Protective Role of Quercetin in Carbon Tetrachloride Induced Toxicity in Rat Brain: Biochemical, Spectrophotometric Assays and Computational Approach

Abstract

Carbon tetrachloride (CCL4) induces oxidative stress by free radical toxicities, inflammation, and neurotoxicity. Quercetin (Q), on the other hand, has a role as anti-inflammatory, antioxidant, antibacterial, and free radical-scavenging. This study explored protection given by quercetin against CCL4 induced neurotoxicity in rats at given concentrations. Male Wistar rats were divided into four groups Group C: control group; Group CCL4: given a single oral dose of 1 mL/kg bw CCL4; Group Q: given a single i.p injection of 100 mg/kg bw quercetin; and Group Q + CCL4: given a single i.p injection of 100 mg/kg bw quercetin before two hours of a single oral dose of 1 mL/kg bw CCL4. The results from brain-to-body weight ratio, morphology, lipid peroxidation, brain urea, ascorbic acid, reduced glutathione, sodium, and enzyme alterations (aspartate aminotransferase (AST), alanine aminotransferase (ALT), catalase, and superoxide dismutase) suggested alterations by CCL4 and a significant reversal of these parameters by quercetin. In silico analysis of quercetin with various proteins was conducted to understand the molecular mechanism of its protection. The results identified by BzScore4 D showed moderate binding between quercetin and the following receptors: glucocorticoids, estrogen beta, and androgens and weak binding between quercetin and the following proteins: estrogen alpha, Peroxisome proliferator-activated receptors (PPARγ), Herg k+ channel, Liver x, mineralocorticoid, progesterone, Thyroid α, and Thyroid β. Three-dimensional/four-dimensional visualization of binding modes of quercetin with glucocorticoids, estrogen beta, and androgen receptors was performed. Based on the results, a possible mechanism is hypothesized for quercetin protection against CCL4 toxicity in the rat brain.

Keywords: CCL4; VirtualToxLab; neurotoxicity; oxidative stress markers; quercetin.

Figure 1

Cortex sections of normal and treated groups at a scale bar of 100 µm. (a) Normal histological appearance of brain tissues with neurocytes having well-defined nuclei. (b) CCL4-treated brain cortex section with widespread intracellular vacuolization and infiltration of inflammatory cells (aster). Neurocytes have dark eosinophilic cytoplasm, with cells having heterochromatic nuclei. (c) Quercetin-treated brain tissue has fewer vacuoles and inflammation. (d) Q + CCL4-treated brain section with mild vacuolization and mild infiltration of inflammatory cells (n = 3).

Figure 2

(a–e). Effect of CCL4 (1 mg/kg) and Q (100 mg/kg b.w) on the brain-to-body weight ratio, ALT, AST, brain urea, and brain sodium (n = 6). Data were analyzed by (one-way ANOVA), and Tukey’s test was used for multiple comparisons. Treated groups are compared to the control group. **** p < 0.0001, ** p < 0.01, ns is non-significant.

Figure 3

Docking conformation of quercetin with different targets. (a) Predicted bonded interactions (blue dashed lines) between quercetin and glucocorticoid; (b) binding interaction between quercetin and androgen; (c) binding interaction of quercetin and estrogen alpha. The ligand is based on atom type and the protein-based on amino acid residue type coloring.