The effects of puerarin on electroretinogram, oxidative stress and STAT3 expression were determined, in diabetic rat retina and serum. Forty Sprague-Dawley rats were randomly divided into the normal control (NC), the diabetic model (DM), the low dose (250 mg/kg) puerarin (LP) or the high dose (500 mg/kg) puerarin group (HP). A diabetic rat model was induced by streptozotocin and animals were continuously treated for 4 weeks; fasting blood glucose was measured at 2 and 4 weeks after modeling. An electroretinogram and serum and tissue levels of glucose, insulin, superoxide dismutase (SOD), malondialdehyde (MDA) and total antioxidant capacity (T-AOC) were measured; real-time PCR and ELISA were used to determine STAT3 mRNA and protein expression, respectively, from the retina. The blood glucose and insulin levels in the puerarin groups were significantly lower and higher, respectively than that in the DM group. The amplitude of b-wave of electroretinogram in the DM and the LP groups was significantly lower than that in the NC group; in the LP and HP groups it was significantly higher than the DM group. The serum and retinal tissue activity of SOD and MDA was significantly lower and higher, respectively, in the DM group compared to the NC group; both the LP and HP groups had significantly higher SOD and lower MDA than the DM group. The levels of STAT3 mRNA and protein levels in the DM, LP and HP groups were significantly higher than the NC group; and levels of STAT3 mRNA and protein expression were significantly lower in the LP and HP groups than the DM group. In summary, puerarin can reduce the oxidative stress damage of the retina, and its mechanism is related to the inhibition of STAT3 expression.

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We prepared poly(lactide-co-glycolide) (PLGA) encapsulated with chlorin e6 (Ce6) in an effort to increase the stability and efficiency of photosensitizers for photodynamic therapy (PDT). We determined that Ce6-loaded PLGA nanoparticles (PLGA-Ce6 NPs) had drug-loading efficiency of 5%. The efficiency of encapsulation was 82%, the zeta potential was- 25 mV, and the average diameter was 130 nm. The encapsulation of Ce6 in PLGA nanoparticles showed excellent stability. The nanoparticles exhibited sustained Ce6 release profiles with 50% released at the end of 3 days, whereas free Ce6 showed rapid release within 1 day. Ce6 release patterns were controlled by encapsulation into PLGA. The uptake of PLGA-Ce6 NPs was significantly enhanced by endocytosis in the first 8 hours in the HCT-116 cell line. An intracellular reactive oxygen species assay revealed the enhanced uptake of the nanoparticles. An in vitro anti-tumor activity assay showed that the PLGA-Ce6 NPs exhibited enhanced phototoxicity toward HCT-116 cells and a slightly lower IC50 value in HCT-116 cells than Ce6 solution alone. Exposure of HCT-116 cell spheroids to PLGA-Ce6 NPs penetrated more profoundly and had better phototoxicity than pure drugs. These findings suggest that PLGA-Ce6 NPs might serve as PDT for colorectal cancer.