Rapid quantification of cellular flavonoid levels using quercetin and a fluorescent diphenylboric acid 2-amino ethyl ester probe

Abstract

Flavonoids are abundant in fruits and vegetables and have various biological activities. A rapid, sensitive method for assessing cellular quercetin levels is necessary because cellular levels are often low. A new method for measuring cellular flavonoid levels is proposed using diphenylboric acid 2-aminoethyl ester (DPBA), a fluorescent probe, and quercetin, a representative flavonoid. This spectrofluorometry-based assay is simple and allows rapid quantification of the cellular quercetin content with high sensitivity. CHO-K1 cells were incubated with quercetin for 5 min, and then the cellular quercetin concentration was assayed using DPBA spectrofluorometry. Results, compared with high-performance liquid chromatography (HPLC), thin layer chromatography (TLC), and conventional spectrophotometry measurements, were highly correlated with HPLC data (R > 0.99). The method is more sensitive than TLC and conventional spectrophotometry. Spectrofluorometric measurement using DPBA is a simple, rapid, and sensitive method for assessing cellular quercetin levels.