Spectroscopy study and co-administration effect on the interaction of mycophenolic acid and human serum albumin

Mycophenolic acid (MPA), an immunosuppressor, is always administered in combination with several drugs in clinical therapy, which may alter the binding of MPA to human serum albumin (HSA) and could influence its pharmacological activities. Thus, this study evaluated the interaction between HSA and MPA, as well as investigated the effect of co-administrated drugs on the MPA–protein binary system using fluorescence spectroscopy. Results revealed that MPA has a strong capability to quench the fluorescence of HSA, and the acting forces for the binding are hydrogen bonds and van der Waals forces. Competition on combined administration showed that balofloxacin significantly affects the MPA–HSA interaction, as reflected by the remarkable decrease in fluorescence intensity. Furthermore, cefminox sodium has competitive capability with MPA to some extent, whereas methyl prednisone and amlodipine besylate have a minor influence on the binary system. However, simvastatin has no appreciable effect on the MPA–HSA interaction. In addition, three-dimensional fluorescence spectra and circular dichroism spectroscopy, which were employed to determine the conformation, showed that the binding of MPA with HSA can induce conformation changes in HSA.