**5. Conclusions**

The present study showed that CPA4-1 exerted an inhibitory e ffect on AGE formation and breaking effect on AGE-collagen cross-linking. CPA4-1 treatment ameliorated BRB leakage and retinal acellular capillary formation in db/db mice. These results suggested the potential of CPA4-1 as a therapeutic supplement for protection against retinal vascular permeability diseases.
