Aurones: Small Molecule Visible Range Fluorescent Probes Suitable for Biomacromolecules
作者:Natasha Shanker、Ozlem Dilek、Kamalika Mukherjee、Dennis W. McGee、Susan L. Bane
DOI:10.1007/s10895-011-0919-y
日期:2011.11
Aurones, derivatives of 2-benylidenebenzofuran-3(2H)-one, are natural products that serve as plant pigments. There have been reports that some of these substances fluoresce, but little information about their optical properties is in the literature. In this report, series of aurone derivatives were synthesized as possible fluorescent probes that can be excited by visible light. We found that an amine substituent shifted the lowest energy absorption band from the near-UV to the visible region of the electromagnetic spectrum. Four amine-substituted aurone derivatives were synthesized to explore the effect of this substituent on the absorption and emission properties of the aurone chromophore. The emission maxima and intensities of the molecules are strongly dependent on the nature of the substituent and the solvent polarity. Overall, the emission intensity increases and the maximum wavelength decreases in less polar solvents; thus, the aurones may be useful probes for hydrophobic sites on biological molecules. A limited investigation with model protein, nucleic acid and fixed cells supports this idea. It is known that the sulfur analog of aurone can undergo photo-induced E/Z isomerization. This possibility was investigated for one of the aminoaurones, which was observed to reversible photoisomerize. The two isomers have similar absorption spectra, but the emission properties are distinct. We conclude that appropriately substituted aurones are potentially useful as biological probes and photoswitches.
黄酮,一种2-苯基亚胺苯并呱-3(2H)-酮的衍生物,是一种作为植物色素的天然产物。有报道称这些物质中有一些具有荧光特性,但关于它们的光学性质的文献资料很少。在这篇报告中,我们合成了一系列作为可见光激发的荧光探针的黄酮衍生物。我们发现,一个胺取代基将最低能量吸收带从近紫外区转移到了电磁谱的可见区域。合成了四种胺取代的黄酮衍生物,以探讨该取代基对黄酮色素的吸收和发射特性的影响。分子的发射峰值和强度在很大程度上取决于取代基的性质和溶剂的极性。总体而言,在极性较小的溶剂中,发射强度增加而峰值波长下降;因此,黄酮可能作为生物分子上疏水位点的有用探针。对模型蛋白质、核酸和固定细胞的有限研究支持了这一观点。已知黄酮的硫类类似物可以发生光诱导的E/Z异构化。我们对一种氨基黄酮进行了这方面的研究,观察到其可逆光异构反应。这两种异构体具有相似的吸收光谱,但发射特性有所不同。我们得出结论,适当取代的黄酮在生物探针和光开关方面具有潜在的应用价值。