Sulforaphane protects against cisplatin-induced nephrotoxicity

Protective effects of sulforaphane against toxic substances and contaminants: A systematic review

BACKGROUND

Sulforaphane (SFN) is a dietary isothiocyanate, derived from glucoraphanin, present in cruciferous vegetables belonging to the Brassica genus. It is a biologically active phytochemical that acts as a nuclear factor erythroid 2-related factor 2 (Nrf2) inducer. Thus, it has been reported to have multiple protective functions including anticancer responses and protection against a toxic agent's action.

PURPOSE

The present work systematically reviewed and synthesised the protective properties of sulforaphane against a toxic agent. This review reveals the mechanism of the action of SFN in each organ or system.

METHODS

The PRISMA guideline was followed in this sequence: researched literature, organised retrieved documents, abstracted relevant information, assessed study quality and bias, synthesised data, and prepared a comprehensive report. Searches were conducted on Science Direct and PubMed using the keywords "Sulforaphane" AND ("protective effects" OR "protection against").

RESULTS

Reports showed that liver and the nervous system are the target organs on which attention was focused, and this might be due to the key role of oxidative stress in liver and neurodegenerative diseases. However, protective activities have also been demonstrated in the lungs, heart, immune system, kidneys, and endocrine system. SFN exerts its protective effects by activating the Nrf2 pathway, which enhances antioxidant defenses and reduces oxidative stress. It also suppresses inflammation by decreasing interleukin production. Moreover, SFN inhibits apoptosis by preventing caspase 3 cleavage and increasing Bcl2 levels. Overall, SFN demonstrates multifaceted mechanisms to counteract the adverse effects of toxic agents.

CONCLUSION

SFN has potential clinical applications as a chemoprotective agent. Nevertheless, more studies are necessary to set the safe doses of SFN in humans.

NRF2 in kidney physiology and disease

The role of NRF2 in kidney biology has received considerable interest over the past decade. NRF2 transcriptionally controls genes responsible for cellular protection against oxidative and electrophilic stress and has anti-inflammatory functions. NRF2 is expressed throughout the kidney and plays a role in salt and water handling. In disease, animal studies show that NRF2 protects against tubulointerstitial damage and reduces interstitial fibrosis and tubular atrophy, and may slow progression of polycystic kidney disease. However, the role of NRF2 in proteinuric glomerular diseases is controversial. Although the NRF2 inducer, bardoxolone methyl (CDDO-Me), increases glomerular filtration rate in humans, it has not been shown to slow disease progression in diabetic kidney disease and Alport syndrome. Furthermore, bardoxolone methyl was associated with negative effects on fluid retention, proteinuria, and blood pressure. Several animal studies replicate findings of worsened proteinuria and a more rapid progression of kidney disease, although considerable controversy exists. It is clear that further study is needed to better understand the effects of NRF2 in the kidney. This review summarizes the available data to clarify the promise and risks associated with targeting NRF2 activity in the kidney.

Sulforaphane exhibits potent renoprotective effects in preclinical models of kidney diseases: A systematic review and meta-analysis

AIMS

Sulforaphane (SFN), a naturally occurring isothiocyanate found in cruciferous vegetables, has received extensive attention as a natural activator of the Nrf2/Keap1 cytoprotective pathway. In this review, a meta-analysis and systematic review of the renoprotective effects of SFN were performed in various preclinical models of kidney diseases.

MAIN METHODS

The primary outcome was the impact of SFN on renal function biomarkers (uremia, creatininemia, proteinuria or creatinine clearance) and secondary outcomes were kidney lesion histological indices/kidney injury molecular biomarkers. The effects of SFN were evaluated according to the standardized mean differences (SMDs). A random-effects model was applied to estimate the overall summary effect.

KEY FINDINGS

Twenty-five articles (out of 209 studies) were selected from the literature. SFN administration significantly increased creatinine clearance (SMD +1.88 95 % CI: [1.09; 2.68], P < 0.0001, I² = 0 %) and decreased the plasma creatinine (SMD -1.24, [-1.59; -0.88], P < 0.0001, I² = 36.0 %) and urea (SMD -3.22 [-4.42, -2.01], P < 0.0001, I² = 72.4 %) levels. SFN administration (median dose: 2.5 mg/kg, median duration: 3 weeks) significantly decreased urinary protein excretion (SMD -2.20 [-2.68; -1.73], P < 0.0001, I² = 34.1 %). It further improved two kidney lesion histological indices namely kidney fibrosis (SMD -3.08 [-4.53; -1.63], P < 0.0001, I² = 73.7 %) and glomerulosclerosis (SMD -2.24 [-2.96; -1.53], P < 0.0001, I² = 9.7 %) and decreased kidney injury molecular biomarkers (SMD -1.51 [-2.00; -1.02], P < 0.0001, I² = 0 %).

SIGNIFICANCE

These findings provide new insights concerning preclinical strategies for treating kidney disease or kidney failure with SFN supplements and should stimulate interest in clinical evaluations of SFN in patients with kidney disease.

Insights into the Molecular Mechanisms of NRF2 in Kidney Injury and Diseases

Redox is a constant phenomenon in organisms. From the signaling pathway transduction to the oxidative stress during the inflammation and disease process, all are related to reduction-oxidation (redox). Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor targeting many antioxidant genes. In non-stressed conditions, NRF2 maintains the hemostasis of redox with housekeeping work. It expresses constitutively with basal activity, maintained by Kelch-like-ECH-associated protein 1 (KEAP1)-associated ubiquitination and degradation. When encountering stress, it can be up-regulated by several mechanisms to exert its anti-oxidative ability in diseases or inflammatory processes to protect tissues and organs from further damage. From acute kidney injury to chronic kidney diseases, such as diabetic nephropathy or glomerular disease, many results of studies have suggested that, as a master of regulating redox, NRF2 is a therapeutic option. It was not until the early termination of the clinical phase 3 trial of diabetic nephropathy due to heart failure as an unexpected side effect that we renewed our understanding of NRF2. NRF2 is not just a simple antioxidant capacity but has pleiotropic activities, harmful or helpful, depending on the conditions and backgrounds.

The Self-Administered Use of Complementary and Alternative Medicine (CAM) Supplements and Antioxidants in Cancer Therapy and the Critical Role of Nrf-2-A Systematic Review

Complementary and alternative medicine (CAM) supplements are widely used by cancer patients. Dietary supplements, vitamins and minerals, herbal remedies, and antioxidants are especially popular. In a systematic literature review, 37 studies, each including more than 1000 participants, on CAM, dietary supplement, and vitamin use among cancer patients were identified. Accordingly, cancer patients use antioxidants such as vitamin C (from 2.6% (United Kingdom) to 41.6% (United States)) and vitamin E (from 2.9% (China) to 48% (United States)). Dietary supplements and vitamins are taken for different reasons, but often during conventional cancer treatment involving chemotherapy or radiotherapy and in a self-decided manner without seeking medical advice from healthcare professionals. Drug-drug interactions with dietary supplements or vitamins involving multiple signaling pathways are well described. Since most of the anticancer drugs generate reactive oxygen species (ROS), an adaptive stress response of healthy and malignant cells, mainly driven by the Nrf-2-Keap I network, can be observed. On the one hand, healthy cells should be protected from ROS-overproducing chemotherapy and radiotherapy; on the other hand, ROS production in cancer cells is a "desirable side effect" during anticancer drug treatment. We here describe the paradoxical use of antioxidants and supplements during cancer therapy, possible interactions with anticancer drugs, and the involvement of the Nrf-2 transcription factor.

Sulforaphane-cisplatin combination inhibits the stemness and metastatic potential of TNBCs via down regulation of sirtuins-mediated EMT signaling axis

BACKGROUND

Sulforaphane (SFN) is a naturally occurring organosulfur compound found in cruciferous vegetables such as broccoli, brussels sprouts and cabbage. SFN is known for its multiple therapeutic properties, such as HDAC inhibitory, chemo preventive and anti-cancer effects. Cisplatin (CIS) has limited effect against metastatic triple-negative breast cancer (TNBC). Additionally, CIS impose severe side effects to normal cells, and later TNBC cells develops resistance. Studies suggest that the overexpression of sirtuins (SIRTs) promotes CIS resistance and metastasis by activating epithelial-to-mesenchymal transition (EMT) pathway in TNBC.

PURPOSE

In view of the above information, we investigated the therapeutic efficacy of SFN, in combination with CIS against TNBC metastasis and CIS resistance.

METHODS

The anti-cancerous effect of SFN-CIS combination on human TNBC cell lines was demonstrated by utilizing MTT assay and, apoptosis and cell cycle assay followed by FACS analysis. The synergistic effect of SFN-CIS combination on the experimental metastasis was demonstrated by utilizing migration, invasion, chemotaxis, mammosphere and colony formation assay on human TNBC MDA-MB-231 and MDA-MB-468 cells. The role of SIRTs-mediated EMT signaling axis in the metastasis and chemoresistance was investigated by western blotting technique as well as sirtuin activity tests. This was further validated by using Chromatin immunoprecipitation (ChIP) analysis.

RESULTS

We found that SFN-CIS combination synergistically inhibits cellular growth of MDA-MB-231 and MDA-MB-468 cells. More importantly, SFN was found to protect normal kidney cells from CIS-induced toxicity. Further, SFN-CIS combination was found to synergistically inhibit metastatic-events via significantly altering EMT markers which was further associated with the suppression of SIRTs functions in TNBC cells. ChIP analysis validated that SFN-CIS combination suppresses EMT mechanism through altered chromatin modifications at E-cadherin promoter resulting in its re-expression.

CONCLUSION

The results of the current study suggests that CIS when supplemented with SFN, inhibits metastasis and stemness potential of TNBC cells by down regulating SIRTs-mediated EMT cascade. Overall this study affirms that, this novel combination could be a promising strategy against SIRT-mediated TNBC metastasis and CIS-resistance.

Evaluating the Anti-Inflammatory and Antioxidant Effects of Broccoli Treated with High Hydrostatic Pressure in Cell Models

Isothiocyanates (ITCs) are important functional components of cruciferous vegetables. The principal isothiocyanate molecule in broccoli is sulforaphane (SFN), followed by erucin (ERN). They are sensitive to changes in temperature, especially high temperature environments where they are prone to degradation. The present study investigates the effects of high hydrostatic pressure on isothiocyanate content, myrosinase activity, and other functional components of broccoli, and evaluates its anti-inflammatory and antioxidant effects. Broccoli samples were treated with different pressures and for varying treatment times; 15 min at 400 MPa generated the highest amounts of isothiocyanates. The content of flavonoids and vitamin C were not affected by the high-pressure processing strategy, whereas total phenolic content (TPC) exhibited an increasing tendency with increasing pressure, indicating that high-pressure processing effectively prevents the loss of the heat-sensitive components and enhances the nutritional content. The activity of myrosinase (MYR) increased after high-pressure processing, indicating that the increase in isothiocyanate content is related to the stimulation of myrosinase activity by high-pressure processing. In other key enzymes, the ascorbate peroxidase (APX) activity was unaffected by high pressure, whereas peroxidase (POD) and polyphenol oxidase (PPO) activity exhibited a 1.54-fold increase after high-pressure processing, indicating that high pressures can effectively destroy oxidases and maintain food quality. With regards to efficacy evaluation, NO production was inhibited and the expression levels of inducible nitric oxide synthase (iNOS) and Cyclooxygenase-2 (COX-2) were decreased in broccoli treated with high pressures, whereas the cell viability remained unaffected. The efficacy was more significant when the concentration of SFN was 60 mg·mL-1. In addition, at 10 mg·mL-1 SFN, the reduced/oxidized glutathione (GSH/GSSG) ratio in inflammatory macrophages increased from 5.99 to 9.41. In conclusion, high-pressure processing can increase the isothiocyanate content in broccoli, and has anti-inflammatory and anti-oxidant effects in cell-based evaluation strategies, providing a potential treatment strategy for raw materials or additives used in healthy foods.

Toll-Like Receptors in Acute Kidney Injury

Acute kidney injury (AKI) is an important health problem, affecting 13.3 million individuals/year. It is associated with increased mortality, mainly in low- and middle-income countries, where renal replacement therapy is limited. Moreover, survivors show adverse long-term outcomes, including increased risk of developing recurrent AKI bouts, cardiovascular events, and chronic kidney disease. However, there are no specific treatments to decrease the adverse consequences of AKI. Epidemiological and preclinical studies show the pathological role of inflammation in AKI, not only at the acute phase but also in the progression to chronic kidney disease. Toll-like receptors (TLRs) are key regulators of the inflammatory response and have been associated to many cellular processes activated during AKI. For that reason, a number of anti-inflammatory agents targeting TLRs have been analyzed in preclinical studies to decrease renal damage during AKI. In this review, we updated recent knowledge about the role of TLRs, mainly TLR4, in the initiation and development of AKI as well as novel compounds targeting these molecules to diminish kidney injury associated to this pathological condition.

Protection against chemotherapy- and radiotherapy-induced side effects: A review based on the mechanisms and therapeutic opportunities of phytochemicals

BACKGROUND

Although great achievements have been made in the field of cancer therapy, chemotherapy and radiotherapy remain the mainstay cancer therapeutic modalities. However, they are associated with various side effects, including cardiocytotoxicity, nephrotoxicity, myelosuppression, neurotoxicity, hepatotoxicity, gastrointestinal toxicity, mucositis, and alopecia, which severely affect the quality of life of cancer patients. Plants harbor a great chemical diversity and flexible biological properties that are well-compatible with their use as adjuvant therapy in reducing the side effects of cancer therapy.

PURPOSE

This review aimed to comprehensively summarize the molecular mechanisms by which phytochemicals ameliorate the side effects of cancer therapies and their potential clinical applications.

METHODS

We obtained information from PubMed, Science Direct, Web of Science, and Google scholar, and introduced the molecular mechanisms by which chemotherapeutic drugs and irradiation induce toxic side effects. Accordingly, we summarized the underlying mechanisms of representative phytochemicals in reducing these side effects.

RESULTS

Representative phytochemicals exhibit a great potential in reducing the side effects of chemotherapy and radiotherapy due to their broad range of biological activities, including antioxidation, antimutagenesis, anti-inflammation, myeloprotection, and immunomodulation. However, since a majority of the phytochemicals have only been subjected to preclinical studies, clinical trials are imperative to comprehensively evaluate their therapeutic values.

CONCLUSION

This review highlights that phytochemicals have interesting properties in relieving the side effects of chemotherapy and radiotherapy. Future studies are required to explore the clinical benefits of these phytochemicals for exploitation in chemotherapy and radiotherapy.

Protective Role of Nrf2 in Renal Disease

Chronic kidney disease (CKD) is one of the fastest-growing causes of death and is predicted to become by 2040 the fifth global cause of death. CKD is characterized by increased oxidative stress and chronic inflammation. However, therapies to slow or prevent CKD progression remain an unmet need. Nrf2 (nuclear factor erythroid 2-related factor 2) is a transcription factor that plays a key role in protection against oxidative stress and regulation of the inflammatory response. Consequently, the use of compounds targeting Nrf2 has generated growing interest for nephrologists. Pre-clinical and clinical studies have demonstrated that Nrf2-inducing strategies prevent CKD progression and protect from acute kidney injury (AKI). In this article, we review current knowledge on the protective mechanisms mediated by Nrf2 against kidney injury, novel therapeutic strategies to induce Nrf2 activation, and the status of ongoing clinical trials targeting Nrf2 in renal diseases.

Cruciferous vegetables: rationale for exploring potential salutary effects of sulforaphane-rich foods in patients with chronic kidney disease

Sulforaphane (SFN) is a sulfur-containing isothiocyanate found in cruciferous vegetables (Brassicaceae) and a well-known activator of nuclear factor-erythroid 2-related factor 2 (Nrf2), considered a master regulator of cellular antioxidant responses. Patients with chronic diseases, such as diabetes, cardiovascular disease, cancer, and chronic kidney disease (CKD) present with high levels of oxidative stress and a massive inflammatory burden associated with diminished Nrf2 and elevated nuclear transcription factor-κB-κB expression. Because it is a common constituent of dietary vegetables, the salutogenic properties of sulforaphane, especially it’s antioxidative and anti-inflammatory properties, have been explored as a nutritional intervention in a range of diseases of ageing, though data on CKD remain scarce. In this brief review, the effects of SFN as a senotherapeutic agent are described and a rationale is provided for studies that aim to explore the potential benefits of SFN-rich foods in patients with CKD.

The Role of Lysosome-associated Membrane Protein 2 in Prostate Cancer Chemopreventive Mechanisms of Sulforaphane

Prostate cancer chemoprevention by sulforaphane, which is a metabolic by-product of glucoraphanin found in broccoli, in preclinical models is associated with induction of both apoptosis and autophagy. However, the molecular mechanism underlying sulforaphane-mediated autophagy, which is protective against apoptotic cell death by this phytochemical, is still poorly understood. This study demonstrates a role for lysosome-associated membrane protein 2 (LAMP2) in sulforaphane-mediated autophagy and apoptosis. Western blotting revealed dose-dependent induction of LAMP2 protein after treatment with sulforaphane as well as its naturally occurring analogs in PC-3 and 22Rv1 human prostate cancer cell lines that was confirmed by microscopy (sulforaphane). The mRNA level of LAMP2 was also increased upon treatment with sulforaphane in both cell lines. Sulforaphane-mediated increase in the level of autophagy marker microtubule-associated protein light-chain 3B was augmented by RNAi of LAMP2 in PC-3 and 22Rv1 cells. Apoptosis induction by sulforaphane treatment was also increased significantly by knockdown of the LAMP2 protein in PC-3 and 22Rv1 cells. Augmentation of sulforaphane-mediated apoptosis by RNAi of LAMP2 was accompanied by induction and activation of proapoptotic protein Bak. Oral administration of sulforaphane to TRAMP mice also resulted in induction of LAMP2 protein expression. Targeted microarray in sulforaphane-treated PC-3 cells revealed induction of many autophagy-related genes (e.g., HSP90AA1, NRF2, etc) and their expression positively correlated with that of LAMP2 in prostate cancer The Cancer Genome Atlas. In conclusion, this study reveals that induction of LAMP2 by sulforaphane inhibits its ability to induce apoptotic cell death at least in human prostate cancer cells.

Sulforaphane Potentiates Anticancer Effects of Doxorubicin and Cisplatin and Mitigates Their Toxic Effects

The success of cancer therapy is often compromised by the narrow therapeutic index of many anticancer drugs and the occurrence of drug resistance. The association of anticancer therapies with natural compounds is an emerging strategy to improve the pharmaco-toxicological profile of cancer chemotherapy. Sulforaphane, a phytochemical found in cruciferous vegetables, targets multiple pathways involved in cancer development, as recorded in different cancers such as breast, brain, blood, colon, lung, prostate, and so forth. As examples to make the potentialities of the association chemotherapy raise, here we highlight and critically analyze the information available for two associations, each composed by a paradigmatic anticancer drug (cisplatin or doxorubicin) and sulforaphane.

Myricetin Abrogates Cisplatin-Induced Oxidative Stress, Inflammatory Response, and Goblet Cell Disintegration in Colon of Wistar Rats

Cisplatin [cis-diamminedichloroplatinum II] is an extensively prescribed drug in cancer chemotherapy; it is also useful for the treatment of diverse types of malignancies. Conversely, cisplatin is associated with a range of side effects such as nephrotoxicity, hepatotoxicity, gastrointestinal toxicity, and so on. Myricetin (3,5,7-trihydroxy-2-(3,4,5-trihydroxyphenyl)-4chromenone) is a very common natural flavonoid found in fruits, tea, and plants. It has been found to have high-value pharmacological properties and strong health benefits. To examine the role of myricetin in colon toxicity induced by cisplatin, we conducted a concurrent prophylactic study in experimental animals that were treated orally with myricetin for 14 days at two doses—25 and 50 mg/kg of body weight. On the 14th day, a single intraperitoneal injection of cisplatin (7.5 mg/kg body weight) was administered in all groups except control. The effects of myricetin in cisplatin-induced toxicity in the colon were assessed in terms of antioxidant status, phase-II detoxification enzymes, the level of inflammatory markers, and goblet cell disintegration. Myricetin was found to restore the level of all the antioxidant enzymes analyzed in the study. In addition, the compound ameliorated cisplatin-induced lipid peroxidation, increase in xanthine oxidase activity, and phase-II detoxifying enzyme activity. Myricetin also attenuated deteriorative effects induced by cisplatin by regulating the level of molecular markers of inflammation (NF-κB, Nrf-2, IL-6, and TNF-α), restoring Nrf-2 levels, and controlling goblet cell disintegration. The current study reinforces the conclusion that myricetin exerts protection in colon toxicity via up-regulation of inflammatory markers, improving anti-oxidant status, and protecting tissue damage.

Sulforaphane-Loaded Ultradeformable Vesicles as A Potential Natural Nanomedicine for the Treatment of Skin Cancer Diseases

Sulforaphane is a multi-action drug and its anticancer activity is the reason for the continuous growth of attention being paid to this drug. Sulforaphane shows an in vitro antiproliferative activity against melanoma and other skin cancer diseases. Unfortunately, this natural compound cannot be applied in free form on the skin due to its poor percutaneous permeation determined by its physico-chemical characteristics. The aim of this investigation was to evaluate ethosomes^® and transfersomes^® as ultradeformable vesicular carriers for the percutaneous delivery of sulforaphane to be used for the treatment of skin cancer diseases. The physico-chemical features of the ultradeformable vesicles were evaluated. Namely, ethosomes^® and transfersomes^® had mean sizes <400 nm and a polydispersity index close to 0. The stability studies demonstrated that the most suitable ultradeformable vesicles to be used as topical carriers of sulforaphane were ethosomes^® made up of ethanol 40% (w/v) and phospholipon 90G 2% (w/v). In particular, in vitro studies of percutaneous permeation through human stratum corneum and epidermis membranes showed an increase of the percutaneous permeation of sulforaphane. The antiproliferative activity of sulforaphane-loaded ethosomes^® was tested on SK-MEL 28 and improved anticancer activity was observed in comparison with the free drug.

Protective effects of zingerone on cisplatin-induced nephrotoxicity in female rats

Zingerone (ZO), one of the active components of ginger (Zingiber officinale), is a phenolic alkanone with antioxidant, antiapoptotic, and anti-inflammatory properties. Cisplatin (CP) is a widely used chemotherapeutic drug for solid tumors, but its therapeutic use is limited due to dose-dependent nephrotoxicity. In the present study, we investigated the ameliorative effect of ZO against CP-induced nephrotoxicity. Intraperitoneal administration of single-dose CP (7 mg/kg body weight) on the first day enhanced kidney lipid peroxidation and reduced antioxidant enzyme activities such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GSH). CP increased serum urea and creatinine levels and disrupted histological integrity while causing a decrease aquaporin 1 (AQP1) level in the kidney tissues. CP induced inflammatory responses by elevating the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-33 (IL-33) and nuclear factor kappa B (NF-κB), and activities of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, it also caused oxidative DNA damage and activation of apoptotic pathway by increasing of 8-hydroxy-2'-deoxyguanosine (8-OHdG), p53, cysteine aspartate-specific protease-3 (caspase-3), and Bcl-2-associated x protein (bax) while decreasing B cell lymphoma-2 (Bcl-2). However, treatment with ZO at a dose of 25 and 50 mg/kg b.wt. for 7 days significantly decreased oxidative stress, apoptosis, inflammation, and histopathological alterations while increased AQP1 levels in the kidney tissue. The results of the current study suggested that ZO as an effective natural product attenuates CP-induced nephrotoxicity.

Combinations of the antioxidants sulforaphane or curcumin and the conventional antineoplastics cisplatin or doxorubicin as prospects for anticancer chemotherapy

Drugs used in clinical oncology have narrow therapeutic indices with adverse toxicity often involving oxidative damage. Chemoresistance to these conventional antineoplastics is usually mediated by oxidative stress-upregulated pathways such as those of nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor-1 alpha (HIF-1α). Accordingly, the use of antioxidants in combinational approaches has begun to be considered for fighting cancer because of both the protective role against adverse effects and the ability to sensitize chemoresistant cancer cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been identified as a mediator of the cytoprotection but it is not regularly associated with tumor chemosensitization. However, some Nrf2 inducers could be exerting cytoprotective and chemosensitizing roles through a simple integrated mechanism in which the cellular level of reactive oxygen species is controlled, thus inhibiting the oxidative damage in non-target tissues and the tumor chemoresistance mediated by NF-κB or HIF-1α. As examples to show the general idea of this antioxidant combination chemotherapy, this review explores the preclinical information available for four combinations, each composed by a paradigmatic oncological drug (cisplatin or doxorubicin) and a recognized antioxidant (sulforaphane or curcumin). The issues for translating these outcomes to clinical trials are briefly discussed.

Contrast media (meglumine diatrizoate) aggravates renal inflammation, oxidative DNA damage and apoptosis in diabetic rats which is restored by sulforaphane through Nrf2/HO-1 reactivation

Diabetes mellitus is an independent risk factor for renal impairment in patients exposed to contrast media. It doubles the risk and decreases survival rate of contrast induced nephropathy (CIN). Sulforaphane has antioxidant properties via Nrf2 activation. The interaction of diabetes and/or sulforaphane with contrast media on Nrf2 regulation is not yet understood. Herein, diabetes was induced by a single intra-peritoneal injection of streptozotocin. Animals were then divided into five groups; control non-diabetic group; diabetic group; diabetic/sulforaphane group; diabetic/CIN group; diabetic/CIN/sulforaphane group. Animals were assessed 24 h after CIN induction. Sulforaphane improved the impaired nephrotoxicity parameters, histopathological features, and oxidative stress markers induced by contrast media (meglumine diatrizoate) in diabetic rats. Immunofluorescence detection revealed increased Nrf2 expression in kidney sections after sulforaphane pretreatment. Moreover, gene expression of Nrf2 and HO-1 were up-regulated, while IL-6 and caspase3 were down-regulated in kidney tissues of animals pretreated with sulforaphane. In NRK-52E cells, sulforaphane pretreatment significantly ameliorated the cytotoxicity of meglumine diatrizoate. However, silencing Nrf2 using small interfering RNA (siRNA) abolished the cytoprotective effects of sulforaphane. Collectively, the results of this study suggest that Nrf2/HO-1 pathway has a protective role against CIN and support the clinical implication of Nrf2 activators, such as sulforaphane, in CIN particularly in diabetic patients.

Sulforaphane alleviates cadmium-induced toxicity in human mesenchymal stem cells through POR and TNFSF10 genes expression

Sulforaphane is a dietary compound possessing anti-inflammatory, antioxidant, anti-diabetic, anti-carcinogenic, and anti-aging properties. The role of sulforaphane in the context of cadmium (Cd)-induced toxicity through the alteration of nuclear morphology, mitochondrial membrane potential, and gene expression patterns, however, remains unclear. Thus, we assessed the protective role of sulforaphane against Cd-induced nuclear and mitochondrial damage in human mesenchymal stem cells (hMSCs). Cells were exposed to Cd and sulforaphane, either alone or in combination, for 48 h. The cell viability was assessed by adopting MTT assay. The nuclear morphology was investigated using Acridine orange/Ethidium bromide (AO/EB) dual staining and Hoechst staining. The mitochondrial membrane potential loss and lysosomal staining were analyzed using JC-1 staining and LysoRed staining respectively. The gene expression was studied using quantitative real-time PCR analysis. After 48 h of exposure to Cd, the viability of hMSCs decreased in a dose-dependent manner. In contrast, a single treatment with the phytochemical sulforaphane did not cause any remarkable reduction in hMSC viability. Combined treatment with Cd and sulforaphane resulted in a marked recovery in cell viability compared to that observed in cells treated with Cd alone. Analysis of nuclear morphology indicated that Cd induced necrotic cell death, while combined Cd and sulforaphane treatment prevented nuclear morphology changes. Cd ions also significantly attenuate the mitochondrial membrane potential (MMP) and alter gene expression in hMSCs; however, we observed that sulforaphane improves MMP under conditions of Cd-sulforaphane co-treatment of hMSCs. The gene expression results indicate that POR, TNFRSF1A and TNFSF10 genes expression are significantly upregulated by Cd-sulforaphane co-treatment than Cd or sulforaphane treatment alone. Our study results clearly indicate that sulforaphane can protect hMSCs against Cd-induced changes in nuclear morphology, attenuation of MMP, and alteration of gene expression patterns. Thus, intake of sulforaphane-enriched vegetables and fruits will be helpful to overcome Cd-induced toxicity in humans.

The role of nuclear factor erythroid-2-related factor 2 expression in radiocontrast-induced nephropathy

Radiocontrast-induced nephropathy (CIN) is the third most common cause of acute renal failure. The pathophysiology of CIN is related to tubular injury caused by oxidative stress, and nuclear factor erythroid-2-related factor 2 (Nrf2) is critical in coordinating intracellular antioxidative processes. We thus investigated the role of Nrf2 in CIN. CIN was established in mice and in NRK-52E cells via iohexol administration according to the protocols of previous studies. To determine the role of Nrf2 in CIN, Nrf2 expression was reduced in vivo using Nrf2 knockout (KO) mice (B6.129 × 1-Nfe2 l2tm1Ywk/J) and in vitro with siRNA treatment targeting Nrf2. Increased Nrf2 expression was observed after iohexol treatment both in vivo and in vitro. Serum creatinine at 24 h after iohexol injection was significantly higher in KO mice than in wild-type (WT) mice. Histologic examination showed that iohexol-induced tubular vacuolization and structural disruption were aggravated in Nrf2 KO mice. Significant increases in apoptosis and F4/80(+) inflammatory cell infiltration were demonstrated in KO mice compared to WT mice. In addition, the increase in reactive oxygen species after iohexol treatment was augmented by Nrf2 inhibition both in vivo and in vitro. Nrf2 may be implicated in the pathogenesis of CIN via the modulation of antioxidant, anti-apoptotic, and anti-inflammatory processes.

Cardioprotective strategies preserve the stability of respiratory chain supercomplexes and reduce oxidative stress in reperfused ischemic hearts

Electron leakage from dysfunctional respiratory chain and consequent superoxide formation leads to mitochondrial and cell injury during ischemia and reperfusion (IR). In this work we evaluate if the supramolecular assembly of the respiratory complexes into supercomplexes (SCs) is associated with preserved energy efficiency and diminished oxidative stress in post-ischemic hearts treated with the antioxidant N-acetylcysteine (NAC) and the cardioprotective maneuver of Postconditioning (PostC). Hemodynamic variables, infarct size, oxidative stress markers, oxygen consumption and the activity/stability of SCs were compared between groups. We found that mitochondrial oxygen consumption and the activity of respiratory complexes are preserved in mitochondria from reperfused hearts treated with both NAC and PostC. Both treatments contribute to recover the activity of individual complexes. NAC reduced oxidative stress and maintained SCs assemblies containing Complex I, Complex III, Complex IV and the adapter protein SCAFI more effectively than PostC. On the other hand, the activities of CI, CIII and CIV associated to SCs assemblies were preserved by this maneuver, suggesting that the activation of other cardioprotective mechanisms besides oxidative stress contention might participate in maintaining the activity of the mitochondrial respiratory complexes in such superstructures. We conclude that both the monomeric and the SCs assembly of the respiratory chain contribute to the in vivo functionality of the mitochondria. However, although the ROS-induced damage and the consequent increased production of ROS affect the assembly of SCs, other levels of regulation as those induced by PostC, might participate in maintaining the activity of the respiratory complexes in such superstructures.

Preventing childhood and lifelong disability: Maternal dietary supplementation for perinatal brain injury

The majority of brain injuries that lead to cerebral palsy, developmental disability, and mental health disorders have their onset in utero. These lifelong conditions come with great economic and emotional burden as they impact function in nearly all domains of affected individuals' lives. Unfortunately, current therapeutic options are limited. There remains a focus on rescue, rehabilitation, and regeneration after the injury has occurred, rather than aiming to prevent the initial injury. Prevention would imply treating the mother during pregnancy to alter the fetal environment and in turn, treat the fetus. Fear of harming the developing fetus remains as a result of errors of the past such as the release of thalidomide. In this review, we outline evidence from animal studies and clinical trials that have explored maternal dietary supplementation with natural health products (including nutraceuticals and functional foods) for perinatal brain injury prevention. Namely, we discuss magnesium sulphate, creatine, choline, melatonin, resveratrol and broccoli sprouts/sulforaphane. Although clinical trials have only been completed in this realm for magnesium sulphate, results in animal models have been promising, suggesting that this is a productive avenue for further research. Natural health products may provide safe, effective, affordable, and easily accessible prevention of fetal brain injury and resulting lifelong disabilities.

Sulforaphane prevents maleic acid-induced nephropathy by modulating renal hemodynamics, mitochondrial bioenergetics and oxidative stress

Maleic acid (MA)-induced nephropathy that is characterized by proteinuria, glycosuria, phosphaturia and a deficient urinary acidification and concentration. Sulforaphane (SF) is an indirect antioxidant that shows nephroprotective effects. The aim of the present work was to test the pre-treatment with SF against the MA-induced nephropathy. Wistar rats (230-260 g) were separated in the following groups: control, MA (which received 400 mg/kg of MA), SF + MA (which received MA and 1 mg/kg of SF each day for four days) and SF (which only received SF). MA induced proteinuria, an increase in urinary excretion of N-acetyl-β-d-glucosaminidase, and a decrease in plasma glutathione peroxidase activity, renal blood flow, and oxygenation and perfusion of renal cortex. All these impairments correlated with higher levels of oxidative damage markers and exacerbated superoxide anion production on renal cortex. Moreover, MA impaired mitochondrial bioenergetics associated to complex I, mitochondrial membrane potential and respiratory control index and increased the mitochondrial production of hydrogen peroxide. Further it disrupted mitochondrial morphology. SF prevented all the above-described alterations. In conclusion, the protective effect of SF against MA-induced nephropathy is associated with preservation of mitochondrial bioenergetics, amelioration of oxidative stress and improvement of renal hemodynamics and renal cortex oxygenation.

Curcumin prevents cisplatin-induced decrease in the tight and adherens junctions: relation to oxidative stress

Curcumin is a polyphenol and cisplatin is an antineoplastic agent that induces nephrotoxicity associated with oxidative stress, apoptosis, fibrosis and decrease in renal tight junction (TJ) proteins. The potential effect of curcumin against alterations in TJ structure and function has not been evaluated in cisplatin-induced nephrotoxicity. The present study explored whether curcumin is able to prevent the cisplatin-induced fibrosis and decreased expression of the TJ and adherens junction (AJ) proteins occludin, claudin-2 and E-cadherin in cisplatin-induced nephrotoxicity. Curcumin (200 mg kg(-1)) was administered in three doses, and rats were sacrificed 72 h after cisplatin administration. Curcumin was able to scavenge, in a concentration-dependent way, superoxide anion, hydroxyl radical, peroxyl radical, singlet oxygen, peroxynitrite anion, hypochlorous acid and hydrogen peroxide. Cisplatin-induced renal damage was associated with alterations in plasma creatinine, expression of neutrophil gelatinase-associated lipocalin and of kidney injury molecule-1, histological damage, increase in apoptosis, fibrosis (evaluated by transforming growth factor β1, collagen I and IV and α-smooth muscle actin expressions), increase in oxidative/nitrosative stress (evaluated by Hsp70/72 expression, protein tyrosine nitration, superoxide anion production in isolated glomeruli and proximal tubules, and protein levels of NADPH oxidase subunits p47(phox) and gp91(phox), protein kinase C β2, and Nrf2) as well as by decreased expression of occludin, claudin-2, β-catenin and E-cadherin. Curcumin treatment prevented all the above-described alterations. The protective effect of curcumin against cisplatin-induced fibrosis and decreased proteins of the TJ and AJ was associated with the prevention of glomerular and proximal tubular superoxide anion production induced by NADPH oxidase activity.

Plant-Derived Agents for Counteracting Cisplatin-Induced Nephrotoxicity

Cisplatin (CSP) is a chemotherapeutic agent commonly used to treat a variety of malignancies. The major setback with CSP treatment is that its clinical efficacy is compromised by its induction of organ toxicity, particular to the kidneys and ears. Despite the significant strides that have been made in understanding the mechanisms underlying CSP-induced renal toxicity, advances in developing renoprotective strategies are still lacking. In addition, the renoprotective approaches described in the literature reveal partial amelioration of CSP-induced renal toxicity, stressing the need to develop potent combinatorial/synergistic agents for the mitigation of renal toxicity. However, the ideal renoprotective adjuvant should not interfere with the anticancer efficacy of CSP. In this review, we have discussed the progress made in utilizing plant-derived agents (phytochemicals) to combat CSP-induced nephrotoxicity in preclinical studies. Furthermore, we have also presented strategies to utilize phytochemicals as prototypes for the development of novel renoprotective agents for counteracting chemotherapy-induced renal damage.

Sulforaphane Ameliorates Bladder Dysfunction through Activation of the Nrf2-ARE Pathway in a Rat Model of Partial Bladder Outlet Obstruction

Purpose. We evaluated the effect of sulforaphane (SFN) treatment on the function and changes of expression of Nrf2-ARE pathway in the bladder of rats with bladder outlet obstruction (BOO). Materials and Methods. A total of 18 male Sprague-Dawley rats at age of 8 weeks were divided into 3 groups (6 of each): the sham operated group, the BOO group, and the BOO+SFN group. We examined histological alterations and the changes of oxidative stress markers and the protein expression of the Nrf2-ARE pathway. Results. We found that SFN treatment could prolong micturition interval and increase bladder capacity and bladder compliance. However, the peak voiding pressure was lower than BOO group. SFN treatment can ameliorate the increase of collagen fibers induced by obstruction. SFN treatment also increased the activity of SOD, GSH-Px, and CAT compared to the other groups. The level of bladder cell apoptosis was decreased in BOO rats with SFN treatment. Moreover, SFN could reduce the ratio of Bax/Bcl-2 expression. Furthermore, SFN could activate the Nrf2 expression with elevation of its target antioxidant proteins. Conclusions. The sulforaphane-mediated decrease of oxidative stress and activation of the Nrf2-ARE pathway may ameliorate bladder dysfunction caused by bladder outlet obstruction.

Sulforaphane Attenuates Contrast-Induced Nephropathy in Rats via Nrf2/HO-1 Pathway

Background. Oxidative stress plays an important role in the pathogenesis of contrast-induced nephropathy (CIN). The aim of this study was to investigate the antioxidant effects of sulforaphane (SFN) in a rat model of CIN and a cell model of oxidative stress in HK2 cells. Methods. Rats were randomized into four groups (n = 6 per group): control group, Ioversol group (Ioversol-induced CIN), Ioversol + SFN group (CIN rats pretreated with SFN), and SFN group (rats treated with SFN). Renal function tests, malondialdehyde (MDA), and reactive oxygen species (ROS) were measured. Western blot, real-time polymerase chain reaction analysis, and immunohistochemical analysis were performed for nuclear factor erythroid-derived 2-like 2 (Nrf2) and heme oxygenase-1 (HO-1) detection. Results. Serum blood urea nitrogen (BUN), creatinine, and renal tissue MDA were increased after contrast exposure. Serum BUN, creatinine, and renal tissue MDA were decreased in the Ioversol + SFN group as compared with those in the Ioversol group. SFN increased the expression of Nrf2 and HO-1 in CIN rats and in Ioversol-induced injury HK2 cells. SFN increased cell viability and attenuated ROS level in vitro. Conclusions. SFN attenuates experimental CIN in vitro and in vivo. This effect is suggested to activate the Nrf2 antioxidant defenses pathway.

Nrf2 activators as potential modulators of injury in human kidney cells

Cisplatin is a chemotherapeutic agent used in the treatment of solid tumors, with clinical use often complicated by kidney toxicity. Nuclear factor (erythroid-derived-2)-like 2 (Nrf2) is a transcription factor involved in kidney protectant effects. The purpose of this study was to determine whether the Nrf2 activators oltipraz, sulforaphane, and oleanolic acid could protect human kidney cells against cisplatin-induced injury and to compare the protective effects between three Nrf2 activators. Human proximal tubule cells (hPTC) and human embryonic kidney 293 cells (HEK293) were exposed to cisplatin doses in the absence and presence of Nrf2 activators. Pre- and delayed-cisplatin and Nrf2 activator exposures were also assessed. Cell viability was enhanced with Nrf2 activator exposures, with differences detected between pre- and delayed-treatments. Both sulforaphane and oltipraz increased the expression of anti-oxidant genes GCLC and NQO1. These findings suggest potential human kidney protective benefits of Nrf2 activators with planned exposures to cisplatin.

Protective effect of Wuzhi tablet (Schisandra sphenanthera extract) against cisplatin-induced nephrotoxicity via Nrf2-mediated defense response

Cisplatin is a potent anti-cancer agent for various types of tumors. However, the clinical use of cisplatin is often limited by its nephrotoxicity. This study reports that WZ tablet (WZ, a preparation of an ethanol extract of Schisandra sphenanthera) mitigates cisplatin-induced toxicity in renal epithelial HK-2 cells and in mice. Pretreatment of HK-2 cells with WZ ameliorated cisplatin-induced cytotoxicity caused by oxidative stress, as was demonstrated by reductions in the levels of reactive oxygen species (ROS) and increased levels of glutathione (GSH). WZ facilitated the nuclear accumulation of the transcription factor NF-E2-related factor 2 (Nrf2) and the subsequent expression of its target genes such as

NAD(P)H

quinine oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1) and glutamate cysteine ligase (GCL). Protective effects of WZ on cisplatin-induced nephrotoxicity were also observed in mice. WZ attenuated cisplatin-induced renal dysfunction, structural damage and oxidative stress. The nuclear accumulation of Nrf2 and its target genes were increased by WZ treatment. Taken together, these findings demonstrated WZ have a protective effect against cisplatin-induced nephrotoxicity by activation of the Nrf2 mediated defense response, which is of significant importance for therapeutic intervention in cisplatin induced renal injury.

Sulforaphane protects against acetaminophen-induced hepatotoxicity

Oxidative stress is closely associated with acetaminophen (APAP)-induced toxicity. Heme oxygenase-1 (HO-1), an antioxidant defense enzyme, has been shown to protect against oxidant-induced tissue injury. This study investigated whether sulforaphane (SFN), as a HO-1 inducer, plays a protective role against APAP hepatotoxicity in vitro and in vivo. Pretreatment of primary hepatocyte with SFN induced nuclear factor E2-factor related factor (Nrf2) target gene expression, especially HO-1 mRNA and protein expression, and suppressed APAP-induced glutathione (GSH) depletion and lipid peroxidation, which eventually leads to hepatocyte cell death. A comparable effect was observed in mice treated with APAP. Mice were treated with 300 mg/kg APAP 30 min after SFN (5 mg/kg) administration and were then sacrificed after 6 h. APAP alone caused severe liver injuries as characterized by increased plasma AST and ALT levels, GSH depletion, apoptosis, and 4-hydroxynonenal (4-HNE) formations. This APAP-induced liver damage was significantly attenuated by pretreatment with SFN. Furthermore, while hepatic reactive oxygen species (ROS) levels were increased by APAP exposure, pretreatment with SFN completely blocked ROS formation. These results suggest that SFN plays a protective role against APAP-mediated hepatotoxicity through antioxidant effects mediated by HO-1 induction. SFN has preventive action in oxidative stress-mediated liver injury.

Modulation of apoptosis by sulforaphane is associated with PGC-1α stimulation and decreased oxidative stress in cardiac myoblasts

Sulforaphane is a naturally occurring isothiocyanate capable of stimulating cellular antioxidant defenses and inducing phase 2 detoxifying enzymes, which can protect cells against oxidative damage. Oxidative stress and apoptosis are intimately involved in the pathophysiology of cardiac diseases. Although sulforaphane is known for its anticancer benefits, its role in cardiac cells is just emerging. The aim of the present study was to investigate whether sulforaphane can modulate oxidative stress, apoptosis, and correlate with PGC-1α, a transcriptional cofactor involved in energy metabolism. H9c2 cardiac myoblasts were incubated with R-sulforaphane 5 µmol/L for 24 h. Cell viability, ANP gene expression, oxidative stress and apoptosis markers, and protein expression of PGC-1α were studied. In cells treated with sulforaphane, cellular viability increased (12 %) and ANP gene expression decreased (46 %) compared to control cells. Moreover, sulforaphane induced a significant increase in superoxide dismutase (103 %), catalase (101 %), and glutathione S-transferase (72 %) activity, reduced reactive oxygen species levels (15 %) and lipid peroxidation (65 %), as well as stimulated the expression of the cytoprotective enzyme heme oxygenase-1 (4-fold). Sulforaphane also promoted an increase in the expression of the anti-apoptotic protein Bcl-2 (60 %), decreasing the Bax/Bcl-2 ratio. Active Caspase 3\7 and p-JNK/JNK were also reduced by sulforaphane, suggesting a reduction in apoptotic signaling. This was associated with an increased protein expression of PGC-1α (42 %). These results suggest that sulforaphane offers cytoprotection to cardiac cells by activating PGC1-α, reducing oxidative stress, and decreasing apoptosis signaling.

Protective effects of ethyl pyruvate in cisplatin-induced nephrotoxicity

This study was performed to investigate the effect of ethyl pyruvate on changes in renal functions and oxidative stress related renal injury caused by cisplatin (cis-dichlorodiammine platinum-II; CDDP). Male Wistar albino rats were divided into four groups (n = 8): (1) control group (1 ml Ringer's lactate solution i.p.); (2) ethyl pyruvate (EP) group (50 mg/kg Ringer's EP solution (REPS) i.p.); (3) cisplatin group (a single dose of cisplatin (5 mg/kg, i.p.); and (4) cisplatin + EP group (a single dose of cisplatin (5 mg/kg, i.p.) + REPS 50 mg/kg/day, i.p.) for five days. At the sixth day, kidneys of rats were mounted to a Langendorff apparatus. Renal perfusion pressures were recorded. Blood samples were taken for serum urea, creatinine, total oxidant status (TOS), total antioxidant status (TAS) and oxidative stres index (OSI) evaluations. Kidney tissues were obtained for malondialdehyde (MDA) analyses and histopathological examination. Perfusion pressures, serum urea, creatinine, TOS, OSI and tissue MDA levels were found significantly higher, whereas TAS was notably lower in cisplatin group. Histopathological examination showed apparent renal paranchymal injury in cisplatin group. In cisplatin + REPS group, perfusion pressures, serum urea, creatinine and tissue MDA levels were decreased. Moreover, EP co-administration provided less inflammatory cell infiltration, tubular dilatation, whereas TOS, TAS and OSI improved significantly versus cisplatin group. These findings show that EP has protective effects against cisplatin nephrotoxicity.

Curcumin prevents maleate-induced nephrotoxicity: relation to hemodynamic alterations, oxidative stress, mitochondrial oxygen consumption and activity of respiratory complex I

The potential protective effect of the dietary antioxidant curcumin (120 mg/Kg/day for 6 days) against the renal injury induced by maleate was evaluated. Tubular proteinuria and oxidative stress were induced by a single injection of maleate (400 mg/kg) in rats. Maleate-induced renal injury included increase in renal vascular resistance and in the urinary excretion of total protein, glucose, sodium, neutrophil gelatinase-associated lipocalin (NGAL) and N-acetyl β-D-glucosaminidase (NAG), upregulation of kidney injury molecule (KIM)-1, decrease in renal blood flow and claudin-2 expression besides of necrosis and apoptosis of tubular cells on 24 h. Oxidative stress was determined by measuring the oxidation of lipids and proteins and diminution in renal Nrf2 levels. Studies were also conducted in renal epithelial LLC-PK1 cells and in mitochondria isolated from kidneys of all the experimental groups. Maleate induced cell damage and reactive oxygen species (ROS) production in LLC-PK1 cells in culture. In addition, maleate treatment reduced oxygen consumption in ADP-stimulated mitochondria and diminished respiratory control index when using malate/glutamate as substrate. The activities of both complex I and aconitase were also diminished. All the above-described alterations were prevented by curcumin. It is concluded that curcumin is able to attenuate in vivo maleate-induced nephropathy and in vitro cell damage. The in vivo protection was associated to the prevention of oxidative stress and preservation of mitochondrial oxygen consumption and activity of respiratory complex I, and the in vitro protection was associated to the prevention of ROS production.

Effect of redox modulating NRF2 activators on chronic kidney disease

Chronic kidney disease (CKD) is featured by a progressive decline of kidney function and is mainly caused by chronic diseases such as diabetes mellitus and hypertension. CKD is a complex disease due to cardiovascular complications and high morbidity; however, there is no single treatment to improve kidney function in CKD patients. Since biological markers representing oxidative stress are significantly elevated in CKD patients, oxidative stress is receiving attention as a contributing factor to CKD pathology. Nuclear factor erythroid-2 related factor 2 (NRF2) is a predominant transcription factor that regulates the expression of a wide array of genes encoding antioxidant proteins, thiol molecules and their generating enzymes, detoxifying enzymes, and stress response proteins, all of which can counteract inflammatory and oxidative damages. There is considerable experimental evidence suggesting that NRF2 signaling plays a protective role in renal injuries that are caused by various pathologic conditions. In addition, impaired NRF2 activity and consequent target gene repression have been observed in CKD animals. Therefore, a pharmacological intervention activating NRF2 signaling can be beneficial in protecting against kidney dysfunction in CKD. This review article provides an overview of the role of NRF2 in experimental CKD models and describes current findings on the renoprotective effects of naturally occurring NRF2 activators, including sulforaphane, resveratrol, curcumin, and cinnamic aldehyde. These experimental results, coupled with recent clinical experiences with a synthetic triterpenoid, bardoxolone methyl, have brought a light of hope for ameliorating CKD progression by preventing oxidative stress and maintaining cellular redox homeostasis.

Renal tight junction proteins are decreased in cisplatin-induced nephrotoxicity in rats

Cisplatin (CP) is an antineoplastic agent that induces nephrotoxicity and oxidative stress. It is unknown whether renal tight junction (TJ) proteins expression and localization are modified in CP-induced nephrotoxicity.

OBJECTIVE

To study if the expression of the TJ proteins occludin, claudin-2, claudin-5 and zonula occludens-1 (ZO-1) is modified in rats with CP-induced nephrotoxicity.

MATERIALS AND METHODS

Male Wistar rats (n = 5/group) were injected with saline solution (V group), and the other group (CP group) was injected with a single dose of saline solution and CP (7.5 mg/kg i.p.). Rats were sacrificed 72 h after CP injection and blood, and 24-h urine samples were collected. Several plasma and urinary injury biomarkers as well as renal histopathology lesions, oxidative and nitrosative stress markers were evaluated, and protein levels of ocludin, claudin-2, claudin-5, ZO-1 were measured by Western blot. Statistically significant changes noted with different p < 0.05 versus V.

RESULTS

Nephrotoxicity was evident by histological alterations, glycosuria, decrease in creatinine clearance, increase in fractional excretion of sodium, serum creatinine and kidney injury molecule-1. These changes were associated with oxidative/nitrosative stress (increased renal abundance of 3-nitrotyrosine and protein kinase Cβ2 and decreased renal expression of nuclear factor-erythroid-2-related factor 2) and decreased activity of antioxidant enzymes. Finally, it was found that CP-induced renal damage was associated with decreased renal expression of occludin and claudin-2.

DISCUSSION AND CONCLUSION

CP altered the TJ proteins expression and localization in the proximal tubule that was associated with oxidative/nitrosative stress.

Activation of Nrf2 protects against triptolide-induced hepatotoxicity

Triptolide, the major active component of Tripterygium wilfordii Hook f. (TWHF), has a wide range of pharmacological activities. However, the toxicities of triptolide, particularly the hepatotoxicity, limit its clinical application. The hepatotoxicity of triptolide has not been well characterized yet. The aim of this study was to investigate the role of NF-E2-related factor 2 (Nrf2) in triptolide-induced toxicity and whether activation of Nrf2 could protect against triptolide-induced hepatotoxicity. The results showed that triptolide caused oxidative stress and cell damage in HepG2 cells, and these toxic effects could be aggravated by Nrf2 knockdown or be counteracted by overexpression of Nrf2. Treatment with a typical Nrf2 agonist, sulforaphane (SFN), attenuated triptolide-induced liver dysfunction, structural damage, glutathione depletion and decrease in antioxidant enzymes in BALB/C mice. Moreover, the hepatoprotective effect of SFN on triptolide-induced liver injury was associated with the activation of Nrf2 and its downstream targets. Collectively, these results indicate that Nrf2 activation protects against triptolide-induced hepatotoxicity.

Hepatic sulfotransferase as a nephropreventing target by suppression of the uremic toxin indoxyl sulfate accumulation in ischemic acute kidney injury

Ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) is evoked by diverse pathophysiological conditions and/or surgical procedures. Here, we evaluated the nephropreventive effect of sulfotransferase (SULT) inhibitors, quercetin, and resveratrol, which hamper hepatic indoxyl sulfate (IS) production. I/R of the kidney caused severe renal injury with marked accumulation of serum and renal IS and urinary excretion of kidney injury molecule-1. Oral administration of AST-120 resulted in a significant restoration of kidney injury, suggesting that uremic toxins, which can be suppressed or adsorbed by AST-120 in the intestine, contribute to the progression or development of I/R-induced AKI. Oral administration of resveratrol or quercetin, SULT inhibitors, suppressed IS accumulation, accompanied by significant amelioration of renal dysfunction. The expression of nuclear factor E2-related factor 2 (Nrf2) in the renal nuclear fractions was markedly elevated by renal I/R, but suppressed by treatment with SULT inhibitors. IS is primarily taken up by HK-2 cells derived from human proximal tubular cells via organic anion transporters, which then evokes activation of Nrf2, most likely due to intracellular oxidative stress. Renal basolateral organic anion transporters OAT1 and OAT3, which mediate renal tubular uptake of IS in basolateral membrane, were markedly downregulated by renal I/R, but restored by SULT inhibitors. Our results suggest that renal accumulation of IS in ischemic AKI induces oxidative stress and downregulation of organic anion transporters resulting in kidney damage, which could be restored to some extent by inhibiting hepatic SULT activity as a nephropreventive target.

C-Phycocyanin prevents cisplatin-induced nephrotoxicity through inhibition of oxidative stress

The aim of this study was to evaluate whether the antioxidant C-phycocyanin (C-PC, 5–30 mg kg⁻¹ i.p.) was able to prevent cisplatin (CP, 18 mg kg⁻¹ i.p.) induced nephrotoxicity by reducing oxidative stress in CD-1 mice.

Curcumin pretreatment induces Nrf2 and an antioxidant response and prevents hemin-induced toxicity in primary cultures of cerebellar granule neurons of rats

Curcumin is a bifunctional antioxidant derived from Curcuma longa. This study identifies curcumin as a neuroprotectant against hemin-induced damage in primary cultures of cerebellar granule neurons (CGNs) of rats. Hemin, the oxidized form of heme, is a highly reactive compound that induces cellular injury. Pretreatment of CGNs with 5–30 μM curcumin effectively increased by 2.3–4.9 fold heme oxygenase-1 (HO-1) expression and by 5.6–14.3-fold glutathione (GSH) levels. Moreover, 15 μM curcumin attenuated by 55% the increase in reactive oxygen species (ROS) production, by 94% the reduction of GSH/glutathione disulfide (GSSG) ratio, and by 49% the cell death induced by hemin. The inhibition of heme oxygenase system or GSH synthesis with tin mesoporphyrin and buthionine sulfoximine, respectively, suppressed the protective effect of curcumin against hemin-induced toxicity. These data strongly suggest that HO-1 and GSH play a major role in the protective effect of curcumin. Furthermore, it was found that 24 h of incubation with curcumin increases by 1.4-, 2.3-, and 5.2-fold the activity of glutathione reductase, glutathione S-transferase and superoxide dismutase, respectively. Additionally, it was found that curcumin was capable of inducing nuclear factor (erythroid-derived 2)-like 2 (Nrf2) translocation into the nucleus. These data suggest that the pretreatment with curcumin induces Nrf2 and an antioxidant response that may play an important role in the protective effect of this antioxidant against hemin-induced neuronal death.

Modulation of mitochondrial functions by the indirect antioxidant sulforaphane: a seemingly contradictory dual role and an integrative hypothesis

The chemotherapeutic isothiocyanate sulforaphane (SFN) was early linked to anticarcinogenic and antiproliferative activities. Soon after, this compound, derived from cruciferous vegetables, became an excellent and useful trial for anti-cancer research in experimental models including growth tumor, metastasis, and angiogenesis. Many subsequent reports showed modifications in mitochondrial signaling, functionality, and integrity induced by SFN. When cytoprotective effects were found in toxic and ischemic insult models, seemingly contradictory behaviors of SFN were discovered: SFN was inducing deleterious changes in cancer cell mitochondria that eventually would carry the cell to death via apoptosis and also was protecting noncancer cell mitochondria against oxidative challenge, which prevented cell death. In both cases, SFN exhibited effects on mitochondrial redox balance and phase II enzyme expression, mitochondrial membrane potential, expression of the family of B cell lymphoma 2 homologs, regulation of proapoptotic proteins released from mitochondria, activation/inactivation of caspases, mitochondrial respiratory complex activities, oxygen consumption and bioenergetics, mitochondrial permeability transition pore opening, and modulation of some kinase pathways. With the ultimate findings related to the induction of mitochondrial biogenesis by SFN, it could be considered that SFN has effects on mitochondrial dynamics that explain some divergent points. In this review, we list the reports involving effects on mitochondrial modulation by SFN in anti-cancer models as well as in cytoprotective models against oxidative damage. We also attempt to integrate the data into a mechanism explaining the various effects of SFN on mitochondrial function in only one concept, taking into account mitochondrial biogenesis and dynamics and making a comparison with the theory of reactive oxygen species threshold of cell death. Our interest is to achieve a complete view of cancer and protective therapies based on SFN that can be extended to other chemotherapeutic compounds with similar characteristics. The work needed to test this hypothesis is quite extensive.