Cytoprotective effect of eckol against oxidative stress-induced mitochondrial dysfunction: involvement of the FoxO3a/AMPK pathway

Protective Effect and Mechanisms of Eckol on Chronic Ulcerative Colitis Induced by Dextran Sulfate Sodium in Mice

The use of functional foods and their bioactive components is receiving increasing attention as a complementary and alternative therapy for chronic ulcerative colitis (UC). This study explored the protective effect and mechanisms of Eckol, a seaweed-derived bioactive phlorotannin, on the dextran sodium sulfate (DSS)-induced chronic UC in mice. Eckol (0.5-1.0 mg/kg) reduced DSS-enhanced disease activity indexes, and alleviated the shortening of colon length and colonic tissue damage in chronic UC mice. The contents of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were significantly decreased, and the level of anti-inflammatory IL-10 was enhanced in the serum and colonic tissues collected from Eckol-treated mice compared with the DSS controls. Eckol administration significantly reduced the number of apoptotic cells and the expression of cleaved Caspase-3, and increased the B-cell lymphoma-2 (Bcl-2)/B-cell lymphoma-2- associated X (Bax) ratio in DSS-challenged colons. There were more cluster of differentiation (CD)11c⁺ dendritic cells and CD8⁺ T cells, and less CD4⁺ T cells infiltrated to inflamed colonic tissues in the Eckol-treated groups. Expression of colonic Toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB) p65, phosphorylated-signal transducer and activator of transcription (pSTAT)3 was significantly down-regulated by Eckol compared with the DSS-challenged group. In conclusion, our data suggest that Eckol appeared to be a potential functional food ingredient for protection against chronic UC. The anti-colitis mechanisms of Eckol might be attributed to the down-regulation of the TLR4/NF-κB/STAT3 pathway, inhibition of inflammation and apoptosis, as well as its immunoregulatory activity.

Using bioinformatics and systems biology methods to identify the mechanism of interaction between COVID-19 and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is considered a risk factor for severe COVID-19, but the mechanism remains unknown. This study used bioinformatics to help define the relationship between these diseases. The GSE147507 (COVID-19), GSE126848 (NAFLD), and GSE63067 (NAFLD-2) datasets were screened using the Gene Expression Omnibus. Common differentially expressed genes were then identified using a Venn diagram. Gene ontology analysis and KEGG pathway enrichment were performed on the differentially expressed genes. A protein-protein interaction network was also constructed using the STRING platform, and key genes were identified using the Cytoscape plugin. GES63067 was selected for validation of the results. Analysis of ferroptosis gene expression during the development of the 2 diseases and prediction of their upstream miRNAs and lncRNAs. In addition, transcription factors (TFs) and miRNAs related to key genes were identified. Effective drugs that act on target genes were found in the DSigDB. The GSE147507 and GSE126848 datasets were crossed to obtain 28 co-regulated genes, 22 gene ontology terms, 3 KEGG pathways, and 10 key genes. NAFLD may affect COVID-19 progression through immune function and inflammatory signaling pathways. CYBB was predicted to be a differential ferroptosis gene associated with 2 diseases, and the CYBB-hsa-miR-196a/b-5p-TUG1 regulatory axis was identified. TF-gene interactions and TF-miRNA coregulatory network were constructed successfully. A total of 10 drugs, (such as Eckol, sulfinpyrazone, and phenylbutazone) were considered as target drugs for Patients with COVID-19 and NAFLD. This study identified key gene and defined molecular mechanisms associated with the progression of COVID-19 and NAFLD. COVID-19 and NAFLD progression may regulate ferroptosis through the CYBB-hsa-miR-196a/b-5p-TUG1 axis. This study provides additional drug options for the treatment of COVID-19 combined with NAFLD disease.

Therapeutic effects of phlorotannins in the treatment of neurodegenerative disorders

Phlorotannins are natural polyphenolic compounds produced by brown marine algae and are currently found in nutritional supplements. Although they are known to cross the blood-brain barrier, their neuropharmacological actions remain unclear. Here we review the potential therapeutic benefits of phlorotannins in the treatment of neurodegenerative diseases. In mouse models of Alzheimer's disease, ethanol intoxication and fear stress, the phlorotannin monomer phloroglucinol and the compounds eckol, dieckol and phlorofucofuroeckol A have been shown to improve cognitive function. In a mouse model of Parkinson's disease, phloroglucinol treatment led to improved motor performance. Additional neurological benefits associated with phlorotannin intake have been demonstrated in stroke, sleep disorders, and pain response. These effects may stem from the inhibition of disease-inducing plaque synthesis and aggregation, suppression of microglial activation, modulation of pro-inflammatory signaling, reduction of glutamate-induced excitotoxicity, and scavenging of reactive oxygen species. Clinical trials of phlorotannins have not reported significant adverse effects, suggesting these compounds to be promising bioactive agents in the treatment of neurological diseases. We therefore propose a putative biophysical mechanism of phlorotannin action in addition to future directions for phlorotannin research.

Role of FOXO3a Transcription Factor in the Regulation of Liver Oxidative Injury

Oxidative stress has been identified as a key mechanism in liver damage caused by various chemicals. The transcription factor FOXO3a has emerged as a critical regulator of redox imbalance. Multiple post-translational changes and epigenetic processes closely regulate the activity of FOXO3a, resulting in synergistic or competing impacts on its subcellular localization, stability, protein-protein interactions, DNA binding affinity, and transcriptional programs. Depending on the chemical nature and subcellular context, the oxidative-stress-mediated activation of FOXO3a can induce multiple transcriptional programs that play crucial roles in oxidative injury to the liver by chemicals. Here, we mainly review the role of FOXO3a in coordinating programs of genes that are essential for cellular homeostasis, with an emphasis on exploring the regulatory mechanisms and potential application of FOXO3a as a therapeutic target to prevent and treat liver oxidative injury.

Brown Algae Phlorotannins: A Marine Alternative to Break the Oxidative Stress, Inflammation and Cancer Network

According to the WHO, cancer was responsible for an estimated 9.6 million deaths in 2018, making it the second global leading cause of death. The main risk factors that lead to the development of this disease include poor behavioral and dietary habits, such as tobacco use, alcohol use and lack of fruit and vegetable intake, or physical inactivity. In turn, it is well known that polyphenols are deeply implicated with the lower rates of cancer in populations that consume high levels of plant derived foods. In this field, phlorotannins have been under the spotlight in recent years since they have shown exceptional bioactive properties, with great interest for application in food and pharmaceutical industries. Among their multiple bioactive properties, phlorotannins have revealed the capacity to interfere with several biochemical mechanisms that regulate oxidative stress, inflammation and tumorigenesis, which are central aspects in the pathogenesis of cancer. This versatility and ability to act either directly or indirectly at different stages and mechanisms of cancer growth make these compounds highly appealing for the development of new therapeutical strategies to address this world scourge. The present manuscript revises relevant studies focusing the effects of phlorotannins to counteract the oxidative stress-inflammation network, emphasizing their potential for application in cancer prevention and/or treatment.

The Inhibition Effect of the Seaweed Polyphenol, 7-Phloro-Eckol from Ecklonia Cava on Alcohol-Induced Oxidative Stress in HepG2/CYP2E1 Cells

The liver is vulnerable to oxidative stress-induced damage, which leads to many diseases, including alcoholic liver disease (ALD). Liver disease endanger people's health, and the incidence of ALD is increasing; therefore, prevention is very important. 7-phloro-eckol (7PE) is a seaweed polyphenol, which was isolated from Ecklonia cava in a previous study. In this study, the antioxidative stress effect of 7PE on HepG2/CYP2E1 cells was evaluated by alcohol-induced cytotoxicity, DNA damage, and expression of related inflammation and apoptosis proteins. The results showed that 7PE caused alcohol-induced cytotoxicity to abate, reduced the amount of reactive oxygen species (ROS) and nitric oxide (NO), and effectively inhibited DNA damage in HepG2/CYP2E1 cells. Additionally, the expression levels of glutathione (GSH), superoxide dismutase (SOD), B cell lymphoma 2 (Bcl-2), and Akt increased, while γ-glutamyltransferase (GGT), Bcl-2 related x (Bax), cleaved caspase-3, cleaved caspase-9, nuclear factor-κB (NF-κB), and JNK decreased. Finally, molecular docking proved that 7PE could bind to BCL-2 and GSH protein. These results indicate that 7PE can alleviate the alcohol-induced oxidative stress injury of HepG2 cells and that 7PE may have a potential application prospect in the future development of antioxidants.

Sesamin and sesamol attenuate H2O2-induced oxidative stress on human neuronal cells via the SIRT1-SIRT3-FOXO3a signaling pathway

Background: An imbalance of free radicals and antioxidant defense systems in physiological processes can result in protein/DNA damage, inflammation, and cellular apoptosis leading to neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Sesamin and sesamol, compounds derived from sesame seeds and oil, have been reported to exert various pharmacological effects, especially antioxidant activity. However, their molecular mechanisms against the oxidative stress induced by exogenous hydrogen peroxide (H₂O₂) remain to be elucidated. Aim: In this study, neuroprotective effects of sesamin and sesamol on H₂O₂-induced human neuroblastoma (SH-SY5Y) cell death and possible signaling pathways in the cells were explored. Methods: MTT assay and flow cytometry were conducted to determine cell viability and apoptotic profiles of neuronal cells treated with sesamin and sesamol. Carboxy-DCFDA assay was used to measure reactive oxygen species (ROS). Moreover, Western blot analysis was performed to investigate protein profiles associated with neuroprotection. Results: Pretreatment of the cells with 1 µM of sesamin and sesamol remarkably reduced the SH-SY5Y cell death induced by 400 µM H₂O₂ as well as the intracellular ROS production. Moreover, the molecular mechanisms underlying neuroprotection of the compounds were associated with activating SIRT1-SIRT3-FOXO3a expression, inhibiting BAX (proapoptotic protein), and upregulating BCL-2 (anti-apoptotic protein). Conclusion: The findings suggest that sesamin and sesamol are compounds that potentially protect neuronal cells against oxidative stress similar to that of the resveratrol, the reference compound. These antioxidants are thus of interest for further investigation in in vivo models of neuroprotection.

Effect of Transcriptional Regulatory Factor FoxO3a on Central Nervous System Oxygen Toxicity

Central nervous system (CNS) oxygen toxicity (CNS-OT) is a toxic reaction that appears after the inhalation of gas at an excessive oxygen partial pressure during underwater operation or hyperbaric oxygen (HBO) treatment. The mechanism of CNS-OT has not been clearly characterized. Though it has been attributed to the excessive oxidative stress induced by HBO, evidences against this hypothesis have been reported. Here we find that Forkhead box protein O3 (FoxO3a) is important for CNS-OT protection. FoxO3a knock-out (KO) mice had a shorter latency to develop convulsions and greater number of seizures within a certain period of time. The acute lung injury (ALI) induced by CNS-OT was also more severe in FoxO3a KO mice. Further analysis reveals a significant decrease in the activity of catalase (CAT), an antioxidant enzyme and a significant increase in the content of malondialdehyde (MDA), an oxidative product, in brain tissues of FoxO3a KO mice. Short-time HBO exposure could increase FoxO3a expression level and trigger its nuclear translocation. The level of nuclear localized FoxO3a peaked at 8 h after exposure. Our results demonstrate that the activity of FoxO3a is highly sensitive to HBO exposure and FoxO3a plays important roles in protecting CNS-OT. Further mechanic analysis reveals that FoxO3a protects CNS-OT via activating antioxidative signaling pathway.

Eckol Alleviates Intestinal Dysfunction during Suckling-to-Weaning Transition via Modulation of PDX1 and HBEGF

Maintaining intestinal health in livestock is critical during the weaning period. The precise mechanisms of intestinal dysfunction during this period are not fully understood, although these can be alleviated by phlorotannins, including eckol. This question was addressed by evaluating the changes in gene expression and intestinal function after eckol treatment during suckling-to-weaning transition. The biological roles of differentially expressed genes (DEGs) in intestinal development were investigated by assessing intestinal wound healing and barrier functions, as well as the associated signaling pathways and oxidative stress levels. We identified 890 DEGs in the intestine, whose expression was altered by eckol treatment, including pancreatic and duodenal homeobox (PDX)1, which directly regulate heparin-binding epidermal growth factor-like growth factor (HBEGF) expression in order to preserve intestinal barrier functions and promote wound healing through phosphoinositide 3-kinase (PI3K)/AKT and P38 signaling. Additionally, eckol alleviated H₂O₂-induced oxidative stress through PI3K/AKT, P38, and 5’-AMP-activated protein kinase (AMPK) signaling, improved growth, and reduced oxidative stress and intestinal permeability in pigs during the weaning period. Eckol modulates intestinal barrier functions, wound healing, and oxidative stress through PDX/HBEGF, and improves growth during the suckling-to-weaning transition. These findings suggest that eckol can be used as a feed supplement in order to preserve the intestinal functions in pigs and other livestock during this process.

Pyrroloquinoline Quinone Inhibits Oxidative Stress in Rats with Diabetic Nephropathy

Background

Diabetic nephropathy (DN) is one of the chronic microvascular complications of diabetes. This study focused on the protective effects of pyrroloquinoline quinone (PQQ) on oxidative stress (OS) in DN.

Material/Methods

Thirty Sprague Dawley rats were randomly selected for this study; 10 rats were randomly selected as the control group. The other 20 rats were established for the DN model. After establishment of the successful model, the DN model rats were randomly divided into a DN group and a PQQ group. The PQQ group was fed with a PQQ diet. Blood urea nitrogen (BUN), serum creatinine (SCr), and blood glucose levels were measured in each group, and OS-related protein expression and AMPK pathway were detected by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). At the same time, we constructed a DN model by culturing NRK-52E cells with high glucose to detect the molecular mechanisms.

Results

The kidney function of the DN group was significantly decreased, SCr and BUN levels were significantly increased, and the renal structure under the microscope was disordered, and interstitial edema was obvious. The expression of SOD1, SOD2, GPX1, and GPX3 were significantly decreased, and the level of reactive oxygen species (ROS) was significantly increased. PQQ treatment can effectively alleviate renal function, improve structural damage, and inhibit OS. In vivo, PQQ can effectively inhibit high glucose-induced OS damage and activate the AMPK/FOXO3a signaling pathway.

Conclusions

PQQ improves renal structural damage and functional damage, and protects kidney cells in DN by inhibiting OS, which may be related to activating the AMPK/FOXO3a pathway.

Eckol inhibits Reg3A-induced proliferation of human SW1990 pancreatic cancer cells

Pancreatic cancer (PaC) is characterized by a highly inflammatory tumor microenvironment, and inflammatory mediators are implicated in the progression of this cancer. Regenerating gene protein (Reg) 3A is significantly upregulated during pancreatic inflammation, and has been demonstrated to serve an important role during PaC progression, based on its increased expression levels in PaC and potent cell proliferation-promoting activity. The aim of the present study was to investigate the effect of eckol, a phlorotannin compound with a variety of biological activities including anti-inflammatory, anti-tumor and cytoprotective effects, on Reg3A-induced proliferation of human SW1990 PaC cells. SW1990 cells were pre-treated with eckol for 48 h at concentrations of 5, 10 and 20 µg/ml. Subsequently, Reg3A protein was added to the culture media at a final concentration of 50 ng/ml in the presence or absence of eckol for 24 h. The cytotoxicity and proliferative capacity of the SW1990 cells was determined using an MTT and flow cytometry analysis. Cell colony formation was also used to determine the effect of eckol on the anchorage-independent growth and colony-forming capacity of Reg3A-treated PaC cells. The expression levels of cyclin D1, STAT3, JAK2, and NF-κB p65 were measured with reverse transcription-quantitative PCR and western blotting. Eckol reduced Reg3A-promoted cell survival, inhibited Reg3A-induced cell cycle progression and inhibited colony growth of SW1990 cells in soft agar in a concentration-dependent manner. Additionally, the Reg3A-mediated upregulation of expression of JAK2, STAT3, NF-κBp65 and cyclin D1 was reduced when treated with eckol. Reg3A is upregulated during pancreatic inflammation and exhibits a pro-growth function and may thus serve a critical role during inflammation-driven PaC malignancies. Eckol may be a potential protective agent against progression of PaC accompanied by pancreatic inflammation.

Eckol Inhibits Particulate Matter 2.5-Induced Skin Keratinocyte Damage via MAPK Signaling Pathway

Toxicity of particulate matter (PM) towards the epidermis has been well established in many epidemiological studies. It is manifested in cancer, aging, and skin damage. In this study, we aimed to show the mechanism underlying the protective effects of eckol, a phlorotannin isolated from brown seaweed, on human HaCaT keratinocytes against PM_2.5-induced cell damage. First, to elucidate the underlying mechanism of toxicity of PM_2.5, we checked the reactive oxygen species (ROS) level, which contributed significantly to cell damage. Experimental data indicate that excessive ROS caused damage to lipids, proteins, and DNA and induced mitochondrial dysfunction. Furthermore, eckol (30 μM) decreased ROS generation, ensuring the stability of molecules, and maintaining a steady mitochondrial state. The western blot analysis showed that PM_2.5 promoted apoptosis-related protein levels and activated MAPK signaling pathway, whereas eckol protected cells from apoptosis by inhibiting MAPK signaling pathway. This was further reinforced by detailed investigations using MAPK inhibitors. Thus, our results demonstrated that inhibition of PM_2.5-induced cell apoptosis by eckol was through MAPK signaling pathway. In conclusion, eckol could protect skin HaCaT cells from PM_2.5-induced apoptosis via inhibiting ROS generation.

Characterizing Eckol as a Therapeutic Aid: A Systematic Review

The marine biosphere is a treasure trove of natural bioactive secondary metabolites and the richest source of structurally diverse and unique compounds, such as phlorotannins and halo-compounds, with high therapeutic potential. Eckol is a precursor compound representing the dibenzo-1,4-dioxin class of phlorotannins abundant in the Ecklonia species, which are marine brown algae having a ubiquitous distribution. In search of compounds having biological activity from macro algae during the past three decades, this particular compound has attracted massive attention for its multiple therapeutic properties and health benefits. Although several varieties of marine algae, seaweed, and phlorotannins have already been well scrutinized, eckol deserves a place of its own because of the therapeutic properties it possesses. The relevant information about this particular compound has not yet been collected in one place; therefore, this review focuses on its biological applications, including its potential health benefits and possible applications to restrain diseases leading to good health. The facts compiled in this review could contribute to novel insights into the functions of eckol and potentially enable its use in different uninvestigated fields.

Pretreated fucoidan confers neuroprotection against transient global cerebral ischemic injury in the gerbil hippocampal CA1 area via reducing of glial cell activation and oxidative stress

Fucoidan is a sulfated polysaccharide derived from brown algae and possesses various beneficial activities, including antioxidant property. Previous studies have shown that fucoidan displays protective effect against ischemia-reperfusion injury in some organs. However, few studies have been reported regarding the protective effect of fucoidan against transient cerebral ischemic insults and its related mechanisms. Therefore, in this study, we examined the neuroprotective effect of fucoidan against transient global cerebral ischemia (tGCI), as well as underlying its mechanism using a gerbil model of tGCI which shows a loss of pyramidal neurons in the hippocampal cornu ammonis 1 (CA1) area after 5 min of tGCI. Fucoidan (25 and 50 mg/kg) was intraperitoneally administered once daily for 5 days before tGCI. Pretreatment with 50 mg/kg of fucoidan, not 25 mg/kg of fucoidan, attenuated tGCI-induced hyperactivity and protected CA1 pyramidal neurons from tGCI. In addition, pretreatment with 50 mg/kg of fucoidan inhibited activations of astrocytes and microglia in the ischemic CA1 area. Furthermore, pretreatment with 50 mg/kg of fucoidan significantly reduced the increased 4-hydroxy-2-noneal and superoxide anion radical production in the ischemic CA1 area and significantly increased expressions of SOD1 and SOD2 in the CA1 pyramidal neurons before and after tGCI. Additionally, treatment with diethyldithiocarbamate (an inhibitor of SODs) to the fucoidan-treated gerbils notably abolished the fucoidan-mediated neuroprotection. In brief, our present results indicate that fucoidan can effectively protect neurons from tGCI through attenuation of activated glial cells and reduction of oxidative stress via increase of SODs. Thus, we strongly suggest that fucoidan can be used as a useful preventive agent in cerebral ischemia.

Protective Effect of Eckol against Acute Hepatic Injury Induced by Carbon Tetrachloride in Mice

Several in vitro studies have shown the potential hepatoprotective properties of eckol, a natural phlorotannin derived from the brown alga. However, the in vivo hepatoprotective potential of eckol has not been determined. In this study, we performed an in vivo study to investigate the protective effect of eckol and its possible mechanisms on the carbon tetrachloride (CCl₄)-induced acute liver injury model in mice. Results revealed that eckol pre-treatment at the dose of 0.5 and 1.0 mg/kg/day for 7 days significantly suppressed the CCl₄-induced increases of alanine transaminase (ALT) and aspartate aminotransferase (AST) levels in serum and meliorated morphological liver injury. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) analysis showed that the number of positive apoptotic hepatocytes in the eckol-treated group was lower than that in the CCl₄ model group. Western blotting analysis also demonstrated the enhanced expression of bcl-2 and suppressed expression of cleaved caspase-3 by eckol. The CCl₄-induced oxidative stress in liver was significantly ameliorated by eckol, which was characterized by reduced malondialdehyde (MDA) formations, and enhanced superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities and glutathione (GSH) content. Moreover, the CCl₄-induced elevations of pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were markedly suppressed in the eckol-treated group. However, eckol enhanced the level of IL-10, a potent anti-inflammatory cytokine, and recruited CD11c⁺ dendritic cells into the liver tissues of CCl₄-treated mice. These results indicated that eckol has the protective effect on CCl₄-induced acute liver injury via multiple mechanisms including anti-apoptosis, anti-oxidation, anti-inflammation and immune regulation.

FOXO3a is essential for murine endometrial decidualization through cell apoptosis during early pregnancy

Embryo implantation is essential for normal pregnancy, and the process of decidualization is critical for embryo implantation. However, the mechanism of decidualization during early pregnancy is still unknown. Forkhead box O3a (FOXO3a) is the most important functional transcription factor of the forkhead box family and is a highly conserved transcription factor of apoptosis-related genes. In the mouse uterus, FOXO3a was found to be expressed regularly from Days 1-7 of early pregnancy. Upon further exploration, it was found that FOXO3a was expressed at significantly higher levels at the implantation site than at the interimplantation site on Days 5-7 of pregnancy. Under artificial decidualization, FOXO3a was highly expressed in the first and second decidual zones. After decidualization, the expression of FOXO3a was significantly increased both in vivo and vitro. In primary stromal cells, apoptosis was reduced by decreased expression of FOXO3a after inducing decidualization. Moreover, when FOXO3a-small interfering RNA was transfected into the uteri of mice, the expression of decidualization- and apoptosis-related factors was impaired. Thus, FOXO3a might play an important role in decidualization during early pregnancy, and cell apoptosis might be one of pathways for FOXO3a-regulated decidualization.

A Review on the Effect of Traditional Chinese Medicine Against Anthracycline-Induced Cardiac Toxicity

Anthracyclines are effective agents generally used to treat solid-tumor and hematologic malignancies. The use of anthracyclines for over 40 years has improved cancer survival statistics. Nevertheless, the clinical utility of anthracyclines is limited by its dose-dependent cardiotoxicity that adversely affects 10-30% of patients. Anthracycline-induced cardiotoxicity may be classified as acute/subacute or chronic/late toxicity and leads to devastating adverse effects resulting in poor quality of life, morbidity, and premature mortality. Traditional Chinese medicine has a history of over 2,000 years, involving both unique theories and substantial experience. Several studies have investigated the potential of natural products to decrease the cardiotoxic effects of chemotherapeutic agents on healthy cells, without negatively affecting their antineoplastic activity. This article discusses the mechanism of anthracycline-induced cardiotoxicity, and summarizes traditional Chinese medicine treatment for anthracycline-induced heart failure (HF), cardiac arrhythmia, cardiomyopathy, and myocardial ischemia in recent years, in order to provide a reference for the clinical prevention and treatment of cardiac toxicity.

Amelioration of streptozotocin‑induced pancreatic β cell damage by morin: Involvement of the AMPK‑FOXO3‑catalase signaling pathway

Pancreatic β cells are sensitive to oxidative stress, which is one of the predominant causes of cell damage and the emergence of diabetes. The identification of effective therapeutic strategies to protect pancreatic cells from oxidative stress has increased interest in the screening of antioxidants from natural products. The present study aimed to investigate the protective effects of morin against streptozotocin (STZ)‑induced cell damage in a rat insulinoma cell line (RINm5F pancreatic β cells) and to identify the underlying mechanisms. The results indicated that morin inhibited the increase in intracellular reactive oxygen species, attenuated the activity of poly (ADP‑ribose) polymerase, restored intracellular nicotinamide adenine dinucleotide levels and reduced the apoptotic cell death of STZ‑treated pancreatic β cells. Treatment with morin significantly upregulated catalase in pancreatic β cells, and ameliorated the STZ‑induced loss of catalase at the genetic, protein and enzymatic level. In further experiments, morin induced the phosphorylation of 5' adenosine monophosphate‑activated protein kinase (AMPK), which subsequently promoted the translocation of forkhead box O3 (FOXO3) to the nucleus. Specific small interfering RNAs (siRNAs) against AMPK and FOXO3 suppressed morin‑induced catalase expression. Furthermore, catalase‑specific siRNA abolished the protective effects of morin against STZ‑stimulated cell death. Taken together, these results indicated that morin protected RINm5F cells from STZ‑induced cell damage by triggering the phosphorylation of AMPK, thus resulting in subsequent activation of FOXO3 and induction of catalase.

Cardioprotective Effects of a Phlorotannin Extract Against Doxorubicin-Induced Cardiotoxicity in a Rat Model

Long-term therapy with doxorubicin (DOX) is associated with high incidence of cumulative and irreversible dilated cardiomyopathy. The goal of this study was to evaluate the cardioprotective effects and safety of a phlorotannin extract from a brown algae Ecklonia cava (Seapolynol™, SPN) against DOX-induced cardiotoxicity in a rat model. A total of 42 rats were divided into six groups: control, low-dose SPN (LDS), high-dose SPN (HDS), DOX, DOX with low-dose SPN (DOX+LDS), and DOX with high-dose SPN (DOX+HDS). Echocardiography was performed at baseline and after 6 weeks. In left ventricular (LV) ejection fraction, DOX and DOX+LDS groups showed significant decreases (P < .001), while LDS, HDS, and DOX+HDS groups showed no significant change compared with control group. In LV mass index, DOX and DOX+LDS groups showed significant increases (P < .001 and P = .013), while LDS, HDS, and DOX+HDS groups showed no significant change compared with control group. In electron microscopy of the LV wall tissue, DOX+HDS group showed markedly less impaired myofibrils and mitochondria compared with both DOX and DOX+LDS groups. On the findings in echocardiography and electron microscopy, 6-week oral administration of SPN was safe and cardioprotective in a DOX-induced rat cardiotoxicity model in a dose-dependent manner.

Recent advances in pharmacological research on Ecklonia species: a review

The genus Ecklonia (Lessoniaceae, Phaeophyceae), commonly called kelp (brown algae), is abundant on the coasts of Japan and Korea. During the past few decades, Ecklonia species have received tremendous attention for their wide range of therapeutic properties and multiple health benefits, such as great nutritional value and being rich in vitamins, minerals, dietary fiber, proteins, and polysaccharides. Several novel functional ingredients with diversified biological activities have been isolated and possess antimicrobial, antiviral, hepatoprotective, cardioprotective, anti-inflammatory, neuroprotective, anticarcinogenic, immunomodulatory, hypolipidemic, anti-diabetic, and antioxidant therapeutic properties. The present review discusses the phytochemical, pharmacological, therapeutic, nutritional, and health benefits of different species of genus Ecklonia, as well as their use in the prevention of disease and maintenance of good health.

Vitexin attenuates acute doxorubicin cardiotoxicity in rats via the suppression of oxidative stress, inflammation and apoptosis and the activation of FOXO3a

Doxorubicin (DOX) is one of the most effective chemotherapeutic drugs. However, its clinical use has been hampered due to the development of cardiotoxicity. Vitexin, which is the active ingredient of hawthorn leaf extract, has various biological activities, including antioxidant and anti-inflammatory actions. The present study aimed to investigate whether vitexin was able to protect against DOX-induced acute cardiotoxicity in model rats and the mechanisms of this protective effect were assessed. Adult Sprague-Dawley rats were randomly assigned into the control (saline only), model (DOX only) and vitexin-treated (DOX plus vitexin) groups. Rats in the model and vitexin-treated groups were injected with DOX (2 mg/kg; i.p.) once a week for 4 weeks. Rats in the vitexin-treated group were administered 30 mg/kg oral vitexin once daily at doses for 4 weeks. The levels of lactate dehydrogenase, creatine kinase isoenzyme-MB, malondialdehyde, superoxide dismutase, catalase and myeloperoxidase were assessed using assay kits. The levels of inflammatory mediators, including tumor necrosis factor-α, interleukin (IL)-1β, IL-6, nuclear factor (NF)-κB, and caspase-3, were assayed by the enzyme-linked immunosorbent assay method. Western blot analysis was performed to assess the protein expression levels of p-FOXO3a. Vitexin pretreatment significantly protected against DOX-induced myocardial damage, which was characterized by increased serum creatine kinase isoenzyme-MB and lactate dehydrogenase. Vitexin significantly ameliorated oxidative stress injury evoked by DOX, demonstrated by the inhibition of lipid peroxidation and the elevation of antioxidant enzyme activities. Furthermore, DOX provoked inflammatory responses by increasing the expression levels of IL-1β, IL-6, NF-κB and tumor necrosis factor-α, whereas vitexin pretreatment significantly inhibited these inflammatory responses. Notably, DOX induced apoptotic tissue damage by increasing caspase-3 activity, whereas vitexin administration was able to decrease caspase-3 activity. In addition, vitexin induced elevated FOXO3a protein expression levels in the vitexin-treated group. In conclusion, the findings of the present study suggested that vitexin possesses cardioprotective action against DOX-induced cardiotoxicity by suppressing oxidative stress, inflammation and apoptotic signals.

Gallic Acid Promotes Wound Healing in Normal and Hyperglucidic Conditions

Skin is the outermost layer of the human body that is constantly exposed to environmental stressors, such as UV radiation and toxic chemicals, and is susceptible to mechanical wounding and injury. The ability of the skin to repair injuries is paramount for survival and it is disrupted in a spectrum of disorders leading to skin pathologies. Diabetic patients often suffer from chronic, impaired wound healing, which facilitate bacterial infections and necessitate amputation. Here, we studied the effects of gallic acid (GA, 3,4,5-trihydroxybenzoic acid; a plant-derived polyphenolic compound) on would healing in normal and hyperglucidic conditions, to mimic diabetes, in human keratinocytes and fibroblasts. Our study reveals that GA is a potential antioxidant that directly upregulates the expression of antioxidant genes. In addition, GA accelerated cell migration of keratinocytes and fibroblasts in both normal and hyperglucidic conditions. Further, GA treatment activated factors known to be hallmarks of wound healing, such as focal adhesion kinases (FAK), c-Jun N-terminal kinases (JNK), and extracellular signal-regulated kinases (Erk), underpinning the beneficial role of GA in wound repair. Therefore, our results demonstrate that GA might be a viable wound healing agent and a potential intervention to treat wounds resulting from metabolic complications.

A load of mice to hypergravity causes AMPKα repression with liver injury, which is overcome by preconditioning loads via Nrf2

An understanding of the effects of hypergravity on energy homeostasis is necessary in managing proper physiological countermeasures for aerospace missions. This study investigated whether a single or multiple load(s) of mice to hypergravity has an effect on molecules associated with energy metabolism. In the liver, AMPKα level and its signaling were repressed 6 h after a load to +9 Gz hypergravity for 1 h, and then gradually returned toward normal. AMPKα level was restored after 3 loads to +9 Gz, suggestive of preconditioning adaptation. In cDNA microarray analyses, 221 genes were differentially expressed by +9 Gz, and the down-regulated genes included Nrf2 targets. Nrf2 gene knockout abrogated the recovery of AMPKα elicited by 3 loads to +9 Gz, indicating that Nrf2 plays a role in the adaptive increase of AMPKα. In addition, +9 Gz stress decreased STAT3, FOXO1/3 and CREB levels, which was attenuated during the resting time. Similarly, apoptotic markers were enhanced in the liver, indicating that the liver may be vulnerable to hypergravity stress. Preconditioning loads prevented hepatocyte apoptosis. Overall, a load of mice to +9 Gz hypergravity causes AMPKα repression with liver injury, which may be overcome by multiple loads to hypergravity as mediated by Nrf2.

Hydrogen-rich water attenuates amyloid β-induced cytotoxicity through upregulation of Sirt1-FoxO3a by stimulation of AMP-activated protein kinase in SK-N-MC cells

Amyloid β (Aβ) peptides are identified in cause of neurodegenerative diseases such as Alzheimer's disease (AD). Previous evidence suggests Aβ-induced neurotoxicity is linked to the stimulation of reactive oxygen species (ROS) production. The accumulation of Aβ-induced ROS leads to increased mitochondrial dysfunction and triggers apoptotic cell death. This suggests antioxidant therapies may be beneficial for preventing ROS-related diseases such as AD. Recently, hydrogen-rich water (HRW) has been proven effective in treating oxidative stress-induced disorders because of its ROS-scavenging abilities. However, the precise molecular mechanisms whereby HRW prevents neuronal death are still unclear. In the present study, we evaluated the putative pathways by which HRW protects against Aβ-induced cytotoxicity. Our results indicated that HRW directly counteracts oxidative damage by neutralizing excessive ROS, leading to the alleviation of Aβ-induced cell death. In addition, HRW also stimulated AMP-activated protein kinase (AMPK) in a sirtuin 1 (Sirt1)-dependent pathway, which upregulates forkhead box protein O3a (FoxO3a) downstream antioxidant response and diminishes Aβ-induced mitochondrial potential loss and oxidative stress. Taken together, our findings suggest that HRW may have potential therapeutic value to inhibit Aβ-induced neurotoxicity.

Acute exercise induced mitochondrial H₂O₂ production in mouse skeletal muscle: association with p(66Shc) and FOXO3a signaling and antioxidant enzymes

Exercise induced skeletal muscle phenotype change involves a complex interplay between signaling pathways and downstream regulators. This study aims to investigate the effect of acute exercise on mitochondrial H2O2 production and its association with p(66Shc), FOXO3a, and antioxidant enzymes. Male ICR/CD-1 mice were subjected to an acute exercise. Muscle tissues (gastrocnemius and quadriceps femoris) were taken after exercise to measure mitochondrial H2O2 content, expression of p(66Shc) and FOXO3a, and the activity of antioxidant enzymes. The results showed that acute exercise significantly increased mitochondrial H2O2 content and expressions of p(66Shc) and FOXO3a in a time-dependent manner, with a linear correlation between the increase in H2O2 content and p(66Shc) or FOXO3a expression. The activity of mitochondrial catalase was slightly reduced in the 90 min exercise group, but it was significantly higher in groups with 120 and 150 min exercise compared to that of 90 min exercise group. The activity of SOD was not significantly affected. The results indicate that acute exercise increases mitochondrial H2O2 production in the skeletal muscle, which is associated with the upregulation of p(66Shc) and FOXO3a. The association of p(66Shc) and FOXO3a signaling with exercise induced H2O2 generation may play a role in regulating cellular oxidative stress during acute exercise.