Liu Jianli, He Yonglin, Liu Dan, He Yin, Tang Zhipeng, Lou Hong, Huo Yapeng, Cao Xiangyu
School of Life Science, Liaoning University 66 Chongshan Middle Road Shenyang Liaoning P. R. China
RSC Adv. 2018 Feb 13;8(13):7280-7286. doi: 10.1039/c7ra13272g. eCollection 2018 Feb 9.
Astilbin (ASN) is a flavonoid compound isolated from the rhizome of L. (Smilacaceae). It has many bioactivities, such as selective immunosuppression, antioxidant, anti-hepatic injury, , and is widely used in traditional Chinese medical treatments. The interaction of ASN with bovine serum albumin (BSA) was studied in a physiological buffer (pH = 7.40) using multi-spectroscopic techniques in combination with molecular docking methods. UV-vis absorption measurements proved that a ASN-BSA complex could be formed. Fluorescence data revealed that ASN could strongly quench the intrinsic fluorescence of BSA in terms of a static quenching procedure. The process of binding was spontaneous and the binding occurred mainly through hydrogen bonding and van der Waals forces. The distance between donor (BSA) and acceptor (ASN) was calculated to be 4.80 nm based on Förster's non-radiative energy transfer theory. The binding constant ( = 7.31 × 10 mol L) and the number of binding sites ( ≈ 1) at 298 K suggested that ASN only occupied one site in BSA with high affinity. Moreover, the results of molecular docking indicated that ASN was more likely to be located in site I (sub-domain IIA) of BSA. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that ASN induced conformational changes of BSA. The findings would be beneficial for research on the transportation, distribution and some important bioactivities of ASN in the human body.
落新妇苷（ASN）是从菝葜科植物根茎中分离得到的一种黄酮类化合物。它具有多种生物活性，如选择性免疫抑制、抗氧化、抗肝损伤等，在中医治疗中被广泛应用。采用多光谱技术结合分子对接方法，在生理缓冲液（pH = 7.40）中研究了ASN与牛血清白蛋白（BSA）的相互作用。紫外可见吸收光谱测量证明可以形成ASN - BSA复合物。荧光数据表明，ASN能通过静态猝灭过程强烈猝灭BSA的内源荧光。结合过程是自发的，结合主要通过氢键和范德华力发生。根据Förster非辐射能量转移理论，供体（BSA）与受体（ASN）之间的距离计算为4.80 nm。298 K时的结合常数（ = 7.31 × 10 mol L）和结合位点数（ ≈ 1）表明，ASN仅以高亲和力占据BSA中的一个位点。此外，分子对接结果表明，ASN更有可能位于BSA的位点I（亚结构域IIA）。同步荧光光谱和三维荧光光谱结果表明，ASN诱导了BSA的构象变化。这些发现将有助于研究ASN在人体内的运输、分布及一些重要生物活性。
