A fluorescence quenching test for the detection of flavonoid transformation

A novel fluorescence quenching test for the detection of flavonoid degradat ion by microorganisms was developed. The test is based on the ability of th e flavonoids to quench the fluorescence of 1,6-diphenyl-1,3,5-hexatriene (D PH). Several members of the anthocyanidins, flavones, isoflavones, flavonol s, flavanones. dihydroflavanones, chalcones, dihydrochalcones and catechins were tested with regard to their quenching properties. The anthocyanidins were the most potent quenchers of DPH fluorescence, while the flavanones, d ihydroflavanones and dihydrochalcones, quenched the fluorescence only weakl y. The catechins had no visible impact on DPH fluorescence. The developed t est allows a quick and easy differentiation between flavonoid-degrading and flavonoid-non-degrading bacteria. The investigation of individual reaction s of flavonoid transformation with the developed test system is also possib le. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.