Quantification and Distribution Evaluation of Quercetin and Kaempferol in Rat Eyes after Oral Administration of EEDK Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry

Abstract

Although recent pharmacological studies have demonstrated the beneficial effects of the ethanol extract of Diospyros kaki (EEDK) against eye diseases in vitro and in vivo, they could not conclude whether two strong antioxidants, quercetin and kaempferol, in the EEDK were bioavailable in eye tissue after oral administration. A method based on ultra-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-MS/MS) was herein developed for the highly selective and sensitive quantification of quercetin and kaempferol in rat eye tissue. The method was applied to investigate the distribution of quercetin and kaempferol in rat eyes after oral administration of EEDK at 0, 5, and 35 min after it was successfully validated for specificity, linearity, a low limit of quantification, precision, accuracy, extraction recovery, and matrix effect. The distribution of quercetin and kaempferol in rat eyes at 35 min after oral administration of the EEDK was 0.0099% and 0.0041%, respectively. These results will be useful for the precise determination of optimized in vivo EEDK dose and time for the effective prevention and treatment of eye diseases.