[Prevention and treatment of age-related macular degeneration by extract of Fructus lycii and its constituents lutein/zeaxanthin: an in vive and in vitro experimental research].

Objective: To investigate the in vivo inhibition of extract of Fructus lycii (FL) on the expressions of cathepsin B (Cat B) and cystatin C (Cys C) in high-fat diet and hydroquinone (HQ) induced model mice with age-related macular degeneration (AMD), and to explore the in vitro effects of lutein and zeaxanthin on hydrogen peroxide (H2O2,) induced expressions of matrix metalloproteinase 2 (MMP-2) and tissue inhibitor of metalloproteinase 2 (TIMP-2) on ARPE-19 cells.

Methods: Fifty female 8-month-old C57BL/6 mice were recruited in this research. Ten mice fed with regular diet was taken as the age control group. The rest 40 mice were fed with high fat diet for 6 months, followed by adding HQ (0. 8%) in the drinking water for 3 consecutive months. Then the modeled mice were randomly divided into the model control group (n =10), the high (at the daily dose of 3.75 g/kg), middle (at the daily dose of 2.50 g/kg), and low dose (at the daily dose of 1.25 g/kg) FL groups, 10 in each group. The extract of FL at each dose was respectively administered to mice by gastrogavage for 3 successive months. By the end of the experiment, the mice were killed and their eyeballs were removed. The protein expressions of Cat B and Cys C were observed by immunohistochemical assay. The mRNA and protein expressions of Cat B and Cys C were detected by real-time PCR and Western blot respectively. The drug concentrations of H2O2, lutein, and zeaxanthin were screened and detected using the activity of cell proliferation. The protein expressions of MMP-2 and TIMP-2 were detected using Western blot.

Results: Compared with the age control group, the mRNA and protein expressions of Cat B and Cys C were significantly higher in the in vivo model control group (P <0.05, P <0.01). The mRNA expressions of Cat B and Cys C were weaker in the middle and high dose FL groups than in the model control group (P <0. 05, P <0. 01). In in vitro cells, lutein and zeaxanthin could down-regulate the protein expressions of MMP-2 and TIMP-2 in H202 induced ARPE-19 cells (P <0. 05, P <0. 01).

Conclusions: Extract of FL could down-regulate the high protein expressions of Cat B and Cys C in high-fat diet and HQ induced model mice. Lutein and zeaxanthin could down-regulate the protein expressions of MMP-2 and TIMP-2 in H202 induced ARPE-19 cells.