Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 2. Luminescent Additives That Increase the Chemiluminescence Quantum Yield

The present review examines the use of chemiluminescence detection to evaluate the course of free radical reactions in biological model systems. The application of the method is analyzed by using luminescent additives that enhance the luminescence thanks to a triplet–singlet transfer of the electron excitation energy from radical reaction products and its emission in the form of light with a high quantum yield; these additives are called chemiluminescence enhancers or activators. Examples of these substances are provided; differences between the so-called chemical and physical enhancers are described; coumarin derivatives, as the most promising chemiluminescence enhancers for studying lipid peroxidation, are considered in detail. The main problems related to the use of coumarin derivatives are defined, and possible ways of solving these problems are presented. Intrinsic chemiluminescence and the mechanism of luminescence accompanying biomolecule peroxidation are discussed in the first part of the review.