Benzofuran Spiropyrans as Analytical Reagents for Low-Molecular-Weight Aminothiols

Abstract

The problem of determining biologically active low-molecular-weight aminothiols, such as cysteine and glutathione, requires the development of new methods and analytical reagents. Among the latter substances, a group of spiropyrans can be distinguished, which are photochromic organic substances reaching an equilibrium between their cyclic and open forms in solutions. We consider a possibility of using benzofuran spiropyrans as analytical reagents for aminothiols and studied the effect of various substituents in their structure on the change in optical properties in the presence of cysteine and glutathione. An equilibrium in solutions of benzofuran spiropyrans bearing a hydroxyl group in position 7 shifts in the presence of analytes towards the formation of a colored open form. The considered spiropyrans were used to create a simple, selective, and sensitive procedure for the spectrophotometric and kinetic determination of cysteine and glutathione in vitro.