氟喹诺酮类抗生素的光敏毒性及其抑制机理研究

发布时间：2018-04-14 14:36

本文选题：氟喹诺酮类抗生素 + 光敏毒性　；参考：《中国科学院研究生院(上海应用物理研究所)》2017年博士论文

【摘要】：氟喹诺酮(FQs)是具有喹诺酮基本结构的抗菌素类药物,目前在全球范围内被广泛使用。该类抗菌素具有抗菌谱宽、药效好、毒副作用相对较低等优点,但也存在光敏毒性和光诱导细胞突变等多种毒副作用。虽然光敏毒性的发生率较低,但是由于服药人群的数量庞大,仍然会导致大量的患者服药后遭受额外的痛苦与烦恼。研究其光敏毒性形成机理汇聚了众多科研人员的努力,得到了较多有意义的研究结果。但是迄今为止,造成FQs光敏毒性的结构性因素尚未得到系统、有效地阐明。本论文采用激光光解和脉冲辐解的瞬态研究手段与凝胶电泳、高效液相色谱、紫外可见吸收光谱、稳态荧光发射光谱等稳态研究手段相结合的方式,并辅以理论计算,对FQs的结构-光敏毒性关系进行了系统地研究。从化学结构的角度揭示引起光敏毒性的根源。本论文还尝试引入外源性抗氧化剂,探索减轻或抑制FQs光敏毒性的机理;并改进了光敏毒性的常用检测方法——四氮唑兰类比色法,使检测结果更为可靠。本论文以培氟沙星(PEF)和二氟沙星(DIF)为研究对象,探究1号位点取代基对FQs光敏毒性的影响。研究发现,如果1号位点为氟代苯基,可使FQs的激发波长蓝移,由UVA波段蓝移到UVB波段;而太阳光紫外线波段绝大部分UVB波段紫外线被臭氧层吸收,到达地表的紫外线主要集中在UVA波段,这一蓝移效应有效地减轻了光敏毒性。前人文献认为,氟原子较多时,一般因为脱氟反应加剧而使光敏毒性较大。而本研究表明,空间位阻效应使激发波长蓝移的影响可以大于脱氟效应的影响。本论文以安托沙星(ANT)和左氧氟沙星(LEV)为研究对象,探究5号位点取代基对FQs光敏毒性的影响。研究发现,5号位点为氨基(ANT)时,通过理论计算表明该结构下FQs分子由基态跃迁到激发态只需要较低的能量,且具有较高的跃迁几率。但是却检测不到明显的荧光发射过程和三重激发态。通过系统地分析得知,氨基的加入,改变了激发态FQs瞬态产物的分子内电荷转移机制,使瞬态产物多以无辐射跃迁的方式返回基态,不产生三重激发态,从而减轻FQs对生物分子的光敏损伤。减轻光敏毒性途径通常包括改进光敏性物质的化学结构和引入外源性抗氧化剂。所以本论文也尝试引入外源性抗氧化剂来减轻FQs的光敏毒性。研究发现,氧化石墨烯(GONs)可以通过物理性屏蔽紫外线、电荷转移和能量转移等方式清除FQs在光照下的瞬态活性物种并可以通过电荷转移的方式修复受损的蛋白质分子,有效降低FQs的光敏毒性。因为GONs已经广泛运用于药物分子的载体,基于本论文的研究结果,将GONs作为FQs的药物载体有可能同时起到药物缓释和降低光敏毒性的作用,对于提升FQs疗效和降低其毒副作用是一个可行的方案。考虑到光敏毒性成因中活性氧自由基(ROS)起到重要作用,本论文对ROS的常用检测方法进行了研究。作为ROS的母体化合物,超氧阴离子自由基的常用检测方法是四氮唑兰类比色法。本论文首次发现原本属于弱还原剂的该类比色剂在紫外光照射下有很强的光氧化性,不再是超氧阴离子自由基的特异性检测试剂。通过加入超氧化物歧化酶(SOD)对检测方法进行改进,得到了较准确的超氧阴离子自由基产额计算公式,有助于准确分析FQs光敏毒性的成因,也有利于纳米材料在光照下的纳米毒性来源的准确分析。
[Abstract]:(FQs) is a fluoroquinolone antibiotic drugs has the basic structure of quinolone, currently in the global scope is widely used. This kind of antibiotics has wide antibacterial spectrum, good efficacy, side effects are relatively low, but there are also photosensitive toxicity and light induced cell mutation and other kinds of side effects. Although the photosensitive toxicity occurred the rate is low, but due to the number of large crowds, will still lead to a large number of patients suffer from pain and trouble. Additional study the formation mechanism of phototoxicity brought together many researchers to get the results more meaningful. But so far, the structural factors caused by FQs toxicity has not yet been photosensitive system to clarify, effectively. The thesis adopts the research methods of transient and gel electrophoresis radiolysis and pulsed laser photolysis, HPLC, UV Vis absorption spectra, fluorescence emission. The steady state of the means of spectral combination, supplemented by theoretical calculation, structure of FQs photosensitive toxicity were studied. In order to reveal the root cause photosensitive toxicity from the perspective of their chemical structure. This paper also tries to introduce exogenous antioxidants, explore the mechanism to reduce or inhibit the FQs photosensitive toxicity and improved; the methods of detecting the toxicity of NBT - photosensitive color analogy method, which makes the results more reliable. In this paper, pefloxacin and levofloxacin (PEF) two (DIF) as the research object, explore the impact of 1 sites of substituents on the FQs photosensitive toxicity. The study found that if 1 sites for difluorophenyl that can make the FQs excitation wavelength blue shift from UVA band to UVB band blue shift; and the solar ultraviolet band most ultraviolet UVB absorbed by ozone, ultraviolet radiation reaching the earth's surface is mainly concentrated in the UVA band, the blue shift effect To effectively alleviate the photosensitive toxicity. The previous literature that the fluorine atom is more general, because the defluorination reaction increased the photosensitive toxicity. This study shows that the steric effect effect of the excitation wavelength blue shift can be larger than the effect of defluorination effect. In this paper, Antoine floxacin (ANT) and levofloxacin (LEV) as the research object, explore the impact of 5 sites of substituents on the FQs photosensitive toxicity. The study found that 5 loci of amino (ANT), through theoretical calculations show that the FQs molecule of the structure from the ground state to the excited state transitions only need lower energies, transition probability and high detection. But no obvious fluorescence emission process and three excited states. Through systematic analysis, amino join, change the excited state of FQs products in transient charge transfer mechanism, the transient products return to the ground state of the nonradiative transition, No three excited state, so as to reduce the FQs of photosensitive damage of biological molecules. Reduce toxicity pathways usually include chemical structure of photosensitive photosensitive material improvement and the introduction of exogenous antioxidants. So this paper also phototoxicity to introduce exogenous antioxidants to reduce FQs. The study found that graphene oxide (GONs) by physical of UV shielding, charge transfer and energy transfer way clear transient FQs active species in the light and protein molecules can pass through the charge transfer way to repair damaged, effectively reduce the toxicity of FQs. Because of the photo carrier GONs has been widely used in drug molecules, the research results of this thesis are based on the GONs as a drug vector FQs may delay the release of medicine and reduce the photosensitive toxicity effect, to enhance the FQs effect and reduce the side effect is a feasible scheme. Considering the causes of toxicity in photosensitive active oxygen free radical (ROS) plays an important role, the common detection method of ROS is studied. As the parent compound ROS, commonly used detection methods of superoxide radical anion is blue tetrazolium colorimetric method. The analogy first discovered originally belonged to the weak reducing agent analogy color under ultraviolet radiation light has strong oxidation, is no longer the specificity of detection reagent of superoxide anion radical by adding superoxide dismutase (SOD) on the detection method is improved to get more accurate superoxide anion free radical yield formula, causes contribute to the accurate analysis of FQs photosensitive toxicity, accurate analysis is also conducive to toxicity of nano materials in nano source of light.

【学位授予单位】：中国科学院研究生院(上海应用物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ465

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