Spectral Characteristics Research Of The Interaction Between The Active Components Of Several Plants And Human Serum Albumin And DNA

Anti tumor,anti-bacterial and some other physiological activities with natural plant active ingredients have been gradually known in recent years.The rich source,structural diversity and low side effect of these active ingredients have aroused widespread concern in many disciplines.Proteins and nucleic acids are of important biological macromolecules in life.Serum albumin(SA)bear the carrier function of various endogenous and exogenous compounds.And deoxyribonucleic acid(DNA)is the main target of many anticancer and antimicrobial molecules.Therefore,It is necessary It is necessary to make a study from the molecular level on supramolecular mechanism between plant components with pharmacological activity and biological macromolecules.It would provide a possible theoretical guidance to supramolecular assembly,molecular recognition,drug design and development and other fields.Interaction mechanism between seven kinds of plant components with anti-cancer activity and human serum albumin(HSA),calf thymus DNA(ctDNA)by using various spectroscopic techniques was introduced in this paper.The main research contents are as follows:1.Study on the spectral characteristics of the interaction of pterostilbene with human serum albuminThe interaction mechanism between pterostilbene(PTE)and human serum albumin(HSA)under physiological conditions has been studied by using fluorescence spectroscopy,UV absorption spectroscopy and surface enhanced Raman spectroscopy.The results show that the HSA fluorescence static quenching has emerged due to the combination with pterostilbene along with the non radiation energy transfer effect.Meanwhile,a 1:1 complex between PTE and HSA has formed,which the binding distance is 1.495 nm,the binding constant(KA)between PTE and HSA is 1.12 × 104(298 K),4.07 × 104(304 K)and 2.45 × 105 L / mol(310 K),respectively.The study by surface enhanced Raman spectroscopic reveals that the combination of pterostilbene molecules with HSA is by methoxy group.The hydrophobic effect is the main role betweetn pterostilbene molecules and HSA on the basis of thermodynamic data obtained.That marker competition experiments show the primary binding site for PTE was located at the site III in HSA.From three-dimensional fluorescence spectroscopy,UV absorption spectroscopy,synchronous fluorescence spectroscopy and surface enhanced Raman spectra,it can be seen that the conformation of HSA has apparently changed with the addition of PTE,resulting in the less hydrophobic property around tryptophan residues of HSA,whereas the conformation of PTE does not change obviously.2.Spectroscopic study on the interaction between p-Coumaric acid and human serum albuminUnder simulated physiological conditions,the binding mechanism between p-Coumaric acid(p-CA)and human serum albumin(HSA)was investigated by fluorescence spectroscopy,UV absorption spectroscopy and surface enhanced Raman spectroscopy(SERS).The results show that the effect between p-CA and HSA was a static fluorescence quenching with F?rster's non-radioactive energy transformation.At 298,304 and 310 K,the binding constants(KA)between p-CA and HSA were 3.41 × 104,2.09 × 104 and 1.38 × 104 L / mol,respectively,the binding site(n)value was approximate to 1.The study by surface enhanced Raman spectroscopic reveal that the combination of p-CA with HSA is by phenolic group.Marker competition experiments show the primary binding site for p-CA was located at the site I in HSA.The thermodynamic parameters of the reaction process show that the interaction between p-CA and HSA is mainly electrostatic attraction.According to F?rster energy transfer theory,the distance of between p-CA and HSA is 5.11 nm.From synchronous fluorescence spectra and three-dimensional fluorescence spectra,it can be seen that the conformation of HSA does not obviously change due to the combination with p-CA.3.Spectroscopic study on the interaction between naringenin(NG),Corilagin(Cor)and juglone(Jug)and human serum albuminBy the fluorescence quenching spectra,UV absorption spectroscopy,synchronous fluorescence,three-dimensional fluorescence spectroscopy and site competition experiments,the interaction mechanism between naringenin(NG),Corilagin(Cor),Juglone(Jug)and HSA has been investigated.The experimental results show that NG,Cor and Jug have the quenching effect on the intrinsic fluorescence of HSA.The quenching mechanism was different for NG,Cor,Jug,that is,the static quenching and non radiation energy transfer process,the static quenching,the moving and static quenching along with non radiation energy transfer process,respectively.By the calculation of the binding constant of NG-HSA,Cor-HSA and Jug-HSA system(KA),the number of binding sites(n)and reaction thermodynamic parameters(?G,?H and ?S),the non covalent interactions process between drugs and HSA is obtained.Site competition experiment results show that the binding sites of naringenin molecules is mainly site II,those of Currie La Gin and Hu Taokun are the same site III.By F?rster non radiative energy transfer theory,the binding distance between drugs and HSA can be obtained.From the study of synchronous fluorescence spectra and three-dimensional fluorescence spectra,it can be seen that HSA combines with the three species of plant active substance,whereas its secondary structure and the conformation do not obviously change.4.Study on the interaction between cinnamic acid(CA)and calf thymus DNAIn physiological conditions,using ethidium bromide(EB)as a fluorescence probe by fluorescence spectroscopy,absorption spectroscopy,resonance scattering spectroscopy and surface enhanced Raman spectroscopy method combined with the ionic strength and melting experiments of cinnamic acid(CA)and calf thymus DNA(ctDNA)of the mechanism were studied.The results showed that cinnamon effect of acid and ctDNA absorption spectrum produced hypochromic effect.The addition of cinnamon acid could quench the fluorescence of EB-ctDNA system and the quenching mechanism was static quenching.The binding constant is 1.63 × 103(293 K)and 4.97 × 103 L / mol(310 K).The resonance scattering and the melting point of ctDNA showed that cinnamic acid can be gathered based in ctDNA,forming a supramolecular system,the Tm value increased 6 degrees.The thermodynamic parameters showed that cinnamic acid and ctDNA bases was driven mainly by hydrophobic interaction.Surface enhanced Raman spectroscopy revealed that cinnamon acid in ctDNA embedding position.The base stacking was formed with the base A or G.And the results also indicated that the combination of the acid and ctDNA was carried out by means of embedding in this experimental condition.The process is the spontaneous and endothermic process of entropy driven.5.Spectral characteristics of interaction between corilagin,juglone and chalcone with calf thymus DNAIn the pH7.4 Tris buffer solution,the interaction mechanism between Currie La Gin(Cor),juglone(Jug)and chalcone(Cha)of three kinds of anticancer drug molecules with calf thymus DNA(ctDNA)were studied by the absorption spectra,fluorescence spectra and resonance scattering spectral method combined with the influence of ionic strength,ctDNA melting experiments.The results showed that three compounds with ctDNA were found after hypochromic effect,and could effectively quench the fluorescence of EB-ctDNA.Quenching methods was different and the binding constants were calculated.Scattering spectrum and melting point of ctDNA showed that three compounds could be gathered in the ctDNA junction and formed a supramolecular system and caused the Tm value to increased by 5~6 ?,three kinds of drugs were embedded and combined with the ctDNA.The strength of chalcone,corilagin,juglone,the change of ionic strength had little effect on its binding.In addition,according to the results of thermodynamic parameters,the non covalent interactions between the three compounds and ctDNA were calculated.