A Solid Dispersion of Quercetin Shows Enhanced Nrf2 Activation and Protective Effects against Oxidative Injury in a Mouse Model of Dry Age-Related Macular Degeneration

Abstract EN

Age-related macular degeneration (AMD) represents a major reason for blindness in the elderly population.

Oxidative stress is a predominant factor in the pathology of AMD.

We previously evaluated the effects of phospholipid complex of quercetin (Q-PC) on oxidative injury in ARPE-19 cells, but the underlying mechanisms are not fully understood.

Herein, the solid dispersion of quercetin-PC (Q-SD) was prepared with solubility being 235.54 μg/mL in water and 2.3×104 μg/mL in chloroform, which were significantly higher than that of quercetin (QT) and Q-PC.

Q-SD also exhibited a considerably higher dissolution rate than QT and Q-PC.

Additionally, Q-SD had Cmax of 4.143 μg/mL and AUC of 12.015 μg·h/mL in rats, suggesting better bioavailability than QT and Q-PC.

Then, a mouse model of dry AMD (Nrf2 wild-type (WT) and Nrf2 knockout (KO)) was established for evaluating the effects of Q-SD in vivo.

Q-SD more potently reduced retinal pigment epithelium sediments and Bruch’s membrane thickness than QT and Q-PC at 200 mg/kg in Nrf2 WT mice and did not work in Nrf2 KO mice at the same dosage.

Additionally, Q-SD significantly decreased ROS and MDA contents and restored SOD, GSH-PX, and CAT activities of serum and retinal tissues in Nrf2 WT mice, but not in Nrf2 KO mice.

Furthermore, Q-SD more potently increased Nrf2 mRNA expression and stimulated its nuclear translocation in retinal tissues of Nrf2 WT mice.

Q-SD significantly increased the expression of Nrf2 target genes HO-1, HQO-1, and GCL of retinal tissues in Nrf2 WT mice, not in Nrf2 KO mice.

Altogether, Q-SD had improved physicochemical and pharmacokinetic properties compared to QT and Q-PC and exhibited more potent protective effects on retina oxidative injury in vivo.

These effects were associated with activation of Nrf2 signaling and upregulation of antioxidant enzymes.