The effect of carnosic acid on a cataract model induced by sodium selenite in rats

Objective: To investigate the biochemical and clinical effects of carnosic acid in a cataract model induced by sodium selenite (Na₂SeO₃) in rats. Materials and Methods: Twenty-eight male Sprague-Dawley rats, with an average weight of 50–60 grams and at postnatal day 10, were divided into four groups. A statistical power analysis determined that each group should include at least seven subjects. Na₂SeO₃ was used to induce the cataract model. A single subcutaneous dose of 30 nmol/g Na₂SeO₃ was administered to each of the 21 rats in the experimental groups, in accordance with the literature, except for the control group, which received only saline (SF). Simultaneously, Group 2 received intraperitoneal dimethyl sulfoxide (DMSO), and Group 3 received a single intraperitoneal dose of 20 mg/kg carnosic acid dissolved in DMSO. On day 14, prior to euthanasia under anesthesia, cardiac puncture was performed for blood collection, followed by enucleation of the eyes from all sacrificed rats. The lenses were isolated through evisceration, placed on blotting paper, and stored at -80 °C until biochemical evaluation. Lens tissues were imaged using the ImageJ program. Findings: Microscopic examinations revealed a statistically significant difference in cataract grades among the groups (p < 0.0001). Morphological evaluations showed that the most prominent levels of cataract formation were observed in Groups 1 and 2, with no significant difference between their cataract grades. The group with the lowest cataract level after the control group was identified as Group 3. The cataract grade in Group 3 was found to be significantly lower than those in Groups 1 and 2 (p < 0.0001). Statistically significant differences were observed in the levels of superoxide dismutase (SOD) and catalase (CAT) measured in serum and lens tissues among the groups (p < 0.05). However, no statistically significant difference was detected in the levels of glutathione peroxidase (GPX1) measured in the tissue (p > 0.05). The levels of SOD in serum and tissue were significantly higher in Group 3 compared to the other groups (respectively; 0.171 ± 0.038 ng/ml, 0.692 ± 0.104 ng/ml). Significant differences were also observed in CAT levels in serum and tissue (p = 0.004 and p = 0.001, respectively). The tissue CAT level in Group 3 was found to be significantly higher than in the other groups (p < 0.05).Due to insufficient sample volume, GPX1 levels could not be measured in the serum, and no statistically significant difference was observed among the groups in tissue GPX1 levels (p > 0.05). Conclusion: In conclusion, this study demonstrated that carnosic acid significantly reduced cataract formation in the sodium selenite-induced cataract model, likely by enhancing antioxidant capacity in both morphological and biochemical analyses. This study demonstrates the potential of carnosic acid as a pharmacological agent for preventing cataract development outside of surgery and provides the scientific basis for further studies. Key words: Carnosic acid, sodium selenite, cataract, antioxidant-oxidant balance