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. 2025 Jun 25;15(7):1006.
doi: 10.3390/life15071006.

Biochemical Study of Bilberry Extract Potential in Preventing Retinal Damage in Rat Model of Diabetes Induced by Streptozotocin/Nicotinamide

Maja Petrović  1 , Marija Trenkić  1   2 , Marija Veselinović  1   2 , Aleksandra Smiljković  1   2 , Dušan Sokolović  3
Affiliations

Biochemical Study of Bilberry Extract Potential in Preventing Retinal Damage in Rat Model of Diabetes Induced by Streptozotocin/Nicotinamide

Maja Petrović et al. Life (Basel). .

Abstract

Type 2 diabetes mellitus is a growing global health concern, with diabetic retinopathy (DR) representing a major microvascular complication that contributes significantly to vision impairment. Oxidative stress plays a critical role in the pathogenesis of DR, which is associated with changes in vascularization-associated molecules, such as iNOS, VEGF, and MMP-9. The present study investigates the therapeutic potential of bilberry (Vaccinium myrtillus L.) extract-rich in anthocyanins-applied for 14 days on blood glucose levels, lipid profile, and retinal oxidative stress (lipid peroxidation (TBARS) and advanced oxidized protein products (AOPPs)) in a streptozotocin/nicotinamide (STZ/NA)-induced diabetes rat model. Results showed a significant reduction in non-fasting blood glucose, retinal TBARS, and AOPP levels, and normalization of VEGF and MMP-9 expression in bilberry-treated diabetic rats. Bilberry extract also partially improved lipid profile by lowering LDL levels. However, no significant effects on fasting glucose or serum insulin were observed. These findings suggest that bilberry extract may offer protective effects against oxidative retinal damage and could serve as a complementary approach in managing early diabetic retinopathy.

Keywords: VGEF; bilberry extract; diabetes; retinal damage.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Representative chromatogram of bilberry extract with anthocyanins labeled numerically as given in Table 1.
Figure 2
Figure 2
The concentration of fasting and non-fasting blood glucose (A) and insulin (B) in rats with STZ/NA-induced hyperglycemia treated with bilberry extract (BE) in the dose of 50 mg/kg of anthocyanin equivalents for 14 days at the end of the treatment period. Values are given as mean ± SD. The difference between groups was determined by one-way ANOVA, followed by Tuckey’s post hoc test; a p < 0.001 vs. control group (C); b p < 0.05 vs. STZ/NA group.
Figure 3
Figure 3
The concentration of serum lipids the in rats with STZ/NA-induced hyperglycemia treated with bilberry extract (BE) in the dose of 50 mg/kg of anthocyanin equivalents for 14 days at the end of the treatment period. Values are mean ± SD. The difference between groups was determined by one-way ANOVA, followed by Tuckey’s post hoc test; a p < 0.05 vs. control; b p < 0.05 vs. STZ/NA group.
Figure 4
Figure 4
The concentration of thiobarbituric acid reactive substances (TBARSs) in the retina of rats with STZ/NA-induced hyperglycemia treated with bilberry extract (BE) in the dose of 50 mg/kg of anthocyanin equivalents for 14 days at the end of the treatment period. Values are given as mean ± SD. The difference between groups was determined by one-way ANOVA, followed by Tuckey’s post hoc test; a p < 0.05 vs. control group (C); b p < 0.05 vs. STZ/NA group.
Figure 5
Figure 5
The concentration of advanced oxidized protein products (AOPPs) in the retina of rats with STZ/NA-induced hyperglycemia treated with bilberry extract (BE) in the dose of 50 mg/kg of anthocyanin equivalents for 14 days at the end of the treatment period. Values are given as mean ± SD. The difference between groups was determined by one-way ANOVA, followed by Tuckey’s post hoc test; a p < 0.001 vs. control group (C); b p < 0.001 vs. STZ/NA group.
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