The role of lutein-rich purple sweet potato leaf extract on the amelioration of diabetic retinopathy in streptozotocin-induced Sprague-Dawley rats

The objective of this study is to access the effect of purple sweet potato leaf (PSPL) extract on diabetic retinopathy (DR) of streptozotocin (STZ)-induced male Sprague-Dawley (SD) rats. In this study, rats were injected intraperitoneally with a single dose of 60 mg/kg STZ, and diabetes was confirmed on day 7. Rats were further divided into a few groups, which were then orally administered with one of the following treatments: 25 mg/kg of gliclazide (D25G), 200 mg/kg of PSPL extract (DT 200), and 400 mg/kg of PSPL extract (DT 400). However, the normal control (NS) and control group for diabetic (DNS) were given normal saline (NS) for 12 weeks. The results show that the treated group demonstrated a reduction in serum oral glucose tolerance test (OGTT) levels of DT 200 and DT 400, and an increase in the serum and retinal insulin levels, and restored oxidative stress markers in serum and retina on week 12. The PSPL extract exhibited protective effects in maintaining the kidney, liver, retina, and pancreas architecture in 400 mg/kg compared to the 200 mg/kg treated group and D25G, thereby restoring fully transparent lenses in diabetes-induced rats. In conclusion, 400 mg/kg PSPL is the most effective dose for the amelioration of STZ-induced DR pathology in male SD rats.

Phytochemical component and toxicological evaluation of purple sweet potato leaf extract in male Sprague–Dawley rats

This study assessed the toxicity of lutein-rich purple sweet potato leaf (PSPL) extract in male Sprague–Dawley rats.

Methods and study design: A total of 54 adult male Sprague–Dawley rats were used. For the acute toxicity study, three rats in the acute control group were fed 2,000 mg/kg of PSPL for 14 days. The subacute toxicity study included six rats each in four groups administered 50, 250, 500, or 1,000 mg/kg for 28 days and observed for further 14 days without treatment in the subacute control and subacute satellite groups. Changes in body weight; blood biochemistry; hematological parameters; relative organ weight; and histological sections of the heart, kidney, liver, pancreas, aorta, and retina were observed for signs of toxicity.

Results: The gradual increase in weekly body weight, normal level full blood count, normal liver and kidney profile, relative organ weight, and histological sections of all stained organ tissue in the treated group compared with the acute, subacute, and satellite control groups demonstrated the absence of signs of toxicity.

Conclusion: Lutein-rich PSPL extract shows no signs of toxicity up to 2,000 mg/kg/day.