Photochemical release (uncaging) of bioactive messengers with three-dimensional spatial resolution in light-scattering media would be greatly facilitated if the photolysis could be powered by pairs of IR photons rather than the customary single UV photons. The quadratic dependence on light intensity would confine the photolysis to the focus point of the laser, and the longer wavelengths would b...

Two bioactive coumarins including 7-hydroxycoumarin (umbelliferone) and 7-hydroxyl-6-methoxy-3, 70-dicoumarylether (daphnoretin) were separated from the ethyl acetate extract of the stems of Edgeworthia chrysantha Lindl (E. papyrifera) by high speed countercurrent chromatography (HSCCC). The two-phase solvent system used was composed of n-hexane-ethyl acetate–methanol–water at an optimized volu...

A series of 6H,7H-7-(4-Hydroxy-3-coumarinyl)[1]benzopyrano[4,3-b][1]benzopyran-6-ones 4a-g and 3-(2-hydroxybenzoyl)-2H-chromen-2-ones 5a-g derivatives were synthesized by reaction 4-hydroxycoumarin with 2-hydroxyarylaldehydes 2a-f or 2-hydroxynaphtaldehyde 2g using different solvents acid/base catalysts. The approach relies on a regioselective cascade involving one/two molar equiv the 4-hydroxy...

In this work, a series of anti-tyrosinase and anti-butyrylcholinesterase coumarin derivatives 4a–f 5a–f were synthesized starting from 4-hydroxycoumarin. The condensation 2-(arylimin)-4-hydroxycoumarins 3a–f with dimethylformamide dimethyl acetal (DMF-DMA), used as key reaction, afforded the precursors 4a–f, whose acid treatment led to formation 5a–f. These prepared heterocycles characterized b...

silica gel has been used for synthesis of biscoumarin derivatives starting from 4-hydroxycoumarin and aryl aldehydes. the reaction conditions are completely in agreement with green chemistry principles including sing water as media and a recyclable and safe catalyst. this method is also simple and inexpensive and leads to high yield of products in short reaction times.

Formation of R-helical coiled-coil dimers represents one of the simplest examples of a specific protein-protein interaction. This dimerization mode is commonly observed among transcription regulator proteins, where the process is referred to as leucine zipper formation. Inhibitors of leucine zipper dimerization would allow one to control gene expression. As a first step toward identifying such ...

New coumarin derivatives, namely (2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-phenylthiazolidin-3-yl)acetamide, N-(2-(3-methoxyphenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide, 2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-(2,3,4trimethoxyphenyl)thiazolidin-3-yl)acetamide and N-(2-(4-bromophenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)ac...

Silica gel has been used for synthesis of biscoumarin derivatives starting from 4-hydroxycoumarin and aryl aldehydes. The reaction conditions are completely in agreement with green chemistry principles including sing water as media and a recyclable and safe catalyst. This method is also simple and inexpensive and leads to high yield of products in short reaction times.