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Sulforaphane (SFN) promotes protective effects in different cell types. Nonetheless, it remains to be clarified by which mechanism SFN exerts benefits in mammalian cells. Mitochondria are a major source of adenosine triphosphate (ATP) and reactive species in nucleated cells. Mitochondrial impairment result in cellular redox biology disruption, bioenergetic status collapse, and inflammation. Evidence suggest that mitochondrial dysfunction plays a role in neurological disorders. Since a cure was not discovered yet to some of these diseases, investigating strategies to promote mitochondrial protection is pharmacologically relevant and may improve life quality of patients suffering from these maladies. Natural molecules, such as SFN, are potent inducers of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and, consequently, stimulate the expression of genes whose products, such as heme oxygenase-1 (HO-1), induce cytoprotective actions in mammalian tissues. In this work, we investigated whether SFN (5 µM) would be capable to prevent the dysfunctions caused by chlorpyrifos (CPF) on the human dopaminergic SH-SY5Y cells. Moreover, we examined the effects of a pretreatment with SFN at the same concentration on the mouse microglial BV2 cells stimulated by lipopolysaccharide (LPS) in an experimental model of neuroinflammation. SFN prevented the mitochondrial impairment and the neuroinflammation caused by the chemical stressors in both cell types. Inhibition of heme oxygenase-1 (HO-1) suppressed the mitochondrial protection and anti-inflammatory action afforded by SFN in this experimental model. Overall, SFN promoted cytoprotection by a mechanism dependent on the HO-1 enzyme in the SH-SY5Y and BV2 cells., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The reactive dicarbonyl methylglyoxal (MG) behaves as a pro-oxidant agent, causing redox dysfunction and cell death by different mechanisms in mammalian cells. MG is also a mitochondrial toxicant, impairing the oxidative phosphorylation (OXPHOS) system and leading to bioenergetics and redox collapses. MG induces glycation and exerts an important role in neurodegenerative and cardiovascular diseases. Isoorientin (ISO), a C-glucosyl flavone found in Aspalathus linearis, Fagopyrum esculentum, and Passiflora edulis, among others, is an antioxidant and anti-inflammatory molecule. ISO is a potent inducer of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), the master modulator of the redox environment in mammals. We investigated here whether ISO would prevent the mitochondria-related redox and bioenergetics impairments induced by MG in the human neuroblastoma SH-SY5Y cells. The cells were administrated with ISO at 20 μM for 18 h prior to the exposure to MG at 500 μM for further 24 h. It was observed that ISO efficiently prevented the mitochondrial impairments caused by MG. ISO upregulated the activity of the enzyme γ-glutamate-cysteine ligase (γ-GCL), consequently stimulating the synthesis of glutathione (GSH). The inhibition of γ-GCL, adenosine monophosphate-activated protein kinase (AMPK), and phosphoinositide 3-kinase/Akt (PI3K/Akt) suppressed the beneficial effects induced by ISO on the MG-challenged cells. Moreover, silencing of Nrf2 blocked the ISO-dependent γ-GCL and GSH upregulation and the effects on the mitochondria of the MG-challenged cells. Then, ISO caused mitochondrial protection by an AMPK-PI3K/Akt/Nrf2/γ-GCL/GSH-dependent manner in MG-administrated SH-SY5Y cells., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The C-glucosyl flavone isoorientin (ISO) is obtained by humans from the diet and exhibits several cytoprotective effects, as demonstrated in different experimental models. However, it was not previously shown whether ISO would be able to prevent mitochondrial impairment in cells exposed to a chemical stressor. Thus, we treated the human neuroblastoma SH-SY5Y cells with ISO (0.5-20 µM) for 18 h before a challenge with chlorpyrifos (CPF) at 100 µM for additional 24 h. We observed that ISO prevented the CPF-induced lipid peroxidation and protein carbonylation and nitration in the membranes of mitochondria extracted from CPF-treated cells. ISO also attenuated the CPF-elicited increase in the production of reactive species in this experimental model. Moreover, ISO prevented the CPF-induced disruption in the activity of components of the oxidative phosphorylation (OXPHOS) system in the SH-SY5Y cells. ISO also promoted an anti-inflammatory action in the cells exposed to CPF. CPF caused a decrease in the activity of the enzyme heme oxygenase-1 (HO-1), a cytoprotective agent. On the other hand, ISO upregulated HO-1 activity in SH-SY5Y cells. Inhibition of HO-1 by zinc protoporphyrin-IX (ZnPP-IX) suppressed the cytoprotection induced by ISO in the CPF-treated cells. Besides, silencing of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) abolished the ISO-induced HO-1 upregulation and mitochondrial benefits induced by this flavone on the CPF-challenged cells. Thus, ISO protected mitochondria of the CPF-treated cells by an Nrf2/HO-1-dependent fashion in the SH-SY5Y cells., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Mitochondria are a primary source and a target of reactive oxygen species (ROS). Increased mitochondrial production of ROS is associated with bioenergetics decline, cell death, and inflammation. Here we investigated whether a pretreatment (for 24 h) with sesamol (SES; at 12.5-50 µM) would be efficient in preventing the mitochondrial collapse induced by hydrogen peroxide (H 2 O 2 , at 300 µM) in the human neuroblastoma SH-SY5Y cell line. We have found that a pretreatment with SES at 25 µM decreased the effects of H 2 O 2 on lipid peroxidation, protein carbonylation, and protein nitration in membranes obtained from the mitochondria isolated from the SH-SY5Y cells. In this regard, SES pretreatment decreased the production of superoxide anion radical (O 2 -• ) by the mitochondria of H 2 O 2 -treated cells. SES also prevented the mitochondrial dysfunction induced by H 2 O 2 , as assessed by analyzing the activity of the complexes I and V. The H 2 O 2 -induced reduction in the production of adenosine triphosphate (ATP) was also prevented by SES. The levels of the pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), as well as the activity of the transcription factor nuclear factor-κB (NF-κB) were downregulated by the SES pretreatment in the H 2 O 2 -challenged cells. Silencing of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor abolished the protection induced by SES regarding mitochondrial function and inflammation. Thus, SES depends on Nrf2 to promote mitochondrial protection in cells facing redox impairment., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Chlorpyrifos (CPF), an insecticide, induces pro-oxidant, pro-inflammatory, and pro-apoptotic effects in animal cells. Contamination with CPF occurs not only in farms, since CPF is found in the food consumed in homes. Recently, it was demonstrated that CPF affects the mitochondria, inhibiting components of the electron transfer chain (ETC), causing loss of mitochondrial membrane potential (MMP), and reducing the synthesis of adenosine triphosphate (ATP) by the Complex V. Pinocembrin (PB) is found in propolis and exhibits antioxidant, anti-inflammatory, and anti-apoptotic effects in mammalian cells. PB is a potent inducer of the nuclear factor erythroid 2-related factor 2 (Nrf2), which is a major transcription factor controlling the expression of heme oxygease-1 (HO-1), among others. In the present work, we investigated whether PB would be able to prevent the mitochondrial and immune dysfunctions in the human neuroblastoma SH-SY5Y cells exposed to CPF. PB was tested at 1-25 µM for 4 h before the administration of CPF at 100 µM for additional 24 h. We found that PB prevented the CPF-induced inhibition of ETC, loss of MMP, and decline in the ATP synthesis. PB also promoted anti-inflammatory actions in this experimental model. Silencing of Nrf2 or inhibition of HO-1 suppressed the PB-induced effects in the CPF-challenged cells. Thus, PB promoted beneficial effects by a mechanism dependent on the Nrf2/HO-1/CO + BR axis in the CPF-treated cells., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Mitochondrial dysfunction has been viewed in several diseases, including neurological disorders. In the glutamate (GLU)-mediated excitotoxicity, it has been described mitochondrial impairment, disrupted redox environment, and increased rates of cell death in the affected brain areas. Astaxanthin (AST) is a potent antioxidant and anti-inflammatory xanthophyll that also promotes beneficial mitochondria-related effects in brain cells. However, it is not completely clear how AST would be able to promote mitochondrial protection in those cell types. Thus, we investigated here how AST would protect mitochondria in the dopaminergic SH-SY5Y cell line exposed to GLU. AST was administrated to the cells at 1-40 μM for 24 h prior to the exposure to GLU at 80 mM for additional 24 h. AST prevented the GLU-induced impairment in the activity of the Complexes I and V, the loss in mitochondrial membrane potential (MMP), and the decline in the synthesis of ATP. AST also induced an antioxidant effect in the membranes of mitochondria obtained from the GLU-treated SH-SY5Y cells. Inhibition of the enzyme heme oxygenase-1 (HO-1) or silencing of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) suppressed the AST-promoted cellular and mitochondrial protection. Either tricarbonyldichlororuthenium(II) dimer (CORM-2, a source of carbon monoxide - CO) or bilirubin (BR), that are products of the HO-1-biliverdin reductase (BVR) axis, blocked some of the effects caused by GLU in the SH-SY5Y cells. Overall, our data demonstrate that AST prevented mitochondrial dysfunction by a mechanism related to the Nrf2/HO-1 axis in GLU-challenged cells., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Tanshinone I (T-I, C 18 H 12 O 3 ) is a diterpene found in Salvia miltiorrhiza Bunge (Danshen) and promotes cytoprotection in several experimental models. Chlorpyrifos (CPF) is an agrochemical that causes bioenergetics failure, redox impairment, inflammation, and cell death in animal tissues. Here, we investigated whether T-I would be able to prevent the consequences resulting from the exposure of the human dopaminergic SH-SY5Y cells to CPF. We found that a pretreatment with T-I at 2.5 µM for 2 h suppressed lipid peroxidation and protein carbonylation and nitration on the membranes of mitochondria extracted from the CPF-treated cells. Also, T-I reduced the production of radical superoxide (O 2 -• ) by the mitochondria of the CPF-challenged cells. The production of nitric oxide (NO • ) and hydrogen peroxide (H 2 O 2 ) was also decreased by T-I in the cells exposed to CPF. The CPF-induced decrease in the activity of the complexes I-III, II-III, and V was abolished by a pretreatment with T-I. Loss of mitochondrial membrane potential (ΔΨ m ) and reduction in the production of adenosine triphosphate (ATP) were also prevented by T-I in the CPF-treated cells. T-I also induced anti-inflammatory effects in the CPF-treated cells by decreasing the levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) and the activity of the nuclear factor-κB (NF-κB). Inhibition of heme oxygenase-1 (HO-1) or silencing of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) blocked the T-I-promoted mitochondrial protection and anti-inflammatory action. Overall, T-I depended on the Nrf2/HO-1 axis to prevent the deleterious effects caused by CPF in this experimental model., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Methylglyoxal (MG) is a reactive dicarbonyl presenting both endogenous (e.g. glycolysis) and exogenous (e.g. food cooking) sources. MG induces neurotoxicity, at least in part, by affecting mitochondrial function, including a decline in the oxidative phosphorylation (OXPHOS) system activity, bioenergetics failure, and redox disturbances. Sulforaphane (SFN) is an isothiocyanate found mainly in cruciferous vegetables and exerts antioxidant and anti-inflammatory effects in mammalian cells. SFN also decreases mitochondrial vulnerability to several chemical stressors. SFN is a potent activator of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), which is a master regulator of the mammalian redox biology. Here, we have investigated whether and how SFN would be able to prevent the MG-induced mitochondrial collapse in the human neuroblastoma SH-SY5Y cells. The cells were exposed to SFN at 5 µM for 24 h prior to the administration of MG at 500 µM for additional 24 h. We found that SFN prevented the MG-induced OXPHOS dysfunction and mitochondrial redox impairment. SFN stimulated the activity of the enzyme γ-glutamylcysteine ligase (γ-GCL), leading to increased synthesis of glutathione (GSH). Inhibition of γ-GCL with buthionine sulfoximine (BSO) or silencing of Nrf2 using small interfering RNA (siRNA) against this transcription factor reduced the levels of GSH and abolished the mitochondrial protection promoted by SFN in the MG-treated cells. Thus, SFN protected mitochondria of the MG-challenged cells by a mechanism involving the Nrf2/γ-GCL/GSH axis.

Methylglyoxal (MG) is an endogenously produced toxicant that induces mitochondrial dysfunction leading to impaired redox biology homeostasis, bioenergetics collapse, and cell death in mammalian cells. However, MG toxicity is particularly relevant to neurons and glia given their chemical and metabolic characteristics. Here, we have investigated whether a pretreatment with carnosic acid (CA) would be able to promote mitochondrial protection in human neuroblastoma SH-SY5Y cells exposed to MG. We found that a pretreatment with CA at 1 μM for 12 h prevented the MG-induced lipid peroxidation and protein carbonylation and nitration in the membranes of mitochondria obtained from the SH-SY5Y cells. CA also prevented the MG-elicited Complexes I and V dysfunction, adenosine triphosphate (ATP) levels decline, and loss of mitochondrial membrane potential (MMP). Moreover, CA also reduced the mitochondrial production of the radical anion superoxide (O 2 -• ) in the MG-challenged cells. We found that CA upregulated the synthesis of glutathione (GSH) by increasing the activity of the γ-glutamylcysteine ligase (γ-GCL). Inhibition of the GSH synthesis by buthionine sulfoximine (BSO) abolished the CA-induced mitochondrial protection. Besides, inhibition of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway, as well as silencing of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), suppressed the CA-stimulated protection and the synthesis of GSH. Thus, CA promoted mitochondrial protection by a PI3K/Akt/Nrf2/γ-GCL/GSH axis in MG-treated SH-SY5Y cells.

Mitochondria are the major site of adenosine triphosphate (ATP) production in mammalian cells. Moreover, mitochondria produce most of the reactive oxygen species (ROS) in nucleated cells. Redox and bioenergetic abnormalities have been seen in mitochondria during the onset and progression of neurodegenerative diseases. In that context, excitotoxicity induced by glutamate (GLU) plays an important role in mediating neurotoxicity. Several drugs have been used in the treatment of diseases involving excitotoxicity. Nonetheless, some patients (20-30%) present drug resistance. Thus, it is necessary to find chemicals able to attenuate mitochondrial dysfunction in the case of excitotoxicity. In this work, we treated the human neuroblastoma SH-SY5Y cell line with the diterpene carnosic acid (CA) at 1 μM for 12 h prior to the exposure to GLU for further 24 h. We found that CA prevented the GLU-induced mitochondrion-related redox impairment and bioenergetic decline in SH-SY5Y cells. CA also downregulated the pro-apoptotic stimulus elicited by GLU in this experimental model. CA exerted mitochondrial protection by a mechanism associated with the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), since silencing of this protein with small interfering RNA (siRNA) suppressed the CA-induced protective effects. Future directions include investigating whether CA would be able to modulate mitochondrial function and/or dynamics in in vivo experimental models of excitotoxicity.

The link between mitochondrial dysfunction, redox impairment, and inflammation leads to increased rates of brain cells loss in neurodegenerative diseases and in affective disorders. Carvacrol (CAR) is a component of essential oils found in Labiatae. CAR exerts antioxidant and anti-inflammatory effects in different cell types, as assessed in both in vitro and in vivo experimental designs. Nonetheless, it was not previously investigated whether and how CAR would prevent mitochondrial impairment in human cells exposed to a pro-oxidant challenge. Therefore, we analyzed here whether a pretreatment (for 4 h) with CAR (10-1000 µM) would promote mitochondrial protection in the human neuroblastoma cells SH-SY5Y exposed to hydrogen peroxide (H 2 O 2 ). We found that CAR at 100 µM prevented the H 2 O 2 -induced decline in the activity of the complexes I and V, as well as on the levels of adenosine triphosphate (ATP). CAR also prevented the H 2 O 2 -elicited decrease in the activity of the mitochondrial enzymes aconitase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. Moreover, CAR induced an antioxidant action by decreasing the levels of lipid peroxidation, protein carbonylation, and protein nitration in the mitochondrial membranes. Interestingly, CAR prevented the pro-inflammatory action of H 2 O 2 by downregulating the transcription factor nuclear factor-κB (NF-κB). The inhibition of the heme oxygenase-1 (HO-1) enzyme by zinc protoporphyrin IX (ZnPP IX, 10 µM) suppressed the preventive effects caused by CAR regarding mitochondrial function and inflammation. Thus, it is suggested that CAR caused cytoprotective effects by an HO-1-dependent manner in SH-SY5Y cells exposed to H 2 O 2 .