Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy.
Department of Pharmacy, University of Pisa, 56126 Pisa, Italy.
Int J Environ Res Public Health. 2021 Mar 2;18(5):2412. doi: 10.3390/ijerph18052412.
The study of the interaction of persistent organic pollutants with biosubstrates helps to unravel the pathways for toxicity, however, few mechanistic data are present in the literature for these systems. We analyzed the binding of paraquat (PQ) and diquat (DQ) herbicides to natural calf thymus DNA and a DNA G-quadruplex by spectrophotometric titrations, ethidium bromide exchange tests, viscometry, and melting experiments. The interaction with bovine serum albumin (BSA) protein was studied spectrofluorimetrically at different temperatures. The retention of the targets on positive, negative, and neutral micellar aggregates and liposomes was analyzed by ultrafiltration experiments. Despite some favorable features, PQ and DQ only externally bind natural DNA and do not interact with DNA oligonucleotides. Both herbicides bind bovine serum albumin (BSA). PQ binds BSA mainly according to an electrostatics-driven process. However, ultrafiltration data also show that some hydrophobic contribution participates in the features of these systems. The practical problems related to unfavorable spectroscopic signals and inner filter effects are also discussed. Overall, both herbicides show a low affinity for nucleic acids and weak penetration into liposomes; in addition, the equilibrium constants values found for BSA system suggest optimal conditions for transport in the body.
持久性有机污染物与生物基质相互作用的研究有助于揭示其毒性途径，但这些系统的机制数据在文献中很少见。我们通过分光光度滴定、溴化乙锭交换试验、粘度和熔点实验分析了百草枯（PQ）和敌草快（DQ）除草剂与天然小牛胸腺 DNA 和 DNA G-四链体的结合。在不同温度下通过荧光光谱法研究了与牛血清白蛋白（BSA）蛋白的相互作用。通过超滤实验分析了目标在正、负和中性胶束聚集体以及脂质体上的保留情况。尽管具有一些有利的特征，但 PQ 和 DQ 仅外部结合天然 DNA，而不与 DNA 寡核苷酸相互作用。两种除草剂都与牛血清白蛋白（BSA）结合。PQ 主要根据静电驱动过程与 BSA 结合。然而，超滤数据还表明，一些疏水性贡献参与了这些系统的特征。还讨论了与不理想的光谱信号和内滤效应相关的实际问题。总的来说，两种除草剂对核酸的亲和力都较低，对脂质体的穿透能力较弱；此外，BSA 体系中发现的平衡常数值表明在体内转运的最佳条件。
