Protective effect of quercetin and chlorogenic acid, two polyphenols widely present in edible plant varieties, on visible light-induced retinal degeneration in vivo

The protective effect of quercetin and chlorogenic acid (CA) on visible light-induced retinal damage was investigated in pigmented rabbits. Quercetin and CA effectively suppressed the levels of oxidative stress markers increased by light exposure and significantly increased the levels of heme oxygenase-1 in retina (p < 0.05). The levels of inflammatory cytokines, including monocyte chemoattractant protein 1, interleukin (IL)-8, IL-1 β, tumour necrosis factor-alpha, cyclooxygenase 2 and inducible nitric oxide synthase in retinal tissues, were significantly reduced by quercetin and CA; additionally, quercetin significantly inhibited the expression of nuclear factor kappa B (p < 0.05). Moreover, photooxidative stress-induced changes in expression levels of apoptotic proteins and angiogenesis factors were regulated by quercetin and CA. Histological analysis revealed that the thickness of the outer nuclear layer was maintained by quercetin but not by CA. Results suggest that quercetin and CA play an important role in alleviating retinal degeneration.