SPECTROSCOPIC STUDY OF INTERACTION OF SODIUM DOLUTEGRAVIR WITH HUMAN SERUM ALBUMIN

Abstract

Drug-protein binding has become an important research field in life sciences, chemistry and clinical medicine. Under physiological conditions, in vitro interaction between the antiviral drug 2 Sodium (4R, 12aS)-9-{[(2,4-difluorophenyl)methyl]carbamoyl}-4-methyl-6,8-dioxo3,4,6,8, 12,12a-hexahydro-2H-pyrido[1’,2’:4,5]pyrazino[2, 1-b][1,3]oxazin-7 –olate (dolutegravir sodium, DN) and human serum albumin (HSA) was investigated at excitation wavelength 280 nm and at different temperatures (298 K and 313 K) by fluorescence emission spectroscopy. The emission of HSA was characterized by a broad emission band at 346 nm. The results of the experiment showed that DN quench the intrinsic fluorescence of the protein as a result of static interaction in the HSA -DN system, which is confirmed by shifts in the difference UV spectra of the HSA -DN and the reduction of the binding constant for the HSA -DN system with increasing temperature. The constant (KA =9,82· 103 L·mol-1 at 298 K) and the number of binding sites of the HSA –DN system are established. The negative values of enthalpy change (ΔHº) and entropy change (ΔSº) can be attributed in part to van der Waals forces and in part to the formation of hydrogen bonds. A value of 2,14 nm for the average distance r between DN (acceptor) and tryptophan residues of HSA (donor) was derived from the fluorescence resonance energy transfer. The overlap of the absorbance spectrum of DN with the fluorescence emission spectrum of HAS has been shown. 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 with DN would be useful in pharmaceutical industry and clinical medicine.