Lipoic acid as a novel treatment for Alzheimer's disease and related dementias

A comprehensive bibliometric analysis of global research on the role of acrolein in Alzheimer's disease pathogenesis: involvement of amyloid-beta

Background

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive and behavioral decline. Acrolein, an environmental pollutant and endogenous compound, is implicated in AD development. This research employs bibliometric analysis to assess current trends and key areas concerning acrolein-AD interaction.

Methods

The Web of Science was used to extensively review literature on acrolein and AD. Relevant data were systematically gathered and analyzed using VOSviewer, CiteSpace, and an online bibliometric tool.

Results

We identified 120 English publications in this specialized field across 19 journals. The Journal of Alzheimer's Disease was the most prominent. The primary contributors, both in terms of scientific output and influence, were the USA, the University of Kentucky, and Ramassamy C, representing countries/regions, institutions, and authors, respectively. In this field, the primary focus was on thoroughly studying acrolein, its roles, and its mechanisms in AD utilizing both in vivo and in vitro approaches. A significant portion of the research was based on proteomics, revealing complex molecular processes. The main focuses in the field were "oxidative stress," "lipid peroxidation," "amyloid-beta," and "cognitive impairment." Anticipated future research trajectories focus on the involvement of the internalization pathway, covering key areas such as synaptic dysfunction, metabolism, mechanisms, associations, neuroinflammation, inhibitors, tau phosphorylation, acrolein toxicity, brain infarction, antioxidants, chemistry, drug delivery, and dementia. Our analysis also supported our previous hypothesis that acrolein can interact with amyloid-beta to form a protein adduct leading to AD-like pathology and altering natural immune responses.

Conclusion

This study provides a broad and all-encompassing view of the topic, offering valuable insights and guidance to fellow researchers. These emerging directions underscore the continuous exploration of the complexities associated with AD. The analyses and findings aim to enhance our understanding of the intricate relationship between acrolein and AD for future research.

Evaluation of the biological efficiency of Terminalia chebula fruit extract against neurochemical changes induced in brain of diabetic rats: an epigenetic study

Diabetes mellitus (DM) is a chronic and progressive metabolic disorder that can stimulate neuroinflammation and increase oxidative stress in the brain. Therefore, the present study was aimed to assess the efficacy of ethanolic Terminalia chebula extract against the neurochemical and histopathological changes induced in the brains of diabetic rats. The study clarified the reduction in oxidative stress induced in the brains of diabetic rats by the significant (P ≤ 0.05) increase in levels of the antioxidants with decreasing the peroxidation products via ethanolic T. chebula extract at both doses (400 and 600 mg/kg). Moreover, T. chebula extract improved the brain integrity by lowering levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), β-amyloid (Aβ) content, monocyte chemoattractant protein-1 (MCP-1) and acetylcholine esterase (ACHE) significantly (P ≤ 0.05) in a dose dependent manner compared to brain of diabetic rats. Severe nuclear pyknosis and degeneration were noticed in neurons of the cerebral cortex, hippocampus and striatum in brains of diabetic rats. The severity of these alterations decreased with T. chebula extract at a dose of 600 mg/kg compared to the other treated groups. The different electrophoretic protein and isoenzyme assays revealed that the lowest similarity index (SI%) values exist in the brains of diabetic rats compared to the control group. The quantity of the most native proteins and isoenzyme types increased significantly (P ≤ 0.05) in the brains of diabetic rats, and these electrophoretic variations were completely diminished by T. chebula extract. The study concluded that T. chebula extract ameliorated the biochemical, histopathological and electrophoretic abnormalities induced in the brains of diabetic rats when administered at a dose of 600 mg/kg.

Exploring structural determinants of neuroprotection bias on novel glypromate conjugates with bioactive amines

Neurodegenerative disorders of the central nervous system (CNS) such as Alzheimer's and Parkinson's diseases, afflict millions globally, posing a significant public health challenge. Despite extensive research, a critical hurdle in effectively treating neurodegenerative diseases is the lack of neuroprotective drugs that can halt or reverse the underlying disease processes. In this work, we took advantage of the neuroprotective properties of the neuropeptide glycyl-l-prolyl-l-glutamic acid (Glypromate) for the development of new peptidomimetics using l-pipecolic acid as a proline surrogate and exploring their chemical conjugation with relevant active pharmaceutical ingredients (API) via a peptide bond. Together with prolyl-based Glypromate conjugates, a total of 36 conjugates were toxicologically and biologically evaluated. In this series, the results obtained showed that a constrained ring (l-proline) at the central position of the peptide motif accounts for enhanced toxicological profiles and biological effects using undifferentiated and differentiated human neuroblastoma SH-SY5Y cells. Additionally, it was shown that biased biological responses are API-dependent. Conjugation with (R)-1-aminoindane led to a 38-43% reduction of protein aggregation induced by Aβ25-35 (10 μM), denoting a 3.2-3.6-fold improvement in comparison with the parent neuropeptide, with no significative difference between functionalization at α and γ-carboxyl ends. On the other hand, the best-performing neuroprotective conjugate against the toxicity elicited by 6-hydroxydopamine (6-OHDA, 125 μM) was obtained by conjugation with memantine at the α-carboxyl end, resulting in a 2.3-fold improvement of the neuroprotection capacity in comparison with Glypromate neuropeptide. Altogether, the chemical strategy explored in this work shows that the neuroprotective capacity of Glypromate can be modified and fine-tuned, opening a new avenue for the development of biased neurotherapeutics for CNS-related disorders.

Alpha-Lipoic acid alleviates imidacloprid-induced neuro-behavioral deficits in rats via Nrf2/HO-1 pathway

Imidacloprid (IMI), a widely used pesticide in agriculture and a potential food contaminant, poses significant health concerns. This study sought to comprehensively evaluate its neurotoxic effects while investigating the potential protective role of alpha-lipoic acid (ALA), a naturally occurring dietary antioxidant renowned for its capacity to combat oxidative stress, support cardiovascular health, and maintain optimal nerve function. In this study, 28 rats were divided evenly into four groups and administered oral treatments of corn oil, IMI, IMI + ALA, and ALA, respectively. The results of the study indicated that rats exposed to IMI exhibited significant neurobehavioral impairments, decreased levels of antioxidant enzymes and acetylcholinesterase activity, reduced expression of HO-1 and Nrf2, and increased levels of pro-inflammatory cytokines like IL-6 and TNF-α in their hippocampal tissues. Furthermore, histopathological analysis of the brain tissues, specifically cortex and hippocampus, from the IMI-treated group revealed varying degrees of neuronal degeneration. In contrast, rats co-administered ALA alongside IMI showed noticeable improvements in all the assessed toxicological parameters. This study underscores the vital significance of ALA as a potential therapeutic adjunct in mitigating the adverse neurobehavioral consequences of insecticide exposure. By harnessing the Nrf2/HO-1 pathway, ALA demonstrates its ability to shield against IMI-induced neurotoxicity, offering a promising avenue for enhancing public health and safety. As a result, our findings advocate for the incorporation of ALA as a daily dietary supplement to fortify resilience against oxidative stress-related neurobehavioral deficits linked to pesticide exposure, thereby advancing our understanding of neuroprotection strategies in the face of environmental challenges.

Dry and wet experiments reveal diagnostic clustering and immune landscapes of cuproptosis patterns in patients with ankylosing spondylitis

Cuproptosis is a new manner of mitochondrial cell death induced by copper. There is evidence that serum copper has a crucial impact on ankylosing spondylitis (AS) by copper-induced inflammatory response. However, the molecular mechanisms of cuproptosis modulators in AS remain unknown. We aimed to use a bioinformatics-based method to comprehensively investigate cuproptosis-related subtype identification and immune microenvironment infiltration of AS. Additionally, we further verified the results by in vitro experiments, in which peripheral blood and fibroblast cells from AS patients were used to evaluate the functions of significant cuproptosis modulators on AS. Finally, eight significant cuproptosis modulators were identified by analysis of differences between controls and AS cases from GSE73754 dataset. Eight prognostic cuproptosis modulators (LIPT1, DLD, PDHA1, PDHB, SLC31A1, ATP7A, MTF1, CDKN2A) were identified using a random forest model for prediction of AS risk. A nomogram model of the 8 prognostic cuproptosis modulators was then constructed; the model could be beneficial in clinical settings, as indicated by decision curve analysis. Consensus clustering analysis was used to divide AS patients into two cuproptosis subtypes (clusterA & B) according to significant cuproptosis modulators. The cuproptosis score of each sample was calculated by principal component analysis to quantify cuproptosis subtypes. The cuproptosis scores were higher in clusterB than in clusterA. Additionally, cases in clusterA were closely associated with the immunity of activated B cells, Activated CD4 T cell, Type17 T helper cell and Type2 T helper cell, while cases in clusterB were linked to Mast cell, Neutrophil, Plasmacytoid dendritic cell immunity, indicating that clusterB may be more correlated with AS. Notably, key cuproptosis genes including ATP7A, MTF1, SLC31A1 detected by RT-qPCR with peripheral blood exhibited significantly higher expression levels in AS cases than controls; LIPT1 showed the opposite results; High MTF1 expression is correlated with increased osteogenic capacity. In general, this study of cuproptosis patterns may provide promising biomarkers and immunotherapeutic strategies for future AS treatment.

Unravelling diagnostic clusters and immune landscapes of cuproptosis patterns in intervertebral disc degeneration through dry and wet experiments

Cuproptosis is a manner of mitochondrial cell death induced by copper. However, cuproptosis modulators' molecular processes in intervertebral disc degeneration (IDD) are still unclear. To better understand the processes of cuproptosis regulators in IDD, a thorough analysis of cuproptosis regulators in the diagnostic biomarkers and subtype determination of IDD was conducted. Then we collected clinical IDD samples and successfully established IDD model in vivo and in vitro, and carried out real-time quantitative polymerase chain reaction (RT-qPCR) validation of significant cuproptosis modulators. Totally we identified 8 crucial cuproptosis regulators in the present research. Using a random forest model, we isolated 8 diagnostic cuproptosis modulators for the prediction of IDD risk. Then, based on our following decision curve analysis, we selected the five diagnostic cuproptosis regulators with importance scores greater than two and built a nomogram model. Using a consensus clustering method, we divided IDD patients into two cuproptosis clusters (clusterA and clusterB) based on the important cuproptosis regulators. Additionally, each sample's cuproptosis value was evaluated using principal component analysis in order to quantify the cuproptosis clusters. Patients in clusterB had higher cuproptosis scores than patients in clusterA. Moreover, we found that clusterB was involved in the immunity of natural killer cell, while clusterA was related to activated CD4 T cell, activated B cell, etc. Notably, cuproptosis modulators detected by RT-qPCR showed generally consistent expression levels with the bioinformatics results. To sum up, cuproptosis modulators play a crucial role in the pathogenic process of IDD, providing biomarkers and immunotherapeutic approaches for IDD.

Experimental and Computational Insights into the Molecular Interactions between Human Transferrin and Apigenin: Implications of Natural Compounds in Targeting Neuroinflammation

Neuroinflammation plays a vital role in Alzheimer's disease (AD) pathogenesis and other neurodegenerative disorders (NDs). Presently, only symptomatic treatments are available and no disease-modifying drugs are available for AD and other NDs. Thus, targeting AD-associated neuroinflammation with anti-inflammatory compounds and antioxidants has recently been given much focus. Now, flavonoids are being increasingly investigated as therapeutic agents to treat inflammation; apigenin has a neuroprotective effect. Iron dyshomeostasis plays a key role in sustaining the neuroinflammatory phenotype, highlighting the importance of maintaining iron balance, in which human transferrin (HTF) plays a vital role in this aspect. Herein, we explored the binding and dynamics of the HTF-apigenin complex using multifaceted computational and experimental approaches. Molecular docking revealed that apigenin occupies the iron-binding pocket of HTF, forming hydrogen bonds with critical residues Arg475 and Thr686. Molecular dynamics simulations deciphered a dynamic view of the HTF-apigenin complex's behavior (300 ns) and suggested that the complex maintained a relatively stable conformation. The results of spectroscopic observations delineated significant binding of apigenin with HTF and stable HTF-apigenin complex formation. The observed binding mechanism and conformational stability could pave the way for developing novel therapeutic strategies to target neuroinflammation by apigenin in the context of iron homeostasis.

Antioxidant dihydrolipolic acid protects against in vitro aluminum-induced toxicity

Dihydrolipoic acid (DHLA) is a natural antioxidant known for its ability to counteract metal toxicity and oxidative stress. It has shown the potential to safeguard cells from harmful environmental substances. It may hold therapeutic benefits in treating neurodegenerative disorders by defending against oxidative damage and chronic inflammation. Thus, this study aimed to explore the potential neuroprotective effects of DHLA against aluminum (Al)-induced toxicity using an Alzheimer's disease (AD) model in vitro. The study focused on two important pathways: GSK-3β and the Wnt signaling pathways. The SH-SY5Y cell line was differentiated to establish AD, and the study group were as follows: control, Al, DHLA, Al-DHLA, AD, AD-Al, AD-DHLA, and AD-Al-DHLA. The impact of DHLA on parameters related to oxidative stress was assessed. The activity of the GSK-3β pathway was measured by evaluating the levels of PPP1CA, PP2A, GSK-3β, and Akt. The Wnt signaling pathway was assessed by measuring Wnt/β-catenin in the different study groups. Exposure to DHLA significantly reduced oxidative stress by effectively decreasing the levels of reactive oxygen species, thereby protecting against protein oxidation and limiting the production of malonaldehyde. Moreover, the DHLA-treated groups exhibited a remarkable increase in the total antioxidant capacity. Furthermore, the study observed an upregulation of the Wnt signaling pathway and a downregulation of the GSK-3β pathway in the groups treated with DHLA. In summary, the neuroprotective effects of DHLA, primarily achieved by reducing oxidative stress and modulating critical imbalanced pathways associated with AD, indicate its potential as a promising addition to the treatment regimens of AD patients.

Memory Recovery Effect of a New Bioactive Innovative Combination in Rats with Experimental Dementia

Alzheimer's disease manifests as a complex pathological condition, with neuroinflammation, oxidative stress and cholinergic dysfunction being a few of the many pathological changes. Due to the complexity of the disease, current therapeutic strategies aim at a multitargeted approach, often relying on a combination of substances with versatile and complementary effects. In the present study, a unique combination of α-lipoic acid, citicoline, extracts of leaves from olive tree and green tea, vitamin D3, selenium and an immune-supporting complex was tested in scopolamine-induced dementia in rats. Using behavioral and biochemical methods, we assessed the effects of the combination on learning and memory, and elucidated the mechanisms of these effects. Our results showed that, compared to its components, the experimental combination was most efficient in improving short- and long-term memory as assessed by the step-through method as well as spatial memory as assessed by T-maze and Barnes maze underlined by decreases in AChE activity (p < 0.05) and LPO (p < 0.001), increases in SOD activity in the cortex (p < 0.05) and increases in catalase (p < 0.05) and GPx (p < 0.01) activities and BDNF (p < 0.001) and pCREB (p < 0.05) levels in the hippocampus. No significant histopathological changes or blood parameter changes were detected, making the experimental combination an effective and safe candidate in a multitargeted treatment of AD.

α-lipoic acid ameliorates hepatotoxicity induced by chronic ammonia toxicity in crucian carp (Carassius auratus gibelio) by alleviating oxidative stress, inflammation and inhibiting ERS pathway

High environment ammonia (HEA) poses a deadly threat to aquatic animals and indirectly impacts human healthy life, while nutritional regulation can alleviate chronic ammonia toxicity. α-lipoic acid exhibits antioxidative effects in both aqueous and lipid environments, mitigating cellular and tissue damage caused by oxidative stress by aiding in the neutralization of free radicals (reactive oxygen species). Hence, investigating its potential as an effective antioxidant and its protective mechanisms against chronic ammonia stress in crucian carp is highly valuable. Experimental fish (initial weight 20.47 ± 1.68 g) were fed diets supplemented with or without 0.1% α-lipoic acid followed by a chronic ammonia exposure (10 mg/L) for 42 days. The results revealed that chronic ammonia stress affected growth (weight gain rate, specific growth rate, and feed conversion rate), leading to oxidative stress (decreased the activities of antioxidant enzymes catalase, superoxide dismutase, glutathione peroxidase; decreased total antioxidant capacity), increased lipid peroxidation (accumulation of malondialdehyde), immune suppression (decreased contents of nonspecific immune enzymes AKP and ACP, 50% hemolytic complement, and decrease of immunoglobulin M), impaired ammonia metabolism (reduced contents of Glu, GS, GSH, and Gln), imbalance of expression of induced antioxidant-related genes (downregulation of Cu/Zu SOD, CAT, Nrf2, and HO-1; upregulation of GST and Keap1), induction of pro-apoptotic molecules (transcription of BAX, Caspase3, and Caspase9), downregulation of anti-apoptotic gene Bcl-2 expression, and induction of endoplasmic reticulum stress (upregulation of IRE1, PERK, and ATF6 expression). The results suggested that the supplementation of α-lipoic acid could effectively induce humoral immunity, alleviate oxidative stress injury and endoplasmic reticulum stress, and ultimately alleviate liver injury induced by ammonia poisoning (50-60% reduction). This provides theoretical basis for revealing the toxicity of long-term ammonia stress and provides new insights into the anti-ammonia toxicity mechanism of α-lipoic acid.

Research on ferroptosis as a therapeutic target for the treatment of neurodegenerative diseases

Ferroptosis is an iron- and lipid peroxidation (LPO)-mediated programmed cell death type. Recently, mounting evidence has indicated the involvement of ferroptosis in neurodegenerative diseases, especially in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and so on. Treating ferroptosis presents opportunities as well as challenges for neurodegenerative diseases. This review provides a comprehensive overview of typical features of ferroptosis and the underlying mechanisms that contribute to its occurrence, as well as their implications in the pathogenesis and advancement of major neurodegenerative disorders. Meanwhile, we summarize the utilization of ferroptosis inhibition in both experimental and clinical approaches for the treatment of major neurodegenerative disorders. In addition, we specifically summarize recent advances in developing therapeutic means targeting ferroptosis in these diseases, which may guide future approaches for the effective management of these devastating medical conditions.

Crystal structure of histone deacetylase 6 complexed with (R)-lipoic acid, an essential cofactor in central carbon metabolism

The enzyme cofactor (R)-lipoic acid plays a critical role in central carbon metabolism due to its catalytic function in the generation of acetyl-CoA, which links glycolysis with the tricarboxylic acid cycle. This cofactor is also essential for the generation of succinyl CoA within the tricarboxylic acid cycle. However, the biological functions of (R)-lipoic acid extend beyond metabolism owing to its facile redox chemistry. Most recently, the reduced form of (R)-lipoic acid, (R)-dihydrolipoic acid, has been shown to inhibit histone deacetylases (HDACs) with selectivity for the inhibition of HDAC6. Here, we report the 2.4 Å-resolution X-ray crystal structure of the complex between (R)-dihydrolipoic acid and HDAC6 catalytic domain 2 from Danio rerio, and we report a dissociation constant (KD) of 350 nM for this complex as determined by isothermal titration calorimetry. The crystal structure illuminates key affinity determinants in the enzyme active site, including thiolate-Zn2+ coordination and S-π interactions in the F583-F643 aromatic crevice. This study provides the first visualization of the connection between HDAC function and the biological response to oxidative stress: the dithiol moiety of (R)-dihydrolipoic acid can serve as a redox-regulated pharmacophore capable of simultaneously targeting the catalytic Zn2+ ion and the aromatic crevice in the active site of HDAC6.

Mitochondrial heterogeneity in diseases

As key organelles involved in cellular metabolism, mitochondria frequently undergo adaptive changes in morphology, components and functions in response to various environmental stresses and cellular demands. Previous studies of mitochondria research have gradually evolved, from focusing on morphological change analysis to systematic multiomics, thereby revealing the mitochondrial variation between cells or within the mitochondrial population within a single cell. The phenomenon of mitochondrial variation features is defined as mitochondrial heterogeneity. Moreover, mitochondrial heterogeneity has been reported to influence a variety of physiological processes, including tissue homeostasis, tissue repair, immunoregulation, and tumor progression. Here, we comprehensively review the mitochondrial heterogeneity in different tissues under pathological states, involving variant features of mitochondrial DNA, RNA, protein and lipid components. Then, the mechanisms that contribute to mitochondrial heterogeneity are also summarized, such as the mutation of the mitochondrial genome and the import of mitochondrial proteins that result in the heterogeneity of mitochondrial DNA and protein components. Additionally, multiple perspectives are investigated to better comprehend the mysteries of mitochondrial heterogeneity between cells. Finally, we summarize the prospective mitochondrial heterogeneity-targeting therapies in terms of alleviating mitochondrial oxidative damage, reducing mitochondrial carbon stress and enhancing mitochondrial biogenesis to relieve various pathological conditions. The possibility of recent technological advances in targeted mitochondrial gene editing is also discussed.

Chromone Containing Hybrid Analogs: Synthesis and Applications in Medicinal Chemistry

The use of privileged scaffolds has proven beneficial for generating novel bioactive scaffolds in drug discovery program. Chromone is one such privileged scaffold that has been exploited for designing pharmacologically active analogs. The molecular hybridization technique combines the pharmacophoric features of two or more bioactive compounds to avail a better pharmacological activity in the resultant hybrid analogs. The current review summarizes the rationale and techniques involved in developing hybrid analogs of chromone, which show potential in fields of obesity, diabetes, cancer, Alzheimer's disease and microbial infections. Here the molecular hybrids of chromone with various pharmacologically active analogs or fragments (donepezil, tacrine, pyrimidines, azoles, furanchalcones, hydrazones, quinolines, etc.) are discussed with their structure-activity relationship against above-mentioned diseases. Detailed methodologies for the synthesis of corresponding hybrid analogs have also been described, with suitable synthetic schemes. The current review will shed light on various strategies utilized for the design of hybrid analogs in the field of drug discovery. The importance of hybrid analogs in various disease conditions is also illustrated.

Alpha-Lipoic Acid Ameliorates Doxorubicin-Induced Cognitive Impairments by Modulating Neuroinflammation and Oxidative Stress via NRF-2/HO-1 Signaling Pathway in the Rat Hippocampus

Chemotherapy-induced cognitive impairment (CICI) is a common complication associated with the use of chemotherapeutics. Doxorubicin (DOX) is a reactive oxygen species (ROS) producing anticancer agent capable of causing potential neurotoxic effects via cytokine-induced oxidative and nitrosative damage to brain tissues. On the other hand, alpha-lipoic acid (ALA), a nutritional supplement, is reputable for its excellent antioxidant, anti-inflammatory, and anti-apoptotic activities. Consequently, the objective of the current investigation was to examine any potential neuroprotective and memory-improving benefits of ALA against DOX-induced behavioral and neurological anomalies. DOX (2 mg/kg/week, i.p.) was administrated for 4 weeks to Sprague-Dawley rats. ALA (50, 100, and 200 mg/kg) was administered for 4 weeks. The Morris water maze (MWM) and novel objective recognition task (NORT) tests were used to assess memory function. Biochemical assays with UV-visible spectrophotometry were used to analyze oxidative stress markers [malondialdehyde (MDA), protein carbonylation (PCO)], endogenous antioxidants [reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px)] and acetylcholinesterase (AChE) activity in hippocampal tissue. Inflammatory markers [tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and nuclear factor kappa B (NF-κB)], nuclear factor erythroid 2-related factor-2 (NRF-2) and hemeoxygenase-1 (HO-1) levels were estimated using enzyme-linked immunosorbent assay (ELISA). In addition, reactive oxygen species (ROS) levels were measured in hippocampus tissue using 2-7-dichlorofluorescein-diacetate (DCFH-DA) assay with fluorimetry. ALA treatment significantly protected against DOX-induced memory impairment. Furthermore, ALA restored hippocampal antioxidants, halted DOX-induced oxidative and inflammatory insults via upregulation of NRF-2/HO-1 levels, and alleviated the increase in NF-κB expression. These results indicate that ALA offers neuroprotection against DOX-induced cognitive impairment, which could be attributed to its antioxidant potential via the NRF-2/HO-1 signaling pathway.

Protective Potentials of Alpha-Lipoic Acid against Ionizing Radiation-Induced Brain Damage in Rats

Background

This study was aimed at determining the effects of alpha-lipoic acid on ionizing irradiation-induced oxidative damage and apoptosis in the brain of rats.

Methods

The animals were exposed to whole-brain X-radiation with a 15 Gy single dose in the absence or presence of alpha-lipoic acid (200 mg/kg body weight) pretreatment for one week. The rats were divided into four groups (5 rats in each group): vehicle control, alpha-lipoic acid alone (ALA), radiation alone (RAD), and radiation plus alpha-lipoic acid (RAD+ALA). In the next stage, malondialdehyde (MDA), nitric oxide, catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the brain tissue of the rats were measured. Furthermore, the Western blot analysis technique was performed to assess the NOX2, NOX4, and caspase-3 protein expression levels.

Results

Twenty-four hours after the irradiation, MDA and nitric oxide levels in the irradiated rats were significantly higher than those in the control group (p < 0.001); however, the pretreatment with alpha-lipoic acid resulted in a significant reduction in these stress oxidative markers (p < 0.05). Moreover, a significant decrease in CAT, SOD, and GPx levels was observed in the radiation group alone compared to the control group (p < 0.01); in contrast, the activities of these antioxidant enzymes significantly increased in the radiation plus alpha-lipoic acid group in comparison to the radiation group alone (p < 0.05). The results of Western blot analysis revealed that NOX2, NOX4, and caspase-3 protein expressions significantly elevated in the irradiated rats compared to the control group (p < 0.001). The pretreatment with alpha-lipoic acid could significantly decrease the expression levels of NOX2, NOX4, and caspase-3 in comparison with the radiation group alone (p < 0.05).

Conclusion

According to the obtained findings, it can be mentioned that the alpha-lipoic acid pretreatment could mitigate the ionizing irradiation-induced oxidative damage and apoptosis in the brain of the rats.

Concise Overview of Glypromate Neuropeptide Research: From Chemistry to Pharmacological Applications in Neurosciences

Neurodegenerative diseases of the central nervous system (CNS) pose a serious health concern worldwide, with a particular incidence in developed countries as a result of life expectancy increase and the absence of restorative treatments. Presently, treatments for these neurological conditions are focused on managing the symptoms and/or slowing down their progression. As so, the research on novel neuroprotective drugs is of high interest. Glypromate (glycyl-l-prolyl-l-glutamic acid, also known as GPE), an endogenous small peptide widespread in the brain, holds great promise to tackle neurodegenerative diseases such as Parkinson's, Alzheimer's, and Huntington's, s well as other CNS-related disorders like Rett and Down's syndromes. However, the limited pharmacokinetic properties of Glypromate hinder its clinical application. As such, intense research has been devoted to leveraging the pharmacokinetic profile of this neuropeptide. This review aims to offer an updated perspective on Glypromate research by exploring the vast array of chemical derivatizations of more than 100 analogs described in the literature over the past two decades. The collection and discussion of the most relevant structure-activity relationships will hopefully guide the discovery of new Glypromate-based neuroprotective drugs.

Strategies for Treatment of Disease-Associated Dementia Beyond Alzheimer's Disease: An Update

Memory, cognition, dementia, and neurodegeneration are complexly interlinked processes with various mechanistic pathways, leading to a range of clinical outcomes. They are strongly associated with pathological conditions like Alzheimer's disease, Parkinson's disease, schizophrenia, and stroke and are a growing concern for their timely diagnosis and management. Several cognitionenhancing interventions for management include non-pharmacological interventions like diet, exercise, and physical activity, while pharmacological interventions include medicinal agents, herbal agents, and nutritional supplements. This review critically analyzed and discussed the currently available agents under different drug development phases designed to target the molecular targets, including cholinergic receptor, glutamatergic system, GABAergic targets, glycine site, serotonergic targets, histamine receptors, etc. Understanding memory formation and pathways involved therein aids in opening the new gateways to treating cognitive disorders. However, clinical studies suggest that there is still a dearth of knowledge about the pathological mechanism involved in neurological conditions, making the dropouts of agents from the initial phases of the clinical trial. Hence, a better understanding of the disease biology, mode of drug action, and interlinked mechanistic pathways at a molecular level is required.

The Effects of Antioxidant Nutraceuticals on Cellular Sulfur Metabolism and Signaling

Significance: Nutraceuticals are ingested for health benefits, in addition to their general nutritional value. These dietary supplements have become increasingly popular since the late 20th century and they are a rapidly expanding global industry approaching a half-trillion U.S. dollars annually. Many nutraceuticals are promulgated as potent antioxidants. Recent Advances: Experimental support for the efficacy of nutraceuticals has lagged behind anecdotal exuberance. However, accumulating epidemiological evidence and recent, well-controlled clinical trials are beginning to support earlier animal and in vitro studies. Although still somewhat limited, encouraging results have been suggested in essentially all organ systems and against a wide range of pathophysiological conditions. Critical Issues: Health benefits of "antioxidant" nutraceuticals are largely attributed to their ability to scavenge oxidants. This has been criticized based on several factors, including limited bioavailability, short tissue retention time, and the preponderance of endogenous antioxidants. Recent attention has turned to nutraceutical activation of downstream antioxidant systems, especially the Keap1/Nrf2 (Kelch like ECH associated protein 1/nuclear factor erythroid 2-related factor 2) axis. The question now becomes, how do nutraceuticals activate this axis? Future Directions: Reactive sulfur species (RSS), including hydrogen sulfide (H2S) and its metabolites, are potent activators of the Keap1/Nrf2 axis and avid scavengers of reactive oxygen species. Evidence is beginning to accumulate that a variety of nutraceuticals increase cellular RSS by directly providing RSS in the diet, or through a number of catalytic mechanisms that increase endogenous RSS production. We propose that nutraceutical-specific targeting of RSS metabolism will lead to the design and development of even more efficacious antioxidant therapeutic strategies. Antioxid. Redox Signal. 38, 68-94.

Role of Probiotics and Diet in the Management of Neurological Diseases and Mood States: A Review

Alzheimer's (AD) and Parkinson's diseases (PD) are common in older people. Autism spectrum disorders (ASD), anxiety, depression, stress, and cognitive impairment are prevalent among people irrespective of age. The incidence of neurological disorders has been increasing in recent decades. Communication between the gut microbiota and the brain is intrinsically complicated, and it is necessary for the maintenance of the gut, brain, and immune functions of the host. The bidirectional link among the gut, gut microbiota and the brain is designated as the "microbiota-gut-brain axis." Gut microbiota modulates the host immune system and functions of tissue barriers such as gut mucosa and blood-brain barrier (BBB). Gut microbial dysfunction disturbs the gut-brain interplay and may contribute to various gut disorders, neurocognitive and psychiatric disorders. Probiotics could protect intestinal integrity, enhance gut functions, promote intestinal mucosal and BBB functions, and support the synthesis of brain-derived neurotrophic factors, which enhance neuronal survival and differentiation. Probiotics could be considered an adjunct therapy to manage metabolic and psychiatric diseases. Predominantly, Lactobacillus and Bifidobacterium strains are documented as potent probiotics, which help to maintain the bidirectional interactions between the gut and brain. The consumption of probiotics and probiotics containing fermented foods could improve the gut microbiota. The diet impacts gut microbiota, and a balanced diet could maintain the integrity of gut-brain communication by facilitating the production of neurotrophic factors and other neuropeptides. However, the beneficial effects of probiotics and diet might depend upon several factors, including strain, dosage, duration, age, host physiology, etc. This review summarizes the importance and involvement of probiotics and diet in neuroprotection and managing representative neurological disorders, injuries and mood states.

Integrated multi-omics analysis of Huntington disease identifies pathways that modulate protein aggregation

Huntington disease (HD) is a neurodegenerative disease associated with polyglutamine expansion in the protein huntingtin (HTT). Although the length of the polyglutamine repeat correlates with age at disease onset and severity, psychological, cognitive and behavioral complications point to the existence of disease modifiers. Mitochondrial dysfunction and metabolic deregulation are both associated with the HD but, despite multi-omics characterization of patients and model systems, their mechanisms have remained elusive. Systems analysis of multi-omics data and its validation by using a yeast model could help to elucidate pathways that modulate protein aggregation. Metabolomics analysis of HD patients and of a yeast model of HD was, therefore, carried out. Our analysis showed a considerable overlap of deregulated metabolic pathways. Further, the multi-omics analysis showed deregulated pathways common in human, mice and yeast model systems, and those that are unique to them. The deregulated pathways include metabolic pathways of various amino acids, glutathione metabolism, longevity, autophagy and mitophagy. The addition of certain metabolites as well as gene knockouts targeting the deregulated metabolic and autophagy pathways in the yeast model system showed that these pathways do modulate protein aggregation. Taken together, our results showed that the modulation of deregulated pathways influences protein aggregation in HD, and has implications for progression and prognosis. This article has an associated First Person interview with the first author of the paper.

Review of lipoic acid: From a clinical therapeutic agent to various emerging biomaterials

Lipoic acid (LA), an endogenous small molecule in organisms, has been extensively used for the highly efficient clinical treatment of malignant diseases, which include diabetes, Alzheimer's disease, and cancer over the past seven decades. Tremendous progresses have been made on the use of LA in nanomedicine for the development of various biomaterials because of its unique biological properties and highly adaptable structure since the first discovery. However, there are few reviews thus far, to our knowledge, summarizing this hot subject of research of LA and its derived biomaterials. For this purpose, we present herein the first comprehensive summary on the design and development of LA and its derived materials for biomedical applications. This review first discusses the therapeutic use of LA followed by the description of synthesis and preclinical study of LA-derived-small molecules. The applications of various LA and poly (lipoic acid) (PLA)-derived-biomaterials are next summarized in detail with an emphasis on the use of LA for the design of biomaterials and the diverse properties. This review describes the development of LA from a clinical therapeutic agent to a building unit of various biomaterials field, which will promote the further discovery of new therapeutic uses of LA as therapeutic agents and facile development of LA-based derivates with greater performance for biomedical applications.

Cross-species metabolomic analysis of tau- and DDT-related toxicity

Exposure to the pesticide dichlorodiphenyltrichloroethane (DDT) has been associated with increased risk of Alzheimer's disease (AD), a disease also associated with hyperphosphorylated tau (p-tau) protein aggregation. We investigated whether exposure to DDT can exacerbate tau protein toxicity in Caenorhabditiselegans using a transgenic strain that expresses human tau protein prone to aggregation by measuring changes in size, swim behavior, respiration, lifespan, learning, and metabolism. In addition, we examined the association between cerebrospinal fluid (CSF) p-tau protein-as a marker of postmortem tau burden-and global metabolism in both a human population study and in C. elegans, using the same p-tau transgenic strain. From the human population study, plasma and CSF-derived metabolic features associated with p-tau levels were related to drug, amino acid, fatty acid, and mitochondrial metabolism pathways. A total of five metabolites overlapped between plasma and C. elegans, and four between CSF and C. elegans. DDT exacerbated the inhibitory effect of p-tau protein on growth and basal respiration. In the presence of p-tau protein, DDT induced more curling and was associated with reduced levels of amino acids but increased levels of uric acid and adenosylselenohomocysteine. Our findings in C. elegans indicate that DDT exposure and p-tau aggregation both inhibit mitochondrial function and DDT exposure can exacerbate the mitochondrial inhibitory effects of p-tau aggregation. Further, biological pathways associated with exposure to DDT and p-tau protein appear to be conserved between species.

Chitosan Nanoparticles Containing Lipoic Acid with Antioxidant Properties as a Potential Nutritional Supplement

Simple Summary

Alfa-lipoic acid (ALA) is an important antioxidant that could be added to animal feed as a nutritional supplement. To improve its stability in the digestive system, ALA was encapsulated in chitosan nanoparticles. The nanoparticles containing ALA were stable in stomach-like conditions and were able to cross the intestinal barrier. Chitosan-based nanoparticles seem to be an attractive administration method for antioxidants, or other sensible additives, in food.

Abstract

The addition of the antioxidant α-lipoic acid (ALA) to a balanced diet might be crucial for the prevention of comorbidities such as cardiovascular diseases, diabetes, and obesity. Due to its low half-life and instability under stomach-like conditions, α-lipoic acid was encapsulated into chitosan nanoparticles (Ch-NPs). The resulting chitosan nanoparticles containing 20% w/w ALA (Ch-ALA-NPs) with an average diameter of 44 nm demonstrated antioxidant activity and stability under stomach-like conditions for up to 3 h. Furthermore, fluorescent Ch-ALA-NPs were effectively internalized into 3T3-L1 fibroblasts and were able to cross the intestinal barrier, as evidenced by everted intestine in vitro experiments. Thus, chitosan-based nanoparticles seem to be an attractive administration method for antioxidants, or other sensible additives, in food.

Effects of α-Lipoic Acid on Phagocytosis of Oligomeric Beta-Amyloid1–42 in BV-2 Mouse Microglial Cells

Background and objectives: This study aimed to investigate the enhancing effect of vitamin-like alpha-lipoic acid (ALA) on phagocytosis of oligomeric beta-amyloid (oAβ)_1–42 in BV-2 mouse microglial cells.

Methods: An in vitro model was established to investigate phagocytosis of oAβ_1–42 in BV-2 cells. Transmission electron microscopy images indicated that the morphology of prepared oAβ_1–42 was spherical particles. BV-2 cells treated with ALA were incubated with 5(6)-carboxyfluorescein-labeled oAβ_1–42 (FAM-oAβ_1–42) for 24 h, followed by flow cytometer analysis, western blotting, real-time quantitative PCR, and immunocytochemistry (ICC) analysis to assess the in vitro phagocytosis ability of oAβ_1–42.

Results: Alpha-lipoic acid significantly increased messenger RNA (mRNA) expression of the CD36 receptor in BV-2 cells. ICC analysis showed that ALA significantly elevated CD36 protein expression in BV-2 cells both with and without oAβ_1–42 treatment. Results from the flow cytometry analysis indicated that the CD36 receptor inhibitor significantly attenuated ALA-promoted phagocytosis of FAM-oAβ_1–42 in BV-2 cells. Moreover, ICC analysis revealed that ALA caused the translocation of peroxisome proliferator-activated receptor-γ (PPAR-γ), which is known to regulate the expression of CD36 mRNA in BV-2 cells. ALA also elevated both the mRNA and protein expression of cyclooxygenase-2 (COX-2), which is a key enzyme involved in the synthesis of 15-deoxy-^Δ12,14-prostaglandin J2 in BV-2 cells.

Conclusion: We postulated that ALA enhances oAβ_1–42 phagocytosis by upregulating the COX-2/15-deoxy-^Δ12,14-prostaglandin J2/PPAR-γ/CD36 pathway in BV-2 cells. Finally, future studies should be conducted with an in vivo study to confirm the findings.

Vitamin A Deficiency Exacerbates Gut Microbiota Dysbiosis and Cognitive Deficits in Amyloid Precursor Protein/Presenilin 1 Transgenic Mice

Vitamin A deficiency (VAD) plays an essential role in the pathogenesis of Alzheimer’s disease (AD). However, the specific mechanism by which VAD aggravates cognitive impairment is still unknown. At the intersection of microbiology and neuroscience, the gut-brain axis is undoubtedly contributing to the formation and function of neurological systems, but most of the previous studies have ignored the influence of gut microbiota on the cognitive function in VAD. Therefore, we assessed the effect of VAD on AD pathology and the decline of cognitive function in AD model mice and determined the role played by the intestinal microbiota in the process. Twenty 8-week-old male C57BL/6J amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice were randomly assigned to either a vitamin A normal (VAN) or VAD diet for 45 weeks. Our results show that VAD aggravated the behavioral learning and memory deficits, reduced the retinol concentration in the liver and the serum, decreased the transcription of vitamin A (VA)-related receptors and VA-related enzymes in the cortex, increased amyloid-β peptides (Aβ40 and Aβ42) in the brain and gut, upregulate the translation of beta-site APP-cleaving enzyme 1 (BACE1) and phosphorylated Tau in the cortex, and downregulate the expression of brain-derived neurotrophic factor (BDNF) and γ-aminobutyric acid (GABA) receptors in the cortex. In addition, VAD altered the composition and functionality of the fecal microbiota as exemplified by a decreased abundance of Lactobacillus and significantly different α- and β-diversity. Of note, the functional metagenomic prediction (PICRUSt analysis) indicated that GABAergic synapse and retinol metabolism decreased remarkably after VAD intervention, which was in line with the decreased expression of GABA receptors and the decreased liver and serum retinol. In summary, the present study provided valuable facts that VAD exacerbated the morphological, histopathological, molecular biological, microbiological, and behavioral impairment in the APP/PS1 transgenic mice, and the intestinal microbiota may play a key mediator role in this mechanism.

Boron-based hybrids as novel scaffolds for the development of drugs with neuroprotective properties

Novel boron-based compounds (BBCs) were synthesized and evaluated as potential candidates for the development of novel drugs against Alzheimer's disease (AD). The neuroprotective profile of novel BBCs was evaluated using Aβ1-42-treated-SH-SY5Y cells while their antioxidant activity was evaluated by total antioxidant capacity (TAC) and total oxidative status (TOS) assays. Results showed that BLA (a novel boron-based hybrid containing an antioxidant portion) inhibited cell death induced by Aβ1-42-exposure in differentiated SH-SY5Y cells, resulting in an increase in cell viability by 25-33% (MTT assay) and by 63-71% (LDH assay) in a concentration range of 25-100 μM. Antioxidant assays demonstrated a good capability of BLA to counteract the oxidative status. Moreover, BLA possessed a significant ability to inhibit acetylcholinesterase (AChE) (22.96% at 50 μM), an enzyme whose enzymatic activity is increased in AD patients. In the present work, absorption and distribution properties of boron-based hybrids were predicted using Pre-ADMET software. In vitro preliminary results suggested that boron-based hybrids could be new structural scaffolds for the development of novel drugs for the management of AD.

Decrypting the potential role of α-lipoic acid in Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases with motor disturbances, cognitive decline, and behavioral impairment. It is characterized by the extracellular aggregation of amyloid-β plaques and the intracellular accumulation of tau protein. AD patients show a cognitive decline, which has been associated with oxidative stress, as well as mitochondrial dysfunction. Alpha-lipoic acid (α-LA), a natural antioxidant present in food and used as a dietary supplement, has been considered a promising agent for the prevention or treatment of neurodegenerative disorders. Despite multiple preclinical studies indicating beneficial effects of α-LA in memory functioning, and pointing to its neuroprotective effects, to date only a few studies have examined its effects in humans. Studies performed in animal models of memory loss associated with aging and AD have shown that α-LA improves memory in a variety of behavioral paradigms. Furthermore, molecular mechanisms underlying α-LA effects have also been investigated. Accordingly, α-LA shows antioxidant, antiapoptotic, anti-inflammatory, glioprotective, metal chelating properties in both in vivo and in vitro studies. In addition, it has been shown that α-LA reverses age-associated loss of neurotransmitters and their receptors. The review article aimed at summarizing and discussing the main studies investigating the neuroprotective effects of α-LA on cognition as well as its molecular effects, to improve the understanding of the therapeutic potential of α-LA in patients suffering from neurodegenerative disorders, supporting the development of clinical trials with α-LA.

Alpha lipoic acid ameliorates scopolamine induced memory deficit and neurodegeneration in the cerebello-hippocampal cortex

Scopolamine- induced memory loss is used to study new drug discovery in Alzheimer's disease (AD) pathogenesis. This study was aimed at evaluating the role of an antioxidant supplement alpha-lipoic acid (AHA), in ameliorating the oxidative damaging effects of scopolamine on cognition, memory, and the neurohistology of the cerebello-hippocampal cortex. Twenty adult male Wistar rats used were categorized into four (4) groups (n = 5): Group A- Control, Group B- 200 mg/kg of AHA, Group C- Scopolamine (memory-impaired model), and Group D- Neurodegenerative repair model (Scopolamine + AHA). The treatment lasted for fourteen (14) days. Y-maze and hang-wire (limb use test) were used as behavioural index to assess memory and motor function while brain tissues were processed for histology (H and E stain), histochemistry using Cresyl Fast violet stain for Nissl bodies, and immunohistochemistry of astrocytes using glial fibrillary acidic protein (GFAP). Results showed that scopolamine led to a decline in brain weight, impaired memory and motor function, induced oxidative tissue damage cumulating in loss of neuronal cells, chromatolysis, the proliferation of reactive astrocytes (neuroinflammation biomarker) in the cerebello-hippocampal cortex; but upon administration of AHA these neuropathological characterizations were inhibited and reversed by AHA demonstrating its antioxidant and neuro- repair potential. In conclusion, AHA is a useful therapeutic agent against scopolamine-induced cognitive and memory deficit because it has the ability to ameliorate oxidative tissue damage by attenuating reactive astrocytes proliferation and neuron chromatolysis thereby improving memory and motor function.

Successful Application of Alpha Lipoic Acid Niosomal Formulation in Cerebral Ischemic Reperfusion Injury in Rat Model

Purpose: Free radicals such as hydroxyl and peroxide are contributing factors to neuronal destruction in cerebral ischemia. Alpha-lipoic acid (ALA) is one of the potent known antioxidants. Preparation of ALA niosomes allows IV injection and can increase bioavailability and penetration into the central nervous system (CNS).

Methods: Film hydration method was used to prepare different niosomes composed of Span®, Tween®, and cholesterol at different molar ratio. ALA and niosome-forming compounds were dissolved in chloroform, before removing the organic solvent by rotary evaporator. Animals were randomly divided into four groups: Sham, control group, intravenous (IV) injection of empty niosomes plus intraperitoneal (IP) injection of ALA solution, and finally, IV injection of ALA niosomes. Rats were subjected to deep anesthesia before inducing cerebral ischemia, then, their internal common carotid arteries were clamped for 15 min and reperfusion was done for 30 min. Niosomal ALA was injected intravenously just before declamping.

Results: Mean volume diameter of the prepared niosomes was between 4.36 ± 0.82 and 19.95 ± 1.21 μm in different formulations. Encapsulation efficiency percent (EE%) of ALA in the selected formulation, Span60/Tween60/cholesterol (35:35:30 molar ratio), was 94.5 ± 0.2, and 59.27 ± 5.61% of ALA was released after 4h. In the niosomal group, the rate of reduction in complications of cerebral ischemia such as histopathologic changes and acute damage (from score 3 to 1) in CNS was higher than other groups.

Conclusion: The obtained results show that niosomes can be used as effective drug delivery systems for ALA in cerebral ischemia.

Therapeutic Potential of Alpha-Lipoic Acid in Viral Infections, including COVID-19

Oxidative stress (OS), resulting from a disrupted balance between reactive oxygen species (ROS) and protective antioxidants, is thought to play an important pathogenetic role in several diseases, including viral infections. Alpha-lipoic acid (LA) is one of the most-studied and used natural compounds, as it is endowed with a well-defined antioxidant and immunomodulatory profile. Owing to these properties, LA has been tested in several chronic immunoinflammatory conditions, such as diabetic neuropathy and metabolic syndrome. In addition, a pharmacological antiviral profile of LA is emerging, that has attracted attention on the possible use of this compound for the cotreatment of several viral infections. Here, we will review the emerging literature on the potential use of LA in viral infections, including COVID-19.

Investigation of alpha-lipoic acid effect on memory impairment considering strain-dependent differences in mice

AIMS

Memory impairment is regarded as one of the most challenging neurological disorders. The present study aimed to investigate behavioral and biochemical differences among similar mouse strains following Scopolamine (SCO) exposure as a widespread memory disturbing agent, and a supremely potent antioxidant, alpha-lipoic acid (ALA).

MATERIALS AND METHODS

Three sets of mouse strains (i.e. SW, NMRI, and NIH mice) were subjected to 2 mg/kg intraperitoneal SCO and/or 50 mg/kg ALA 30 min before each Morris Water Maze (MWM) trial for five consecutive days. Upon completion of the trials, the hippocampal region of the animals was dissected for histopathological and biochemical analyses.

KEY FINDINGS

The results exhibited significant impairments caused by SCO in behavioral tests, including probe test, escape latency, and distance traveled in two strains of NMRI and NIH. Nevertheless, at swimming speed, SCO had no meaningful effect on SW and NIH strains. The level of oxidative stress parameters including MDA, ROS, and SOD increased, FRAP and TTM levels related to the hippocampus decreased. There was also a significant increase in hippocampal acetylcholinesterase levels, ADP/ATP ratio, p-NFkB, and Cyt-c. Conversely, ALA administration resulted in a significant improvement in SCO-induced spatial learning and memory impairments only in the SW and NIH mice, which was associated with a significant reduction in hippocampal AChE activity, ADP/ATP ratio, ROS and MDA levels, and SOD activity.

SIGNIFICANCE

In addition of highlighting the efficacious role of ALA in cognitive functions, the findings of this study signified the behavioral dissimilarities among similar animal strains in case of different chemical exposures.

Hericium erinaceus (Bull.) Pers. Ethanolic Extract with Antioxidant Properties on Scopolamine-Induced Memory Deficits in a Zebrafish Model of Cognitive Impairment

Hericium erinaceus (H. erinaceus) is a rare and appreciated fungal species belonging to the division Basidiomycota used for centuries in traditional Chinese medicine for its medicinal value. This species of mushrooms brings the most diverse benefits for the human body, and can have beneficial effects for treating Alzheimer’s disease (AD). This study investigated whether ethanolic extract from the fungal biomass of H. erinaceus enhances cognitive function via the action on cholinergic neurons using the scopolamine (SCOP)-induced zebrafish (Danio rerio) model of memory impairment. The ethanolic extract from the fungal biomass of H. erinaceus was previously obtained using an ultrasonic extraction method (UE). The administration of H. erinaceus extract to zebrafish, with a pattern of AD induced by scopolamine, showed an improvement in memory evaluated by behavioral and biochemical tests on brain tissue. These results suggest that H. erinaceus has preventive and therapeutic potentials in managing memory deficits and brain oxidative stress in zebrafish with AD.

The radioprotective effects of alpha-lipoic acid on radiotherapy-induced toxicities: A systematic review

PURPOSE

Radiation therapy is one of the main cancer treatment modalities applied in 50-70% of cancer patients. Despite the many advantages of this treatment, such as non-invasiveness, organ-preservation, and spatiotemporal flexibility in tumor targeting, it can lead to complications in irradiated healthy cells/tissues. In this regard, the use of radio-protective agents can alleviate radiation-induced complications. This study aimed to review the potential role of alpha-lipoic acid in the prevention/reduction of radiation-induced toxicities on healthy cells/tissues.

METHODS

A systematic search was performed following PRISMA guidelines to identify relevant literature on the "role of alpha-lipoic acid in the treatment of radiotherapy-induced toxicity" in the electronic databases of Web of Science, Embase, PubMed, and Scopus up to January 2021. Based on the inclusion and exclusion criteria of the present study, 278 articles were screened. Finally, 29 articles were included in this systematic review.

RESULTS

The obtained results showed that in experimental in vivo models, the radiation-treated groups had decreased survival rate and body weight compared to the control groups. It was also found that radiation can induce mild to severe toxicities on gastrointestinal, circulatory, reproductive, central nervous, respiratory, endocrine, exocrine systems, etc. However, the use of alpha-lipoic acid could alleviate the radiation-induced toxicities in most cases. This radio-protective agent exerts its effects through mechanisms of anti-oxidant, anti-apoptosis, anti-inflammatory, and so on.

CONCLUSION

According to the obtained results, it can be mentioned that co-treatment of alpha-lipoic acid with radiotherapy ameliorates the radiation-induced toxicities in healthy cells/tissues.

Amelioration of Metal-Induced Cellular Stress by α-Lipoic Acid and Dihydrolipoic Acid through Antioxidative Effects in PC12 Cells and Caco-2 Cells

α-Lipoic acid (ALA) and its reduced form dihydrolipoic acid (DHLA) are endogenous dithiol compounds with significant antioxidant properties, both of which have the potential to detoxify cells. In this study, ALA (250 μM) and DHLA (50 μM) were applied to reduce metal (As, Cd, and Pb)-induced toxicity in PC12 and Caco-2 cells as simultaneous exposure. Both significantly decreased Cd (5 μM)-, As (5 μM)-, and Pb (5 μM)-induced cell death. Subsequently, both ALA and DHLA restored cell membrane integrity and intracellular glutathione (GSH) levels, which were affected by metal-induced toxicity. In addition, DHLA protected PC12 cells from metal-induced DNA damage upon co-exposure to metals. Furthermore, ALA and DHLA upregulated the expression of survival-related proteins mTOR (mammalian target of rapamycin), Akt (protein kinase B), and Nrf2 (nuclear factor erythroid 2-related factor 2) in PC12 cells, which were previously downregulated by metal exposure. In contrast, in Caco-2 cells, upon co-exposure to metals and ALA, Nrf2 was upregulated and cleaved PARP-1 (poly (ADP-ribose) polymerase-1) was downregulated. These findings suggest that ALA and DHLA can counterbalance the toxic effects of metals. The protection of ALA or DHLA against metal toxicity may be largely due to an enhancement of antioxidant defense along with reduced glutathione level, which ultimately reduces the cellular oxidative stress.

Sulfur-containing therapeutics in the treatment of Alzheimer's disease

Sulfur is widely existent in natural products and synthetic organic compounds as organosulfur, which are often associated with a multitude of biological activities. OBenzothiazole, in which benzene ring is fused to the 4,5-positions of the thiazolerganosulfur compounds continue to garner increasing amounts of attention in the field of medicinal chemistry, especially in the development of therapeutic agents for Alzheimer's disease (AD). AD is a fatal neurodegenerative disease and the primary cause of age-related dementia posing severe societal and economic burdens. Unfortunately, there is no cure for AD. A lot of research has been conducted on sulfur-containing compounds in the context of AD due to their innate antioxidant potential and some are currently being evaluated in clinical trials. In this review, we have described emerging trends in the field, particularly the concept of multi-targeting and formulation of disease-modifying strategies. SAR, pharmacological targets, in vitro/vivo ADMET, efficacy in AD animal models, and applications in clinical trials of such sulfur compounds have also been discussed. This article provides a comprehensive review of organosulfur-based AD therapeutic agents and provides insights into their future development.

Fecal Fungal Dysbiosis in Chinese Patients With Alzheimer's Disease

Gut bacterial dysbiosis plays a vital role in the development of Alzheimer’s disease (AD). However, our understanding of alterations to the gut fungal microbiota and their correlations with host immunity in AD is still limited. Samples were obtained from 88 Chinese patients with AD, and 65 age- and gender-matched, cognitively normal controls. Using these samples, we investigated the fungal microbiota targeting internal transcribed spacer 2 (ITS2) rRNA genes using MiSeq sequencing, and analyzed their associations with the host immune response. Our data demonstrated unaltered fungal diversity but altered taxonomic composition of the fecal fungal microbiota in the AD patients. The analysis of the fungal microbiota was performed using 6,585,557 high-quality reads (2,932,482 reads from the controls and 3,653,075 from the AD patients), with an average of 43,042 reads per sample. We found that several key differential fungi such as Candida tropicalis and Schizophyllum commune were enriched in the AD patients, while Rhodotorula mucilaginosa decreased significantly. Interestingly, C. tropicalis and S. commune were positively correlated with IP-10 and TNF-α levels. In contrast, C. tropicalis was negatively correlated with IL-8 and IFN-γ levels, and R. mucilaginosa was negatively correlated with TNF-α level. PiCRUSt analysis revealed that lipoic acid metabolism, starch and sucrose metabolism were significantly decreased in the AD fungal microbiota. This study is the first to demonstrate fecal fungal dysbiosis in stable AD patients at a deeper level, and to identify the key differential fungi involved in regulating host systemic immunity. The analysis of the fungal microbiota in AD performed here may provide novel insights into the etiopathogenesis of AD and pave the way for improved diagnosis and treatment of AD.

Alpha-lipoic acid: A promising adjuvant for nonsteroidal anti-inflammatory drugs therapy with improved efficacy and gastroprotection

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used in a wide variety of diseases due to their analgesic and anti-inflammatory effects, but their usage have been limited due to significant ulcerogenic side effects. In the present study, we aimed to evaluate the effect of α-lipoic acid (ALA) treatment on the anti-inflammatory activity of indomethacin (Indo) as well as the possible therapeutic effect of ALA on high dose Indo-induced gastropathy in female mice. Mice were treated with Indo (5 or 30 mg/kg, p.o) alone or in combination with ALA (50, 100 or 200 mg/kg, i.p). in vivo anti-inflammatory effect was evaluated by formalin-induced paw edema measured as paw thickness and edema. Gastric damage was evaluated macroscopically and histologically by scoring mucosal hemorrhage, erosion, edema and inflammation. To our results, Indo was ineffective at 5 mg/kg, but co-treatment with Indo and ALA significantly reduced paw edema, implying that ALA augmented the anti-inflammatory effect of subtherapeutic dose of Indo. However, ALA was not able to induce a further increase in the anti-inflammatory effect of Indo at 30 mg/kg. Unlike the treatment with Indo at 5 mg/kg, Indo at 30 mg/kg caused severe gastric damage that prevented by co-treatment with ALA. These results suggest that combination of ALA with NSAIDs can both increase anti-inflammatory effect and prevent NSAIDs-induced gastric damage. ALA would be promising adjuvant that can reduce dose for effective NSAID therapy, which improves safety profile of NSAIDs especially in cases long-term administration of high dose needed.

Chromone-lipoic acid conjugate: Neuroprotective agent having acceptable butyrylcholinesterase inhibition, antioxidant and copper-chelation activities

PURPOSE

Alzheimer's disease (AD) is a multifaceted neurodegenerative disease. To target simultaneously multiple pathological processes involved in AD, natural-origin compounds with unique characteristics are promising scaffolds to develop novel multi-target compounds in the treatment of different neurodegenerative disease, especially AD. In this study, novel chromone-lipoic acid hybrids were prepared to find a new multifunctional lead structure for the treatment of AD.

METHODS

Chromone-lipoic acid hybrids were prepared through click reaction and their neuroprotection and anticholinesterase activity were fully evaluated. The anti-amyloid aggregation, antioxidant and metal-chelation activities of the best compound were also investigated by standard methods to find a new multi-functional agent against AD.

RESULTS

The primary biological screening demonstrated that all compounds had significant neuroprotection activity against H2O2-induced cell damage in PC12 cells. Compound 19 as the most potent butyrylcholinesterase (BuChE) inhibitor (IC50 = 7.55 μM) having significant neuroprotection activity as level as reference drug was selected for further biological evaluations. Docking and kinetic studies revealed non-competitive mixed-type inhibition of BuChE by compound 19. It could significantly reduce formation of the intracellular reactive oxygen species (ROS) and showed excellent reducing power (85.57 mM Fe+2), comparable with quercetin and lipoic acid. It could also moderately inhibit Aβ aggregation and selectively chelate with copper ions in 2:1 M ratio.

CONCLUSION

Compound 19 could be considered as a hopeful multifunctional agent for the further development gainst AD owing to the acceptable neuroprotective and anti-BuChE activity, moderate anti-Aβ aggregation activity, outstanding antioxidant activity as well as selective copper chelation ability. A new chromone-lipoic acid hybrid was synthesized as anti-Alzheimer agent with BuChE inhibitory activity, anti-Aβ aggregation, metal-chelation and antioxidant properties.

Novel molecular hybrids of indoline spiropyrans and α-lipoic acid as potential photopharmacological agents: Synthesis, structure, photochromic and biological properties

Organic photochromic compounds are attracting great interest as photoswitchable components of various bioconjugates for using in photopharmacology, targeted drug delivery and bio-imaging. Here we report on the synthesis of two novel molecular hybrids of indoline spiropyrans and alpha-lipoic acid via an esterification reaction. Preliminary photochemical studies revealed photochromic activity of 5-methoxy-substituted spirocompounds in their acetonitrile solutions. Both hybrid spiropyrans along with their parent substances in the hybrids were tested for the short-term cytotoxicity on HeLa cell cultures. The results of cytotoxicity studies showed unpredictable biocompatibility of the hybrids in comparison with the parent hydroxyl-substituted spiropyrans and α-lipoic acid, especially at the relatively high concentration of 2 mM. Using flow cytometry, we demonstrated that the both hybrids induced antioxidant response in the model cells. After the 24 h treatment, the hybrids administered at lower (500 µM) concentration caused suppressed cytosolic ROS and/or induced cellular thiols. At higher concentration, one of the hybrids demonstrated properties qualitatively similar to alpha-lipoic acid, yet far more strong. Together, flow cytometry results suggested that both hybrids of spiropyrans possess emergent biochemical and signaling antioxidant properties, exceeding those of alpha-lipoic acid.

Are Reactive Sulfur Species the New Reactive Oxygen Species?

Significance: Oxidative stress in moderation positively affects homeostasis through signaling, while in excess it is associated with adverse health outcomes. Both activities are generally attributed to reactive oxygen species (ROS); hydrogen peroxide as the signal, and cysteines on regulatory proteins as the target. However, using antioxidants to affect signaling or benefit health has not consistently translated into expected outcomes, or when it does, the mechanism is often unclear. Recent Advances: Reactive sulfur species (RSS) were integral in the origin of life and throughout much of evolution. Sophisticated metabolic pathways that evolved to regulate RSS were easily "tweaked" to deal with ROS due to the remarkable similarities between the two. However, unlike ROS, RSS are stored, recycled, and chemically more versatile. Despite these observations, the relevance and regulatory functions of RSS in extant organisms are generally underappreciated. Critical Issues: A number of factors bias observations in favor of ROS over RSS. Research conducted in room air is hyperoxic to cells, and promotes ROS production and RSS oxidation. Metabolic rates of rodent models greatly exceed those of humans; does this favor ROS? Analytical methods designed to detect ROS also respond to RSS. Do these disguise the contributions of RSS? Future Directions: Resolving the ROS/RSS issue is vital to understand biology in general and human health in particular. Improvements in experimental design and analytical methods are crucial. Perhaps the most important is an appreciation of all the attributes of RSS and keeping an open mind.

Dietary alpha-lipoic acid supplementation improves spermatogenesis and semen quality via antioxidant and anti-apoptotic effects in aged breeder roosters

The purpose of the present study was to investigate the effects of dietary alpha-lipoic acid (ALA) supplementation on the reproductive performance of aged breeder roosters. Sixteen 50-wk-old ROSS 308 breeder roosters were randomly allocated to two groups: roosters received a basal diet (CON), or a basal diet supplemented with 300 mg/kg of ALA (ALA). The results indicated that dietary ALA supplementation significantly increased sperm concentration, motility, viability, and membrane functional integrity. ALA also dramatically increased seminiferous tubule epithelial height (SEH) and testis scores. The ALA group had a higher serum concentration of testosterone than the CON group. ALA supplementation remarkably increased total antioxidant capacity (T-AOC), the enzyme activities of glutathione peroxidase (GPx), and catalase (CAT) in the testes; following a decrease in malondialdehyde (MDA) levels. In addition, we noted significant upregulation of Nrf2 mRNA and protein expression of and mRNA expression of its Downstream Genes (GPx1, NQO1, and GCLC), as well as significant downregulation of Keap1 mRNA expression in testicular tissue of aged roosters with ALA supplementation. The protein expression of Caspase 3 was downregulated and the protein expression of proliferating cell nuclear antigen (PCNA) was upregulated by ALA supplementation. The mRNA expression of spermatogenesis-related genes (ER1, AKT1, and Cav1) were markedly augmented in the ALA group compared with the CON group. In conclusion, dietary ALA supplementation enhanced the testicular antioxidant capacity through the Nrf2-signaling pathway, exerted anti-apoptotic effects, and improved the reproductive performance of aged roosters.

α-lipoic acid protects testis and epididymis against linuron-induced oxidative toxicity in adult rats

Linuron is well known for its antiandrogenic property. However, the effects of linuron on testicular and epididymal pro- and antioxidant status are not well defined. On the other hand, α-lipoic acid is well known as universal antioxidant. Therefore, the purpose of this study was twofold: firstly to investigate whether linuron exposure alters antioxidant status in the testis and epididymis of rats and if so, whether the supplementation of α-lipoic acid mitigates linuron-induced oxidative toxicity in rats. To address this question, α-lipoic acid at a dose of 70 mg/Kg body weight (three times a week) was administered to linuron exposed rats (10 or 50 mg/Kg body weight, every alternate day over a period of 60 days), and the selected reproductive endpoints were analyzed after 60 days. Respective controls were maintained in parallel. Linuron at selected doses reduced testicular daily sperm count, and epididymal sperm count, sperm motility, sperm viability, and number of tail coiled sperm, reduced activity levels of 3β- and 17β-hydroxysteroid dehydrogenases, decreased expression levels of StAR mRNA, inhibition of testosterone levels, and elevated levels of testicular cholesterol in rats over controls. Linuron intoxication deteriorated the structural integrity of testis and epididymis associated with reduced the reproductive performance over controls. Conversely, α-lipoic acid supplementation enhanced sperm quality and improved the testosterone synthesis pathway in linuron exposed rats over its respective control. Administration of α-lipoic acid restored inhibition of testicular and epididymal enzymatic (superoxide dismutase, catalase, glutathione reductase, glutathione peroxidise) and non-enzymatic (glutathione content), increased lipid peroxidation and protein carbonyl content produced by linuron in rats. α-lipoic acid supplementation inhibited the expression levels of testicular caspase-3 mRNA levels and also its activity in linuron treated rats. To summate, α-lipoic acid-induced protection of reproductive health in linuron treated rats could be attributed to its antioxidant, and steroidogenic properties.

Alpha-lipoic acid: A possible pharmacological agent for treating dry eye disease and retinopathy in diabetes

Alpha-lipoic acid (ALA) is a naturally occurring dithiol micronutrient which acts as a cofactor for mitochondrial enzyme activity. Due to its potential antioxidant activity, it is considered as "universal antioxidant". Previous studies reported the pharmacological benefits of ALA such as glycaemic control, improved insulin sensitivity and alleviation of diabetic complications such as neuropathy and cardiovascular diseases. Dry eye disease and retinopathy are prevalent in diabetic patients. Experimental studies demonstrated the beneficial effects of ALA in dry eye and diabetic retinopathy. ALA can prevent the dry eye by down regulating the expression of matrix metalloproteinase-9 in the corneal epithelial cells and activating the antioxidant status of the ocular surface. Furthermore, its direct antioxidant effect can also prevent oxidative stress-induced corneal surface erosion and lachrymal gland damage. ALA prevents diabetic retinopathy through inhibition of O-linked β-N-acetylglucosamine transferase and nuclear factor-kappa B activity and alleviation of oxidative stress. It can activate the nuclear factor erythroid-2-related factor 2 and AMP-activated protein kinase in retinal ganglion cells. Clinical trials conducted in pre-retinopathic diabetic patients showed ALA with genistein and vitamins could protect the retinal cells and decline the inflammatory effect in diabetic patients. However, studies are scant to explore its beneficial effects in dry eye disease and diabetic retinopathy. Therefore, this review article discusses an update on the role of ALA in dry eye disease and diabetic retinopathy, two ocular diseases prevalent in diabetic patients.

The protective effect of alpha lipoic acid (ALA) on social interaction memory, but not passive avoidance in sleep-deprived rats

Sleep is involved in maintaining energy, regulating heat, and recovering tissues. Furthermore, proper cognitive functions need sufficient sleep. Many studies have revealed the impairment effect of sleep deprivation (SD) on cognitive functions including learning and memory. Alpha lipoic acid (ALA) is a potent free radical scavenger, biological antioxidant, and neuroprotective agent. Furthermore, ALA improves learning and memory performance, decreases oxidative stress, and enhances antioxidant biomarkers. In this study, we aimed to investigate the effect of ALA on social interaction and passive avoidance memories in sleep-deprived rats. Total sleep deprivation (TSD) apparatus was used to induce SD (for 24 h). Three-chamber paradigm test and shuttle box apparatus were used to evaluate social interaction and passive avoidance memory, respectively. Rats' locomotor apparatus was used to assess locomotion. ALA was administered intraperitoneally at doses of 17 and 35 mg/kg for 3 consecutive days. The results showed SD impaired both types of memories. ALA at the dose of 35 mg/kg restored social interaction memory in sleep-deprived rats; while, at the dose of 17 mg/kg attenuated impairment effect of SD. Moreover, ALA at the dose of 35 mg/kg impaired passive avoidance memory in sham-SD rats and at both doses did not rescue passive avoidance memory in sleep-deprived rats. In conclusion, ALA showed impairment effect on passive avoidance memory, while improved social interaction memory in sleep-deprived rats.

Manganese-induced neurotoxicity and the potential protective effects of lipoic acid and Spirulina platensis

Manganese (Mn) is essential for many physiological processes; however, its excessive accumulation in the brain causes severe dysfunctions in the nervous system. Oxidative stress is thought to be involved in Mn-induced neurotoxicity. The aim of this study was to evaluate the neurotoxic effects of Mn and the potential protective effects of alpha lipoic acid (ALA) and Spirulina platensis (SP), each alone and in combination. Sixty-four male albino rats were divided into eight equal groups: group 1 was used as control, group 2 received saline, which used as a vehicle, group 3 received ALA (50 mg/kg/day), group 4 received SP (300 mg/kg/day), group 5 received Mn (74 mg/kg, 5 days/week), group 6 received Mn + ALA, group 7 received Mn + SP, group 8 received Mn + ALA + SP. Groups 6, 7 and 8 received the same previously mentioned doses. All treatments were orally gavaged for 8 weeks. Mn administration caused neurobehavioral changes, increases of brain and serum Mn and malondialdehyde (MDA), with decreased glutathione peroxidase (GPx), dopamine and acetylcholine levels. The co-treatment with ALA and SP revealed their ability to protect against oxidative damage, neurobehavioral and biochemical changes induced by Mn.

Novel α-Lipoic Acid/3-n-Butylphthalide Conjugate Enhances Protective Effects against Oxidative Stress and 6-OHDA Induced Neuronal Damage

Neurodegenerative diseases are irreversible conditions that result in progressive degeneration and death of nerve cells. Although the underlying mechanisms may vary, oxidative stress is considered to be one of the major causes of neuronal loss. Importantly, there are still no comprehensive treatments to completely cure these diseases. Therefore, protecting neurons from oxidative damage may be the most effective therapeutic strategy. Here we report a neuroprotective effects of a novel hybrid compound (dlx-23), obtained by conjugating α-lipoic acid (ALA), a natural antioxidant agent, and 3-n-butylphthalide (NBP), a clinical anti-ischemic drug. Dlx-23 protected against neuronal death induced by both H₂O₂ induced oxidative stress in Cath.-a-differentiated (CAD) cells and 6-OHDA, a toxin model of Parkinson's disease (PD) in SH-SY5Y cells. These activities proved to be more potent than the parent compound (ALA) alone. Dlx-23 scavenged free radicals, increased glutathione levels, and prevented mitochondria damage. In addition, live imaging of primary cortical neurons demonstrated that dlx-23 protected against neuronal growth cone damage induced by H₂O₂. Taken together these results suggest that dlx-23 has substantial potential to be further developed into a novel neuroprotective agent against oxidative damage and toxin induced neurodegeneration.