Evaluation of the Mitochondria-Related Redox and Bioenergetics Effects of Gastrodin in SH-SY5Y Cells Exposed to Hydrogen Peroxide

Mitochondrion is the main site of ATP production in animal cells and also orchestrates signaling pathways associated with cell survival and death. Mitochondrial dysfunction has been linked to bioenergetics and redox impairment in human diseases, such as neurodegeneration and cardiovascular disease. Protective agents able to attenuate mitochondrial impairment are of pharmacological interest. Gastrodin (GAS; 4-hydroxybenzyl alcohol 4-O-beta-D-glucoside) is a phenolic glucoside obtained from the Chinese herbal medicine Gastrodia elata Blume and exhibits antioxidant, anti-inflammatory, and antiapoptotic effects in several cell types. GAS is able to cross the blood-brain barrier, reducing the impact of different stressors on the cognition of experimental animals. In the present work, we investigated whether GAS would protect mitochondria of human SH-SY5Y neuroblastoma cells against an exposure to a pro-oxidant agent. The cells were treated with GAS at 25 μM for 30 min before the administration of hydrogen peroxide (H₂O₂) at 300 μM for an additional 3 or 24 h, depending on the assay. We evaluated both mitochondrial redox state and function parameters and analyzed the mechanism by which GAS protected mitochondria in this experimental model. Silencing of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor suppressed the GAS-induced mitochondrial protection seen here. Moreover, Nrf2 knockdown abrogated the effects of GAS on cell viability, indicating a potential role for Nrf2 in both mitochondrial and cellular protection promoted by GAS. Further research would be necessary to investigate whether GAS would be able to induce similar effects in in vivo experimental models.

Naringenin Attenuates H2O2-Induced Mitochondrial Dysfunction by an Nrf2-Dependent Mechanism in SH-SY5Y Cells

Mitochondria are the major site of ATP production in mammalian cells. Furthermore, these organelles are a source and a target of reactive oxygen species (ROS), such as radical anion superoxide (O₂^-·) and hydrogen peroxide (H₂O₂). The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is the master regulator of the mammalian redox biology and controls the expression of antioxidant and phase II detoxifying enzymes in several cell types. Naringenin (NGN, 5,7-dihydroxy-2-(4-hydroxyphenyl)-2,3-dihydrochromen-4-one), a flavanone, exhibits cytoprotective effects by acting as an antioxidant and anti-inflammatory agent. NGN is a potent activator of Nrf2. Nonetheless, it was not examine yet whether NGN would induce mitochondrial protection in cells under redox stress. Therefore, we investigate here whether Nrf2 would be involved in the mitochondrial protection elicited by NGN in SH-SY5Y cells exposed to H₂O₂. We observed that a pretreatment with NGN at 80 µM for 2 h reduced the levels of lipid peroxidation, protein carbonylation, and protein nitration in the membranes of mitochondria obtained from H₂O₂-treated SH-SY5Y cells. Additionally, NGN prevented the H₂O₂-induced impairment in the function of the enzymes aconitase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. The activites of the complexes I and V, as well as the production of ATP, were restored by NGN. NGN also suppressed the H₂O₂-induced mitochondria-related apoptosis. Interestingly, NGN promoted an increase in the levels of both total and mitochondrial glutathione (GSH). Silencing of Nrf2 abolished the protective effects induced by NGN. Overall, NGN induced mitochondrial protection by an Nrf2-dependent mechanism in H₂O₂-treated SH-SY5Y cells.

Sulforaphane Promotes Mitochondrial Protection in SH-SY5Y Cells Exposed to Hydrogen Peroxide by an Nrf2-Dependent Mechanism

Sulforaphane (SFN; C₆H₁₁NOS₂) is an isothiocyanate found in cruciferous vegetables, such as broccoli, kale, and radish. SFN exhibits antioxidant, anti-apoptotic, anti-tumor, and anti-inflammatory activities in different cell types. However, it was not previously demonstrated whether and how this natural compound would exert mitochondrial protection experimentally. Therefore, we investigated here the effects of a pretreatment (for 30 min) with SFN at 5 μM on mitochondria obtained from human neuroblastoma SH-SY5Y cells exposed to hydrogen peroxide (H₂O₂) at 300 μM for 24 h. We found that SFN prevented loss of viability in H₂O₂-treated SH-SY5Y cells. Furthermore, SFN decreased lipid peroxidation, protein carbonylation, and protein nitration in mitochondrial membranes of H₂O₂-exposed cells. Importantly, SFN enhanced the levels of both cellular and mitochondrial glutathione (GSH). SFN also suppressed the H₂O₂-mediated inhibition of mitochondrial components involved in the maintenance of the bioenergetics state, such as aconitase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase, as well as complexes I and V. Consequently, SFN prevented the decline induced by H₂O₂ on the levels of ATP in SH-SY5Y cells. Silencing of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor by using small interfering RNA (siRNA) abolished the mitochondrial and cellular protection elicited by SFN. Therefore, SFN abrogated the H₂O₂-induced mitochondrial impairment by an Nrf2-dependent manner.

Molecular Mechanisms Underlying the Anti-depressant Effects of Resveratrol: a Review

Major depression is a public health problem, affecting 121 million people worldwide. Patients suffering from depression present high rates of morbidity, causing profound economic and social impacts. Furthermore, patients with depression present cognitive impairments, which could influence on treatment adherence and long-term outcomes. The pathophysiology of major depression is not completely understood yet but involves reduced levels of monoamine neurotransmitters, bioenergetics, and redox disturbances, as well as inflammation and neuronal loss. Treatment with anti-depressants provides a complete remission of symptoms in approximately 50% of patients with major depression. However, these drugs may cause side effects, as sedation and weight gain. In this context, there is increasing interest in studies focusing on the anti-depressant effects of natural compounds found in the diet. Resveratrol is a polyphenolic phytoalexin (3,4',5-trihydroxystilbene; C₁₄H₁₂O₃; MW 228.247 g/mol) and has been found in peanuts, berries, grapes, and wine and induces anti-oxidant, anti-inflammatory, and anti-apoptotic effects in several mammalian cell types. Resveratrol also elicits anti-depressant effects, as observed in experimental models using animals. Therefore, resveratrol may be viewed as a potential anti-depressant agent, as well as may serve as a model of molecule to be modified aiming to ameliorate depressive symptoms in humans. In the present review, we describe and discuss the anti-depressant effects of resveratrol focusing on the mechanism of action of this phytoalexin in different experimental models.

Maternal folic acid consumption during gestation and its long-term effects on offspring's liver: a systematic review

Abstract Objectives: describing the effects of maternal supplementation with folic acid (FA) exclusively during gestation on offspring's liver at later stages in life. Supplementation with FA during gestation has been recommended by the medical society worldwide. The liver has a central role on the substances of metabolism and homeostasis and some studies have shown that a high intake of FA at other periods in life may cause hepatic damage. Methods: a systematic review through which the following databases were consulted: Medline, through platforms of Pubmed, Lilacs and Scielo. The research was performed by keywords such as: "Folic acid", "Gestation", "Rat", "Offspring" and "Liver". Articles which evaluate the effect of FA consumption during both gestation and lactation were excluded. Results: FA consumption avoids disorders on expression of peroxisome proliferator-activated receptor alpha (PPARα) and glucocorticoid receptor (GccR), its lack did not change enzyme activity of the male offspring's liver in adulthood. Supplementation with FA during gestation did not change iron hepatic levels or lipid composition, but had an antioxidant effect on it. Conclusions: supplementation with FA at recommended doses did not cause toxic effects and is very likely to avoid deleterious effects in the liver of the offspring regarding the epigenetic level.

Carnosic Acid Suppresses the H2O2-Induced Mitochondria-Related Bioenergetics Disturbances and Redox Impairment in SH-SY5Y Cells: Role for Nrf2

The phenolic diterpene carnosic acid (CA, C₂₀H₂₈O₄) exerts antioxidant, anti-inflammatory, anti-apoptotic, and anti-cancer effects in mammalian cells. CA activates the nuclear factor erythroid 2-related factor 2 (Nrf2), among other signaling pathways, and restores cell viability in several in vitro and in vivo experimental models. We have previously reported that CA affords mitochondrial protection against various chemical challenges. However, it was not clear yet whether CA would prevent chemically induced impairment of the tricarboxylic acid cycle (TCA) function in mammalian cells. In the present work, we found that a pretreatment of human neuroblastoma SH-SY5Y cells with CA at 1 μM for 12 h prevented the hydrogen peroxide (H₂O₂)-induced impairment of the TCA enzymes (aconitase, α-ketoglutarate dehydrogenase (α-KGDH), succinate dehydrogenase (SDH)) and abolished the inhibition of the complexes I and V and restored the levels of ATP by a mechanism associated with Nrf2. CA also exhibited antioxidant abilities by enhancing the levels of reduced glutathione (GSH) and decreasing the content oxidative stress markers (cellular 8-oxo-2'-deoxyguanosine (8-oxo-dG), and mitochondrial malondialdehyde (MDA), protein carbonyl, and 3-nitrotyrosine). Silencing of Nrf2 by small interfering RNA (siRNA) abrogated the protective effects elicited by CA in mitochondria of SH-SY5Y cells. Therefore, CA prevented the H₂O₂-triggered mitochondrial impairment by an Nrf2-dependent mechanism. The specific role of Nrf2 in ameliorating the function of TCA enzymes function needs further research.

Pinocembrin Attenuates Mitochondrial Dysfunction in Human Neuroblastoma SH-SY5Y Cells Exposed to Methylglyoxal: Role for the Erk1/2-Nrf2 Signaling Pathway

Pinocembrin (PB; 5,7-dihydroxyflavanone) is found in propolis and exhibits antioxidant activity in several experimental models. The antioxidant capacity of PB is associated with the activation of the nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) signaling pathway. The Nrf2/ARE axis mediates the expression of antioxidant and detoxifying enzymes, such as glutathione peroxidase (GPx), glutathione reductase (GR), heme oxygenase-1 (HO-1), and the catalytic (GCLC) and regulatory (GCLM) subunits of the rate-limiting enzyme in the synthesis of glutathione (GSH), γ-glutamate-cysteine ligase (γ-GCL). Nonetheless, it is not clear how PB exerts mitochondrial protection in mammalian cells. Human neuroblastoma SH-SY5Y cells were pretreated (4 h) with PB (0-25 µM) and then exposed to methylglyoxal (MG; 500 µM) for further 24 h. Mitochondria were isolated by differential centrifugation. PB (25 µM) provided mitochondrial protection (decreased lipid peroxidation, protein carbonylation, and protein nitration in mitochondrial membranes; decreased mitochondrial free radical production; enhanced the content of GSH in mitochondria; rescued mitochondrial membrane potential-MMP) and blocked MG-triggered cell death by a mechanism dependent on the activation of the extracellular-related kinase (Erk1/2) and consequent upregulation of Nrf2. PB increased the levels of GPx, GR, HO-1, and mitochondrial GSH. The PB-induced effects were suppressed by silencing of Nrf2 with siRNA. Therefore, PB activated the Erk1/2-Nrf2 signaling pathway resulting in mitochondrial protection in SH-SY5Y cells exposed to MG. Our work shows that PB is a strong candidate to figure among mitochondria-focusing agents with pharmacological potential.

A review of the protective role of melatonin during phosphine-induced cardiotoxicity: focus on mitochondrial dysfunction, oxidative stress and apoptosis

OBJECTIVES

Acute poisoning with aluminium phosphide (AlP) is a major cause of mortality in developing countries. AlP mortality is due to cardiac dysfunction leading to cardiomyocyte death. The main mechanism is an inhibition of cytochrome c oxidase in the cardiomyocyte mitochondria, resulting in a decreased ATP production and oxidative stress. Unfortunately, the administration of exogenous drugs does not meet the desired requirements of an effective therapy. Melatonin is an amphiphilic molecule and can easily pass through all cellular compartments with the highest concentration recorded in mitochondria. It is known as a vigorous antioxidant, acting as a potent reactive oxygen species (ROS) scavenger. Our aim is to summarize the mechanisms by which melatonin may modulate the deteriorating effects of AlP poisoning on cardiac mitochondria.

KEY FINDINGS

Melatonin not only mitigates the inhibition of respiratory chain complexes, but also increases ATP generation. Moreover, it can directly inhibit the mitochondrial permeability transition pore (mPTP) opening, thus preventing apoptosis. In addition, melatonin inhibits the release of cytochrome c from mitochondria to hinder caspase activation leading to cell survival.

SUMMARY

Based on the promising effects of melatonin on mitochondria, melatonin may mitigate AlP-induced cardiotoxicity and might be potentially suggested as cardioprotective in AlP-intoxicated patients.

Pinocembrin Provides Mitochondrial Protection by the Activation of the Erk1/2-Nrf2 Signaling Pathway in SH-SY5Y Neuroblastoma Cells Exposed to Paraquat

Pinocembrin (PB; 5,7-dihydroxyflavanone; C₁₅H₁₂O₄) is a flavonoid found in propolis and exerts antioxidant, anti-inflammatory, and antimicrobial effects. Furthermore, PB has been studied as a neuroprotective agent. However, it remains to be understood whether and how PB would induce mitochondrial protection in mammalian cells. Therefore, we investigated here the mechanism involved in the protective effects elicited by PB in paraquat (PQ; 100 μM)-treated SH-SY5Y neuroblastoma cells. PB (25 μM) pretreatment (for 4 h) downregulated the levels of Bcl-2-associated X protein (Bax), blocked the release of cytochrome c to the cytosol, and inhibited the PQ-induced activation of caspase-9 and caspase-3. Besides, PB prevented mitochondrial dysfunction by suppressing the PQ-elicited inhibition of complexes I and V. Moreover, PB abrogated the loss of mitochondrial membrane potential (MMP) and the decline in ATP levels in the cells exposed to PQ. PB exerted antioxidant effects on mitochondria by decreasing the levels of redox impairment markers in mitochondrial membranes. Importantly, PB enhanced the levels of mitochondrial reduced glutathione (GSH). Upregulation of enzymes involved in the synthesis of GSH was seen in the cells exposed to PB. PB afforded mitochondrial protection by activating the extracellular signal-regulated kinase/nuclear factor erythroid 2-related factor 2 (Erk1/2-Nrf2) axis, since inhibition of Erk1/2 or silencing of Nrf2 abrogated these effects. Therefore, PB exerted mitochondrial and cellular protection by an Erk1/2-Nrf2-dependent mechanism.

Tanshinone I Induces Mitochondrial Protection through an Nrf2-Dependent Mechanism in Paraquat-TreatedHuman Neuroblastoma SH-SY5Y Cells

Tanshinone I (T-I; 1,6-Dimethylnaphtho[1,2-g][1]benzofuran-10,11-dione; C₁₈H₁₂O₃), which may be found in Salvia miltiorrhiza Bunge (Danshen), is a potent anti-inflammatory, antioxidant, and anti-cancer agent. At least in part, T-I exerts antioxidant activity by activating signaling pathways associated with the maintenance of the redox state in mammalian cells. In this context, the upregulation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) has received attention regarding the role of this transcription factor in modulating the expression of antioxidant enzymes and the metabolism of glutathione (GSH). Even though there is a growing body of evidence suggesting that T-I mediates protection against several pro-oxidant challenges in both in vitro and in vivo experimental models, it remains to be examined whether and how T-I would modulate mitochondrial function during redox disturbances. Therefore, we aimed to reveal whether T-I would exhibit protective effects on mitochondria of SH-SY5Y cells treated with paraquat (PQ), a well-known mitochondrial toxic agent. We found that T-I pretreatment significantly protected mitochondria against PQ-induced redox impairment through an Nrf2-dependent mechanism involving upregulation of antioxidant enzymes, such as Mn-superoxide dismutase (Mn-SOD), glutathione peroxidase (GPx), and both catalytic and modifier subunits of γ-glutamate-cysteine ligase (γ-GCL). T-I prevented complex I and mitochondrial membrane potential (MMP) impairments elicited by PQ. Thus, T-I may be viewed as a new mitochondrial protective agent whose complete mechanism of action needs to be investigated, but it seems to involve mitochondriotropic aspects related to the chemistry of this molecule.

Fluoxetine and the mitochondria: A review of the toxicological aspects

Fluoxetine (a selective serotonin reuptake inhibitor (SSRI)) is used as an antidepressant by modulating the levels of serotonin in the synaptic cleft. Nevertheless, fluoxetine also induces undesirable effects, such as anxiety, sexual dysfunction, sleep disturbances, and gastrointestinal impairments. Fluoxetine has been viewed as an agent that may interfere with cell fate by triggering apoptosis. On the other hand, fluoxetine intake has been associated with increased cancer risk. Nonetheless, data remain contradictory and no conclusions were taken. Several studies demonstrated that fluoxetine interacts with mitochondria triggering apoptosis and/or altering mitochondrial function by modulating the activity of respiratory chain components and enzymes of the Krebs cycle. Furthermore, fluoxetine affects mitochondria-related redox parameters in different experimental models. In this review, data demonstrating the effects of fluoxetine upon mammalian mitochondria are described and discussed, as well as several unsolved questions in this field of research are addressed. A separate section deals with future needs regarding the research involving the impact of fluoxetine treatment upon mitochondria and mitochondria-related signaling.

Evidence for genistein as a mitochondriotropic molecule

Genistein (4',5,7-trihydroxyisoflavone; C15H10O5), an isoflavone, has been investigated as an anti-cancer agent due to its ability to trigger cell death (both intrinsic and extrinsic apoptotic pathways) in different cancer cells in vitro and in vivo. Furthermore, genistein has been viewed as a mitochondriotropic molecule due to the direct effects this isoflavone induces in mitochondria, such as modulation of enzymatic activity of components of the oxidative phosphorylation system. Apoptosis triggering may also be mediated by genistein through activation of the mitochondria-dependent pathway by a mechanism associated with mitochondrial dysfunction (i.e., disruption of the mitochondrial membrane potential - MMP, release of cytochrome c, activation of the apoptosome, among others). Efforts have been made in order to elucidate how genistein coordinate these biochemical phenomena. Nonetheless, some areas of the mitochondria-associated research (mitochondrial biogenesis, redox biology of mitochondria, and mitochondria-associated bioenergetic parameters) need to be explored regarding the role of genistein as a mitochondria-targeted agent. This is a pharmacologically relevant issue due to the possibility of using genistein as a mitochondria-targeted drug in cases of cancer, neurodegeneration, cardiovascular, and endocrine disease, for example. The present review aims to describe, compare, and discuss relevant data about the effects of genistein upon mitochondria.

The Effects of Ellagic Acid upon Brain Cells: A Mechanistic View and Future Directions

Ellagic acid (EA, 2,3,7,8-tetrahydroxy-chromeno; C14H6O8) is a polyphenol derived from fruits (pomegranates, berries) and nuts. EA exhibits antioxidant capacity and induces anti-inflammatory actions in several mammalian tissues. EA has been characterized as a possible neuroprotective agent, but the number of reports is still limited to conclude whether and how EA exerts neuroprotection in humans. In this regard, performing additional studies considering the potential beneficial and/or toxicological roles for EA on brain cells would be an important step towards fully understanding of when and how EA may be securely utilized by humans as a neuroprotective agent. The aim of the present work is to discuss data related to the neuronal and glial effects of EA and the mechanisms underlying such events. Moreover, future directions are suggested as a potential guide to be utilized by researchers interested in investigating the neuronal and glial actions of EA hereafter.

Resveratrol and the mitochondria: From triggering the intrinsic apoptotic pathway to inducing mitochondrial biogenesis, a mechanistic view

BACKGROUND

Mitochondria, the power plants of the cell, are known as a cross-road of different cellular signaling pathways. These cytoplasmic double-membraned organelles play a pivotal role in energy metabolism and regulate calcium flux in the cells. It is well known that mitochondrial dysfunction is associated with different diseases such as neurodegeneration and cancer. A growing body of literature has shown that polyphenolic compounds exert direct effects on mitochondrial ultra-structure and function. Resveratrol is known as one of the most common bioactive constituents of red wine, which improves mitochondrial functions under in vitro and in vivo conditions.

SCOPE OF REVIEW

This paper aims to review the molecular pathways underlying the beneficial effects of resveratrol on mitochondrial structure and functions. In addition, we discuss the chemistry and main sources of resveratrol.

MAJOR CONCLUSIONS

Resveratrol represents the promising effects on mitochondria in different experimental models. However, there are several reports on the detrimental effects elicited by resveratrol on mitochondria.

GENERAL SIGNIFICANCE

An understanding of the chemistry and source of resveratrol, its bioavailability and the promising effects on mitochondria brings a new hope to therapy of mitochondrial dysfunction-related diseases.

Phloretin-induced cytoprotective effects on mammalian cells: A mechanistic view and future directions

Phloretin (C15 H14 O5 ), a dihydrochalcone flavonoid, is mainly found in fruit, leaves, and roots of apple tree. Phloretin exerts antioxidant, anti-inflammatory, and anti-tumor activities in mammalian cells through mechanisms that have been partially elucidated throughout the years. Phloretin bioavailability is well known in humans, but still remains to be better studied in experimental animals, such as mouse and rat. The focus of the present review is to gather information regarding the mechanisms involved in the phloretin-elicited effects in different in vitro and in vivo experimental models. Several manuscripts were analyzed and data raised by authors were described and discussed here in a mechanistic manner. Comparisons between the effects elicited by phloretin and phloridzin were made whenever possible, as well as with other polyphenols, clarifying questions about the use of phloretin as a potential therapeutic agent. Toxicological aspects associated to phloretin exposure were also discussed here. Furthermore, a special section containing future directions was created as a suggestive guide towards the elucidation of phloretin-related actions in mammalian cells and tissues.

Quercetin and the mitochondria: A mechanistic view

Quercetin is an important flavonoid that is ubiquitously present in the diet in a variety of fruits and vegetables. It has been traditionally viewed as a potent antioxidant and anti-inflammatory molecule. However, recent studies have suggested that quercetin may exert its beneficial effects independent of its free radical-scavenging properties. Attention has been placed on the effect of quercetin on an array of mitochondrial processes. Quercetin is now recognized as a phytochemical that can modulate pathways associated with mitochondrial biogenesis, mitochondrial membrane potential, oxidative respiration and ATP anabolism, intra-mitochondrial redox status, and subsequently, mitochondria-induced apoptosis. The present review evaluates recent evidence on the ability of quercetin to interact with the abovementioned pathways, and critically analyses how, such interactions can exert protection against mitochondrial damage in response to toxicity induced by several exogenously and endogenously-produced cellular stressors, and oxidative stress in particular.

Epigallocatechin gallate and mitochondria-A story of life and death

Epigallocatechin gallate (EGCG) is a flavonoid belonging to the chemical class of falvan-3-ols (catechins) esterified with gallic acid. It is the main catechin found in green tea (Camellia sinensis L.) accounting for about 50% of its total polyphenols. Extensive research performed in recent years has revealed that green tea demonstrates a wide range of positive biological activities against serious chronic diseases such as cardiovascular and neurodegenerative pathologies, cancer, metabolic syndrome and type 2 diabetes. These protective properties can be traced back to the potent antioxidant and anti-inflammatory activities of EGCG. Recent studies have suggested that it may exert its beneficial effects by modulating mitochondrial functions impacting mitochondrial biogenesis, bioenergetic control (ATP production and anabolism), alteration of the cell cycle, and mitochondria-related apoptosis. This review evaluates recent evidence on the ability of EGCG to exert critical influence on the above mentioned pathways.

Protective effect of carnosic acid against paraquat-induced redox impairment and mitochondrial dysfunction in SH-SY5Y cells: Role for PI3K/Akt/Nrf2 pathway

Carnosic acid (CA) is a phenolic diterpene isolated from Rosmarinus officinalis and exerts anti-inflammatory, antioxidant, and anticarcinogenic activities in different cell types. It has been reported that CA is able to cause protective effects on experimental models of neurodegeneration. However, the exact mechanism by which CA prevents neuronal degeneration remains to be better studied. We investigated here whether there is a role for CA as a neuroprotective agent in a paraquat (PQ) model of Parkinson's disease (PD) regarding cellular and mitochondrial-related redox parameters. SH-SY5Y cells were treated with CA for 12h and were exposed to 100 μM PQ for 24h. It was found that CA at different concentrations prevented the effects of PQ on cell viability and redox parameters. CA alleviated reactive oxygen and nitrogen species production elicited by PQ, as well as decreased the toxic effect on mitochondrial function. Inhibition of Pi3K/Akt pathway with LY294002 or silencing of Nrf2 expression partially blocked the reversal of redox impairment induced by CA. Therefore, CA activated Nrf2 through modulation of PI3K/Akt pathway resulting in increased levels of antioxidant enzymes and consequent neuroprotection. Thus, CA may be viewed as a potential neuroprotective agent to be used in cases of Parkinson's disease (PD).