Assessment of Anti-Cataract Properties of Flavonoids Using an In Vitro Model of UV-Induced Photooxidation and Protein Aggregation

Abstract

Purpose : We sought to develop a benchtop assay to measure the UV-induced modification and aggregation of lens proteins as a model of age-related cataract formation and to test the efficacy of flavonoid compounds in reducing UV-induced damage to the lens. Many flavonoids have photoprotective properties, are present in common foods, are orally bioavailable, and cross the blood-eye-barrier, giving them a strong potential role in defense against age-related cataract formation.

Methods : Lens homogenates obtained from the free ranging Cayo Santiago population of rhesus macaques were used in this study. Both young (~4 years old) and aged (~16 years old) lenses were used to ensure that this assay properly models age-related changes. Homogenates were made from frozen lens fragments in a buffer of Tris-HCl, NaCl, and EDTA at pH 6.7 to approximate the physiological conditions within the lens. Various concentrations of hydrogen peroxide were added and homogenates were incubated within a UV Stratalinker 1800 for 16 hours to induce photooxidation. Light scattering was measured as absorbance/turbidity within a standard plate reader at 300 nm to assess protein aggregation. Quercetin, apigen, daidzein, and flavone were selected as flavonoids to test in this model as all occur naturally in edible plants.

Results : Old lens samples were found to have approximately twice the absorbance of young samples prior to UV incubation, indicating the higher levels of aggregation present within aged lenses at baseline. Higher protein and hydrogen peroxide content resulted in greater turbidity in a dose-dependant manner. Analysis of the efficacy of each flavonoid is ongoing.

Conclusions : We have demonstrated a simple and rapid method to model cataractogenesis in the lab and to test photoprotective compounds for potential anti-cataract properties in vitro.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.