Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600 036, Tamilnadu, India.
Photochem Photobiol Sci. 2011 Jan;10(1):66-75. doi: 10.1039/c0pp00120a. Epub 2010 Oct 26.
Fisetin, a bioflavonoid, has important biological relevance. It exhibits intramolecular excited state proton transfer (ESIPT), analogous to the structurally similar flavonoids. The presence of multiple prototropic forms of fisetin was observed at various concentrations of different bile salt molecules. The presence of ground state fisetin anion (FA)(GS) (λ(ex) 418 nm; λ(em) 490 nm) in alcohols and bile salt micellar media is a novel observation. The interaction of fisetin with sodium cholate (NaC) and some other bile salts has been studied in detail, using the intrinsic fluorescence of different prototropic forms of fisetin: neutral form (FN, λ(ex) 369 nm, λ(em) ~ 400 nm), ground state anion form ((FA)(GS), λ(ex) 418 nm, λ(em) 490 nm) and phototautomer (FT, λ(ex) 369 nm, λ(em) 540 nm). The hypsochromic shift of (FA*)(ES) emission and bathochromic shift of FT emission with increasing bile salt concentration suggests the progressive reduction of polarity of the bile salt media, which could be resulting from the neutralization of bile salt molecules as their concentration increases.
漆黄素是一种生物类黄酮，具有重要的生物学意义。它表现出分子内激发态质子转移（ESIPT），类似于结构相似的类黄酮。在不同胆汁盐分子的不同浓度下，观察到漆黄素存在多种质子化形式。在醇和胆汁盐胶束介质中，基态漆黄素阴离子（FA）（GS）（λ（ex）418nm；λ（em）490nm）的存在是一个新的观察结果。使用不同质子化形式的漆黄素的本征荧光，详细研究了漆黄素与牛磺胆酸钠（NaC）和其他一些胆汁盐的相互作用：中性形式（FN，λ（ex）369nm，λ（em）~400nm），基态阴离子形式（（FA）（GS），λ（ex）418nm，λ（em）490nm）和光互变异构体（FT，λ（ex）369nm，λ（em）540nm）。随着胆汁盐浓度的增加，（FA）*（ES）发射的蓝移和 FT 发射的红移表明胆汁盐介质极性的逐渐降低，这可能是由于胆汁盐分子的中和，随着其浓度的增加。
