Phenol derivatives as enhancers and inhibitors of luminol-H2O2-horseradish peroxidase chemiluminescence

✍ Scribed by Díaz, A. Navas ;Sánchez, F. García ;González Garcia, J. A.

• Publisher: John Wiley and Sons
• Year: 1998
• Weight: 159 KB
• Volume: 13
• Category: Article
• ISSN: 0884-3996
• DOI: 10.1002/(sici)1099-1271(199803/04)13:2<75::aid-bio469>3.0.co;2-7

✦ Synopsis

Systematic studies on phenol derivatives facilitates an explanation of the enhancement or inhibition of the luminol-H2O2-horseradish peroxidase system chemiluminescence. Factors that govern the enhancement are the one-electron reduction potentials of the phenoxy radicals (PhO./PhOH) vs. luminol radicals (L./LH-) and the reaction rates of the phenol derivatives with the compounds of horseradish peroxidase (HRP-I and HRP-II). Only compounds with radicals with a similar or greater reduction potential than luminol at pH 8.5 (0.8V) can act as enhancers. Radicals with reduction potentials lower than luminol behave in a different way, because they destroy luminol radicals and inhibit chemiluminescence. The relations between the reduction potential, reaction rates and the Hammett constant of the substituent in a phenol suggest that 4-substituted phenols with Hammett constants (sigma) for their substituents similar or greater than 0.20 are enhancers of the luminol-H2O2-horseradish peroxidase chemiluminescence. In contrast, those phenols substituted in position 4 for substituents with Hammett constants (sigma) lower than 0.20 are inhibitors of chemiluminescence. On the basis of these studies, the structure of possible new enhancers was predicted.