host asymmetric frame on the structure, stability, and rearrangement dynamics of the diastereomeric [1(L).H.A](+) complexes and the orientation of the amine reactant B in encounters with [1(L).H.A](+). The results contribute to the development of a dynamic model of chiral recognition of biomolecules by enzyme mimics in the unsolvated state.     

A Concise Synthesis of (R)-GABOB from L-Malic Acid

A concise synthesis of (R)-4-amino-3-hydroxybutanoic acid, starting from L-malic acid, is reported. The approach is based on the conversion of the oxazolidin-2-one 9 into a full protected form of (®)-GABOB by an Arndt-Eistert reaction.     

Inhibition of adenosine 3',5'-cyclic monophosphate phosphodiesterase by flavonoids from licorice roots and 4-arylcoumarins.

Isoliquiritigenin, glabridin, licoarylcoumarin and licoricidin were identified as strong inhibitors of adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase in waste materials which were obtained during the industrial extraction of glycyrrhizin from licorice roots. The structure-activity relationships of 12 flavonoids from licorice roots and 34 4-arylcoumarins were studied. In 4-arylcoumarins, 5,7-dihydroxy derivatives were generally highly inhibitory towards cAMP phosphodiesterase.