An overview on the protective effects of ellagic acid against heavy metals, drugs, and chemicals

Abstract Ellagic acid (EA) is a polyphenol extracted from many plants. EA modulates inflammatory mediators via antioxidant mechanisms, such as catalase (CAT) activities, superoxide dismutase (SOD), enhancement, increase in glutathione (GSH), and lipid peroxidation (LPO) suppression. EA has anti‐apoptotic properties that are thought to be mediated by regulating the expression of B‐cell lymphoma 2 (Bcl‐2), Bcl‐2‐associated X protein (Bax), and caspase‐3. In this article, we surveyed the literature dealing with the protective effects of EA against different heavy metals, drugs, and natural toxins. The findings indicated that EA has remarkable protective properties against various toxicants. Its protective effects were mostly mediated via normalizing lipid metabolism, oxidative stress, and inflammatory mediators, for example, tumor necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), and IL‐1β. The results of this study showed that EA has significant protective effects against a varied range of compounds, either chemical or natural. These effects are mainly mediated via intensifying the antioxidant defense system. However, other mechanisms such as inhibition of inflammatory responses and suppression of apoptosis are important.


| Arsenic
Arsenic contamination is a serious worldwide health risk to the human population due to its carcinogenic nature and highly toxic properties (Mawia et al., 2021).Arsenic levels in the environment are increasing and threaten ecosystems through both natural and anthropogenic activities.The international agency for research on cancer categorizes arsenic in group 1, carcinogenic to humans (Khairul et al., 2017).Binding to thiols, oxidative stress induction, and methylation have been proposed as potential mechanisms for arsenic toxicity in the endocrine system (Nurchi et al., 2020).Oxidative stress is a major cause of male infertility following arsenic-induced testicular toxicity.Arsenic, via free radical-mediated reactions, evokes DNA injury in sperm cells (Flora & Agrawal, 2017).A recent study reported that EA significantly restored CAT enzyme activity, total antioxidant capacity) TAC(, and GSH levels, and reduced malondialdehyde )MDA(.Besides, EA increased sperm quality, restored antioxidant balance, and regulated the expression of nuclear factor erythroid 2-like 2 (Nfe2l2), peroxisome proliferative activated receptor gamma coactivator 1alpha (Ppargc1a), and steroidogenic acute regulatory protein (StAR) genes in the testis (Guvvala et al., 2019).Nfe2l2 is a gene involved in the expression of antioxidant proteins that protect against inflammation and oxidative damage.It serves as a biomarker for the prediction of ROS-linked male infertility (Chen et al., 2012).Ppargc1a is a stress response gene upregulated by cellular stress (Rius-Pérez et al., 2020).Arsenic down-regulates StAR signaling and production of steroid hormones and promotes oxidative stress that leads to reproductive health impairment in males (Kadry & Megeed, 2018).Another study indicated that EA decreased caspase-3 activity and, interleukin-1 beta (IL-1β), tumor necrosis factorα (TNF α), and Bcl-2-associated X protein (BAX) along with upregulation of B-cell lymphoma 2 (Bcl-2) expression F I G U R E 1 Chemical structure of ellagic acid (EA).
in arsenic exposed rats (Firdaus et al., 2018).Mehrzadi et al. re-ported that by increasing serum testosterone and testicular antioxidant markers, EA improved arsenic-induced testicular toxicity.

| Chromium
Chromium is the most abundant mineral in the Earth's crust.Contaminated well water is considered the major route of chromium exposure in humans.Toxic effects include mouth ulcers, indigestion, vomiting, acute tubular necrosis, abdominal pain, kidney failure, and even death (Pavesi & Moreira, 2020).It was shown that EA significantly protected against chromium-induced toxicity in primary human lymphocytes.Besides, EA decreased the apoptotic index and improved the viability and proliferative responses of both activated and resting lymphocytes, and normalized the cytokine secretion such as interleukin-2 (IL-2) and interferonγ (IFNγ) from the activated lymphocytes (Table 1; Bodiga et al., 2022).

| Mercury
Mercury is a toxic element that has raised worldwide public health concerns due to its toxicity.Anxiety, sleep disturbance, and depression are psychological problems attributed to acute exposure to mercury (Raj & Maiti, 2019).Oxidative stress is a fundamental mechanism for mercury-induced liver injury.Treatment of rats with EA after mercury exposure remarkably elevated antioxidant enzymes' activities such as GPx, SOD, and CAT.Furthermore, EA decreased the oxidant content and simultaneously intensified the antioxidant system in the kidney tissue.Mercury-intoxicated rats treated with EA showed no swelling and disorientation in the hepatocytes (Table 1; Bharathi & Jagadeesan, 2014;Jagadeesan & Bharathi, 2014).

TA B L E 1
Protective effect of ellagic acid against heavy metals toxicity.

| Cobalt
Cobalt is a widely dispersed pollutant with many adverse health effects.In humans, systemic cobalt toxicity manifests as a clinical syndrome with a different presentation of neurological, endocrine, and cardiovascular symptoms (Leyssens et al., 2017).EA promoted potent cytoprotective and antigenotoxic effects against cobalt-induced toxicity in primary human lymphocytes by increasing IL-2 and IFNγ levels.Pretreatment with EA even in the presence of metal ions effectively enhanced the IL-2 level secreted by anti-CD3-activated lymphocytes.It also modified the amount of IFNγ secreted by the activated lymphocytes even in the presence of cobalt and reduced the number of apoptotic cells (Table 1; Bodiga et al., 2022).

| Lead
Lead is a heavy metal and an environmental pollutant that is toxic even in very low concentrations.

| PROTEC TIVE EFFEC TS OF E A AG AIN S T DRUG S TOXI CITIE S
The greatest problem during the development of new drugs is organ toxicity (Lin & Will, 2012).Two important reasons for drug attrition are hepatotoxicity and cardiotoxicity (Schuster et al., 2005).Table 2 provides a brief of in vitro and in vivo studies on the effects of EA on selected drug toxicities.The chemical structure of drugs whose toxicity is reduced by EA is shown in Figure 3.

| Cisplatin
Cisplatin is a commonly used chemotherapeutic agent for various tumors.Nephrotoxicity is a common toxicity of cisplatin as renal tubule cells are sensitive to cisplatin accumulation (Motwani et al., 2022).A study showed that the antioxidant property of EA elicited beneficial effects on cisplatin-induced nephrotoxicity and gonadotoxicity.Cisplatin caused enhancement in lipid peroxidation (LPO), and ROS, and diminished GSH content in the kidney and testis.These effects were reversed by EA administration in rats (Goyal et al., 2019).Cisplatin also caused oxidative damage in the liver and heart tissues via overproduction of free radicals.EA significantly reduced MDA levels and improved GSH-Px, GSH, and CAT in the heart and liver tissues of cisplatin-treated rats.Decreased lipid peroxidation in these tissues indicates that EA efficiently suppressed oxidative DNA damage and scavenged free radicals (Table 2; Yüce et al., 2007).

| Bleomycin
Chemotherapeutic drugs treat a diverse range of tumors such as the kidney, lung, colon, and pancreas.To avoid drug resistance and enhancement the chemotherapeutic efficacy, combination therapy is used (Leary et al., 2018;Zhan & Wang, 2018) et al., 2013).EA treatment in rats exposed to bleomycin and cyclophosphamide showed reduced myeloperoxidase (MPO), NO, LPO, and hydroxyproline in lung tissues.Also, histopathological studies provided evidence for the protective effect of EA on bleomycin and cyclophosphamide-induced pulmonary toxicity in rats (Table 2; Saba Khan et al., 2013).

| Cyclophosphamide
Cyclophosphamide is an orally active alkylating agent that is used widely as an anticancer agent (Emadi et al., 2009).Side effects associated with cyclophosphamide use include bone marrow toxicity, infections, hemorrhagic cystitis, gastrointestinal abnormalities, and hair loss (Ponticelli & Glassock, 2019).One of the toxic consequences of cyclophosphamide administration is increased lipid peroxidation, and GSH-Px, GSH, CAT, and SOD reduction in the testis (Ghosh et al., 2002;Selvakumar et al., 2006).In a study, cy-

| Cyclosporine
Cyclosporine A is a neutral lipophilic cyclic undecapeptide with potent immunosuppressive properties (Wu et al., 2018).The potent immunosuppressant effect of cyclosporine A is due to its specific blocking effect on lymphokine generation, differentiation, and signal transduction pathways of T cells.Therefore, it prevents cytokine production and suppresses immune response.
On the other hand, cyclosporine A activates the pro-oxidant pathways and raises the synthesis of ROS and lipid peroxidation products (Rezzani, 2006).In an experimental study, administration of EA to cyclosporine A-treated rats significantly reduced MDA levels and ameliorated GSH, CAT, and peroxidase (Px) (Abdul-Hamid et al., 2016).Rats exposed to cyclosporine A showed increases in the expression of hepatic markers for example aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and lactic dehydrogenase (LDH) whereas, EA treatment decreased hepatic markers, and increased tissue enzymatic (CAT, SOD, and GST) and nonenzymatic (vitamin E, vitamin C, and GSH) antioxidants (Table 2; Pari & Sivasankari, 2008).

| Gentamicin
Gentamicin belongs to the aminoglycoside family of antibacterial drugs used against gram-negative aerobic bacterial infections.
Long-term clinical application of gentamicin may result in nephrotoxicity and ototoxicity (Brkić et al., 2022)

| Sodium valproate
Sodium valproate is an antiepileptic drug with a wide range of applications.It is used in other neurological disorders conditions, such as migraine, schizophrenia, depression, and bipolar disorder, as well (Nanau & Neuman, 2013).Research on animal models demonstrated that valproate causes reversible modification in the sperm morphology, sperm motility, sperm count, and histoarchitecture of the testes.Girish et al. reported that oral administration of EA attenuated valproate-induced testicular and spermatozoal damages.In that study, EA showed a protective effect against valproate-induced weight gain, lower sperm count, and sperm abnormalities (Table 2; Girish et al., 2014).This action of EA may be related to its antiapoptotic and antioxidant properties.

F I G U R E 3
Chemical structure of drugs whose toxicity is reduced by ellagic acid (EA).

| Methotrexate
Methotrexate is a folate analog that inhibits RNA and DNA synthesis (Singh et al., 2012).Mastitis, nausea, vomiting, liver enzyme elevation, bone marrow suppression, hepatotoxicity, and multiorgan toxicity are common side effects of methotrexate (Howard et al., 2016).
In a rat model of methotrexate-induced small intestine damage, animals pretreated with EA exhibited a reduction in serum levels of prostaglandin E2 (PGE 2 ), MDA, NO, MPO, XO, and adenosine deaminase (AD) activities, increased GSH levels, and modified intestine morphology (Table 2; El-Boghdady, 2011).

| Bevacizumab
Bevacizumab is an antiangiogenic drug that has been approved for the treatment of various cancers.Bevacizumab inhibits vascular endothelial growth factor (VEGF) and hypoxia-inducible factor signaling (HIF) (de Aguiar & de Moraes, 2019).Two percent of patients treated with bevacizumab show cardiomyopathy and heart failure (Bordun et al., 2015).In another study, the enzymatic activities of oxidative phosphorylation complexes I, II, III, I + III, IV, II + III, and citrate synthase were evaluated in isolated rat heart intact mitochondria in the presence of bevacizumab.Complex II activity was remarkably decreased compared with the control group and activities of other complexes were not affected by bevacizumab.This conclusion confirmed that complex II is the principal oxidative phosphorylation target for bevacizumab in rat heart mitochondria.Bevacizumab causes dysfunction in the rat heart mitochondria by complex II inhibition, causing permeabilizing of the mitochondrial membrane and mitochondrial swelling.The study showed protective of EA remarkably elevated complex II activity and stopped mitochondrial swelling compared to treated groups with bevacizumab alone (Mohammad Khanlou et al., 2022).

| Clozapine
Clozapine is a tricyclic dibenzodiazepine used to treat resistant schizophrenia.Adverse reactions associated with clozapine are hypotension, blood dyscrasia, neutropenia, agranulocytosis, sedation, seizures, metabolic syndrome, constipation, cardiotoxicity, and hypersalivation (De Fazio et al., 2015).Treatment of rats with EA reduced clozapine-induced ROS formation, decreased GSSG and MDA, and increased GSH.The findings implied that EA protected cardiomyocytes from oxidative injury by inhibiting mitochondrial dysfunction, ROS formation, and lysosomal damage (Ahangari et al., 2022).

| E A AG AIN S T CHEMI C AL S TOXI CITIE S
Humans and animals are exposed to diverse synthetic chemicals and natural substances through the environment.Above 140 million chemical substances have been registered by Chemical Abstract Service (CAS) as of June 2018 (Tang et al., 2018).A chemical can cause acute and chronic toxicities depending the conditions of exposure.A brief of in vitro and in vivo studies that examined the effects of EA against chemical toxins toxicities is given in Table 3.

| Paraquat
Paraquat (1,1′-dimethyl-4,4′ bipyridinium dichloride) is a toxic and inexpensive bipyridylium herbicide that is widely used.Paraquat is fatal in very small amounts and provokes toxic effects on many organs such as the lungs, liver, kidney, heart, stomach, and intestine (Amin et al., 2021).In an animal model, EA showed a protective effect against paraquat-induced kidney dysfunction by increasing the total antioxidant status (TAS) and decreasing the total oxidant status (TOS) (Table 3; Silfeler et al., 2017).Thus, it could be concluded that EA, due to its antioxidant properties, might block oxidative injury and kidney toxicity induced by paraquat.

| Ethanol
Ethanol's toxicity is divided into acute and chronic.Acute alcohol intoxication has well-known clinical manifestations, including neuropsychiatric symptoms, intellectual excitation, intellectual and psychic excitation, cerebellar syndrome accompanying marked drunkenness, and deep coma (Le Daré et al., 2019).Chronic ethanol exposure is toxic to several organs such as digestive tract steatosis, hepatic cirrhosis, pancreatitis, cerebellar atrophy, polyneuritis, chronic gastritis, memory, and cardiovascular dysfunction (Le Daré et al., 2019).Different pathways play a role in ethanolinduced tissue injury such as the formation of 1-hydroxyethyl radicals, changes in cellular NAD + /NADH, and ethanol-mediated mitochondrial damage (Gopal et al., 2021;Li et al., 2022).Sohn and colleagues showed that the protective effect of EA on alcoholinduced toxicity was induced by regulating NO, scavenger receptor class B type 1 (SR-B1), and transforming growth factor-β1 (TGF-β1) production in human hepatocellular carcinoma (HepG2) cells.
Treatment of hepatic HepG2 cells with EA significantly decreased TGF-β1 and NO expression.SR-B1 plays a significant role in mediating the uptake of cholesteryl ester and high-density lipoprotein (HDL)-derived cholesterol in the liver.In liver cells, EA has dosedependent differential effects on SR-B1 expression regulation.
At 100 μM, EA elevated SR-B1 expression in ethanol-treated cells (Table 3; Sohn et al., 2013).Another study indicated that EA supplementation fed with ethanol for 45 days reduced AST, ALT, thiobarbituric acid reactive substances (TBARS), and hydroperoxides (HP), as well as modulated lipid metabolism.The study also showed a marked histopathological amelioration of kidney toxicity following the EA treatments (Devipriya et al., 2008).

| Rotenone
Rotenone is an isoflavone classified as "moderately hazardous."The plant-derived pesticide rotenone is a powerful complex I-specific inhibitor that is generally applied to model optic neuropathies and Parkinson's disease in the lab (Cimdins et al., 2019).Wei et al. showed that EA protected dopamine neurons from rotenone-induced neurotoxicity by activating the nuclear factor erythroid-2-related factor 2 (Nrf2) signaling pathway.They showed that EA treatment improved locomotor dysfunction in rotenone-treated mice.EA induced higher Nrf2, quinone oxidoreductase 1 (NQO1), and heme oxygenase-1 (HO-1) expressions (Table 3; Wei et al., 2020).In brief, EA by stopping oxidative stress and activating the Nrf2 signaling pathway protected dopamine neurons from rotenone-induced neurotoxicity.

| Acrylamide
Acrylamide (C 3 H 5 NO) is a food contaminant present in a vast range of frequently consumed foods, which makes people's exposure to this toxicant unfortunately unavoidable.Acrylamide promotes neurotoxicity, mutagenicity, and carcinogenicity (Rifai & Saleh, 2020).Acrylamide exposure increases ROS, MDA, and inflammatory cytokines, for example, TNFα and IL-6 levels while decreasing GSH content.In a rat model of acrylamide-induced neurotoxicity, animals were pretreated with EA.They showed lower MDA and NO levels.Also, EA intensified the endogenous antioxidant defense system by enhancement of CAT, SOD, and GPx activities (Table 3; Goudarzi et al., 2019).

| Phthalates
Phthalates are synthetic chemicals with colorless, poorly watersoluble, and low volatility properties.Phthalates are widely used in the plastic industry.Humans are continuously exposed to phthalates through different routes of exposure such as ingestion, inhalation, or dermal absorption (Lyche et al., 2009).Several studies indicated that phthalates cause diverse toxicities in humans and animals, such as neurotoxicity, genotoxicity, hepatotoxicity, and immunotoxicity mainly via oxidative stress induction.It was shown that EA prevented phthalates toxicities by an increase in SOD, CAT, and GPx activities, and GSH enhancement in rats.The study also indicated that EA significantly increased sperm concentration, seminiferous tubular diameter (MSTD), germinal epithelium thickness (GECT), and decreased abnormal sperm rate (Table 3;Başak Türkmen et al., 2022).

| Malathion
Malathion (O,O-dimethyl-S-1,2-bis ethoxy carbonyl ethyl phosphorodithioate) is an organophosphate insecticide that is commonly used to control mosquitoes and various insects that attack vegetables, fruits, shrubs, and landscaping plants (Badr, 2020).In slight oxidative stress, due to compensatory response, the activities of antioxidant enzymes such as SOD, CAT, GSH-Px, and GST are increased while severe oxidative stress depresses the activities of these enzymes due to oxidative injury and a loss in compensatory mechanisms (Zhang et al., 2004).In accordance, malathion caused notable enhancement in the tissue CAT and SOD activities.However, treatment with EA reduced SOD and CAT activities following malathion exposure which may be due to its hydrogen peroxide scavenging and superoxide anion radical scavenging properties (Table 3; Ural et al., 2015).

| Polychlorinated biphenyl
In recent years, industrial and agricultural development has led to an increase in environmental pollutants.Polychlorinated biphenyls are a group of extensively spread environmental pollutants that disrupt normal endocrine functions in animals and humans (Abraham et al., 2002).EA protects against polychlorinated biphenyl-induced inflammation by suppressing lipid peroxidation and enhancing antioxidant enzyme activities such as SOD, and CAT.EA administration to polychlorinated biphenyl-treated animals remarkably prevented the reduction in diameters of seminiferous tubules, Johnsen's testicular score, and germinal cell layer thickness (Table 3; et al., 2010).

| Nicotine
It is presumed that the toxic effects of nicotine are partly due to the raised production of ROS.ROS causes oxidative injury to several molecules in cells, proteins, membrane lipids, and nucleic acids (Hajam et al., 2022).EA efficiently decreased TBARS and HP, increased SOD, CAT, and GPx activities, and improved nicotineinduced DNA damage (Table 3; Sudheer et al., 2007).
clophosphamide administration caused fundamental raises in total abnormality of sperm and tail, plasma MDA level and erythrocyte SOD activity and reduced erythrocyte CAT activity, germinal cell layer thickness, diameters of seminiferous tubules, and Johnsen's Testicular Score along with degeneration, immature germ cells, necrosis, congestion and atrophy in testicular tissue of the rats.EA treatments reduced cyclophosphamide-induced lipid peroxidation and normalized testicular histopathology and sperm morphology (Ceribaşi et al., 2010).Rehman et al. using cyclophosphamideinduced kidney and testicular toxicities showed that EA increased GSH, GR, GST, and GPx levels but decreased xanthine oxidase (XO), MDA, and γ-glutamyltransferase (GGT) levels.In addition, cyclophosphamide caused renal damage that was characterized by an increase in BUN, LDH, and creatinine levels, and EA prevented cyclophosphamide-induced renal toxicity by a decrease in serum BUN, creatinine, and lactic dehydrogenase (LDH) ( -2-one) is one of the most common organophosphorus pesticides(Ghasemi-Niri et al., 2016).Phosalone stimulates inflammatory factors including TNFα and NF-κB and subsequently initiates p53 induction.It also accelerates the oxidative pathway by up-regulation of p38, p53, and retinoblastoma (RB) genes(Altuntas et al., 2003).EA exerted protective effects against phosaloneinduced senescence and decreased inflammatory markers such as TNFα, IL-1β, and IL-6β.EA down-regulated NF-κB, RB, and p53 at all concentrations.Analysis of the cell cycle (G0/G1, S, and G2/M phases) showed that treatment of phosalone-induced cells at all concentrations with EA remarkably elevated the ratio of cells in the S phase compared to the phosalone group.It was found that EA progressively deactivated the phosalone-induced senescence in REF cells, dose-dependently (Table

Toxic agent Dose/concentration of toxic agent, treatment period, and route of exposure Dose/concentration of EA, treatment period, and route of administration In vitro/In vivo model Results of EA treatment References
(Méndez-Echevarría et al., 2018), two anticancer drugs, are used in combination to treat squamous cell carcinoma of the head and neck.Combination therapy has frequently been associated with pulmonary toxicity(Méndez-Echevarría et al., 2018).Lipid peroxides are key signal transduction mediators for inflammatory modifications in lung tis- sue.Bleomycin and cyclophosphamide administration increased oxidative stress by increasing LPO and protein oxidation (Saba Khan