ABSTRACT

Objective:

Cadmium (Cd) is a well-known widespread environmental pollutant and is not rapidly excreted by the kidneys; instead, it accumulates and causes kidney damage. This study aimed to compare the effects of antioxidant curcumin and resveratrol on antioxidant defense in Cd-induced rat kidney tissue.

Methods:

In the study, 36 (200-250 gr) Wistar albino rats were divided into 6 (n=6) groups. Group 1: control; group 2: CdCl2; group 3: curcumin; group 4: CdCl2 + curcumin; group 5: resveratrol; group 6: CdCl2 + resveratrol. At the end of the experiment, malondialdehyde (MDA), total oxidant capacity (TOC), and total antioxidant capacity (TAC) activities were measured in kidney tissues.

Results:

In the CdCl2-treated group, oxidative stress index (OSI), TOC, and MDA levels increased compared with the control group, and TAC values decreased (p<0.05). In the case of resveratrol or curcumin administered with Cd, TAC levels increased, MDA levels, and OSI values decreased compared with the group administered only Cd (p<0.05).

Conclusion:

Both resveratrol and curcumin may have protective effects in the kidneys against CdCl2-induced oxidative damage.

Keywords:

Cadmium, curcumin, resveratrol, kidney damage

INTRODUCTION

Cadmium is widely used in the manufacture of paints, plastics, nickel- cadmium batteries, and in the galvanic coating industry. Exposure sources for living organisms are water, air, and soil. The sources of inhalation exposure are industrial activities, the burning of fossil fuels, and smoking (1,2). Cadmium is highly accumulated in the kidney, liver, pancreas, and lung. Cadmium indirectly generates reactive oxygen- nitrogen species, including superoxide, hydroxyl, and nitric oxide radicals. The indirect role of this metal in free radical formation is its replacement by iron and copper found in cytoplasmic and membrane proteins. The free and weakly bound copper and iron ion levels increase in the Fenton reaction. Copper plays a role in the degradation of hydrogen peroxide through the Fenton reaction and causes oxidative stress and pathological disorders in the liver, kidney, and brain. Lipid peroxidation is the primary mechanism of cadmium poisoning resulting from oxidative stress. Free radicals invade the cell membrane, rendering it unstable, and disrupt the cell membrane structure because of lipid peroxidation (3-5). The mechanisms of acute poisoning with cadmium are in the form of depletion of glutathione, binding to sulfhydryl groups in the protein structure, formation of superoxide ions, and increase of reactive oxygen species (ROS). Cadmium-mediated increased free oxygen groups cause lipid peroxidation and subsequent DNA destruction. Cadmium is not rapidly excreted by the kidneys, but accumulates and causes kidney damage. It also increases the tendency for kidney stone formation. There is a defense mechanism called an antioxidant that prevents the harmful effects of ROS (6-8).

Curcumin is obtained from turmeric (Indian saffron), which is a yellow spice. Curcumin has a wide spectrum of effects, including anti-inflammatory, antioxidant, anticarcinogenic, antidiabetic, antiviral, and neuroprotective effects. It facilitates the removal of many reactive oxygen radicals, especially superoxide anions. In addition, it has been reported to scavenge ROS, inhibit lipid peroxidation, and protect cellular macromolecules from oxidative damage (9).

Resveratrol is a powerful antioxidant, and its osteogenic, anti-inflammatory, and analgesic effects have been described. Resveratrol prevents free radical formation. Its antioxidant activity is attributed to the ribonucleotide, reductase inhibition ability, and cyclooxygenase transcription ability in DNA polymerase activity. Scavenges hydroxyl and superoxide radicals inhibit lipid peroxidation caused by hydroxyl radicals, preventing DNA damage and LDL oxidation. Studies have shown that resveratrol plays a regulatory role in inflammatory events, atherosclerosis, and carcinogenesis. In addition, the antioxidant, anti-cyclooxygenase, lipid, and lipoprotein metabolism-regulating effects of resveratrol have also been demonstrated (10-14).

The objective of this project is to determine the protective effect of curcumin and resveratrol, which have antioxidant properties, in kidney tissue against cadmium-induced oxidative stress in rats. In recent years, studies have focused on researching and developing new drugs with antioxidant properties against cadmium toxicity. In the literature review, no study compared the protective effect of curcumin and resveratrol against cadmium toxicity. In this project, we determined the protective effect of curcumin and resveratrol against cadmium-induced oxidative stress in kidney tissue by comparing them.

MATERIALS AND METHODS

Chemicals

The rats received CdCl2 (Merck Millipore, Billerica, Massachusetts, United States) intraperitoneally (I.P.) at a dose of 5 mg/kg/day (15), curcumin (Sigma Co., MO, USA) I.P. at a dose of 200 mg/kg/day for 4 weeks (16) and Resveratrol (Tocris Bioscience, Bristol, UK) of 10 mg/kg/day was given to the group 5 and group 6 through gavage for 4 weeks (17).

Study Design and Animals

The study procedures were conducted under the guidelines approved by the Local Ethics Committee for animal experiments at the University of Çanakkale Onsekiz Mart Faculty of Medicine (approval number: 2021-02-07). This work was supported by the Çanakkale Onsekiz Mart University Scientific Research Coordination Unit (project number: THD-2021-3626). Animal housing and experiments were conducted in accordance with the Guide for the Care and Use of Laboratory Animals. Wistar albino rats weighing (200±25 g) were maintained in clean plastic cages under standard temperature and humidity conditions. The animals were fed a standard laboratory pellet diet and sterile water. The animals were kept at 25 °C under a 12-h light/12-h dark cycle, with free access to water and food. Inclusion criteria in this study were (a) healthy rats and no abnormalities, (b) 4-month-old female, and (c) weight >250 g. The exclusion criteria were (a) disability or disorder rats and (b) the dead rats after treatment, and (c) male rats.

Sample size calculations were made using the G^*Power 3.1.9.4 program, considering the studies in the literature (18). To achieve power =0.8 and alpha =0.05 to detect this difference would require a total of 36 animals.

There was a randomized design into six groups as follows (six rats in each group):

- Group 1: control,

- Group 2: CdCl2 (5 mg/kg, I.P.) for 10 days,

- Group 3: Curcumin (200 mg/kg/day gavage) for 4 weeks,

- Group 4: CdCl2 (5 mg/kg, I.P.) 10 days + curcumin (200 mg/kg/day gavage) for 4 weeks (from the day of cadmium administration),

- Group 5: Resveratrol (10 mg/kg/day gavage) for 4 weeks,

- Group 6: CdCl2 (5 mg/kg, I.P.) 10 days + resveratrol (10 mg/kg/day gavage) for 4 weeks (from the day of cadmium administration).

All experimental procedures were performed under ketamine/xylazine anesthesia. At the end of the treatment, rats were sacrificed under ketamine/xylazine anesthesia (19). No animals died because of medication.

Spectrophotometric Analysis

The kidneys were washed in ice-cold 1.15% KCl and homogenized. The homogenate was centrifuged at 14,000 rpm for 30 min, and assays were performed on the resultant supernatant. Protein concentration was estimated using the method of Lowry et al. (20). Tissue samples taken for malondialdehyde determination were homogenized and subjected to procedures as outlined previously (21). TAC and TOC levels were measured by a spectrophotometric assay using commercially available kits (Rel Assay Diagnostics, Türkiye). OSI was defined as the ratio of the TAC level to the TOC level.

Statistical Analysis

Values are presented as means ± standard deviation. Statistical analysis was performed using SPSS, version 19.0 (SPSS, IBM Company). Comparison between the two groups for continuous variables was performed using the Mann-Whitney U test. Multiple comparisons were performed by One-Way analysis of variance (ANOVA). P-values 0.05 were accepted as the significance level.

RESULTS

In group 2 given CdCl2, TOC, OSI, and MDA levels increased compared with the control group, and TAC values decreased (p<0.05). TAC levels increased, MDA levels, and OSI values decreased in group 4 and group 6 compared with group 2 (p<0.05). TOC value increased in group 3 and group 5 compared with group 1 (p<0.05) (Table 1).

DISCUSSION

Cadmium is a heavy metal that is associated with pathological changes in target organs, including the lung, liver, and kidney, and causes serious health problems, even at low exposure levels. In many studies, the toxic and carcinogenic effects of cadmium on human health have been investigated. Heavy metals such as Cd+2 cause oxidative stress by disrupting the redox balance in cells. Many studies have reported that Cd+2 toxicity causes damage to biological components of the cell in humans and animals. Cd+2 reduces the GSH content of the cell and the activities of enzymes such as SOD, peroxidases, and CAT, causing ROS accumulation and oxidative stress increment. In other studies, it has been stated that cadmium causes an increase in malondialdehyde levels, which is an indicator of lipid peroxidation, and a decrease in superoxide dismutase and glutathione peroxidase values, which are antioxidant enzymes in organs such as the liver and lungs (6,7,22,23). In our study, TOC, OSI, and MDA levels increased in the Cd+2 administered group compared with the control group, whereas the TAC value decreased. This explains the increase in ROS formation and the inadequacy of the antioxidant defense system among the toxic action mechanisms of Cd+2.

In recent studies, curcumin has attracted attention for its potential antioxidant or anti-apoptotic properties. Curcumin has many beneficial properties, including antioxidant and anti-inflammatory actions (24-26). In this study, it was observed that the TAC level increased and the MDA level and OSI value decreased in the group administered curcumin with Cd. On the basis of our results, we can say that curcumin may benefit kidney tissue in cadmium-induced oxidative stress.

It has been reported that resveratrol prevents oxidative stress-induced tissue damage by preventing the oxidation of membrane lipids and enhancing antioxidant capacity. It has been reported that resveratrol scavenges free radicals (O2-, OH.) in the cell culture medium and prevents the peroxidation of membrane lipids, which develops due to the radical production increased by chromium exposure (27-29). In this study, it was observed that the TAC level increased and the MDA level and OSI value decreased in the group administered resveratrol with Cd. Because of the hydroxyl groups it has, resveratrol donates a hydrogen electron and becomes OH, and prevents peroxidation of cell membranes by scavenging O2 radicals. According to our results, resveratrol contributes to the cell defense system by both reducing the increased radical production caused by Cd and increasing the expression of antioxidant enzymes.

Study Limitations

It is important to acknowledge the limitations of the current study. Because only female rats used in the experiments, these findings might not apply to male rats. Further studies that include different genders, ages, etc. are necessary. Future research should consider this difference.

CONCLUSION

As a result, both resveratrol and curcumin support the defense system of cells by scavenging free radicals that increase the oxidative damage caused by Cd in the kidneys. More extensive studies are required on this subject.

Acknowledgments: This work was approved by Çanakkale Onsekiz Mart University, Scientific Research Unit (THD-2021-3626).

Ethics

Ethics Committee Approval: The study procedures were conducted under the guidelines approved by the Local Ethics Committee for animal experiments at the University of Çanakkale Onsekiz Mart Faculty of Medicine (approval number: 2021-02-07).

Informed Consent: This study does not apply because it involves animal subjects.

Authorship Contributions

Surgical and Medical Practices: S.C., Ş.Ö., Concept: S.C., L.C.İ., Ş.Ö., Design: S.C., L.C.İ., Ş.Ö., Data Collection or Processing: S.C., L.C.İ., Ş.Ö., Analysis or Interpretation: S.C., L.C.İ., Ş.Ö., Literature Search: S.C., L.C.İ., Ş.Ö., Writing: S.C., L.C.İ., Ş.Ö.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.

References

Patrick L. Toxic metals and antioxidants: part II. The role of antioxidants in arsenic and cadmium toxicity. Altern Med Rev 2003; 8: 106-28.

Rani A, Kumar A, Lal A, Pant M. Cellular mechanisms of cadmium-induced toxicity: a review. Int J Environ Health Res 2014; 24: 378-99.

Ingawale DK, Mandlik SK, Naik SR. Models of hepatotoxicity and the underlying cellular, biochemical and immunological mechanism(s): a critical discussion. Environ Toxicol Pharmacol 2014; 37: 118-33.

Jomova K, Valko M. Advances in metal-induced oxidative stress and human disease. Toxicology 2011; 283: 65-87.

Wiwanitkit V. Minor heavy metal: A review on occupational and environmental intoxication. Indian J Occup Environ Med 2008; 12: 116-21.

Liu J, Qian SY, Guo Q, Jiang J, Waalkes MP, Mason RP, et al. Cadmium generates reactive oxygen- and carbon-centered radical species in rats: insights from in vivo spin-trapping studies. Free Radic Biol Med 2008; 45: 475-81.

Liu J, Qu W, Kadiiska MB. Role of oxidative stress in cadmium toxicity and carcinogenesis. Toxicol Appl Pharmacol 2009; 238: 209-14.

Wu X, Cobbina SJ, Mao G, Xu H, Zhang Z, Yang L. A review of toxicity and mechanisms of individual and mixtures of heavy metals in the environment. Environ Sci Pollut Res Int 2016; 23: 8244-59.

Naik SR, Thakare VN, Patil SR. Protective effect of curcumin on experimentally induced inflammation, hepatotoxicity and cardiotoxicity in rats: evidence of its antioxidant property. Exp Toxicol Pathol 2011; 63: 419-31.

Cho J. Antioxidant and neuroprotective effects of hesperidin and its aglycone hesperetin. Arch Pharm Res 2006; 29: 699-706.

Cottart CH, Nivet-Antoine V, Laguillier-Morizot C, Beaudeux JL. Resveratrol bioavailability and toxicity in humans. Mol Nutr Food Res 2010; 54: 7-16.

Das S, Lin HS, Ho PC, Ng KY. The impact of aqueous solubility and dose on the pharmacokinetic profiles of resveratrol. Pharm Res 2008; 25: 2593-600.

Dimpfel W. Different anticonvulsive effects of hesperidin and its aglycone hesperetin on electrical activity in the rat hippocampus in-vitro. J Pharm Pharmacol 2006; 58: 375-9.

Kumar A, Lalitha S, Mishra J. Hesperidin potentiates the neuroprotective effects of diazepam and gabapentin against pentylenetetrazole-induced convulsions in mice: Possible behavioral, biochemical and mitochondrial alterations. Indian J Pharmacol 2014; 46: 309-15.

Hu J, Zhang B, Du L, Chen J, Lu Q. Resveratrol ameliorates cadmium induced renal oxidative damage and inflammation. Int J Clin Exp Med 2017; 10: 7563-72.

Sankrityayan H, Majumdar AS. Curcumin and folic acid abrogated methotrexate induced vascular endothelial dysfunction. Can J Physiol Pharmacol 2016; 94: 89-96.

Wiciński M, Malinowski B, Węclewicz MM, Grześk E, Grześk G. Anti-atherogenic properties of resveratrol: 4-week resveratrol administration associated with serum concentrations of SIRT1, adiponectin, S100A8/A9 and VSMCs contractility in a rat model. Exp Ther Med 2017; 13: 2071-8.

Othman MS, Nada A, Zaki HS, Abdel Moneim AE. Effect of Physalis peruviana L. on cadmium-induced testicular toxicity in rats. Biol Trace Elem Res 2014;159:278-87.

Cosar R, Yurut-Caloglu V, Eskiocak S, Ozen A, Altaner S, Ibis K, et al. Radiation-induced chronic oxidative renal damage can be reduced by amifostine. Med Oncol 2012; 29: 768-75.

Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement with the Folin phenol reagent. J Biol Chem 1951; 193: 265-75.

Ohkawa H, Ohishi N, Yagi K. Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Anal Biochem 1979; 95: 351-8.

Anetor JI. Rising Environmental Cadmium Levels in Developing Countries: Threat to Genome Stability and Health. Niger J Physiol Sci 2012; 27: 103-15.

Lee JC, Son YO, Pratheeshkumar P, Shi X. Oxidative stress and metal carcinogenesis. Free Radic Biol Med 2012; 53: 742-57.

Biswas SK, McClure D, Jimenez LA, Megson IL, Rahman I. Curcumin induces glutathione biosynthesis and inhibits NF-kappaB activation and interleukin-8 release in alveolar epithelial cells: mechanism of free radical scavenging activity. Antioxid Redox Signal 2005; 7: 32-41.

Corona-Rivera A, Urbina-Cano P, Bobadilla-Morales L, Vargas-Lares Jde J, Ramirez-Herrera MA, Mendoza-Magaua ML, et al. Protective in vivo effect of curcumin on copper genotoxicity evaluated by comet and micronucleus assays. J Appl Genet 2007; 48: 389-96.

Menon VP, Sudheer AR. Antioxidant and anti-inflammatory properties of curcumin. Adv Exp Med Biol 2007; 595: 105-25.

Gerogiannaki-Christopoulou M, Athanasopoulos P, Kyriakidis N, Gerogiannaki IA, Spanos M. Trans Resveratrol in wines from the major Greek red and white grape varieties. Food Control 2006; 17: 700-6.

Signorelli P, Ghidoni R. Resveratrol as an anticancer nutrient: molecular basis, open questions and promises. J Nutr Biochem 2005; 16: 449-66.

Soleas GJ, Diamandis EP, Goldberg DM. Resveratrol: a molecule whose time has come? And gone? Clin Biochem 1997; 30: 91-113.

Protective Effects of Curcumin and Resveratrol on Kidney Tissue on Cadmium-induced Oxidative Stress in Rats