SPECTROSCOPIC STUDY OF INTERACTION OF INDOMETHACIN AND DACLATASVIR DIGIDROCHLORIDE WITH HUMAN SERUM ALBUMIN

Fluorescence spectroscopy is one of the most effective methods for studying the binding of drugs to proteins, which is important for the purposes of biochemistry and medicine. When studying the interaction in vitro, human serum albumin (HSA) is used as a model, due to the presence of tryptophan residues in its composition, which are characterized by high sensitivity to the environment. The study of binding is based on the effect of static quenching of the intrinsic fluorescence of HSA by molecules of drugs that act as quenchers. However, such a method of studying the interaction becomes unsuitable if there is overlap (partial or complete) of the fluorescence spectra of the protein and the quenching molecule. Under physiological conditions, in vitro the interaction between indomethacin (IND), daclatasvir dihydrochloride (DAC) and HSA by the by fluorescence emission spectroscopy was studied. The results of the experiment show that the intrinsic fluorescence of the IND and DAC is manifested in the same spectral region as the intrinsic fluorescence of the protein. In the case of an IND, a small site of the spectrum shifted relative to the maximum can be selected, in which quenching of the fl uorescence of the protein is observed. In the case of DAC, its emission spectrum is completely superimposed on the intrinsic fluorescence of the protein. It is established that as a result of static interaction in the HSA -IND and HSA -DAC systems, the intrinsic fluorescence of IND and DAC by protein is quenched. The possibility of determining the binding constants of HSA with molecules of drug substances by quenching their intrinsic fluorescence is shown. The constants and number of binding sites in the HSA-IND and HSADAC systems are established. It is shown that the values of the binding constants, determined by quenching the HSA and by quenching the IND, have satisfactory similarity. A value for the average distance r between IND(DAC) and HSA was derived from the fluorescence resonance energy transfer. Since, the pharmaceutical firms need standardized screens for protein binding in the first step of new drug design, this kind of study of interaction between HSA and IND (DAC) would be useful in pharmaceutical industry and clinical medicine