RESUMO
Neohesperidin dihydrochalcone (NHDHC), known since 1963 as an intensely sweet compound, is determined to be 340 +/- 60 (p less than 0.05) times more potent than sucrose. The unusual temporal properties of this material are hypothesized as being due to the effects of metabolism, conformation, chelation, or hydrophobicity. Forty-four analogues are synthesized to test the four hypotheses, none of which are strongly supported. A method of quantitation of temporal characteristics of tastant molecules is developed so as to allow comparison of taste appearance time (AT) and extinction time (ET) of experimental compounds. Four of the new compounds, 40 and 43-45, exhibit high sweetness potencies, ranging from 280 and 440 times sucrose, and may be useful in selected food systems. The temporal taste characteristics remain unimproved over NHDHC, however.
Assuntos
Chalcona/farmacologia , Propiofenonas/farmacologia , Edulcorantes/farmacologia , Sítios de Ligação , Chalcona/análogos & derivados , Chalcona/metabolismo , Chalconas , Quelantes/metabolismo , Flavonoides/farmacologia , Humanos , Ligação de Hidrogênio , Conformação Molecular , Relação Estrutura-Atividade , Edulcorantes/síntese química , Edulcorantes/metabolismo , Paladar/efeitos dos fármacos , Fatores de TempoRESUMO
Six sweet and five nonsweet simple nonglycosidic dihydrochalcones were prepared, two of which have properties comparable to those of the intensely sweet neohesperidin dihydrochalcone.
Assuntos
Chalcona/análogos & derivados , Propiofenonas/análogos & derivados , Edulcorantes , Relação Estrutura-Atividade , Edulcorantes/síntese químicaAssuntos
Prostaglandinas/síntese química , Animais , Cromatografia em Camada Fina , Colo/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Gerbillinae , Técnicas In Vitro , Conformação Molecular , Contração Muscular/efeitos dos fármacos , Rotação Ocular , Antagonistas de Prostaglandina , Prostaglandinas/farmacologia , Ratos , Estereoisomerismo , Estimulação Química , Útero/efeitos dos fármacosRESUMO
Recent developments in several areas of chemistry, laser technology, photodetector instrumentation, and calorimetry are surveyed, and their probable impact on the measurement of quantum yields is assessed. Chemical developments include: (a) synthesis and design of new luminescent molecules that could possibly serve as standards, (b) application of improved separation techniques to provide samples of extreme purity, and (c) advances in photochemistry that portend the development of wide-range chemical actinometers. The potential use of lasers in quantum-yield measurements and their advantages over conventional sources for application in both optical and calorimetric techniques are pointed out. New methods of quantum-yield measurements, based on the novel characteristics of laser pump sources, are suggested, including the feasibility of measuring yields under time-resolved conditions and of employing internal standards. The possible lifting of wavelength restrictions on both laser sources and detector devices and the implications of these developments for extending the spectral range of quantum-yield measurements are discussed. The current status of calorimetry for determining yields is surveyed, and the impact of recent technology on the feasibility of developing calorimetric methods competitive with optical methods is assessed.
RESUMO
The nature of the emission from central metal ions in complexes can be controlled by chemical alteration of the ligands. For iridium(III) species three types of emission have been observed, each originating from a different and orbitally identifiable excited state. Principles useful for designing new luminescent materials are formulated. They can be used for guiding photochemical research and for designing new analytical methods.
