*2.5. Serum Biomarkers of Oxidative Stress*

Decreased serum levels of superoxide dismutase (SOD) activity, reduced glutathione (GSH) content and thus total antioxidant status along with increased malondialdehyde (MDA) content were observed in the untreated group (model control) when compared to the normal, RA-3, and allopurinol treated groups (Table 2), an indication of oxidative stress. Nevertheless, treatment of the animals with RA-3 at both concentrations (50 and 100 mg/kg) improved the levels of the antioxidants while decreasing the MDA content.

**Table 2.** Effect of RA-3 on the serum levels of oxidative stress markers in the rats.


Data were expressed as mean ± SD (*n* = 5). \* *p* < 0.05 vs. model control group.

#### *2.6. Histological Analysis of the Kidney Tissues*

The results of histological analysis are presented in Figure 4. The sections of kidneys from the normal group showed a normal architecture with intact glomerulus and renal tubules. A marked damage to the kidney indicated by robust display of glomerular congestion, dilated renal tubules and epithelial degeneration was observed on the kidney sections from the model control group. However, kidney sections from the rats treated with RA-3, especially at 100 mg/kg showed a much improved histomorphological structure of the kidney (Figure 4v), characterized by minimal renal tubular dilation and necrosis, indicative of recovery.

**Figure 4.** Photomicrographs of the kidney sections of the rats. (**i**) Section of kidney from normal group, showing normal kidney architecture with intact glomerulus (black arrow) and renal tubules (black triangle); (**ii**) section from model control group, showing glomerular congestion, dilated renal tubules, and epithelial degeneration (red arrow), (**iii**) section from group treated with allopurinol, showing minimal improved renal architecture; (**iv**) section from group treated with RA-3 (50 mg/kg), showing regeneration of epithelium, (**v**) section from group treated with RA-3 (100 mg/kg), showing improved renal architecture characterized by epithelial regeneration and reduced glomerular congestion. The indicator size for each image is 14X-200 μm (H&E).
