Studies On The Drugs And Their Interaction With Biomacromolecules By Spectral Methods

Protein and deoxyribonucleic acid(DNA) are the basic composition of all organisms,and play important roles in all kinds of life activities.DNA is the carrier of genetic materials which acts the main role to the biological evolution,and protein is the expresser of these genetic materials.The investigation of interaction between small drug molecules with biomacromolecules,such as bovine serum albumin(BSA), human serum albumin(HSA) and DNA,is helpful for us to understand the mechanism of function for drugs and exploit new drugs.1.The structure and function of BSA,HSA and DNA were introduced,and the study on the interaction between drug molecules and biomacromolecules by fluorescence and UV-visible spectrophotometry,especially by the fluorescence quenching,was summarized.2.The interaction of the phenylbutazone and ibuprofen with bovine serum albumin was studied by fluorescence spectrometry.The thermodynamic parameters for the binding were obtained by the fluorescence quenching.The reasonable results were obtained by programmed calculation based on the calculating equation established.Compared with the results obtained by the other calculating method,it is proved that the satisfactory results can be obtained by the proposed method.Based on F(o|¨)rster theory of non-radiation energy transfer,the binding distance r of the bovine serum albumin with phenylbutazone and ibuprofen was 1.57 and 1.54 nm, respectively.In addition,the effect of common ions on the binding of the drugs and bovine serum albumin was also examined.The emission intensity of ethidium bromide(EB) in the presence of DNA can be greatly enhanced.The interaction of the DNA with EB was studied and binding parameters,including binding constant and binding sites,were also obtained. 3.Protein has intrinsic fluorescence and can be used as a donor to react with an acceptor.Because of forming of the coordination compound,the protein intrinsic fluorescence can be quenched.Because the bound and unbound drug concentration is difficult to be know during the experiment,the unbound drug concentration is often replaced by the total drug concentration in calculating the binding parameters.The interaction of the two main active components in fruit of Citrus aurantium L.with BSA and HSA was studied by the quenching of intrinsic fluorescence protein.The binding constants and sites of the hesperidin and naringin to proteins were obtained by an improved calculating method and the programmed calculation process.For comparison,other two calculation methods also were applied.The reasonable results were rapidly obtained by programmed calculation process.The△H,△S and△G obtained indicate that the hydrophobic force plays a major role in the interaction of drugs and BSA.The main acting force between naringin and HSA is electrostatic force.However,van der Waals or hydrogen bond plays a major role in the interaction of hesperidin with HSA.Based on the F(o|¨)rster's theory,the binding average distance,r between the protein and drug was evaluated and found to be less than 3 nm.At the same time,the interaction of hesperidin and naringin with BSA and HSA in the presence of four common metal ions was studied by fluorescence and absorption spectrometry.4.Arctiin was determined by fluorescence method in the various different experiment conditions.At the optimal conditions,the good linear response was observed in the arctiin concentration range from 0.05～10.69μg·mL^-1.The interaction between arctiin and DNA was also studied by fluorescence and ultraviolet absorption spectrometry.The biomolecule is possessed of a fluorophore and many binding sites, and the drug molecules are quencher in most studies of biomolecule binding with the small molecule.However,in the work DNA is quencher in the interaction of the DNA with EB.A new method for calculating the binding constants and binding sites was developed and the comparison of the propsed method with the conventional method was made.The reasonable results were obtained by the proposed method.The competitive binding and melting temperature(T_m) were carried out to investigate binding mechanism.In addition,the binding characteristics of arctiin and DNA were further studied by fluorescence method and experimental results showed that the fluorescence of arctiin was quenched easier by single stranded DNA(ssDNA) than that by double stranded DNA(dsDNA),which indicated that the interaction between fluoroquinolone and dsDNA does not belong to intercalation.5.The podophyllotoxin,liquiritin and salidroside were determined by fluorescence spectrometry.The effects of ethanol concentration,temperature,placing time,pH values and foreign substances on the determination of the drugs were examined.At optimal conditions,the good linear responses were observed in the concentration range from 0.04～8.29μg·mL^-1,0.04～8.37μg·mL^-1 and 0.04～18.03μg·mL^-1,for liquiritin and 0.9996 for salidroside and detection limits were 0.024μg·mL^-1,0.017μg·mL^-1 and 0.020μg·mL^-1,respectively.