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Inorg Chem ; 58(12): 8130-8139, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31124666


An investigation of supramolecular phenomena involving zerovalent transition metal complexes was facilitated by the production of the ditopic isocyanide ligand 1,3-bis( p-isocyanophenyl)urea, which was synthesized via substoichiometric phosgenation of 4-isocyanophenylamine and used to coordinate group VI metal carbonyl fragments. The resulting binuclear organometallic complexes were observed to pack into ladder-like anisotropic arrays in the solid state. Crystallographic and computational evidence suggests that this packing motif can be attributed to a combination of intermolecular π-π and urea-π interactions. Similar to other N, N'-diarylureas bearing electron-withdrawing groups, 1,3-bis( p-isocyanophenyl)urea and the organometallic complexes prepared therefrom also exhibit an affinity toward anion binding in nonaqueous solution. Equilibrium constants ( K) for the formation of host-guest complexes between the organometallic derivatives of 1,3-bis( p-isocyanophenyl)urea and chloride, nitrate, and acetate anions exceed 103, 104, and 105 M-1, respectively.

J Phys Chem A ; 122(46): 8989-8997, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30380862


The excited state properties of cyanine dyes and the orientations of their aggregates were studied using density functional theory (DFT). The effects of exchange-correlation functional and solvent model on the absorption spectrum of Cy5 was investigated. Using the 6-31+G(d,p) basis set and B3LYP exchange-correlation functional with IEF-PCM (water) solvent, the predicted spectrum achieved a maximum absorbance within 0.007 eV of experiment. An in-house program based on the theoretical model of Kühn, Renger, and May (KRM), which predicts the orientation of dyes within an aggregate from its absorbance and circular dichroism (CD) spectra or vice versa, was used to investigate the orientation of an experimentally observed dimer. The absorbance spectrum predicted using the KRM model of the dimer structure optimized with the 6-31+G(d,p) basis set, ωB97XD exchange-correlation functional, and IEF-PCM solvent agrees with experimental data.

Bioorg Med Chem ; 24(16): 3752-7, 2016 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-27338657


Veratrum californicum, commonly referred to as corn lily or Californian false hellebore, grows in high mountain meadows and produces the steroidal alkaloid cyclopamine, a potent inhibitor of the Hedgehog (Hh) signaling pathway. The Hh pathway is a crucial regulator of many fundamental processes during vertebrate embryonic development. However, constitutive activation of the Hh pathway contributes to the progression of various cancers. In the present study, a direct correlation was made between the extraction efficiency for cyclopamine from root and rhizome by eight methods, and the associated biological activity in Shh-Light II cells using the Dual-Glo® Luciferase Assay System. Alkaloid recovery ranged from 0.39 to 8.03mg/g, with ethanol soak being determined to be the superior method for obtaining biologically active cyclopamine. Acidic ethanol and supercritical extractions yielded degraded or contaminated cyclopamine with lower antagonistic activity towards Hh signaling.

Alcaloides de Veratrum/farmacologia , Veratrum/química , Biomassa , Linhagem Celular , Cromatografia Líquida de Alta Pressão , Proteínas Hedgehog/antagonistas & inibidores , Proteínas Hedgehog/metabolismo , Transdução de Sinais/efeitos dos fármacos , Alcaloides de Veratrum/isolamento & purificação