Quercetin and Idebenone Ameliorate Oxidative Stress, Inflammation, DNA damage, and Apoptosis Induced by Titanium Dioxide Nanoparticles in Rat Liver.

Titanium dioxide nanoparticles (TiO2-NPs) are extensively used in a wide range of applications; however, many reports have investigated their nanotoxicological effect at the molecular level either in vitro or in vivo systems. The defensive roles of quercetin (Qur) or idebenone (Id) against the hepatotoxicity induced by TiO2-NPs were evaluated in the current study. The results showed that the coadministration of Qur or Id to rats intoxicated with TiO2-NPs markedly ameliorated the elevation in hepatic malondialdehyde (MDA), serum alanine amino-transferase (ALT), glucose, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), immunoglobin G (IgG), and C-reactive protein (CRP) levels compared to their levels in TiO2-NPs-treated rats. The aforementioned antioxidants also effectively modulated the changes in the levels of serum vascular endothelial growth factor (VEGF), nitric oxide (NO), hepatic DNA breakage, caspase-3, and inhibition of drug metabolizing enzymes (cytochrome P450s; CYP4502E12E1) in rat livers induced by TiO2-NPs toxicity. The histopathological examination of the liver section showed that TiO2-NPs caused severe degeneration of most hepatocytes with an increase in collagen in the portal region, while treatment with the antioxidants in question improved liver architecture. These outcomes supported the use of Qur and Id as protective agents against the hepatotoxicity induced by TiO2-NPs and other hepatotoxic drugs.

Introduction

Titanium dioxide (TiO2) is widely used in many applications for decades. However, with the development of nanotechnologies, (TiO2-NPs), with its useful properties, are increasingly manufactured and used. Therefore increased environmental and human exposure can be expected, which has put TiO2 nanoparticles under toxicological scrutiny.[1] The nanoscale material TiO2-NPs is used in the manufacture of paints, cosmetics, in decontamination of water,[2] and as food and pharmaceutical additive in many products including, dental paste, oral capsules, suspensions, tablets, dermal preparations (sunscreens and creams), and in nonparenteral medicines.[1] However, the toxicological impact of TiO2-NPs on human and animal health is well documented.[2-4] Various studies have shown that TiO2-NPs accumulate and cause toxicity in the liver, kidneys, spleen, lung, and heart of animals.[5,6] Titanium dioxide nanoparticles caused serious hepatic, renal, and myocardial inflammatory damage in mice as revealed by changes in the functional biomarkers of these organs in the serum and the perturbed sugar and lipid levels in the blood.[5]

Titanium dioxide nanoparticles cause cellular genotoxicity via the formation of reactive oxygen species (ROS) and the induction of oxidative stress[4] that causes DNA breakage.[6] Park et al[3] also reported that TiO2-NPs potentially induced inflammatory disorders via the initiation of Th2-type cytokines in cultured BEAS-2B cells. Numerous studies have clarified the beneficial effects of antioxidants from fruits and vegetables on various measures of inflammatory oxidative cellular damage.[7]

The flavonol quercetin (Qur, 3,3′,4′,5,7-pentahydroxyflavone) is reported to possess antioxidant, antihypertensive, and antiparasitic activities.[8-10] Quercetin is a natural anti-inflammatory/antiallergy therapeutic agent that ameliorates the discharge of histamine and other inflammatory mediators (such as leukotrienes, prostaglandins, interleukin [IL]-1, IL-6, IL-13, and tumor necrosis factor [TNF]-α) in the body through the stabilization of mast cell membranes and plays a role in the downregulation of IL-6 and TNF-α in lipopolysaccharide-challenged murine macrophages.[7]

Idebenone (Id; 2-[12-hydroxydodecyl]-5,6-dimethoxy-3-methylcyclohexa-2,5-diene-1,4-dione), which is structurally related coenzyme Q10, acts as an antioxidant and electron carrier.[11] The antioxidant properties of Id were detected by the suppression of the oxidative stress biomarkers, including lipid peroxidation via radical scavenging activity.[12] It exerts a shielding power on cerebral energy metabolism[13] and has the ability to protect mitochondria from damage and to enhance respiration through the increase in electron flux along the respiratory chain.[14] This study was undertaken to evaluate the protective efficacy of either Qur or Id in the amelioration of different biomarker profiles (lipid peroxidation, inflammatory, immune, and apoptotic markers, and DNA damage) in the liver of rats exposed to an overdose of TiO2-NPs.

Materials and Methods

Chemicals

Titanium dioxide nanoparticles (<100 nm) was obtained from Sigma Co. (Ontario, CA, USA). All other chemicals were pure and produced by Merck Company.

Characterization of TiO2-NPs

Three samples of TiO2-NPs (anatase) were suspended in 1% carboxymethyl cellulose (CMC) lonely. The nanoparticles were dispersed by ultrasonic vibration for 20 minutes. The size distribution of TiO2-NPs in the CMC suspension (hydrodynamic size) and the zeta potential were analyzed in the suspension with a Brookhaven 90Plus particle size analyzer (Brookhaven Instruments Corporation, Holtsville, New York, USA). Transmission electron microscopy (TEM) was used to evaluate the particle size of TiO2-NPs.

Animals and Treatments

Forty Wistar male albino rats (150-170 g) were used, and the animal utilization protocols were conducted in accordance with the strategies assessed by the Experimental Animal Laboratory and approved by the Animal Care and Use Committee of the College of Pharmacy, King Saud University. The rats were maintained in standard conditions of temperature and humidity and provided with a rat diet and water ad libitum. After a week of acclimation, the rats fasted for 12 hours before treatment. Group 1 is the control group and was administered 1% CMC solution; TiO2-NPs was administered orally to the rats (1 g/kg body weight/day),[15] which were divided into 3 groups of 10 rats each: G2, TiO2-NPs-intoxicated animals; G3, TiO2-NPs-intoxicated animals co-administered Qur (200 mg/kg)[15]; and G4, TiO2-NPs-intoxicated animals co-administered with Id (200 mg/kg).[15] Titanium dioxide nanoparticles Qur and Id were suspended in 1% CMC. Quercetin or Id was administered daily for 21 days. After 21 days, the rats were killed; blood was collected then serum was separated by centrifugation of the blood samples at 3000 rpm. Subsequently, liver samples were collected, homogenized, and stored at −80°C. Portions of the livers were stored in 4% formalin.

Serum Biochemical Analysis

Alanine amino-transferase (ALT) and glucose levels were determined using Diamond Diagnostic Kits (Diamond Diagnostics Inc., Holliston, MA). Tumor necrosis factor-α was quantified using an enxyme-linked immunosorbent assay (ELISA) kit (Endogen, Woburn, Massachusetts). Interleukin-6 levels were evaluated by ultra-sensitive ELISA kit (Quantikine HS Human IL-6 Immunoassay; R&D Systems, Minneapolis, Minnesota). Immunoglobin G levels were measured using ELISA kit (Sigma Chemical Co., St. Louis, Missouri), and CRP was measured using latex-enhanced immunonephelometry on a Behring BN II Nephelometer (Dade Behring). The VEGF level was estimated by quantitative ELISA kit (R&D Systems, United Kingdom). The assay methods used for estimation of different parameters using kits were performed in accordance with the manufacturer’s instructions. The nitrite concentration was assayed spectrophotometrically.[16]

Biochemical Assays of Liver Tissue

The level of malondialdehyde (MDA), a marker of lipid peroxide, was estimated using the method of Buege and Aust.[17] Caspase-3 was evaluated using the Caspase-3/CPP32 Fluorometric Assay Kit (K105) purchased from Biovision, Inc (Mountain View, California). For each assay, Samples were read in a fluorimeter equipped (Jasco, FP-6200; Jasco, Japan) with a 400-nm excitation and a 505-nm emission filter. Fold-increase in Caspase-3 activity was determined by comparing fluorescence of 7-amino-4-trifluoromethyl coumarin in control and treated animals. CYP4502E12E1 activity (p-nitrophenol hydroxylase activity) was determined in the liver tissue through the measurement of p-nitrocatechol generated by an enzymatic reaction using high-performance liquid chromatography method.[18]

Comet Assay

Livers were homogenized in ice-cold phosphate-buffered saline (PBS) to obtain 10% homogenate. This suspension was stirred for 5 minutes and filtered. The cell suspension (100 μL) was mixed with 600 μL of low-melting agarose (0.8% in PBS); 100 μL of this mixture was spread on precoated slides. The coated slides were immersed in lysis buffer (0.045 mol/L Tris/borate/EDTA (TBE), pH 8.4, containing 2.5% sodium dodecyl sulfate [SDS]) for 1 hour. The slides were placed in an electrophoresis chamber containing the same TBE buffer but devoid of SDS. The electrophoresis conditions were 2 V/cm for 20 minutes and 100 mA. Staining with ethidium bromide (EtBr; 20 μg/mL) at 4°C was performed. With the samples still humid, the DNA fragment migration patterns of 100 cells for each dose level were evaluated with a fluorescence microscope (with excitation filter 420-490 nm). Comet tail lengths were measured from the middle of the nucleus to the end of the tail with 40× magnification to count and measure the comet. For visualization of DNA damage, we observed EtBr-stained DNA using a 40× objective on a fluorescence microscope.

Komet 5 image analysis software developed by Kinetic Imaging, Ltd (Liverpool, United Kingdom) was used to quantify single cell gel electrophoresis data. A charge-coupled device camera was used to assess the quantitative and qualitative extent of DNA damage in the cells by measuring the length of DNA migration and the percentage of migrated DNA. The program calculates tail moment. Generally, 100 randomly selected cells were analyzed per sample.[19]

Histopathological Examination

Small pieces of the liver were fixed in 4% formalin, embedded into paraffin, followed by staining of sections with hematoxylin-eosin or Masson trichrome, and observed using a light microscope.[20]

Statistical Analysis

The results are expressed as the mean (standard deviation [SD]). Significant differences were analyzed using 1-way analysis of variance (ANOVA) followed by Bonferroni test post-ANOVA. Limits of significant were ***P ≤ .001, *P ≤ .01, and *P ≤ .05.

Results

Characterization Studies of TiO2-NPs

The zeta potential and hydrodynamicdiameter of the nanoparticle suspension were −27 ± 2.5 mV and 120 ± 7.8 nm, respectively. The average size observed by TEM was 60 ± 10 nm. Only 47% ± 8% of the particles possessed this size; the remaining particles were agglomerates ranging from 100 to 500 nm. Figure 1 illustrates the image of TiO2-NPs using TEM.

Figure 1.

Characterization of Titanium dioxide nanoparticles (TiO2-NPs) by TEM. TEM indicates transmission electron microscopy.

Impacts of Qur and Id on Biochemical Markers

Titanium dioxide nanoparticles induced noticeable rises in hepatic lipid peroxidation (Figure 2), serum ALT, glucose, TNF-α, IL-6, CRP, IgG, NO, and VEGF (Table 1) and hepatic caspase-3 levels were also increased, with a decline in total hepatic cytochrome-P450 (Table 2) compared to the levels observed in the control group (P ≤ .001).The intake of the aforementioned studied agents significantly controlled the deviance in these markers compared to the levels in the intoxicated group (P ≤ .001; Table 2). A marked increase in the tail length and DNA% in the tail were shown in the liver tissue of TiO2-NPs-intoxicated rats (Table 3 and Figure 3). The co-administration of the current agents along with TiO2-NPs significantly protected the liver from DNA damage as indicated by a marked decrease in tail length and DNA%. Rats administered TiO2-NPs experienced severe degeneration of most hepatocytes, with manifested nuclear pyknosis, karyolysis, and cytoplasmic vacuolation. Liver sections of rats administered TiO2-NPs and treated with either Qur (Figure 4C) or Id (Figure 4D) showed normal hepatocytes and blood sinusoids. Masson trichrome staining of the liver sections revealed few collagen fibers in the portal area (Figure 5A). Liver sections from rats administered TiO2-NPs showed an increase in collagen in the portal region (Figure 5B), whereas the livers of rats that received TiO2-NPs in addition to Qur (Figure 5C) or Id (Figure 5D) showed a decrease in collagen in the portal region compared to the TiO2-NPs-intoxicated rats.

Figure 2.

Hepatic lipid peroxide level in control and different treated groups. Data are presented as mean (standard deviation [SD]) from 10 rats, a P ≤ .001, b P ≤ .01, compared to the normal group, *** P ≤ .001, compared to TiO2-NPs intoxicated group.

Table 1.

Serum ALT, Glucose, TNF-α, IL-6, CRP, IgG, NO, and VEGF Levels in Control and Different Treated Groups.a

Parameters	Normal	TiO2-NPs–Intoxicated Group	TiO2-NPs– and Qur	TiO2-NPs– and Id
ALT, U/L	15.24 ± 4.45	47.22 ± 3.54b	25.96 ± 1.93cd	22.92 ± 2.55cd
Glucose, mg/dL	115.8 ± 1.5	130 ± 3.4b	117 ± 1.6d	119 ± 1.6d
TNF-α, pg/mL	231.68 ± 7.99	323.74 ± 4.82b	290.58 ± 5.61bd	270 ± 3.47bde
IL-6, pg/mL	30.6 ± 2.07	48.6 ± 2.61b	36.8 ± 1.92df	35.2 ± 3.11d
CRP, ng/mL	2.918 ± 0.09	4.34 ± 0.32b	3.61 ± 0.42cg	3.20 ± 0.24df
IgG, ng/mL	126.42 ± 3.98	183.28 ± 4.81b	155.18 ± 3.93bd	142.64 ± 2.97bd
NO, µmol/mL	31.8 ± 2.39	74.4 ± 3.51b	46.4 ± 2.07bd	40.8 ± 2.28bde
VEGF, pg/mL	174.56 ± 4.46	249.8 ± 3.55b	200.12 ± 3.77cd	197.12 ± 4.45cd

Abbreviations: ALT, alanine amino-transferase; CRP, C-reactive protein; IL-6, interleukin-6; NO, nitric oxide; TNF-α, tumor necrosis factor-α; VEGF, vascular endothelial growth factor.

a Data are presented as mean (SD) of 10 rats.

b P ≤ .001 compared to normal group.

c P ≤ .01 compared to normal group.

d P ≤ .001 compared to TiO2-NPs-intoxicated group.

e P ≤ .01 compared to the Qur-treated group.

f P ≤ .05 compared to normal group.

g P ≤ .01 compared to TiO2-NPs-intoxicated group.

Table 2.

Caspase-3 and Cytochrome P450 Activity in the Hepatic Tissue of Control and Different Treated Groups.a

Groups	Caspase-3 (nmol/min/100 mg tissue)	Cytochrome P450(nmol/min/100 mg Tissue)
Control	95.6 ± 3.04	42.47 ± 2.36
TiO2-NPs	151.8 ± 1.94b	25.8 ± 2.06b
TiO2-NPs&Qur	123.4 ± 1.39bc	35.03 ± 3.71cd
TiO2-NPs& Id	130.8 ± 1.09b ce	38.7 ± 1.03c

Abbreviations: Id, idebenone; TiO2-NPs, Titanium dioxide nanoparticles; Qur, quercetin.

a Data are presented as mean (SD) of 10 rats.

b P ≤ .001 compared to normal group.

c P ≤ 0.001 compared to TiO2-NPs group.

d P ≤ .05 compared to normal group.

e P ≤ .05 compared to the Qur group.

Table 3.

Tail Length and DNA Percentage in the Tail of Comets Obtained From the Liver Tissue of Control and Different Treated Groups.a

Groups	TiO2-NPs
	Tail Length (mm)	DNA%
Control	1.14 ± 0.13	2.26 ± 0.31
TiO2-NPs	4.27 ± 0.10b	4.32 ± 0.24b
TiO2-NPs&Qur	2.21 ± 0.15bd	2.96 ± 0.12cd
TiO2-NPs and Id	3.28 ± 0.24bef	3.49 ± 0.14bef

Abbreviations: Id, idebenone; TiO2-NPs, titanium dioxide nanoparticles; Qur, quercetin.

aData are presented as mean (SD) from 10 rats.

b P ≤ .001 compared to normal group.

c P ≤ .01 compared to normal group.

d P ≤ .001 compared to TiO2-NPs-intoxicated group.

e P ≤ .01 compared to TiO2-NPs-intoxicated group.

f P ≤ .01 compared to the Qur group, respectively.

Figure 3.

DNA damage in the liver tissue of control and different treated groups. COMET assay showing degree of DNA damage in liver tissue of (A) normal control group, (B) group intoxicated with Titanium dioxide nanoparticles (TiO2-NPs; C) intoxicated group treated with Qur (D) intoxicated group treated with Id. Id indicates idebenone; Qur, quercetin.

Figure 4.

Liver sections stained with hematoxylin and eosin (H&E) from control rats showed normal hepatocytes that are separated by normal blood sinusoids (A). Liver sections from rats received high dose of Titanium dioxide nanoparticles (TiO2-NPs), showed severe degeneration of most hepatocytes with manifested nuclear pyknosis and karyolysis and cytoplasmic vacuolation (B). Liver sections from rats received TiO2-NPs and treated with either Qur (C) or Id (D) showed normal hepatocytes and blood sinusoids (scale bare = 50 µm). Id indicates idebenone; Qur, quercetin.

Figure 5.

Liver sections of rats experimental different groups intoxicated with Titanium dioxide nanoparticles (TiO2-NPs) and stained with Masson trichrome. Liver sections of normal control group showed few collagen fibers in the portal area (A). Liver sections from rats received high dose of TiO2-NPs showed an increase in collagen in the portal region (B). Livers of rats received high dose of TiO2-NPs with Qur (C) or Id (D) showed a decrease in collagen in the portal region compared to intoxicated rats. Id indicates idebenone.

Discussion

In this study, we evaluated the toxic impact and the underlying mechanism of 1 g/kg body weight TiO2-NPs exposure using rat models. We used this dose on the basis that TiO2-NPs are widely used in the food industry, including production of coated candy, fruit preservation, chewing gum, carbonated drinks, milk and dairy products, and other food categories in concentrated dosages.[21] The concentration of TiO2-NPs in food reaches as high as 0.5 to 9 g/kg.[21]

Several studies have reported that TiO2-NPs exert adverse effects on human health through the liberation of ROS.[2] ROS initiate inflammatory responses and are thought to be the cause of various diseases.[22-23] These results corroborated with the existing work that revealed a marked elevation of MDA level in rats exposed to TiO2-NPs compared to that in control group. Liver lipid peroxidation was inhibited by the co-administration of Qur or Id with TiO2-NPs. As a result of its antioxidant effects, Qur was reported to exert hepatoprotective and cardioprotective effects in rats against lipid peroxidation induced by toxic chemicals.[24] Idebenone was reported to exert a major inhibitory effect on oxidative processes and lipid peroxide formation in the brains of rats,[25] which was attributed to its potent antioxidant activity[11] and free radical scavenging activity.[12] The oxidative tissue damage induced by TiO2-NPs observed in this work was documented by a rise in serum ALT, which implies the loss of cell membrane integrity and cellular leakage in the rat liver. The liver injury observed in this work in the TiO2-NPs-intoxicated rat group was documented by the histopathological analysis of liver tissue, which revealed the degeneration of most of the hepatocytes. An analogous observation was made by Wang et al[26] who reported changes in ALT/AST and LDH with histopathological changes, including hydropic deterioration around the central vein, and the dotted necrosis of hepatocytes of rat livers after TiO2-NPs intake. Here in, the ingestion of Qur or Idto TiO2-NPs-intoxicated rats resulted in a significant reduction in serum ALT level compared to that in the intoxicated rats. The liver sections also showed normal hepatocyte architecture, which may suggest the valuable roles of these agents in the protection against hepatic injury induced by TiO2-NPs. This effect of Qur or Id using the protective dose was previously recognized in different models of hepatotoxicity.[27-28]

Quercetin or Id was used at the dosage of 200 mg/kg of body weight. This dosage has been found to be effective in protecting the organs against metal NPs toxicity and capable of reducing oxidative stress and inflammation in rats. [15]

The pathogenic mechanisms introduced by nanoparticles are accompanied by inflammation-derived actions, such as oxidative stress, apoptosis, and DNA damage.[29-31]

In this study, marked increases in glucose levels, together with the rise in TNF-α, IL-6, CRP, and IgG levels in TiO2-NPs-intoxicated rats, were observed relative to the normal group, which caused metabolic diseases (such as diabetes) and immune disorders. Tumor necrosis factor-α is one of the main inducers of inflammatory damage.[32] The upregulation of this cytokine triggers the production of CRP-mediated liver injury.[33] Interleukin-6 promotes the stimulation of transcription factors that bind to DNA elements and induce increases in CRP transcription.[33-34]

Titanium dioxide nanoparticles resulted in a clear increase in circulating IgG, which is considered an additional immune condition induced by these nanoparticles. The formation of various inflammatory cytokines comprising TNF-α has an effective impact on the circulating antibody production during inflammation.[35] These results indicated that TiO2-NPs-induced inflammatory liver injury might occur through the production of inflammatory mediators. Thus, a preventative approach that diminishes the release of inflammatory mediators could induce both hepatic injury and remote organ damage. The intake of the aforementioned antioxidants in combination with TiO2-NPs ingestion successfully attenuated the nanoparticle-induced elevation of serum glucose, TNF-α, IL-6, CRP, and IgG, which confirmed that their hepatoprotective action against tissue damage may be associated with their anti-inflammatory and immune modulatory actions.

The decline in serum glucose after treatment with the 2 agents may be ascribed to their capability to prevent the release of CRP, which exhibits a vital role in metabolic imbalance. Similarly, the hypoglycemic effect of Qur was also established[36]; idebenone was also described to have a modulatory effect on energy metabolism.[24] The anti-inflammatory efficacy of the 2 agents was also previously reported.[10-11] In this study, significant increases were seen in serum NO and VEGF (angiogenic factor) levels in response to the inflammatory stimuli in TiO2-NPs-intoxicatedrats. Previous data stated that large amounts of NO were released in reaction to inflammatory stimuli from various cell types 5.[3] The overexpression of cytokines and chemokines in response to inflammatory tissue injury, together with excess NO, initiate the stimulation of VEGF-producing cells, such as immune and inflammatory cells.[37-38]

The transition from acute to chronic inflammation stimulates angiogenesis. Previously, it was reported that neo-vessels cause notable perpetuation of the inflammatory response through the enhancement of the expression of adhesion molecules and chemokines and permitting the recruitment of inflammatory cells.[39] In addition, previous studies reported a positive correlation between the mRNA expression of TNF-α and VEGF. Both TNF-α and VEGF may lead to a procoagulant state by the enhanced expression of tissue factors in monocytes and/or endothelial cells.[40-41] Multiorgan system failure in acute injury may be attributed to the rise in expression of tissue factors.[41] This suggested the possibility that TNF-α and VEGF might act synergistically to potentiate systemic organ dysfunction and subsequently the liver.[42] The co-ingestion of the compounds in question with TiO2-NPs downregulated the notable elevation of serum NO and the angiogenic biomarkers; this action was thought to be attributable to their valuable anti-inflammatory action. This study showed that TiO2-NPs caused an increase in collagen deposition in the hepatic portal region. This deleterious effect of the used TiO2-NPs may be attributable to the induction of inflammatory mediators, which play a major role in the progression of liver fibrosis. The co-ingestion of either Qur or Id greatly reduced the deposition of collagen in the portal region of rat livers intoxicated with TiO2-NPs, which may be related to their ability to reduce the inflammatory mediators, as documented in the current study.

The entrance of nanoparticles into the nucleus and the interface with DNA were illustrated by Gurr et al.[2] The rate of DNA migration can be interrelated to the extent of DNA fragmentation associated with apoptosis.[43] Apoptosis and oxidative DNA damage are the key events induced by ROS.[3] The data in the current study revealed a marked elevation in the activity of the apoptotic marker caspase 3, coupled with the DNA fragmentation in the liver of rats intoxicated with TiO2-NPs. DNA fragmentation is indicated by a significant rise in the tail length and DNA% in the tail. The potential of TiO2-NPs to induce apoptosis and DNA damage was confirmed by experimental studies.[3-4] Excess ROS formation encourages mitochondrial membrane permeability and damages the respiratory chain, initiating apoptosis.[44] Park et al[3] also reported that caspase-3 activation induced by TiO2-NPs may cause chromosome condensation and DNA fragmentation, which triggers apoptosis in cells. Apoptosis and DNA damage in rat livers induced by TiO2-NPs toxicity were alleviated by the co-administration of the agents in question. Duthie and Dobson[45] reported that Qur exerted a potential impact on the formation of oxidative DNA damage. CYP4502E12E1450 is an important biochemical marker and indicator of hepatic CYP4502E1 metabolizing enzymes. The suppression of these enzymes may be related to the overproduction of inflammatory cytokines. This result was supported by published data, which revealed the direct inhibitory effects of human hepatic CYP-dependent drug metabolism from inflammatory cytokines IL-6 and TNF-α.[46] The co-administration of the Qur or Id to TiO2-NPs-intoxicated rats in the current study significantly elevated the activity of CYP4502E1 compared to that in intoxicated rats. The ability of these antioxidant agents to suppress the effect of TiO2-NPs on CYP4502E12E1 enzymes may be attributable to their ability to inhibit free radical production.[10,12] Titanium dioxide nanoparticles caused severe degeneration of most hepatocytes with manifested nuclear pyknosis and karyolysis and cytoplasmic vacuolation and an increase in collagen in the portal region. Treatment with either Qur or Id restored the normal hepatocytes and blood sinusoids architecture and decreased collagen deposition in the portal region compared to intoxicated rats.

Conclusion

From the current investigation, it can be concluded that the prophylactic ingestion of quercetin and idebenone along with TiO2-NPs may be beneficial in the amelioration of the different risk factors induced by the toxic effects of TiO2-NPs that lead to hepatic tissue damage.