Investigation On The Interaction Between Pyrethriods Pesticide And DNA And The Effect Of Metal Inos?Surfactants

Widespread occurrene of environmental pollutions has resulted in risks to public health and environmental safety. Nowadays, special attentions are paid to potential toxic effects to humans and mammals induced by some current use pesticides. Pyrethroids are characterized by their high efficacy to insects, low environmental mobility and relatively low mammalian toxicity. People and animals can easily come into contact with pyrethroids when they are released into the environment, and be exposed to them in several ways during daily life. Recent studies showed that some pyrethroids displayed different toxic effects and may possess health risks to humans and other mammals. DNA is the material basis of biological genetic information and it is the target of many carcinogenic pesticide molecules. Therefore, studying the combination of properties and mechanism of pyrethroids with DNA will contribute to evaluate and forecast the danger of pesticide from the molecular lever.In this paper, multiple spectroscope techniques and molecule docking, as well as DNA melting experiments and DNA viscosity measurements were employed to investigate the binding mechanism of three kinds of pyrethroids like resmethrin, tau-fluvalinate and flumenthrin with calf thymus DNA (ctDNA) and the influence of exotic matter (metal iron and surfactants) under simulative physiological condition (pH 7.4). Furthermore, chemometrics methods (multivariate curve resolution-alternating least-squares chemometrics (MCR-ALS) and three-way synchronous fluorescence spectroscope with parallel factor analysis modeling (PARAFAC)) were also introduced to analysis spectroscopy data.The main contents of these investigations were summarized as follows:1. A brief introduction about the properties of pyrethroids and its main hazard, comple with the structure and the important role of life activities of DNA were presented in the first chapter. The mode of action and investigating methods on the interaction between DNA and small molecules were introduced in this chapter. At the same time, small molecules with DNA targets detection technology and the existing problems were summarized.2. The interactive properties of three kinds of pyrethroids (resmethrin, tau-fluvalinate and flumenthrin) and calf thymus DNA were investigated in physiological buffer (pH 7.4) by UV-vis absorption and fluorescence coupled with multivariate curve resolution-alternating least-squares chemometrics (MCR-ALS). The results showed that the fluorescence intensities of pyrethroids pesticides could be quenched obviously by ctDNA and quenching processes were static quenching. The calculated thermodynamic parameters, enthalpy(?H<0) and entropy change (AS <0), suggested that hydrogen bonds and van der Waals forces played a predominant role in the binding of pyrethroids pesticides to ctDNA. In addition, the data matrix obtained from UV-vis spectra was resolved by MCR-ALS approach. The pure spectra and the equilibrium concentration profiles for the components were extracted from highly overlapped spectroscopy.3. The aim of this chapter was to investigate the binding mode and binding sites of resmethrin (RES), tau-fluvalinate (TFL) and flumenthrin (FL) with ctDNA in simulative physiological buffer by using fluorescence spectroscopy, iodide-quenching effect and single/double-stranded DNA effects combining with ctDNA melting and viscosity measurements. All the results indicated that the binding of RES, TFL and FL to ctDNA was groove mode. Moreover, three-way synchronous fluorescence spectra data for the competitive binding between TFL/FL and Hoechst 33258 for ctDNA was resolved by PARAFAC, which further ascertained the groove binding of TFL/FL to ctDNA. The FT-1R analyses suggested that resmethrin (RES) was prone to bind to G-C base pairs of ctDNA and the A-T region of the minor groove of ctDNA as the preferential binding for TFL and FL, which was confirmed by the displacement assays with Hoechst 33258 probe, and the molecular docking visualized the specific binding. The observed changes in circular dichroism spectral (CD) signals revealed that RES, TFL and FL induced the perturbation on the base stacking and helicity of B-DNA, but still remained its B-conformation. DNA cleavage assay showed that RES, TFL and FL did not cleave the pUC18 plasmid DNA.4. Influence of Cu2+?Ca2+?Mg2+ on the interactions between RES, TFL?FL and calf thymus DNA (ctDNA) were investigated in the physiological buffer (pH 7.4) by applying UV-vis absorption, fluorescence, CD and FT-IR spectroscopy, combined with viscosity measurements and melting point effect of DNA. The results showed that the binding mode of RES/TFL/FL with ctDNA were still groove binding, but the binding constants were changed when Cu2+?Ca2+?Mg2+ existed respectively. It can be deduced that the effect of metal ions on the binding between pesticides and ctDNA mainly depends on the relative affinity between metal ions and pesticides DNA basic groups or phosphate groups. In addition, the changes in the CD and TF-IR spectra showed that Cu2+, Ca2+ and Mg2+ ions have intervention effects on binding sites and comformation of the interaction of pesticides with ctDNA.5. In this chapter, intervention of surfactants (cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Tween 80 (TW 80)) on the interaction behaviour of resmethrin-ctDNA was inveastigated by using UV-vis spectroscopy, fluorescence, CD and FT-IR spectroscopy, along with ctDNA thermal denaturation studies and viscosity experiments under condition of simulate physiology pH. When three surfactants (SDS, TW 80 and CTAB) were added into RES-ctDNA binary system, respectively, the change tendency of binding constant of RES and ctDNA was various. However, the groove binding mode of RES to ctDNA was still remained and the B-DNA conformation did not change in the respective presence of surfactants (SDS, TW 80 and CTAB).