Sulforaphane

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Information on nutritional supplements people with ALS have been taking

Effects on ALS

Nrf2 activation

The recognition that food-derived nonnutrient molecules can modulate gene expression to influence intracellular molecular mechanisms has seen the emergence of the fields of nutrigenomics and nutrigenetics. The aim of this review is to describe the properties of nutrigenomic activators of transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), comparing the potential for sulforaphane and other phytochemicals to demonstrate clinical efficacy as complementary medicines. Broccoli-derived sulforaphane emerges as a phytochemical with this capability, with oral doses capable of favourably modifying genes associated with chemoprevention. Compared with widely used phytochemical-based supplements like curcumin, silymarin, and resveratrol, sulforaphane more potently activates Nrf2 to induce the expression of a battery of cytoprotective genes. By virtue of its lipophilic nature and low molecular weight, sulforaphane displays significantly higher bioavailability than the polyphenol-based dietary supplements that also activate Nrf2. Nrf2 activation induces cytoprotective genes such as those playing key roles in cellular defense mechanisms including redox status and detoxification. Both its high bioavailability and significant Nrf2 inducer capacity contribute to the therapeutic potential of sulforaphane-yielding supplements. [1]

Oxidative stress and mitochondrial dysfunction are early events in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). Mitochondria are important key players in cellular function based on mitochondrial energy production and their major role in cell physiology. Since neurons are highly depending on mitochondrial energy production due to their high energy demand and their reduced glycolytic capacity mitochondrial dysfunction has fatal consequences for neuronal function and survival. The transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2) is the major regulator of cellular response to oxidative stress. Activation of Nrf2 induces the transcriptional regulation of antioxidant response element (ARE)-dependent expression of a battery of cytoprotective and antioxidant enzymes and proteins. Moreover, activation of Nrf2 protects mitochondria from dysfunction and promotes mitochondrial biogenesis. Therefore, the Nrf2/ARE pathway has become an attractive target for the prevention and treatment of oxidative stress-related neurodegenerative diseases. Small food-derived inducers of the Nrf2/ARE pathway including l-sulforaphane from broccoli and isoliquiritigenin from licorice displayed promising protection of mitochondrial function in models of oxidative stress and neurodegenerative diseases and represent a novel approach to prevent and treat aging-associated neurodegenerative diseases. [2]

Upon oxidative stress and aging, Nrf2 (NFE2-related factor2) triggers antioxidant defense genes to defends against homeostatic failure. Using human(h) or rat(r) lens epithelial cells (LECs) and aging human lenses, we showed that a progressive increase in oxidative load during aging was linked to a decline in Prdx6 expression. DNA binding experiments using gel-shift and ChIP assays demonstrated a progressive reduction in Nrf2/ARE binding (-357/-349) of Prdx6 promoter. The promoter (-918) with ARE showed a marked reduction in young vs aged hLECs, which was directly correlated to decreased Nrf2/ARE binding. A Nrf2 activator, Sulforaphane (SFN), augmented Prdx6, catalase and GSTπ expression in dose-dependent fashion, and halted Nrf2 dysregulation of these antioxidants. SFN reinforced Nrf2/DNA binding and increased promoter activities by enhancing expression and facilitating Nrf2 translocalization in nucleus. Conversely, promoter mutated at ARE site did not respond to SFN, validating the SFN-mediated restoration of Nrf2/ARE signaling. Furthermore, SFN rescued cells from UVB-induced toxicity in dose-dependent fashion, which was consistent with SFN's dose-dependent activation of Nrf2/ARE interaction. Importantly, knockdown of Prdx6 revealed that Prdx6 expression was prerequisite for SFN-mediated cytoprotection. Collectively, our results suggest that loss of Prdx6 caused by dysregulation of ARE/Nrf2 can be attenuated through a SFN, to combat diseases associated with aging. [3]

Oxidative stress and mitochondrial dysfunction are early events in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). Mitochondria are important key players in cellular function based on mitochondrial energy production and their major role in cell physiology. Since neurons are highly depending on mitochondrial energy production due to their high energy demand and their reduced glycolytic capacity mitochondrial dysfunction has fatal consequences for neuronal function and survival. The transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2) is the major regulator of cellular response to oxidative stress. Activation of Nrf2 induces the transcriptional regulation of antioxidant response element (ARE)-dependent expression of a battery of cytoprotective and antioxidant enzymes and proteins. Moreover, activation of Nrf2 protects mitochondria from dysfunction and promotes mitochondrial biogenesis. Therefore, the Nrf2/ARE pathway has become an attractive target for the prevention and treatment of oxidative stress-related neurodegenerative diseases. Small food-derived inducers of the Nrf2/ARE pathway including l-sulforaphane from broccoli and isoliquiritigenin from licorice displayed promising protection of mitochondrial function in models of oxidative stress and neurodegenerative diseases and represent a novel approach to prevent and treat aging-associated neurodegenerative diseases.[4]

The transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2) is the master regulator of the cellular redox homeostasis. Nrf2 target genes comprise of a large network of antioxidant enzymes, proteins involved in xenobiotic detoxification, repair and removal of damaged proteins, inhibition of inflammation, as well as other transcription factors. In recent years it has emerged that as part of its role as a regulator of cytoprotective gene expression, Nrf2 impacts mitochondrial function. Increased Nrf2 activity defends against mitochondrial toxins. Reduced glutathione, the principal small molecule antioxidant in the mammalian cell and a product of several of the downstream target genes of Nrf2, counterbalances mitochondrial ROS production. The function of Nrf2 is suppressed in mitochondria-related disorders, such as Parkinson's disease and Friedrich's ataxia. Studies using isolated mitochondria and cultured cells have demonstrated that Nrf2 deficiency leads to impaired mitochondrial fatty acid oxidation, respiration and ATP production. Small molecule activators of Nrf2 support mitochondrial integrity by promoting mitophagy and conferring resistance to oxidative stress-mediated permeability transition. Excitingly, recent studies have shown that Nrf2 also affects mitochondrial function in stem cells with implications for stem cell self-renewal, cardiomyocyte regeneration, and neural stem/progenitor cell survival. [5]

The nuclear factor erythroid-derived 2 (NF-E2)-related factor 2 (Nrf2) is a transcription factor well-known for its function in controlling the basal and inducible expression of a variety of antioxidant and detoxifying enzymes. As part of its cytoprotective activity, increasing evidence supports its role in metabolism and mitochondrial bioenergetics and function. Neurodegenerative diseases are excellent candidates for Nrf2-targeted treatments. Most neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, frontotemporal dementia and Friedreich's ataxia are characterized by oxidative stress, misfolded protein aggregates, and chronic inflammation, the common targets of Nrf2 therapeutic strategies. Together with them, mitochondrial dysfunction is implicated in the pathogenesis of most neurodegenerative disorders. The recently recognized ability of Nrf2 to regulate intermediary metabolism and mitochondrial function makes Nrf2 activation an attractive and comprehensive strategy for the treatment of neurodegenerative disorders. This review aims to focus on the potential therapeutic role of Nrf2 activation in neurodegeneration, with special emphasis on mitochondrial bioenergetics and function, metabolism and the role of transporters, all of which collectively contribute to the cytoprotective activity of this transcription factor.'[6]

Pro-apoptotic activity

In recent studies, sulforaphane (SFN) has been seen to demonstrate antioxidant and anti-tumor activities. In the present study, the viability inhibition effects of SFN in U251MG glioblastoma cells were analyzed by MTS. Morphology changes were observed by microscope. Apoptotic effects of SFN were evaluated by annexin V binding capacity with flow cytometric analysis. Invasion inhibition effects of SFN were tested by the invasion assay. The molecular mechanisms of apoptotic effects and invasion inhibition effects of SFN were detected by western blot and gelatin zymography. The results indicated that SFN has potent apoptotic effects and invasion inhibition effects against U251MG glioblastoma cells. These effects are both dose dependent. Taken together, SFN possessed apoptotic activity on U251MG cells indicated by increased annexin V-binding capacity, Bad, Bax, cytochrome C expression, and decreased Bcl-2 and survivin expressions. SFN inhibited invasion in U251MG cells via upregulation of E-cadherin and downregulation of MMP-2, MMP-9 and Galectin-3. [7]

Other effects

Sulforaphane [SF; 1-isothiocyanato-4-(methylsulfinyl)-butane], an aliphatic isothiocyanate (ITC) naturally derived from cruciferous vegetables and largely known for its chemopreventive potential also appears to possess anti-inflammatory potential. In this study, structural analogs of SF {compound 1 [1-isothiocyanato-4-(methylcarbonyl)-butane] and 2 [1-isothiocyanato-3-(methylcarbonyl)-propane]} containing a carbonyl group in place of the sulfinyl group in SF, were evaluated for their anti-inflammatory activities. In RAW 264.7 cells, the ITCs at non-toxic concentrations caused an inhibition of NO and prostaglandin E2 (PGE2) release through suppressing expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), as well as a reduction in matrix metalloproteinase-9 (MMP-9) expression, secretion and gelatinolytic activity. Further work performed on human monocytes isolated from blood of healthy donors revealed that the ITCs not only suppressed the expression and release of pro-inflammatory mediators IL-1β, IL-6, TNF-α and MMP-9, but also suppressed their antibody-independent phagocytic and chemotactic migratory abilities. These anti-inflammatory activities were mediated through suppression of the NF-κB and MAPK signaling pathways. In addition, the ITCs were revealed to interact with the cysteines in inhibitor of nuclear factor-κB kinase β subunit (IKKβ), which could contribute at least partly to the suppression of NF-κB signaling. In conclusion, results obtained in this study provide deeper insights into the anti-inflammatory properties of SF and its methylcarbonyl analogs and the underlying mechanisms. These compounds thus serve as promising candidates for clinical applications in controlling inflammatory conditions. [8]

It is conceivable that stimulating proteasome activity for rapid removal of misfolded and oxidized proteins is a promising strategy to prevent and alleviate aging-related diseases. Sulforaphane (SFN), an effective cancer preventive agent derived from cruciferous vegetables, has been shown to enhance proteasome activities in mammalian cells and to reduce the level of oxidized proteins and amyloid β-induced cytotoxicity. Here, we report that SFN activates heat shock transcription factor 1-mediated heat shock response. Specifically, SFN-induced expression of heat shock protein 27 (Hsp27) underlies SFN-stimulated proteasome activity. SFN-induced proteasome activity was significantly enhanced in Hsp27-overexpressing cells but absent in Hsp27-silenced cells. The role of Hsp27 in regulating proteasome activity was further confirmed in isogenic REG cells, in which SFN-induced proteasome activation was only observed in cells stably overexpressing Hsp27, but not in the Hsp27-free parental cells. Finally, we demonstrated that phosphorylation of Hsp27 is irrelevant to SFN-induced proteasome activation. This study provides a novel mechanism underlying SFN-induced proteasome activity. This is the first report to show that heat shock response by SFN, in addition to the antioxidant response mediated by the Keap1-Nrf2 pathway, may contribute to cytoprotection.[9]

Bioavailability

Glucoraphanin from broccoli and its sprouts and seeds is a water soluble and relatively inert precursor of sulforaphane, the reactive isothiocyanate that potently inhibits neoplastic cellular processes and prevents a number of disease states. Sulforaphane is difficult to deliver in an enriched and stable form for purposes of direct human consumption. We have focused upon evaluating the bioavailability of sulforaphane, either by direct administration of glucoraphanin (a glucosinolate, or β-thioglucoside-N-hydroxysulfate), or by co-administering glucoraphanin and the enzyme myrosinase to catalyze its conversion to sulforaphane at economic, reproducible and sustainable yields. We show that following administration of glucoraphanin in a commercially prepared dietary supplement to a small number of human volunteers, the volunteers had equivalent output of sulforaphane metabolites in their urine to that which they produced when given an equimolar dose of glucoraphanin in a simple boiled and lyophilized extract of broccoli sprouts. Furthermore, when either broccoli sprouts or seeds are administered directly to subjects without prior extraction and consequent inactivation of endogenous myrosinase, regardless of the delivery matrix or dose, the sulforaphane in those preparations is 3- to 4-fold more bioavailable than sulforaphane from glucoraphanin delivered without active plant myrosinase. These data expand upon earlier reports of inter- and intra-individual variability, when glucoraphanin was delivered in either teas, juices, or gelatin capsules, and they confirm that a variety of delivery matrices may be equally suitable for glucoraphanin supplementation (e.g. fruit juices, water, or various types of capsules and tablets). [10]

Discussion threads on the ALSTDI forum

Sulforaphane - a less known promising substance for ALS?

References

  1. Houghton et al.: Sulforaphane and Other Nutrigenomic Nrf2 Activators: Can the Clinician's Expectation Be Matched by the Reality?. Oxid Med Cell Longev 2016;2016:7857186. PMID: 26881038. DOI. The recognition that food-derived nonnutrient molecules can modulate gene expression to influence intracellular molecular mechanisms has seen the emergence of the fields of nutrigenomics and nutrigenetics. The aim of this review is to describe the properties of nutrigenomic activators of transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), comparing the potential for sulforaphane and other phytochemicals to demonstrate clinical efficacy as complementary medicines. Broccoli-derived sulforaphane emerges as a phytochemical with this capability, with oral doses capable of favourably modifying genes associated with chemoprevention. Compared with widely used phytochemical-based supplements like curcumin, silymarin, and resveratrol, sulforaphane more potently activates Nrf2 to induce the expression of a battery of cytoprotective genes. By virtue of its lipophilic nature and low molecular weight, sulforaphane displays significantly higher bioavailability than the polyphenol-based dietary supplements that also activate Nrf2. Nrf2 activation induces cytoprotective genes such as those playing key roles in cellular defense mechanisms including redox status and detoxification. Both its high bioavailability and significant Nrf2 inducer capacity contribute to the therapeutic potential of sulforaphane-yielding supplements.
  2. Denzer et al.: Modulation of mitochondrial dysfunction in neurodegenerative diseases via activation of nuclear factor erythroid-2-related factor 2 by food-derived compounds. Pharmacol. Res. 2016;103:80-94. PMID: 26626189. DOI. Oxidative stress and mitochondrial dysfunction are early events in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). Mitochondria are important key players in cellular function based on mitochondrial energy production and their major role in cell physiology. Since neurons are highly depending on mitochondrial energy production due to their high energy demand and their reduced glycolytic capacity mitochondrial dysfunction has fatal consequences for neuronal function and survival. The transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2) is the major regulator of cellular response to oxidative stress. Activation of Nrf2 induces the transcriptional regulation of antioxidant response element (ARE)-dependent expression of a battery of cytoprotective and antioxidant enzymes and proteins. Moreover, activation of Nrf2 protects mitochondria from dysfunction and promotes mitochondrial biogenesis. Therefore, the Nrf2/ARE pathway has become an attractive target for the prevention and treatment of oxidative stress-related neurodegenerative diseases. Small food-derived inducers of the Nrf2/ARE pathway including l-sulforaphane from broccoli and isoliquiritigenin from licorice displayed promising protection of mitochondrial function in models of oxidative stress and neurodegenerative diseases and represent a novel approach to prevent and treat aging-associated neurodegenerative diseases.
  3. Kubo et al.: Sulforaphane reactivates cellular antioxidant defense by inducing Nrf2/ARE/Prdx6 activity during aging and oxidative stress. Sci Rep 2017;7:14130. PMID: 29074861. DOI. Upon oxidative stress and aging, Nrf2 (NFE2-related factor2) triggers antioxidant defense genes to defends against homeostatic failure. Using human(h) or rat(r) lens epithelial cells (LECs) and aging human lenses, we showed that a progressive increase in oxidative load during aging was linked to a decline in Prdx6 expression. DNA binding experiments using gel-shift and ChIP assays demonstrated a progressive reduction in Nrf2/ARE binding (-357/-349) of Prdx6 promoter. The promoter (-918) with ARE showed a marked reduction in young vs aged hLECs, which was directly correlated to decreased Nrf2/ARE binding. A Nrf2 activator, Sulforaphane (SFN), augmented Prdx6, catalase and GSTπ expression in dose-dependent fashion, and halted Nrf2 dysregulation of these antioxidants. SFN reinforced Nrf2/DNA binding and increased promoter activities by enhancing expression and facilitating Nrf2 translocalization in nucleus. Conversely, promoter mutated at ARE site did not respond to SFN, validating the SFN-mediated restoration of Nrf2/ARE signaling. Furthermore, SFN rescued cells from UVB-induced toxicity in dose-dependent fashion, which was consistent with SFN's dose-dependent activation of Nrf2/ARE interaction. Importantly, knockdown of Prdx6 revealed that Prdx6 expression was prerequisite for SFN-mediated cytoprotection. Collectively, our results suggest that loss of Prdx6 caused by dysregulation of ARE/Nrf2 can be attenuated through a SFN, to combat diseases associated with aging.
  4. Denzer et al.: Modulation of mitochondrial dysfunction in neurodegenerative diseases via activation of nuclear factor erythroid-2-related factor 2 by food-derived compounds. Pharmacol. Res. 2016;103:80-94. PMID: 26626189. DOI. Oxidative stress and mitochondrial dysfunction are early events in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). Mitochondria are important key players in cellular function based on mitochondrial energy production and their major role in cell physiology. Since neurons are highly depending on mitochondrial energy production due to their high energy demand and their reduced glycolytic capacity mitochondrial dysfunction has fatal consequences for neuronal function and survival. The transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2) is the major regulator of cellular response to oxidative stress. Activation of Nrf2 induces the transcriptional regulation of antioxidant response element (ARE)-dependent expression of a battery of cytoprotective and antioxidant enzymes and proteins. Moreover, activation of Nrf2 protects mitochondria from dysfunction and promotes mitochondrial biogenesis. Therefore, the Nrf2/ARE pathway has become an attractive target for the prevention and treatment of oxidative stress-related neurodegenerative diseases. Small food-derived inducers of the Nrf2/ARE pathway including l-sulforaphane from broccoli and isoliquiritigenin from licorice displayed promising protection of mitochondrial function in models of oxidative stress and neurodegenerative diseases and represent a novel approach to prevent and treat aging-associated neurodegenerative diseases.
  5. Holmström et al.: The multifaceted role of Nrf2 in mitochondrial function. Curr Opin Toxicol 2016;1:80-91. PMID: 28066829. DOI. The transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2) is the master regulator of the cellular redox homeostasis. Nrf2 target genes comprise of a large network of antioxidant enzymes, proteins involved in xenobiotic detoxification, repair and removal of damaged proteins, inhibition of inflammation, as well as other transcription factors. In recent years it has emerged that as part of its role as a regulator of cytoprotective gene expression, Nrf2 impacts mitochondrial function. Increased Nrf2 activity defends against mitochondrial toxins. Reduced glutathione, the principal small molecule antioxidant in the mammalian cell and a product of several of the downstream target genes of Nrf2, counterbalances mitochondrial ROS production. The function of Nrf2 is suppressed in mitochondria-related disorders, such as Parkinson's disease and Friedrich's ataxia. Studies using isolated mitochondria and cultured cells have demonstrated that Nrf2 deficiency leads to impaired mitochondrial fatty acid oxidation, respiration and ATP production. Small molecule activators of Nrf2 support mitochondrial integrity by promoting mitophagy and conferring resistance to oxidative stress-mediated permeability transition. Excitingly, recent studies have shown that Nrf2 also affects mitochondrial function in stem cells with implications for stem cell self-renewal, cardiomyocyte regeneration, and neural stem/progenitor cell survival.
  6. Esteras et al.: Nrf2 activation in the treatment of neurodegenerative diseases: a focus on its role in mitochondrial bioenergetics and function. Biol. Chem. 2016;397:383-400. PMID: 26812787. DOI. The nuclear factor erythroid-derived 2 (NF-E2)-related factor 2 (Nrf2) is a transcription factor well-known for its function in controlling the basal and inducible expression of a variety of antioxidant and detoxifying enzymes. As part of its cytoprotective activity, increasing evidence supports its role in metabolism and mitochondrial bioenergetics and function. Neurodegenerative diseases are excellent candidates for Nrf2-targeted treatments. Most neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, frontotemporal dementia and Friedreich's ataxia are characterized by oxidative stress, misfolded protein aggregates, and chronic inflammation, the common targets of Nrf2 therapeutic strategies. Together with them, mitochondrial dysfunction is implicated in the pathogenesis of most neurodegenerative disorders. The recently recognized ability of Nrf2 to regulate intermediary metabolism and mitochondrial function makes Nrf2 activation an attractive and comprehensive strategy for the treatment of neurodegenerative disorders. This review aims to focus on the potential therapeutic role of Nrf2 activation in neurodegeneration, with special emphasis on mitochondrial bioenergetics and function, metabolism and the role of transporters, all of which collectively contribute to the cytoprotective activity of this transcription factor.
  7. Zhang et al.: Sulforaphane induces apoptosis and inhibits invasion in U251MG glioblastoma cells. Springerplus 2016;5:235. PMID: 27026929. DOI. In recent studies, sulforaphane (SFN) has been seen to demonstrate antioxidant and anti-tumor activities. In the present study, the viability inhibition effects of SFN in U251MG glioblastoma cells were analyzed by MTS. Morphology changes were observed by microscope. Apoptotic effects of SFN were evaluated by annexin V binding capacity with flow cytometric analysis. Invasion inhibition effects of SFN were tested by the invasion assay. The molecular mechanisms of apoptotic effects and invasion inhibition effects of SFN were detected by western blot and gelatin zymography. The results indicated that SFN has potent apoptotic effects and invasion inhibition effects against U251MG glioblastoma cells. These effects are both dose dependent. Taken together, SFN possessed apoptotic activity on U251MG cells indicated by increased annexin V-binding capacity, Bad, Bax, cytochrome C expression, and decreased Bcl-2 and survivin expressions. SFN inhibited invasion in U251MG cells via upregulation of E-cadherin and downregulation of MMP-2, MMP-9 and Galectin-3.
  8. Reddy et al.: Sulforaphane and its methylcarbonyl analogs inhibit the LPS-stimulated inflammatory response in human monocytes through modulating cytokine production, suppressing chemotactic migration and phagocytosis in a NF-κB- and MAPK-dependent manner. Int. Immunopharmacol. 2015;24:440-450. PMID: 25585231. DOI. Sulforaphane [SF; 1-isothiocyanato-4-(methylsulfinyl)-butane], an aliphatic isothiocyanate (ITC) naturally derived from cruciferous vegetables and largely known for its chemopreventive potential also appears to possess anti-inflammatory potential. In this study, structural analogs of SF {compound 1 [1-isothiocyanato-4-(methylcarbonyl)-butane] and 2 [1-isothiocyanato-3-(methylcarbonyl)-propane]} containing a carbonyl group in place of the sulfinyl group in SF, were evaluated for their anti-inflammatory activities. In RAW 264.7 cells, the ITCs at non-toxic concentrations caused an inhibition of NO and prostaglandin E2 (PGE2) release through suppressing expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), as well as a reduction in matrix metalloproteinase-9 (MMP-9) expression, secretion and gelatinolytic activity. Further work performed on human monocytes isolated from blood of healthy donors revealed that the ITCs not only suppressed the expression and release of pro-inflammatory mediators IL-1β, IL-6, TNF-α and MMP-9, but also suppressed their antibody-independent phagocytic and chemotactic migratory abilities. These anti-inflammatory activities were mediated through suppression of the NF-κB and MAPK signaling pathways. In addition, the ITCs were revealed to interact with the cysteines in inhibitor of nuclear factor-κB kinase β subunit (IKKβ), which could contribute at least partly to the suppression of NF-κB signaling. In conclusion, results obtained in this study provide deeper insights into the anti-inflammatory properties of SF and its methylcarbonyl analogs and the underlying mechanisms. These compounds thus serve as promising candidates for clinical applications in controlling inflammatory conditions.
  9. Gan et al.: Sulforaphane activates heat shock response and enhances proteasome activity through up-regulation of Hsp27. J. Biol. Chem. 2010;285:35528-36. PMID: 20833711. DOI. It is conceivable that stimulating proteasome activity for rapid removal of misfolded and oxidized proteins is a promising strategy to prevent and alleviate aging-related diseases. Sulforaphane (SFN), an effective cancer preventive agent derived from cruciferous vegetables, has been shown to enhance proteasome activities in mammalian cells and to reduce the level of oxidized proteins and amyloid β-induced cytotoxicity. Here, we report that SFN activates heat shock transcription factor 1-mediated heat shock response. Specifically, SFN-induced expression of heat shock protein 27 (Hsp27) underlies SFN-stimulated proteasome activity. SFN-induced proteasome activity was significantly enhanced in Hsp27-overexpressing cells but absent in Hsp27-silenced cells. The role of Hsp27 in regulating proteasome activity was further confirmed in isogenic REG cells, in which SFN-induced proteasome activation was only observed in cells stably overexpressing Hsp27, but not in the Hsp27-free parental cells. Finally, we demonstrated that phosphorylation of Hsp27 is irrelevant to SFN-induced proteasome activation. This study provides a novel mechanism underlying SFN-induced proteasome activity. This is the first report to show that heat shock response by SFN, in addition to the antioxidant response mediated by the Keap1-Nrf2 pathway, may contribute to cytoprotection.
  10. Fahey et al.: Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase. PLoS ONE 2015;10:e0140963. PMID: 26524341. DOI. Glucoraphanin from broccoli and its sprouts and seeds is a water soluble and relatively inert precursor of sulforaphane, the reactive isothiocyanate that potently inhibits neoplastic cellular processes and prevents a number of disease states. Sulforaphane is difficult to deliver in an enriched and stable form for purposes of direct human consumption. We have focused upon evaluating the bioavailability of sulforaphane, either by direct administration of glucoraphanin (a glucosinolate, or β-thioglucoside-N-hydroxysulfate), or by co-administering glucoraphanin and the enzyme myrosinase to catalyze its conversion to sulforaphane at economic, reproducible and sustainable yields. We show that following administration of glucoraphanin in a commercially prepared dietary supplement to a small number of human volunteers, the volunteers had equivalent output of sulforaphane metabolites in their urine to that which they produced when given an equimolar dose of glucoraphanin in a simple boiled and lyophilized extract of broccoli sprouts. Furthermore, when either broccoli sprouts or seeds are administered directly to subjects without prior extraction and consequent inactivation of endogenous myrosinase, regardless of the delivery matrix or dose, the sulforaphane in those preparations is 3- to 4-fold more bioavailable than sulforaphane from glucoraphanin delivered without active plant myrosinase. These data expand upon earlier reports of inter- and intra-individual variability, when glucoraphanin was delivered in either teas, juices, or gelatin capsules, and they confirm that a variety of delivery matrices may be equally suitable for glucoraphanin supplementation (e.g. fruit juices, water, or various types of capsules and tablets).