A potent phosphodiester Keap1-Nrf2 protein-protein interaction inhibitor as the efficient treatment of Alzheimer's disease

Phenylpropanoids of Eleutherococcus senticosus (Rupr. & maxim.) maxim. Alleviate oxidative stress in Alzheimer's disease in vitro and in vivo models by regulating Mst1 and affecting the Nrf2/Sirt3 pathway

Alzheimer's disease (AD) is a common neurodegenerative disorder, and oxidative stress plays a significant role in its progression. Owing to its nourishing effects, Eleutherococcus senticosus (Rupr. & maxim.) maxim. (ES) has gained widespread popularity globally as a functional food and long-term consumption has been shown to enhance memory. The phenylpropanoid components extracted from Eleutherococcus senticosus (Rupr. & maxim.) maxim. (ESP) exhibit a diverse array of bioactivities and are commonly employed in the treatment of central nervous system (CNS) disorders. Nonetheless, the exact mechanisms by which ESP alleviates oxidative stress in AD models require further investigation. Therefore, this study utilized SAMP8 mice as models for AD and employed L-glutamate (L-Glu)-induced HT22 cells to establish an in vitro AD model. The effects of ESP on cognitive function were evaluated using the Morris water maze (MWM) test. Additionally, various techniques such as pathology, immunofluorescence staining (IF), ROS staining, cellular thermal shift assay (CETSA), Mst1 inhibitor analysis, and western blotting (WB) were conducted to further investigate the pharmacological efficacy and potential molecular mechanisms of ESP. In vivo, ESP was found to improve cognitive function in SAMP8 mice and alleviate AD-like pathological features. In vitro, ESP reduced intracellular ROS levels. Mechanistically, CETSA analysis confirmed the binding affinity between ESP and Mst1, demonstrated that ESP modulated the Mst1 signaling pathway to mitigate oxidative stress and decrease ROS levels. These findings suggested that ESP holded significant potential for developing therapeutic strategies for AD.

Design of anti-depressant phosphodiester amino acidic Keap1-Nrf2 protein-protein interaction inhibitors

Inhibiting the protein-protein interaction (PPI) between Keap1 and Nrf2 is theoretically an effective and safe strategy for activation of Nrf2 pathway to treat major depressive disorder (MDD). In this study, through bioinformatic analysis of the brain tissues and peripheral blood of MDD patients and depressive mice, we confirmed the involvement of oxidative stress, inflammation, and the Keap1-Nrf2 pathway in depression. Subsequently, we developed a series of phosphodiester amino acidic diaminonaphthalene compounds as Keap1-Nrf2 PPI inhibitors for the first time. Screening using the LPS-stimulated SH-SY5Y and BV2 cell models identified compound 4-95 showing the best anti-oxidative stress and anti-inflammatory efficacy. The ability of 4-95 to penetrate the blood-brain-barrier was significantly enhanced. In a chronic unpredictable mild stress mouse model, treatment with 4-95 effectively ameliorated anxiety and depression behavior and restored serum neurotransmitter levels by promoting the Nrf2 nuclear translocation. Consequently, oxidative stress was reduced, and the expression of synaptic plasticity biomarkers, such as postsynaptic density protein 95 (PSD95) and synapsin 1 (SYN1) were significantly increased, suggesting the recovery of neuronal function. Collectively, our findings demonstrate that the Keap1-Nrf2 PPI inhibitor holds great promise as a preclinical candidate for the treatment of depression.

Structure-based molecular hybridization design and synthesis of Keap1-Nrf2 inhibitors for anti-inflammatory treatment

The Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway stands as a pivotal mechanism in defending against oxidative stress damage and related inflammation. Blocking the Keap1-Nrf2 protein-protein interaction (PPI) offers a promising therapeutic approach for treating diseases related to oxidative stress and inflammation. Our group previously reported NXPZ-2, a naphthalene sulfonamide derivative targeting Keap1, which effectively inhibits the Keap1-Nrf2 PPI, thereby releasing Nrf2 to exert its anti-inflammatory and antioxidant effects. In the present work, we employed a structure-based molecular hybridization strategy to design a series of novel naphthalene sulfonamides by combining NXPZ-2 with the Nrf2 activator dimethyl fumarate (DMF) or its analogues. Among these new derivatives, compound 1c, specifically (Z)-4-((4-(N-(2-amino-2-oxoethyl)-N-(4-((N-(2-amino-2-oxoethyl)-4-methoxyphenyl)sulfonamide)naphthalen-1-yl) sulfamoyl)phenyl)amino)-4-oxobut-2-enoic acid, exhibited the highest PPI inhibitory activity, with a KD2 value of 0.119 μM. In an LPS-induced RAW264.7 cell model, this compound mitigated LPS-induced cellular damage, suppressed the expression of pro-inflammatory cytokine TNF-α and IL-6, and significantly elevated the intracellular GSH and SOD enzyme activities. Furthermore, in an LPS-induced acute lung injury (ALI) mouse model, the compound demonstrated a remarkable ability to alleviate oxidative damage and inflammation in the lungs. In conclusion, this novel naphthalene sulfonamide represents a promising drug candidate for Keap1-targeting therapy in ALI. Molecular docking analysis revealed that the amide and maleic acid groups of 1c facilitate strong interactions with the Kelch domain of Keap1, explaining the compound's preference for binding through hydrogen bonding and π-π stacking interactions.

A Keap1-recruiting BRD4 degrader offers a single-molecular polypharmacology approach for the treatment of metabolic dysfunction-associated steatohepatitis

The pathogenesis of metabolic dysfunction-associated steatohepatitis (MASH) involves multiple pathophysiological processes, including abnormal lipid metabolism, insulin resistance, oxidative stress, endoplasmic reticulum stress, inflammatory response, and fibrosis. These factors interact to form a complex network and the development of synergistic and pleiotropic drug modalities targeting multiple pathogenesis of MASH may have a better therapeutic effect. Herein, the bifunctional proteolytic targeting chimeras (PROTAC) technology was utilized for developing pleiotropic drugs for MASH treatment. We constructed a Keap1-recruiting degrader KB-3 which stabilizes the natural Keap1 target Nrf2 and degrades BRD4 synergistically, exhibiting combined therapeutic advantages against MASH-related pathologies. Experimental results confirmed that KB-3 could effectively alleviate MASH in mice by improving lipid metabolic disorder, enhancing the defense against oxidative stress, reducing inflammation, and delaying the progression of liver fibrosis. Such Keap1-recruiting degrader offering a single-molecular approach with polypharmacology effects may be an attractive strategy for the treatment of multifactorial disease.

Fluorinated sulfonamide-flavonoid derivatives as novel Keap1-Nrf2 inhibitors: Potent induction of cytoprotective gene HO-1 in vivo

Nuclear factor-erythroid 2 related factor 2 (Nrf2) is a key regulator in cellular defense against oxidative stress. While flavonoids have been identified as Nrf2 activators by inhibiting Keap1-Nrf2 protein-protein interaction (PPI), their limited bioactivity presents significant challenges for therapeutic applications. To compensate for this shortcoming, 28 sulfonamide-flavonoid analogues targeting the Keap1-Nrf2 PPI were synthesized by a fragment-based approach. Among these, SG16, which incorporates a fluorine atom, exhibited potent Nrf2-activated capacity and notable anti-inflammatory properties. In AML12 hepatocytes, SG16 significantly enhanced the expression of antioxidant genes by promoting Nrf2 nuclear translocation. In an acute liver injury (ALI) mouse model, SG16 treatment led to a substantial, hundredfold upregulation of the cytoprotective gene HO-1 mRNA. Meanwhile, a dose-dependent decline in ALT, AST, and inflammatory cytokine levels was observed, reflecting improved liver function. Histopathological evaluations, including hematoxylin and eosin (HE) staining, TUNEL, myeloperoxidase (MPO) activity assessment, and F4/80 macrophage marker analysis, consistently demonstrated substantial attenuation of liver tissue damage following SG16 treatment. Moreover, Co-IP assays combined with experiments in Nrf2 knockout mice suggested that the novel sulfonamide-containing flavonoids are a promising class of Nrf2-targeted therapeutic candidates, warranting further exploration for oxidative stress-related disorders.

Acupuncture Ameliorates Alzheimer's-Like Cognitive Impairment and Pathological Changes via Regulating the Intestinal Fungal Community in APP/PS1 Mice

Background

The disorder of the intestinal fungal community is closely associated with Alzheimer's disease (AD). Gut fungal dysbiosis exacerbates β-amyloid (Aβ) plaque burden through the brain-gut axis, thereby promoting the progression of AD. Previous research has demonstrated that acupuncture can ameliorate AD symptoms by modulating the gut bacterial community. However, the potential regulatory effects of acupuncture on the fungal microbiota have been largely overlooked.

Methods

APP/PS1 mice were used as AD animal model and randomly divided into the AD model (AD) group, the acupuncture (Ac) group, and the probiotics (Pr) group. Mice in the Ac group received acupuncture treatment. In the Pr group, mice were treated with probiotics. Morris water maze, ITS sequencing, immunofluorescence (IF) staining, enzyme-linked immunosorbent assay (ELISA), Hematoxylin and eosin analysis, and Nissl staining were employed to validate our hypothesis.

Results

Acupuncture and probiotics significantly improved the behavioral performance of APP/PS1 mice, reduced the level of Aβ in the brain, and alleviated neuronal damage. Moreover, acupuncture improved the Sobs, Chao and Ace indices, decreased the abundance of Ascomycota, Aspergilaceae, Trichocomaceae, Candida, and unclassified-penicillium, while simultaneously increasing the abundance of Basidiomycota, which differed from the fungal regulation observed with probiotics.

Conclusion

Acupuncture may improve the cognitive impairment of APP/PS1 mice, reduce Aβ plaque burden in the brain, protect neurons, and mitigate intestinal fungi dysbiosis. The beneficial effects of acupuncture on Aβ deposition and cognitive function in APP/PS1 mice may be achieved by regulating the intestinal fungal community.

Health position paper and redox perspectives - Bench to bedside transition for pharmacological regulation of NRF2 in noncommunicable diseases

Nuclear factor erythroid 2-related factor 2 (NRF2) is a redox-activated transcription factor regulating cellular defense against oxidative stress, thereby playing a pivotal role in maintaining cellular homeostasis. Its dysregulation is implicated in the progression of a wide array of human diseases, making NRF2 a compelling target for therapeutic interventions. However, challenges persist in drug discovery and safe targeting of NRF2, as unresolved questions remain especially regarding its context-specific role in diseases and off-target effects. This comprehensive review discusses the dualistic role of NRF2 in disease pathophysiology, covering its protective and/or destructive roles in autoimmune, respiratory, cardiovascular, and metabolic diseases, as well as diseases of the digestive system and cancer. Additionally, we also review the development of drugs that either activate or inhibit NRF2, discuss main barriers in translating NRF2-based therapies from bench to bedside, and consider the ways to monitor NRF2 activation in vivo.

Patenting perspective on Keap1 inhibitors (2019-2024)

INTRODUCTION

Kelch-like ECH-associated protein 1 (Keap1), an E3 ligase negatively regulating the nuclear factor erythroid 2-related factor 2 (Nrf2), has emerged as an auspicious drug target for treating ailments associated with oxidative stress and inflammation. Discovery of Keap1 inhibitors have attracted significant interest.

AREAS COVERED

This review covers patents on Keap1 inhibitors from 2019 to 2024, providing a comprehensive analysis of their structural characteristics, optimization strategies, pharmacological properties and clinical progress.

EXPERT OPINION

Extensive efforts have been devoted to enhance potency and drug-like properties of Keap1 inhibitors. Strategies such as ROS-cleavable prodrug design, bivalent inhibition and PROTACs are emerging. As the range of drug types and applications expands, Keap1 inhibitors are becoming a sagacious option for disease treating.

Ginsenoside Rg1 improves autophagy dysfunction to ameliorate Alzheimer's disease via targeting FGR proto-oncogene

Alzheimer's disease (AD) is a neurodegeneration driven by beta-amyloid (Aβ) deposits in the brain involving autophagy dysfunction. Ginsenoside Rg1, a pharmacologically active compound found in ginseng, has possible therapeutic effects for AD. This study discovered that FGR proto-oncogene (FGR) was a therapeutic target of Rg1 in AD and it was possibly involved in autophagy. C57BL/6 J mice were injected with 5 μL (1 μg/mL) Aβ1-42 in the right lateral ventricle to establish an AD model. AD mouse hippocampus had high FGR expression. Intragastrically administered Rg1 (40 mg/kg) decreased FGR protein levels in AD mice's hippocampus and improved memory function in AD mice. Both sides of the mice hippocampal fissure were administered with 2 μL lentiviral particles (1 × 107 TU) containing FGR overexpression plasmids. FGR overexpression rendered Rg1 ineffectual in restoring memory function and reducing hippocampal neuron damage. We injected 2 μL lentiviral particles (1 × 107 TU) containing short hairpin RNA plasmids targeting FGR to the mice hippocampal fissures. FGR knockdown improved spatial memory function of AD mice, reduced hippocampal neuron apoptosis, and prevented Aβ accumulation. HT22 cells were transfected with small interfering RNA targeting FGR. FGR knockdown increased the viability of Aβ1-42 treated HT22 cells. BACE1 and LC3II/I protein levels were decreased and p62 and SIRT1 were increased in AD mice and cells with FGR knockdown. LC3 was down-regulated after inhibiting FGR expression in Aβ1-42 treated hippocampal neurons. In conclusion, Rg1 exerts anti-AD functions by targeting FGR and downregulating its expression.

Model organisms for investigating the functional involvement of NRF2 in non-communicable diseases

Non-communicable chronic diseases (NCDs) are most commonly characterized by age-related loss of homeostasis and/or by cumulative exposures to environmental factors, which lead to low-grade sustained generation of reactive oxygen species (ROS), chronic inflammation and metabolic imbalance. Nuclear factor erythroid 2-like 2 (NRF2) is a basic leucine-zipper transcription factor that regulates the cellular redox homeostasis. NRF2 controls the expression of more than 250 human genes that share in their regulatory regions a cis-acting enhancer termed the antioxidant response element (ARE). The products of these genes participate in numerous functions including biotransformation and redox homeostasis, lipid and iron metabolism, inflammation, proteostasis, as well as mitochondrial dynamics and energetics. Thus, it is possible that a single pharmacological NRF2 modulator might mitigate the effect of the main hallmarks of NCDs, including oxidative, proteostatic, inflammatory and/or metabolic stress. Research on model organisms has provided tremendous knowledge of the molecular mechanisms by which NRF2 affects NCDs pathogenesis. This review is a comprehensive summary of the most commonly used model organisms of NCDs in which NRF2 has been genetically or pharmacologically modulated, paving the way for drug development to combat NCDs. We discuss the validity and use of these models and identify future challenges.

Oral iron sulfide prevents acute alcohol intoxication by initiating the endogenous multienzymatic antioxidant defense system

Acute alcohol intoxication could cause multiorgan damage, including nervous, digestive, and cardiovascular systems, and in particular, irreversible damage to the brain and liver. Emerging studies have revealed that the endogenous multienzymatic antioxidant defense system (MEAODS) plays a central role in preventing oxidative stress and other toxicological compounds produced by alcohol. However, few available drugs could quickly regulate MEAODS. Herein, we report a nanosized iron sulfide (nFeS) that can rapidly release polysulfide species in gastric juice. The released hydrogen polysulfide activates the Keap1/Nrf2 pathway via S-persulfidation of cysteine residues in Keap1, which promotes the expression of antioxidant enzymes and glutathione synthesis-related enzymes, thus potentiating MEAODS. Results indicate that the activated MEAODS not only alleviates oxidative stress and inflammation in the brain and liver but also mitigates movement dysfunction after only 2.5 hours of oral nFeS treatment. Collectively, this study provides a MEAODS-regulated strategy with nFeS and may aid the prevention of acute alcoholic injury.

Therapeutic effect of nicotinamide mononucleotide on Alzheimer's disease through activating autophagy and anti-oxidative stress

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the deposition of β-amyloid (Aβ) plaques and neurofibrillary tangles composed of tau protein in the brain. These neuropathological hallmarks contribute to cognitive impairment by inducing neuronal loss in the cerebral cortex and hippocampus. Unfortunately, current therapeutic approaches only target symptomatic relief and do not impede disease progression. Nicotinamide mononucleotide (NMN), a precursor of nicotinamide adenine dinucleotide (NAD+), has emerged as a promising candidate for the treatment of age-related neurodegenerative disorders. NMN supplementation could restore NAD+ levels, thereby alleviating neuronal damage and slowing the progression of AD and other aging-associated diseases. AD is closely associated with autophagic impairment and oxidative stress. Our in vivo experiments demonstrated that NMN could ameliorate pathological and behavioral impairments in AD mice. Specifically, NMN enhanced autophagy and promoted p-tau clearance. Meanwhile, NMN could activate the Nrf2/Keap1/NQO1 pathway, thereby reducing the oxidative stress. Immunofluorescence results demonstrated that NMN could alleviate neuronal damage in AD mice. Furthermore, in vitro results showed that the p-tau clearance and antioxidant stress effects of NMN were suppressed by autophagy inhibitor, chloroquine (CQ) or bafilomycin A1 (BafA1), in Aβ-induced PC12 cells. Lastly, when Nrf2 was knocked down, the antioxidant stress, autophagy enhancement, and p-tau clearance effects of NMN were all inhibited. In conclusion, our research indicates that NMN exerts therapeutic effect against AD by activating autophagy and the Nrf2/Keap1/NQO1 pathway through a mutual regulating mechanism of autophagy and antioxidative stress. These findings highlight the promising potential of NMN for the treatment of AD.

Recent advances in Alzheimer's disease: Mechanisms, clinical trials and new drug development strategies

Alzheimer's disease (AD) stands as the predominant form of dementia, presenting significant and escalating global challenges. Its etiology is intricate and diverse, stemming from a combination of factors such as aging, genetics, and environment. Our current understanding of AD pathologies involves various hypotheses, such as the cholinergic, amyloid, tau protein, inflammatory, oxidative stress, metal ion, glutamate excitotoxicity, microbiota-gut-brain axis, and abnormal autophagy. Nonetheless, unraveling the interplay among these pathological aspects and pinpointing the primary initiators of AD require further elucidation and validation. In the past decades, most clinical drugs have been discontinued due to limited effectiveness or adverse effects. Presently, available drugs primarily offer symptomatic relief and often accompanied by undesirable side effects. However, recent approvals of aducanumab (1) and lecanemab (2) by the Food and Drug Administration (FDA) present the potential in disrease-modifying effects. Nevertheless, the long-term efficacy and safety of these drugs need further validation. Consequently, the quest for safer and more effective AD drugs persists as a formidable and pressing task. This review discusses the current understanding of AD pathogenesis, advances in diagnostic biomarkers, the latest updates of clinical trials, and emerging technologies for AD drug development. We highlight recent progress in the discovery of selective inhibitors, dual-target inhibitors, allosteric modulators, covalent inhibitors, proteolysis-targeting chimeras (PROTACs), and protein-protein interaction (PPI) modulators. Our goal is to provide insights into the prospective development and clinical application of novel AD drugs.

Αnti-prion effects of anthocyanins

Prion diseases, also known as Transmissible Spongiform Encephalopathies (TSEs), are protein-based neurodegenerative disorders (NDs) affecting humans and animals. They are characterized by the conformational conversion of the normal cellular prion protein, PrPC, into the pathogenic isoform, PrPSc. Prion diseases are invariably fatal and despite ongoing research, no effective prophylactic or therapeutic avenues are currently available. Anthocyanins (ACNs) are unique flavonoid compounds and interest in their use as potential neuroprotective and/or therapeutic agents against NDs, has increased significantly in recent years. Therefore, we investigated the potential anti-oxidant and anti-prion effects of Oenin and Myrtillin, two of the most common anthocyanins, using the most accepted in the field overexpressing PrPScin vitro model and a cell free protein aggregation model. Our results, indicate both anthocyanins as strong anti-oxidant compounds, upregulating the expression of genes involved in the anti-oxidant response, and reducing the levels of Reactive Oxygen Species (ROS), produced due to pathogenic prion infection, through the activation of the Keap1-Nrf2 pathway. Importantly, they showcased remarkable anti-prion potential, as they not only caused the clearance of pathogenic PrPSc aggregates, but also completely inhibited the formation of PrPSc fibrils in the Cerebrospinal Fluid (CSF) of patients with Creutzfeldt-Jakob disease (CJD). Therefore, Oenin and Myrtillin possess pleiotropic effects, suggesting their potential use as promising preventive and/or therapeutic agents in prion diseases and possibly in the spectrum of neurodegenerative proteinopathies.

Developing theragnostics for Alzheimer's disease: Insights from cancer treatment

The prevalence of Alzheimer's disease (AD) and its associated economic and societal burdens are on the rise, but there are no curative treatments for AD. Interestingly, this neurodegenerative disease shares several biological and pathophysiological features with cancer, including cell-cycle dysregulation, angiogenesis, mitochondrial dysfunction, protein misfolding, and DNA damage. However, the genetic factors contributing to the overlap in biological processes between cancer and AD have not been actively studied. In this review, we discuss the shared biological features of cancer and AD, the molecular targets of anticancer drugs, and therapeutic approaches. First, we outline the common biological features of cancer and AD. Second, we describe several anticancer drugs, their molecular targets, and their effects on AD pathology. Finally, we discuss how protein-protein interactions (PPIs), receptor inhibition, immunotherapy, and gene therapy can be exploited for the cure and management of both cancer and AD. Collectively, this review provides insights for the development of AD theragnostics based on cancer drugs and molecular targets.

Water extract of moschus alleviates erastin-induced ferroptosis by regulating the Keap1/Nrf2 pathway in HT22 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Moschus, first described in the Shennong's Classic of the Materia medicine, is a scarce and precious animal medicine. Modern pharmacological researches have suggested that Moschus has neuroprotective actions, and its mechanism is related to anti-inflammatory, antioxidant, and anti-apoptosis effects. Ferroptosis is one of the major pathologies of Alzheimer's disease (AD) and is widely implicated in the pathogenesis and progression of AD. Although previous studies have suggested that Moschus possesses neuroprotective effect, whether Moschus could mitigate neuronal damages by inhibiting the onset of ferroptosis is unknown in model cells of AD.

AIM OF THE STUDY

The aim of study was to explore the water extract of Moschus (WEM) on ferroptosis caused by erastin and the potential mechanism.

MATERIALS AND METHODS

Erastin was used to stimulate HT22 cells to form ferroptosis model to evaluate the anti-ferroptosis effect of WEM by cell counting kit-8 and lactic dehydrogenase (LDH) tests. The malondialdehyde (MDA) and glutathione (GSH) kits are used for detection of MDA and GSH levels, and 2',7'-dichlorofluorescein diacetate and C11 BODIPY 581/591 fluorescence probe are used for evaluation of reactive oxygen species (ROS) and lipid peroxide (LOOH) levels. And Western blot was used to test nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap1), heme oxygenase-1 (HO-1), and ferroptosis associated proteins including glutathione peroxidase 4 (GPX4), cystine/glutamate antiporter subunit (SLC7A11), ferritin heavy chain 1 (FTH1), ferroportin1 (FPN1), transferrin receptor (TFRC). In addition, the Nrf2 inhibitor ML385 was applied to verify whether WEM prevents erastin-induced ferroptosis by activating the Keap1/Nrf2 pathway.

RESULTS

After WEM treatment, erastin-induced HT22 cell survival was significantly elevated, the accumulation of intracellular MDA, ROS, and LOOH were significantly reduced, the level of GSH and expressions of ferroptosis inhibitors GPX4 and SLC7A11 were significantly increased, and iron metabolism-related proteins TFRC, FPN1, and FTH1 were regulated. These effects of WEM are implemented by activating the Keap1/Nrf2 pathway.

CONCLUSIONS

This study demonstrated that WEM could perform neuroprotective effects by alleviating ferroptosis, verified that WEM treatment of AD can be mediated by the Keap1/Nrf2 pathway, and provided theoretical support for the application of WEM in the treatment of AD.

Neuroprotective effect of acetoxypachydiol against oxidative stress through activation of the Keap1-Nrf2/HO-1 pathway

BACKGROUND

Excessive oxidative stress in the brain is an important pathological factor in neurological diseases. Acetoxypachydiol (APHD) is a lipophilic germacrane-type diterpene extracted as a major component from different species of brown algae within the genus Dictyota. There have been no previous reports on the pharmacological activity of APHD. The present research aims to explore the potential neuroprotective properties of APHD and its underlying mechanisms.

METHODS

The possible mechanism of APHD was predicted using a combination of molecular docking and network pharmacological analysis. PC12 cells were induced by H2O2 and oxygen-glucose deprivation/reoxygenation (OGD/R), respectively. Western blot, flow cytometry, immunofluorescence staining, and qRT-PCR were used to investigate the antioxidant activity of APHD. The HO-1 inhibitor ZnPP and Nrf2 gene silencing were employed to confirm the influence of APHD on the signaling cascade involving HO-1, Nrf2, and Keap1 in vitro.

RESULTS

APHD exhibited antioxidant activity in both PC12 cells subjected to H2O2 and OGD/R conditions by downregulating the release of LDH, the concentrations of MDA, and ROS, and upregulating SOD, GSH-Px, and GSH concentrations. APHD could potentially initiate the Keap1-Nrf2/HO-1 signaling cascade, according to the findings from network pharmacology evaluation and molecular docking. Furthermore, APHD was observed to increase Nrf2 and HO-1 expression at both mRNA and protein levels, while downregulating the protein concentrations of Keap1. Both Nrf2 silencing and treatment with ZnPP reversed the neuroprotective effects of APHD.

CONCLUSIONS

APHD activated antioxidant enzymes and downregulated the levels of LDH, MDA, and ROS in two cell models. The neuroprotective effect is presumably reliant on upregulation of the Keap1-Nrf2/HO-1 pathway. Taken together, APHD from brown algae of the genus Dictyota shows potential as a candidate for novel neuroprotective agents.

Targeting kelch-like (KLHL) proteins: achievements, challenges and perspectives

Kelch-like proteins (KLHLs) are a large family of BTB-containing proteins. KLHLs function as the substrate adaptor of Cullin 3-RING ligases (CRL3) to recognize substrates. KLHLs play pivotal roles in regulating various physiological and pathological processes by modulating the ubiquitination of their respective substrates. Mounting evidence indicates that mutations or abnormal expression of KLHLs are associated with various human diseases. Targeting KLHLs is a viable strategy for deciphering the KLHLs-related pathways and devising therapies for associated diseases. Here, we comprehensively review the known KLHLs inhibitors to date and the brilliant ideas underlying their development.

Axonal injury mediated by neuronal p75NTR/TRAF6/JNK pathway contributes to cognitive impairment after repetitive mTBI

Repetitive mild traumatic brain injury (rmTBI) is one of the leading causes of cognitive disorders. The impairment of axonal integrity induced by rmTBI is speculated to underlie the progression of cognitive dysfunction. However, few studies have uncovered the cellular mechanism regulating axonal impairment. In this study, we showed that after rmTBI, the activation of neuronal p75NTR signaling contributes to abnormal axonal morphology and impaired axonal transport, which further leads to cognitive dysfunction in mice. By neuron-specific knockdown of p75NTR or treatment with p75NTR inhibitor LM11A-31, we observed better recovery of axonal integrity and cognitive function after brain trauma. Further analysis revealed that p75NTR relies on its adaptor protein TRAF6 to activate downstream signaling via TAK1 and JNK. Overall, our results provide novel insight into the role of neuronal p75NTR in axonal injury and suggest that p75NTR may be a promising target for cognitive function recovery after rmTBI.

Understanding mechanisms of antioxidant action in health and disease

Several different reactive oxygen species (ROS) are generated in vivo. They have roles in the development of certain human diseases whilst also performing physiological functions. ROS are counterbalanced by an antioxidant defence network, which functions to modulate ROS levels to allow their physiological roles whilst minimizing the oxidative damage they cause that can contribute to disease development. This Review describes the mechanisms of action of antioxidants synthesized in vivo, antioxidants derived from the human diet and synthetic antioxidants developed as therapeutic agents, with a focus on the gaps in our current knowledge and the approaches needed to close them. The Review also explores the reasons behind the successes and failures of antioxidants in treating or preventing human disease. Antioxidants may have special roles in the gastrointestinal tract, and many lifestyle features known to promote health (especially diet, exercise and the control of blood glucose and cholesterol levels) may be acting, at least in part, by antioxidant mechanisms. Certain reactive sulfur species may be important antioxidants but more accurate determinations of their concentrations in vivo are needed to help assess their contributions.

Advances in developing noncovalent small molecules targeting Keap1

Kelch-like ECH-associated protein 1 (Keap1) is a drug target for diseases involving oxidative stress and inflammation. There are three covalent Keap1-binding drugs on the market, but noncovalent compounds that inhibit the interaction between Keap1 and nuclear factor erythroid 2-related factor 2 (Nrf2) represent an attractive alternative. Both compound types prevent degradation of Nrf2, leading to the expression of antioxidant and antiinflammatory proteins. However, their off-target profiles differ as do their exact pharmacodynamic effects. Here, we discuss the opportunities and challenges of targeting Keap1 with covalent versus noncovalent inhibitors. We then provide a comprehensive overview of current noncovalent Keap1-Nrf2 inhibitors, with a focus on their pharmacological effects, to examine the therapeutic potential for this compound class.

The untapped potential of targeting NRF2 in neurodegenerative disease

Since its initial discovery almost three decades ago, the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) has been shown to regulate a host of downstream transcriptional responses and play a critical role in preventing or promoting disease progression depending on the context. Critically, while the importance of proper nuclear factor erythroid 2-related factor 2 function has been demonstrated across a variety of pathological settings, the ability to progress NRF2-targeted therapeutics to clinic has remained frustratingly elusive. This is particularly true in the case of age-related pathologies, where nuclear factor erythroid 2-related factor 2 is a well-established mitigator of many of the observed pathogenic effects, yet options to target this pathway remain limited. Along these lines, loss of nuclear factor erythroid 2-related factor 2 function has clearly been shown to enhance neuropathological outcomes, with enhancing nuclear factor erythroid 2-related factor 2 pathway activation to prevent neurodegenerative/neurological disease progression continuing to be an active area of interest. One critical obstacle in generating successful therapeutics for brain-related pathologies is the ability of the compound to cross the blood brain barrier (BBB), which has also hampered the implementation of several promising nuclear factor erythroid 2-related factor 2 inducers. Another limitation is that many nuclear factor erythroid 2-related factor 2 activators have undesirable off-target effects due to their electrophilic nature. Despite these constraints, the field has continued to evolve, and several viable means of targeting nuclear factor erythroid 2-related factor 2 in a neuropathological context have emerged. In this perspective, we will briefly discuss the key findings and promising therapeutic options that have been discovered to date, as well as highlight emerging areas of NRF2-neurodegeneration research that provide hope for successfully targeting this pathway in the future.

γ-Secretase Inhibitors Selected by Molecular Docking, to Develop a New Drug Against Alzheimer's Disease

Background

Alzheimer´s disease (AD) is one of the most common forms of dementia, is characterized by memory loss and cognitive impairment that affects more than 30 million people worldwide. The pathogenesis of Alzheimer's disease is primary driven by brain accumulation of the amyloid β peptide generated from the amyloid-β precursor protein (APP) via cleavages by β- and γ-secretase. In this study, we propose an approach by molecular docking to select compounds as γ-secretase inhibitors for decreasing the APP generation.

Methods

We selected potential γ-secretase inhibitors by molecular docking in the potential site between Asp257, Lue268, Asp385, Ile387, Phe388, and Leu432 amino acids in presenilin-1 (PS-1), using a chemical library of over 500,000 compounds.

Results

Eight compounds (AZ1 - AZ8) were selected by molecular docking to develop γ-secretase inhibitors for decreasing the APP generation.

Conclusions

AZ1 - AZ8 compounds could be interacting in the potential site between Asp257, Lue268, Asp385, Ile387, Phe388, and Leu432 amino acids in PS-1. These compounds could specifically interact in the binding pocket in PS-1 to prevent/decrease the APP generation, to develop a new drug against Alzheimer's disease.