3-羟基糖取代对槲皮素与人血清蛋白相互作用的影响

Effect of 3-hydroxy glycosylated substitution on the interaction of quercetin with human serum albumin

黄酮类化合物是许多植物性食品的主要功能活性成分,黄酮与蛋白的相互作用会直接影响其在人体的转运与代谢。该文以槲皮素(quercetin,Que)、异槲皮素(quercetin-3-O-glucoside,Q3G)、槲皮素-3-O-鼠李糖苷(quercetin-3-O-rhamnoside,Q3Rh)、槲皮素-3-O-木糖苷(quercetin-3-O-xyloside,Q3X)和芦丁(quercetin-3-O-rutinoside,Q3Ru)为对象,通过荧光光谱和分子对接技术研究3-羟基糖取代对槲皮素与人血清白蛋白(human serum albumin,HSA)相互作用的影响。结果表明,5种黄酮都是通过静态方式猝灭HSA的内源荧光,并以自发的放热过程与HSA结合形成稳定的复合物。3-羟基糖取代会降低槲皮素对HSA的荧光猝灭效果和与HSA的结合能力,Q3Ru和Q3X的荧光猝灭效果最弱,Q3G的结合能力最弱。同步荧光分析发现,Que、Q3X、Q3Ru、Q3G和Q3Rh会使HSA中色氨酸微环境的极性增加,糖取代可增强其影响,其中葡萄糖的效果最强。热力学和分子对接结果表明,Que、Q3X、Q3Rh、Q3G、Q3Ru通过疏水相互作用、氢键和范德华力结合在人血清蛋白(human serum albumin,HSA)的疏水腔中,并分别形成了4、6、5、2、4个氢键,糖取代不会改变化合物与HSA的结合区域和作用力类型,但会改变其具体的相互作用氨基酸。研究结果有利于解释不同糖取代食品营养成分与蛋白质相互作用差异,及其在体内的转运与代谢,为其构效关系分析提供一定的理论依据。

Flavonoids are the major bioactive compounds of many plant foods,the interaction with proteins can affect its transport and metabolism in human body.To evaluate the influence of 3-OH glycosylated substitution on the interaction of quercetin with human serum albumin(HSA),five common flavonols,quercetin-3-O-rhamnoside(Q3 Rh),quercetin(Que),quercetin-3-O-xyloside(Q3 X),quercetin-3-O-rutinoside(Q3 Ru),and quercetin-3-O-glucoside(Q3 G)were tested by fluorescence spectroscopy and molecular docking techniques.The results indicated that five tested flavonols all quenched the fluorescence of HSA via a static mechanism,stable complexes were formed via a spontaneously exothermic process.Glycosylated substitution on 3-OH decreased the fluorescence quenching efficacy of quercetin on HSA,as well as its binding ability.Q3 Ru and Q3 X exhibited the weakest fluorescence quenching ability,while Q3 G showed the lowest binding ability.Synchronous fluorescence analysis revealed that Que,Q3 Ru,Q3 X,Q3 G,and Q3 Rh increased the polarity in the micro-environment of tryptophan,but did not alter the polarity in the vicinity of tyrosine residue.Glycosylation on 3-OH enhanced the impact on tryptophan micro-environment,glucose exhibited the strongest role.Thermodynamics and molecular docking results indicated that Que,Q3 X,Q3 Rh,Q3 G and Q3 Ru inserted into the hydrophobic cavity of HSA through hydrophobic interactions,hydrogen bonds,and van der Waals forces,and 4,6,5,2 and 4 hydrogen bonds were formed accordingly.Glycosylated substitution would not obviously change the binding region and interaction forces of quercetin with HSA,but could alter the amino acids involved in the formation of complexes.The results could help to explain the different interaction mechanism of food nutrition with different glycosylated substitutions,as well as their transport and metabolism in vitro.And it also provides a certain theoretical foundation for its structure-bioactivity relationship analysis.