Synthesis of methylene blue derivants and their interaction with bovine serum albumin

Objective To synthesize a series of methylene blue derivantsꎬN3ꎬN3ꎬN7ꎬN7-Tetra-n-propyl-3ꎬ7-dia ̄ minophenothiazin-5-ium iodideꎬN3ꎬN3ꎬN7ꎬN7-Tetra-n-butyl-3ꎬ7-diaminophenothiazin-5-ium iodide and N3ꎬN3ꎬ N7ꎬN7-Tetra-n-pentyl-3ꎬ7-diaminophenothiazin-5-ium iodideꎬand study the interactions between these methylene blue derivants and bovine serum albumin(BSA) under physiological condition.Methods These compounds were characterized by means of MS and H-NMRꎬand the interactions between these methylene blue derivants and bovine serum albumin (BSA) under physiological condition were studied using fluorescence spectroscopy.Results The fluorescence of BSA was quenched remarkably by these methylene blue derivants due to the formation of complexesꎬGibbs free energy change(ΔG) was negative.The binding distance between the tryptophan residue of BSA and these methylene blue derivants was less than 7 nm.Conclusion The fluorescence quenching mechanisms of BSA by these methylene blue derivants were considered as static quenchingꎬthe binding process was a spontaneous process and the energy transfer from the tryptophan residue of BSA to these methylene blue derivants can occur according to the Förster non-radioactive resonance energy transfer theory.In ad ̄ 􀅰 5 2 1 􀅰 药学研究􀅰Journal of Pharmaceutical Research 2017 Vol.36ꎬNo.3