Molecular aspects of lipoic acid in the prevention of diabetes complications

Diabetic retinopathy: New concepts of screening, monitoring, and interventions

The science of diabetes care has progressed to provide a better understanding of the oxidative and inflammatory lesions and pathophysiology of the neurovascular unit within the retina (and brain) that occur early in diabetes, even prediabetes. Screening for retinal structural abnormalities, has traditionally been performed by fundus examination or color fundus photography; however, these imaging techniques detect the disease only when there are sufficient lesions, predominantly hemorrhagic, that are recognized to occur late in the disease process after significant neuronal apoptosis and atrophy, as well as microvascular occlusion with alterations in vision. Thus, interventions have been primarily oriented toward the later-detected stages, and clinical trials, while demonstrating a slowing of the disease progression, demonstrate minimal visual improvement and modest reduction in the continued loss over prolonged periods. Similarly, vision measurement utilizing charts detects only problems of visual function late, as the process begins most often parafoveally with increasing number and progressive expansion, including into the fovea. While visual acuity has long been used to define endpoints of visual function for such trials, current methods reviewed herein are found to be imprecise. We review improved methods of testing visual function and newer imaging techniques with the recommendation that these must be utilized to discover and evaluate the injury earlier in the disease process, even in the prediabetic state. This would allow earlier therapy with ocular as well as systemic pharmacologic treatments that lower the and neuro-inflammatory processes within eye and brain. This also may include newer, micropulsed laser therapy that, if applied during the earlier cascade, should result in improved and often normalized retinal function without the adverse treatment effects of standard photocoagulation therapy.

Combination therapy is it in the future for successfully treating peripheral diabetic neuropathy?

In 2022, the Center for Disease Control and Prevention reported that 11.3% of the United States population, 37.3 million people, had diabetes and 38% of the population had prediabetes. A large American study conducted in 2021 and supported by many other studies, concluded that about 47% of diabetes patients have peripheral neuropathy and that diabetic neuropathy was present in 7.5% of patients at the time of diabetes diagnosis. In subjects deemed to be pre-diabetes and impaired glucose tolerance there was a wide range of prevalence estimates (interquartile range (IQR): 6%-34%), but most studies (72%) reported a prevalence of peripheral neuropathy ≥10%. There is no recognized treatment for diabetic peripheral neuropathy (DPN) other than good blood glucose control. Good glycemic control slows progression of DPN in patients with type 1 diabetes but for patients with type 2 diabetes it is less effective. With obesity and type 2 diabetes at epidemic levels the need of a treatment for DPN could not be more important. In this article I will first present background information on the "primary" mechanisms shown from pre-clinical studies to contribute to DPN and then discuss mono- and combination therapies that have demonstrated efficacy in animal studies and may have success when translated to human subjects. I like to compare the challenge of finding an effective treatment for DPN to the ongoing work being done to treat hypertension. Combination therapy is the recognized approach used to normalize blood pressure often requiring two, three or more drugs in addition to lifestyle modification to achieve the desired outcome. Hypertension, like DPN, is a progressive disease caused by multiple mechanisms. Therefore, it seems likely as well as logical that combination therapy combined with lifestyle adjustments will be required to successfully treat DPN.

Protective effect of alpha-lipoic acid and epalrestat on oxaliplatin-induced peripheral neuropathy in zebrafish

INTRODUCTION/AIMS

Oxaliplatin is a platinum-based anti-cancer drug widely used in colorectal cancer patients, but it may cause peripheral neuropathy. As one of the main causes of oxaliplatin-induced peripheral neuropathy (OPN) is oxidative stress, which is also a key factor causing diabetic peripheral neuropathy (DPN), the aim of this study was to evaluate the preventive effects of alpha-lipoic acid (ALA) and epalrestat (EP), which are used for the treatment of DPN, in an OPN zebrafish model.

METHODS

Tg(nbt:dsred) transgenic zebrafish, with sensory nerves in the peripheral lateral line, were treated with oxaliplatin, oxaliplatin/EP, and oxaliplatin/ALA for 4 days. A confocal microscope was used to visualize and quantify the number of axon bifurcations in the distal nerve ending. To analyze the formation of synapses on sensory nerve terminals, quantification of membrane-associated guanylate kinase (MAGUK) puncta was performed using immunohistochemistry.

RESULTS

The number of axon bifurcations and intensity of MAGUK puncta were significantly reduced in the oxaliplatin-treated group compared with those in the embryo medium-treated group. In both the oxaliplatin/EP and oxaliplatin/ALA-treated groups, the number of axon bifurcations and intensity of MAGUK puncta were greater than those in the oxaliplatin-treated group (p < .0001), and no significant difference was observed between larvae treated with oxaliplatin/ALA 1 μM and oxaliplatin/EP 1 μM (p = .4292).

DISCUSSION

ALA and EP have protective effects against OPN in zebrafish. Our findings show that ALA and EP can facilitate more beneficial treatment for OPN.

Immunomodulation through Nutrition Should Be a Key Trend in Type 2 Diabetes Treatment

An organism's ability to function properly depends not solely on its diet but also on the intake of nutrients and non-nutritive bioactive compounds that exert immunomodulatory effects. This principle applies both to healthy individuals and, in particular, to those with concomitant chronic conditions, such as type 2 diabetes. However, the current food industry and the widespread use of highly processed foods often lead to nutritional deficiencies. Numerous studies have confirmed the occurrence of immune system dysfunction in patients with type 2 diabetes. This article elucidates the impact of specific nutrients on the immune system function, which maintains homeostasis of the organism, with a particular emphasis on type 2 diabetes. The role of macronutrients, micronutrients, vitamins, and selected substances, such as omega-3 fatty acids, coenzyme Q10, and alpha-lipoic acid, was taken into consideration, which outlined the minimum range of tests that ought to be performed on patients in order to either directly or indirectly determine the severity of malnutrition in this group of patients.

Effects of alpha lipoic acid supplementation on post-thaw quality of drone semen

This study aimed to determine the effect of alpha-lipoic acid (ALA) on post-thaw quality of bee semen. In the study, semen from sexually mature drone were collected. A series of experiments were carried out in which the retrieved semen was diluted with diluents containing different ALA concentrations or without ALA supplement (control). Cryopreserved sperm were thawed, and evaluated for motility (phase-contrast microscope), plasma and acrosomal membrane integrity, mitochondrial membrane potential, and DNA fregmantation. The results obtained showed that the highest motility after thawing was observed in the groups containing ALA 0.25 mmol (P < 0.05). Likewise, plasma membrane integrity was found to be better preserved in the ALA 0.25 mmol-added group than in other groups. Acrosomal integrity were also higher in the ALA-containing groups than in the control group (P < 0.05). The results of this study show that ALA supplementation especially at 0.25 mmol improved post-thawed sperm motility, plasma membrane functionality, and mitochondrial membrane potantial quality of honeybee semen.

Precision Medicine in Diabetic Kidney Disease: A Narrative Review Framed by Lived Experience

Purpose of review

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease (CKD) for which many treatments exist that have been shown to prevent CKD progression and kidney failure. However, DKD is a complex and heterogeneous etiology of CKD with a spectrum of phenotypes and disease trajectories. In this narrative review, we discuss precision medicine approaches to DKD, including genomics, metabolomics, proteomics, and their potential role in the management of diabetes mellitus and DKD. A patient and caregivers of patients with lived experience with CKD were involved in this review.

Sources of information

Original research articles were identified from MEDLINE and Google Scholar using the search terms "diabetes," "diabetic kidney disease," "diabetic nephropathy," "chronic kidney disease," "kidney failure," "dialysis," "nephrology," "genomics," "metabolomics," and "proteomics."

Methods

A focused review and critical appraisal of existing literature regarding the precision medicine approaches to the diagnosis, prognosis, and treatment of diabetes and DKD framed by a patient partner's/caregiver's lived experience.

Key findings

Distinguishing diabetic nephropathy from CKD due to other types of DKD and non-DKD is challenging and typically requires a kidney biopsy for a diagnosis. Biomarkers have been identified to assist with the prediction of the onset and progression of DKD, but they have yet to be incorporated and evaluated relative to clinical standard of care CKD and kidney failure risk prediction tools. Genomics has identified multiple causal genetic variants for neonatal diabetes mellitus and monogenic diabetes of the young that can be used for diagnostic purposes and to specify antiglycemic therapy. Genome-wide-associated studies have identified genes implicated in DKD pathophysiology in the setting of type 1 and 2 diabetes but their translational benefits are lagging beyond polygenetic risk scores. Metabolomics and proteomics have been shown to improve diagnostic accuracy in DKD, have been used to identify novel pathways involved in DKD pathogenesis, and can be used to improve the prediction of CKD progression and kidney failure as well as predict response to DKD therapy.

Limitations

There are a limited number of large, high-quality prospective observational studies and no randomized controlled trials that support the use of precision medicine based approaches to improve clinical outcomes in adults with or at risk of diabetes and DKD. It is unclear which patients may benefit from the clinical use of genomics, metabolomics and proteomics along the spectrum of DKD trajectory.

Implications

Additional research is needed to evaluate the role of the use of precision medicine for DKD management, including diagnosis, differentiation of diabetic nephropathy from other etiologies of DKD and CKD, short-term and long-term risk prognostication kidney outcomes, and the prediction of response to and safety of disease-modifying therapies.

Effect of Tea Polyphenols, α-Lipoic Acid and Their Joint Use on the Antioxidant and Lipid Metabolism Performance of Hybrid Grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatu) Fed with High-Lipid Diets

This study investigated tea polyphenols (TP), α-lipoic acid (ALA) and their joint use on the antioxidant and lipid metabolic performance of hybrid grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatu) took food with high-fat diets. Six high-lipid diets with isonitrogen (50% of dry matter) and isolipid (17% of dry value) were designed, in which a total content of 1,000 mg/kg additives were added to each group except for the control group (FL). The additives addition ratios in each group were ALA (AL), TP (PL), ALA : TP = 1 : 1 (EL), ALA : TP = 1 : 2 (OL), ALA : TP = 2 : 1 (TL). Each diet was divided into three repeat groups with 30 tails (6.84 ± 0.01 g) in each group and fed for 8 weeks. The consequences were as follows: (1) the highest weight gain rate, specific growth rate, as well as the lowest feed conversion ratio and ingestion rate were discovered in the OL team, which were opposite to the TL group. (2) The body fat content and muscle fat content in the fish oil group were the lowest (P < 0.05), while those of the TL group were the highest. (3) Serum catalase, glutathione peroxidase, total antioxidant capacity, and superoxide dismutase activities were the highest, and the content of reactive oxygen species was the lowest in the OL group. (4) The OL group has the highest hepatic lipase activity and the lowest very low-density lipoprotein content of the liver. In contrast, the TL group had the highest fatty acid synthetase (FAS) activity (P < 0.05). (5) The oil-red aspects of liver tissue displayed lipid particles in other groups were reduced to different degrees compared with FL group, and the OL group showed the best lipid-lowering effect. (6) Compared with the FL group, the relative expressions of FAS, acetyl-CoA carboxylase (acc), and apolipoprotein b-100 (apoB100) genes in the liver were decreased. The relative expressions of lipoprotein lipase (lpl) and peroxisome proliferators-activated receptors-α (pparα) genes related to lipid catabolism were increased, among which the OL group had the most significant change (P < 0.05). (7) According to the 7-day challenge test of Vibrio alginolyticus, the OL group had the highest survival rate. To sum up, both ALA and TP have positive effects on relieving the lipid metabolism disorder of hybrid grouper. If they are jointly used, adding ALA : TP in a ratio of 1 : 2 (OL) may have the best effect, and an addition ratio of 2 : 1 (TL) may inhibit the hybrid grouper growth and increase the feeding cost.

Reactive oxygen species, toxicity, oxidative stress, and antioxidants: chronic diseases and aging

A physiological level of oxygen/nitrogen free radicals and non-radical reactive species (collectively known as ROS/RNS) is termed oxidative eustress or "good stress" and is characterized by low to mild levels of oxidants involved in the regulation of various biochemical transformations such as carboxylation, hydroxylation, peroxidation, or modulation of signal transduction pathways such as Nuclear factor-κB (NF-κB), Mitogen-activated protein kinase (MAPK) cascade, phosphoinositide-3-kinase, nuclear factor erythroid 2-related factor 2 (Nrf2) and other processes. Increased levels of ROS/RNS, generated from both endogenous (mitochondria, NADPH oxidases) and/or exogenous sources (radiation, certain drugs, foods, cigarette smoking, pollution) result in a harmful condition termed oxidative stress ("bad stress"). Although it is widely accepted, that many chronic diseases are multifactorial in origin, they share oxidative stress as a common denominator. Here we review the importance of oxidative stress and the mechanisms through which oxidative stress contributes to the pathological states of an organism. Attention is focused on the chemistry of ROS and RNS (e.g. superoxide radical, hydrogen peroxide, hydroxyl radicals, peroxyl radicals, nitric oxide, peroxynitrite), and their role in oxidative damage of DNA, proteins, and membrane lipids. Quantitative and qualitative assessment of oxidative stress biomarkers is also discussed. Oxidative stress contributes to the pathology of cancer, cardiovascular diseases, diabetes, neurological disorders (Alzheimer's and Parkinson's diseases, Down syndrome), psychiatric diseases (depression, schizophrenia, bipolar disorder), renal disease, lung disease (chronic pulmonary obstruction, lung cancer), and aging. The concerted action of antioxidants to ameliorate the harmful effect of oxidative stress is achieved by antioxidant enzymes (Superoxide dismutases-SODs, catalase, glutathione peroxidase-GPx), and small molecular weight antioxidants (vitamins C and E, flavonoids, carotenoids, melatonin, ergothioneine, and others). Perhaps one of the most effective low molecular weight antioxidants is vitamin E, the first line of defense against the peroxidation of lipids. A promising approach appears to be the use of certain antioxidants (e.g. flavonoids), showing weak prooxidant properties that may boost cellular antioxidant systems and thus act as preventive anticancer agents. Redox metal-based enzyme mimetic compounds as potential pharmaceutical interventions and sirtuins as promising therapeutic targets for age-related diseases and anti-aging strategies are discussed.

An overview of regulation for nutraceuticals and concept of personalized nutraceuticals

Nutraceuticals are essentially nutritional components that have a vital role in developing and maintaining the body's regular functions, which keeps people healthy. The nutraceutical sector is also primarily driven by the existing global population and trends. Examples of foods considered as nutraceuticals include prebiotics, fibre, polyunsaturated fatty acids, probiotics, antioxidants, and other natural or herbal foods. Some of the most serious health problems of the 20th century, like COVID-19 and diabetes mellitus, are managed with the help of the preceding nutraceuticals. As we move into a time of health and medicine, the food industry as a whole has become more focused on research.

Polycystic Ovary Syndrome as Metabolic Disease: New Insights on Insulin Resistance

Polycystic ovary syndrome (PCOS) is a very frequent disease that affects reproductive ability and menstrual regularity. Other than the criteria established at the Rotterdam consensus, in these last few years a new issue, insulin resistance, has been found frequently, and at a very high grade, in patients with PCOS. Insulin resistance occurs for several factors, such as overweight and obesity, but it is now clear that it occurs in patients with PCOS with normal weight, thus supporting the hypothesis that insulin resistance is independent of body weight. Evidence shows that a complex pathophysiological situation occurs that impairs post-receptor insulin signalling, especially in patients with PCOS and familial diabetes. In addition, patients with PCOS have a high incidence of non-alcoholic fatty liver disease related to the hyperinsulinaemia. This narrative review focuses on the recent new insights about insulin resistance in patients with PCOS, to better understand the metabolic impairment accounting for most of the clinical signs/symptoms of PCOS.

The Rationale for Vitamin, Mineral, and Cofactor Treatment in the Precision Medical Care of Autism Spectrum Disorder

Children with autism spectrum disorder may exhibit nutritional deficiencies due to reduced intake, genetic variants, autoantibodies interfering with vitamin transport, and the accumulation of toxic compounds that consume vitamins. Importantly, vitamins and metal ions are essential for several metabolic pathways and for neurotransmitter functioning. The therapeutic benefits of supplementing vitamins, minerals (Zinc, Magnesium, Molybdenum, and Selenium), and other cofactors (coenzyme Q10, alpha-lipoic acid, and tetrahydrobiopterin) are mediated through their cofactor as well as non-cofactor functions. Interestingly, some vitamins can be safely administered at levels far above the dose typically used to correct the deficiency and exert effects beyond their functional role as enzyme cofactors. Moreover, the interrelationships between these nutrients can be leveraged to obtain synergistic effects using combinations. The present review discusses the current evidence for using vitamins, minerals, and cofactors in autism spectrum disorder, the rationale behind their use, and the prospects for future use.

α-Lipoic Acid as Adjunctive Treatment for Schizophrenia: A Randomized Double-Blind Study

BACKGROUND/PURPOSE

There is evidence for low endogenous antioxidant levels and oxidative imbalance in patients with schizophrenia. A previous open-label study with α-lipoic acid (ALA), a potent antioxidant, improved patients' negative and cognitive symptoms and markers of lipid peroxidation. Here we report the results of a randomized double-blind, placebo-controlled study to verify the response of patients with schizophrenia to adjunctive treatment with ALA (100 mg/d) in a 4-month follow-up.

METHODS

We conducted a 16-week, double-blind, placebo-controlled study of ALA at 100 mg/d dosages. We compared negative and positive symptoms, cognitive function, extrapyramidal symptoms, body mass index, and oxidative/inflammatory parameters between placebo and control groups.

RESULTS

We found no significant improvement in body mass index, cognition, psychopathology, antipsychotic adverse effects, or oxidative stress and inflammation in the experimental group compared with placebo. The whole group of patients improved in several measures, indicating a strong placebo effect in this population. A surprising finding was a significant decrease in red blood cells, white blood cells, and platelets in the group treated with ALA.

CONCLUSIONS

The decrease in red blood cells, white blood cells, and platelet counts requires further investigation and attention when prescribing ALA for patients with schizophrenia.

Alpha-Lipoic Acid as an Antioxidant Strategy for Managing Neuropathic Pain

Neuropathic pain (NP) is the most prevalent and debilitating form of chronic pain, caused by injuries or diseases of the somatosensory system. Since current first-line treatments only provide poor symptomatic relief, the search for new therapeutic strategies for managing NP is an active field of investigation. Multiple mechanisms contribute to the genesis and maintenance of NP, including damage caused by oxidative stress. The naturally occurring antioxidant alpha-lipoic acid (ALA) is a promising therapeutic agent for the management of NP. Several pre-clinical in vitro and in vivo studies as well as clinical trials demonstrate the analgesic potential of ALA in the management of NP. The beneficial biological activities of ALA are reflected in the various patents for the development of ALA-based innovative products. This review demonstrates the therapeutic potential of ALA in the management of NP by discussing its analgesic effects by multiple antioxidant mechanisms as well as the use of patented ALA-based products and how technological approaches have been applied to enhance ALA's pharmacological properties.

Protective Effects of Alpha-Lipoic Acid against 5-Fluorouracil-Induced Gastrointestinal Mucositis in Rats

Alpha-lipoic acid (ALA) is extensively utilized in multivitamin formulas and anti-aging products. The purpose of this study was to investigate the potential protective benefits of ALA on 5-fluorouracil (5-FU)-induced gastrointestinal mucositis in Wistar albino rats. Tissues from the stomach, small intestine, and large intestine were excised, and blood sera were obtained to identify biochemical indices such as TNF-α, IL-1β, MDA, GPx, SOD, MMP-1, -2, -8, and TIMP-1. A histopathological study was also performed. The results revealed mucositis-elevated TNF-, IL-1, MDA, MMP-1, -2, -8, and TIMP-1 levels in both tissues and sera, and these values dropped dramatically following ALA treatment. Reduced SOD and GPx activities in mucositis groups were reversed in ALA-treated groups. The damage produced by mucositis in the stomach and small intestine regressed in the ALA-treated group, according to histopathological evaluation. Consequently, the implementation of ALA supplementation in 5-FU therapy may act as a protective intervention for cancer patients with gastrointestinal mucositis. In light of the findings, ALA, a food-derived antioxidant with pleiotropic properties, may be an effective treatment for 5-FU-induced gastrointestinal mucositus, and prevent oxidative stress, inflammation, and tissue damage in cancer patients receiving 5-FU therapy.

Reflections of an Aging Free Radical Part 2: Meeting Inspirational People

Significance: During my long career in the field of redox biology, I met many inspiring people, especially Lester Packer. Recent Advances: This special issue of Antioxidants & Redox Signaling is dedicated to Lester Packer. Critical Issues: In this short review, I explore how Lester and other pioneers helped to develop the redox biology field and how I interacted with them. Future Directions: In our research to advance the field of redox biology, we stand on the shoulders of giants, including Lester Packer.

Evidence-based pathogenesis and treatment of ulcerative colitis: A causal role for colonic epithelial hydrogen peroxide

In this comprehensive evidence-based analysis of ulcerative colitis (UC), a causal role is identified for colonic epithelial hydrogen peroxide (H₂O₂) in both the pathogenesis and relapse of this debilitating inflammatory bowel disease. Studies have shown that H₂O₂ production is significantly increased in the non-inflamed colonic epithelium of individuals with UC. H₂O₂ is a powerful neutrophilic chemotactic agent that can diffuse through colonic epithelial cell membranes creating an interstitial chemotactic molecular “trail” that attracts adjacent intravascular neutrophils into the colonic epithelium leading to mucosal inflammation and UC. A novel therapy aimed at removing the inappropriate H₂O₂ mediated chemotactic signal has been highly effective in achieving complete histologic resolution of colitis in patients experiencing refractory disease with at least one (biopsy-proven) histologic remission lasting 14 years to date. The evidence implies that therapeutic intervention to prevent the re-establishment of a pathologic H₂O₂ mediated chemotactic signaling gradient will indefinitely preclude neutrophilic migration into the colonic epithelium constituting a functional cure for this disease. Cumulative data indicate that individuals with UC have normal immune systems and current treatment guidelines calling for the suppression of the immune response based on the belief that UC is caused by an underlying immune dysfunction are not supported by the evidence and may cause serious adverse effects. It is the aim of this paper to present experimental and clinical evidence that identifies H₂O₂ produced by the colonic epithelium as the causal agent in the pathogenesis of UC. A detailed explanation of a novel therapeutic intervention to normalize colonic H₂O₂, its rationale, components, and formulation is also provided.

Glycine Improved Cryopreserved Spermatozoa Quality in Achai Bull

Achai is a small size cattle breed, resilient to harsh and cold environment. Cryopreservation of Achai bull semen may help to improve its genetics and preserve the germplasm. Reactive oxygen species (ROS) affects the structural and functional integrity of the spermatozoa. During freezing and thawing processes, the ROS make changes in the spermatozoa quality parameters and reduce total antioxidant capacity (T-AOC) of semen that is considered as marker of oxidative stress. This study was designed to determine the effect of glycine along with vitamin E on post-thawed spermatozoa quality and total antioxidant capacity in Achai cattle. The semen collection was done twice a week from four mature fertile Achai cattle bulls (n = 4). The glycine was utilized as 0 mM, 5 mM, 10 mM, 15 mM, and 20 mM along with vitamin E @ 2.3 mM added constantly in each concentration. The control group contained all extenders except glycine. The results revealed that post-thawed spermatozoa motility was found significantly higher (P < 0.05) at 10 mM as compared to 5 mM, 15 mM, and 20 mM. Compared with control group, glycine concentration at 10 mM and other concentrations increased progressive and fast motility (%), curvilinear, straight line, and average path velocity (μm/s). Moreover, beat cross frequency (Hz) was higher (P < 0.05), and post-thaw viability (%), plasma membrane integrity, and mitochondrial membrane potential were significantly higher (P < 0.05) at 10 mM of glycine concentration in comparison to control and other glycine concentrations. Besides, acrosome integrity (%) and DNA integrity (%) as well as post-thawed T-AOC were also significantly higher (P < 0.05) at 10 mM of glycine concentration as compared to other glycine concentrations and control group. It is concluded that 10 mM of glycine along with vitamin E @ 2.3 mM improved cryopreserved semen quality of Achai bull.

Role of Oxidative Stress in the Pathogenesis of Atherothrombotic Diseases

Oxidative stress is generated by the imbalance between reactive oxygen species (ROS) formation and antioxidant scavenger system’s activity. Increased ROS, such as superoxide anion, hydrogen peroxide, hydroxyl radical and peroxynitrite, likely contribute to the development and complications of atherosclerotic cardiovascular diseases (ASCVD). In genetically modified mouse models of atherosclerosis, the overexpression of ROS-generating enzymes and uncontrolled ROS formation appear to be associated with accelerated atherosclerosis. Conversely, the overexpression of ROS scavenger systems reduces or stabilizes atherosclerotic lesions, depending on the genetic background of the mouse model. In humans, higher levels of circulating biomarkers derived from the oxidation of lipids (8-epi-prostaglandin F_2α, and malondialdehyde), as well as proteins (oxidized low-density lipoprotein, nitrotyrosine, protein carbonyls, advanced glycation end-products), are increased in conditions of high cardiovascular risk or overt ASCVD, and some oxidation biomarkers have been reported as independent predictors of ASCVD in large observational cohorts. In animal models, antioxidant supplementation with melatonin, resveratrol, Vitamin E, stevioside, acacetin and n-polyunsaturated fatty acids reduced ROS and attenuated atherosclerotic lesions. However, in humans, evidence from large, placebo-controlled, randomized trials or prospective studies failed to show any athero-protective effect of antioxidant supplementation with different compounds in different CV settings. However, the chronic consumption of diets known to be rich in antioxidant compounds (e.g., Mediterranean and high-fish diet), has shown to reduce ASCVD over decades. Future studies are needed to fill the gap between the data and targets derived from studies in animals and their pathogenetic and therapeutic significance in human ASCVD.

The effects of dietary supplementation of α-lipoic acid on the growth performance, antioxidant capacity, immune response, and disease resistance of northern snakehead, Channa argus

The study was the first time to explore the positive effects of α-LA on growth performance, antioxidant capability, immunity, and disease resistance of northern snakehead (Channa argus). Five hundred and forty northern snakehead fish (initial body weight: 8.74 ± 0.12 g (mean ± SE)) were randomly allocated into six groups with three replicates each. Six diets supplemented with α-LA at doses of 0 (CON), 300 (LA300), 600 (LA600), 900 (LA900), 1200 (LA1200), and 1500 (LA1500) mg/kg were fed to northern snakehead for 8 weeks. The results demonstrated that, when compared with the control group, optimal dietary α-LA increased the weight gain (WG), protein efficiency ratio (PER), and specific growth rate (SGR) and reduced the feed conversion ratio (FCR) of the fish (P < 0.05). Also, optimal dietary α-LA enhanced the immune-related parameters and antioxidant enzyme parameters levels in the head kidney, spleen, and liver of northern snakehead (P < 0.05). Dietary α-LA upregulated the mRNA expression levels of anti-inflammatory cytokines (il10 and tgfβ) and antioxidant related genes (gst, gsh-px, gr and Cu/Zn sod), down-regulated the pro-inflammatory cytokines (il1β, il8, il12 and tnfα) mRNA levels in the liver, spleen and head kidney of the northern snakehead (P < 0.05). The above results demonstrated that optimal dietary α-LA showed enhancement effects on the growth, antioxidant and anti-inflammatory capability, and immune response of northern snakehead. The survival rates in all α-LA treatments were significantly raised after the challenge with Aeromonas veronii (P < 0.05). Based on the quadratic regression analysis of WG, GSH-Px, LYS, and il1β, the optimal dietary α-LA levels were estimated to be 737.0, 775.0, 890.0, and 916.7 mg/kg, respectively. Considering the overall responses in growth performance, antioxidant status, immune response, and inflammatory factors, the recommended dose of α-LA in the diet of fish is 737.0-916.7 mg/kg.

PPARδ Inhibits Hyperglycemia-Triggered Senescence of Retinal Pigment Epithelial Cells by Upregulating SIRT1

Emerging evidence shows that peroxisome proliferator-activated receptor delta (PPARδ) plays a pivotal role in cellular aging. However, its function in retinal disease processes such as hyperglycemia-associated diabetic retinopathy is unclear. Here, we demonstrate that PPARδ inhibits premature senescence of retinal pigment epithelial (RPE) cells induced by high glucose (HG) through SIRT1 upregulation. A specific ligand GW501516-activation of PPARδ suppressed premature senescence and production of reactive oxygen species induced by HG in ARPE-19 cells, a spontaneously arising human RPE cell line. These effects were accompanied by the regulation of the premature senescence-associated genes p53, p21, and SMP-30. Furthermore, GW501516-activated PPARδ almost completely abolished the effects of HG treatment on the formation of phosphorylated H2A histone family member X (γ-H2A.X) foci, a molecular marker of aging. These inhibitory effects of GW501516 were significantly reversed in ARPE-19 cells stably expressing small hairpin RNA targeting PPARδ. Notably, GW501516 significantly increased the mRNA and protein levels of SIRT1, indicating that GW501516-activated PPARδ exerted its beneficial effects through SIRT1. In addition, GW501516 restored HG-suppressed SIRT1 expression, corroborating the role of SIRT1 in the anti-senescence function of PPARδ. The effects of PPARδ on HG-induced premature senescence and the expression of the senescence-associated genes p53, p21, and SMP-30 were mimicked by the SIRT1 activator resveratrol, but blocked by the SIRT1 inhibitor sirtinol. Collectively, these results indicate that GW501516-activated PPARδ inhibits HG-triggered premature senescence of RPE cells by modulating SIRT1 signaling.

Antioxidant for treatment of diabetic complications: A meta-analysis and systematic review

Antioxidants may provide a complementary treatment for patients with chronic diseases. Nevertheless, studies that have measured the effects of antioxidant on diabetes complications have provided conflicting results. This study aimed to elucidate the association between antioxidant and diabetic complications and to develop robust evidence for clinical decisions by systematic reviews and meta-analysis. PubMed, Embase, The Cochrane Library, Web of Science, Scopus databases were searched to collect clinical studies related to the efficacy of antioxidants in the treatment of diabetes complications from inception to May 5, 2021. Statistical meta-analyses were performed using the RevMan 5.4 software. Stata16 software was used to detect publication bias. The data of diabetic nephropathy (DN), diabetic nonalcoholic fatty liver disease (NAFLD), and diabetic periodontitis were collected to analyze the effect of antioxidant on diabetes and the above three complications. The meta-analysis results showed that antioxidant treatment was associated with significantly changes in the fasting plasma glucose (FPG) (standardized mean difference [SMD]: - 0.21 [95% confidence interval [CI]: - 0.33, -0.10], p < 0.001), hemoglobin A1c (HbA1c) (MD: - 0.41 [95% CI: - 0.63, -0.18], p < 0.001), total antioxidant capacity (TAC) (SMD: 0.44 [95% CI: 0.24, 0.63], p < 0.001) and malondialdehyde (MDA) (SMD: - 0.82 [95% CI: - 1.24, -0.41], p < 0.001) than the control group. Antioxidant supplements have the potential to treat three complications of diabetes. In conclusion, the meta-analysis results indicate that antioxidant treatment is effective clinically for diabetes mellitus and its complications.

α-Lipoic Acid Reduces Ceramide Synthesis and Neuroinflammation in the Hypothalamus of Insulin-Resistant Rats, While in the Cerebral Cortex Diminishes the β-Amyloid Accumulation

Background

Oxidative stress underlies metabolic diseases and cognitive impairment; thus, the use of antioxidants may improve brain function in insulin-resistant conditions. We are the first to evaluate the effects of α-lipoic acid (ALA) on redox homeostasis, sphingolipid metabolism, neuroinflammation, apoptosis, and β-amyloid accumulation in the cerebral cortex and hypothalamus of insulin-resistant rats.

Methods

The experiment was conducted on male cmdb/outbred Wistar rats fed a high-fat diet (HFD) for 10 weeks with intragastric administration of ALA (30 mg/kg body weight) for 4 weeks. Pro-oxidant and pro-inflammatory enzymes, oxidative stress, sphingolipid metabolism, neuroinflammation, apoptosis, and β-amyloid level were assessed in the hypothalamus and cerebral cortex using colorimetric, fluorimetric, ELISA, and HPLC methods. Statistical analysis was performed using three-way ANOVA followed by the Tukey HSD test.

Results

ALA normalizes body weight, food intake, glycemia, insulinemia, and systemic insulin sensitivity in HFD-fed rats. ALA treatment reduces nicotinamide adenine dinucleotide phosphate (NADPH) and xanthine oxidase activity, increases ferric-reducing antioxidant power (FRAP) and thiol levels in the hypothalamus of insulin-resistant rats. In addition, it decreases myeloperoxidase, glucuronidase, and metalloproteinase-2 activity and pro-inflammatory cytokines (IL-1β, IL-6) levels, while in the cerebral cortex ALA reduces β-amyloid accumulation. In both brain structures, ALA diminishes ceramide synthesis and caspase-3 activity. ALA improves systemic oxidative status and reduces insulin-resistant rats’ serum cytokines, chemokines, and growth factors.

Conclusion

ALA normalizes lipid and carbohydrate metabolism in insulin-resistant rats. At the brain level, ALA primarily affects hypothalamic metabolism. ALA improves redox homeostasis by decreasing the activity of pro-oxidant enzymes, enhancing total antioxidant potential, and reducing protein and lipid oxidative damage in the hypothalamus of HFD-fed rats. ALA also reduces hypothalamic inflammation and metalloproteinases activity, and cortical β-amyloid accumulation. In both brain structures, ALA diminishes ceramide synthesis and neuronal apoptosis. Although further study is needed, ALA may be a potential treatment for patients with cerebral complications of insulin resistance.

Protective Effects of Alpha Lipoic Acid Against Arsenic Induced Oxidative Stress in Isolated Rat Liver Mitochondria

Arsenic as a heavy metal and toxic pollutant has been established that has the hepatotoxic effect in animal and human models. Previous studies showed that mitochondria as the first target of arsenic toxicity has a pathogenic role in liver diseases. This study investigated alpha lipoic acid (ALA) as an antioxidant could ameliorate against liver toxicity induced by arsenic in rat mitochondria. First, mitochondria were isolated by the liver tissue centrifugation protocol. Then, isolated mitochondria were exposed with different concentrations of ALA and arsenic in different times for receiving the optimum dose and time. Finally, mitochondria were pretreated with the optimum concentrations and times of ALA and then treated with optimum concentration and time of arsenic (160 μg/ml; 30 min). The results demonstrated a significant decrease in total mitochondrial dehydrogenase activity (mitochondrial complex II) by 3, 4 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay after arsenic exposure. Mitochondria treated with arsenic also showed a significant increase in ROS generation, MMP, and MDA levels. The activity of mitochondrial catalase and mitochondrial GSH significantly decreased after exposure of mitochondria with arsenic. Pretreatment of mitochondria with ALA improved mitochondrial complex II activity; decreased mitochondrial membrane damage, MDA, and ROS amounts; and ameliorated mitochondrial GSH levels and mitochondrial catalase activity. These findings revealed that arsenic induced oxidative stress and mitochondria dysfunction, while ALA improved mitochondrial function through increasing of antioxidant defense or preserving of complex II, but suggested that ALA could prevent from mitochondria dysfunction.

Treatment strategies for postviral olfactory dysfunction: A systematic review

Background: The coronavirus disease 2019 (COVID-19) pandemic has been associated with a dramatic increase in postviral olfactory dysfunction (PVOD) among patients who are infected. A contemporary evidence-based review of current treatment options for PVOD is both timely and relevant to improve patient care. Objective: This review seeks to impact patient care by qualitatively reviewing available evidence in support of medical and procedural treatment options for PVOD. Systematic evaluation of data quality and of the level of evidence was completed to generate current treatment recommendations. Methods: A systematic review was conducted to identify primary studies that evaluated treatment outcomes for PVOD. A number of medical literature data bases were queried from January 1998 to May 2020, with completion of subsequent reference searches of retrieved articles to identify all relevant studies. Validated tools for the assessment of bias among both interventional and observational studies were used to complete quality assessment. The summary level of evidence and associated outcomes were used to generate treatment recommendations. Results: Twenty-two publications were identified for qualitative review. Outcomes of alpha-lipoic acid, intranasal and systemic corticosteroids, minocycline, zinc sulfate, vitamin A, sodium citrate, caroverine, intranasal insulin, theophylline, and Gingko biloba are reported. In addition, outcomes of traditional Chinese acupuncture and olfactory training are reviewed. Conclusion: Several medical and procedural treatments may expedite the return of olfactory function after PVOD. Current evidence supports olfactory training as a first-line intervention. Additional study is required to define specific treatment recommendations and expected outcomes for PVOD in the setting of COVID-19.

K+-Responsive Crown Ether-Based Amphiphilic Copolymer: Synthesis and Application in the Release of Drugs and Au Nanoparticles

Due to unique chelating and macrocyclic effects, crown ether compounds exhibit wide application prospects. They could be introduced into amphiphilic copolymers to provide new trigger mode for drug delivery. In this work, new amphiphilic random polymers of poly(lipoic acid-methacrylate-co-poly(ethylene glycol) methyl ether methacrylate-co-N-isopropylacrylamide-co-benzo-18-crown-6-methacrylamide (abbrev. PLENB) containing a crown ether ring and disulphide bond were synthesized via RAFT polymerization. Using the solvent evaporation method, the PLENB micelles were formed and then used to load substances, such as doxorubicin hydrochloride (DOX) and gold nanoparticles. The results showed that PLENB exhibited a variety of lowest critical solution temperature (LCST) in response to the presence of different ions, such as K+, Na+ and Mg2+. In particular, the addition of 150 mM K+ increased the LCST of PLENB from 31 to 37 °C and induced the release of DOX from the PLENB@DOX assemblies with a release rate of 99.84% within 12 h under 37 °C. However, Na+ and Mg2+ ions could not initiate the same response. Furthermore, K+ ions drove the disassembly of gold aggregates from the PLENB-SH@Au assemblies to achieve the transport of Au NPs, which is helpful to construct a K+-triggered carrier system.

Metabolic and clinical effect of alpha-lipoic acid administration in schizophrenic subjects stabilized with atypical antipsychotics: A 12-week, open-label, uncontrolled study

Background

Many of the atypical antipsychotics induce metabolic side effects, limiting their use in clinical practice. Alpha-lipoic acid (ALA) was proposed as a new approach in schizophrenia to improve metabolic effects of atypical antipsychotics. The aim of the study is to evaluate the effect of ALA on metabolic and clinical parameters among schizophrenic subjects.

Methods

15 schizophrenic subjects, in stable atypical antipsychotic monotherapy were included in the study. ALA was administrated at the oral daily dose of 600 ​mg/d in addition to antipsychotic therapy. Metabolic, clinical, and psychopathological parameters were measured at typical antipsychotics. e initial screening, and after 12 weeks.

Results

ALA produced a statistically significant reduction in QTc (p ​= ​0.012), blood glucose (p ​= 0.005), AST (p ​= ​0.021), γGT (p ​= ​0.035), CPK (p ​= ​0.005) and prolactinaemia (p ​= ​0.026). In contrast, there was a significant increase in HbA1c (p ​= ​0.026). No effects on body weight and blood lipid levels (triglycerides, total cholesterol, HDL, LDL) emerged.

Conclusions

ALA treatment appeared to be effective for reducing diabetes risk, liver functionality parameters, hyperprolactinaemia and QTC interval. ALA appears to be safe as adjunctive components in schizophrenia.

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Atypical antipsychotics induce the frequent occurrence of metabolic side effects.

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Prevalence rates of Metabolic Syndrome in patients with schizophrenia are high.

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No specific therapies for metabolic effects of SGAs in schizophrenia are still available.

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ALA was suggested as a potential therapeutic agent in various chronic diseases.

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ALA appeared to be effective to improve metabolic values in schizophrenia.

Therapeutic Benefits of Alpha-Lipoic Acid Supplementation in Diabetes Mellitus: A Narrative Review

Elevated oxidative stress is a common denominator between pathways implicated in the pathogenesis of diabetes mellitus and diabetes complications, prompting the use of antioxidant compounds in diabetes therapy. Alpha-lipoic acid (ALA), has been investigated for its role as a potent antioxidant in diabetes treatment and the results from clinical trials indicate improved glucose metabolism, reduced oxidative stress, improved endothelial dysfunction, a decline in platelet reactivity and moderate improvements to weight loss yet conflicting data regarding insulin metabolism. ALA inhibits nuclear factor kappa B (NFkB), chelates divalent transient metal ions and induces the expression of adenosine monophosphate-activated protein kinase (AMPK). This narrative review explores the results from clinical trials investigating the role of ALA in the treatment of diabetes mellitus.

Nutritional Supplements and Complementary Therapies in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) affects 1 in 5 women of reproductive age, and is characterized by menstrual irregularities, clinical or biochemical hyperandrogenism, and the presence of polycystic ovary morphology. One of the recommended treatment strategies in the international evidence-based guidelines is lifestyle modification, which includes diet and exercise, with the aim of improving a range of health outcomes. The incurable nature of PCOS reinforces the importance of developing novel and innovative symptomatic relief strategies, which are currently the only available approaches for improving quality of life for these women. Women with PCOS tend to be nutrient deficient in many common vitamins and minerals, thought to be associated with the psychological (depression, anxiety, etc.) and physiological (insulin resistance, diabetes, infertility, etc.) sequelae of the condition. Nutrient supplementation and the integration of complementary medicine as adjuncts to traditional lifestyle-based therapies in PCOS could therefore provide additional benefits to these women. In this review, we synthesize the evidence regarding nutrient supplementation and complementary therapies in PCOS, predominantly from randomized controlled trials, systematic reviews, and meta-analyses, to provide an overview of the state of knowledge in this field. The evidence to date suggests that specific vitamins (B-12, inositols, folate, vitamins D, E, and K), vitamin-like nutrients (bioflavonoids and α-lipoic acid), minerals (calcium, zinc, selenium, and chromium picolinate), and other formulations (melatonin, ω-3 fatty acids, probiotics, and cinnamon), as well as some complementary approaches such as acupuncture and yoga may be beneficial in PCOS. However, there remain areas of uncertainty and key limitations in the literature that must be overcome before these therapies can be integrated into routine clinical practice.

Micronutrients May Be a Unique Weapon Against the Neurotoxic Triad of Excitotoxicity, Oxidative Stress and Neuroinflammation: A Perspective

Excitotoxicity has been implicated in many neurological disorders and is a leading cause of oxidative stress and neuroinflammation in the nervous system. Most of the research to date has focused on each of these conditions individually; however, excitotoxicity, oxidative stress, and neuroinflammation have the ability to influence one another in a self-sustaining manner, thus functioning as a "neurotoxic triad." This perspective article re-introduces the concept of the neurotoxic triad and reviews how specific dietary micronutrients have been shown to protect against not only oxidative stress, but also excitotoxicity and neuroinflammation. Future dietary interventions for neurological disorders could focus on the effects on all three aspects of the neurotoxic triad.

Anti-Diabetic Effects of Isolated Lipids from Natural Sources through Modulation of Angiogenesis

BACKGROUND

Aberrant angiogenesis plays a fateful role in the development of diabetes and diabetic complications. Lipids, as a diverse group of biomacromolecules, are able to relieve diabetes through the modulation of angiogenesis.

OBJECTIVE

Owing to the present remarkable anti-diabetic effects with no or few side effects of lipids, the aim of this study was to assess the state-of-the-art research on anti-diabetic effects of lipids via the modulation of angiogenesis.

METHODS

To study the effects of lipids in diabetes via modulation of angiogenesis, we have searched the electronic databases including Scopus, PubMed, and Cochrane.

RESULTS

The promising anti-diabetic effects of lipids were reported in several studies. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil (FO) were reported to significantly induce neovasculogenesis in high glucose (HG)-mediated endothelial progenitor cells (EPCs) neovasculogenic dysfunction in type 2 diabetic mice. Linoleic acid, mono-epoxy-tocotrienol-α (MeT3α), and ginsenoside Rg1 facilitate wound closure and vessel formation. N-Palmitoylethanolamine (PEA), α-linolenic acid (ALA), omega-3 (ω3) lipids from flaxseed (FS) oil, ω-3 polyunsaturated fatty acids (PUFA), lipoic acid, taurine, and zeaxanthin (Zx) are effective in diabetic retinopathy via suppression of angiogenesis. Lysophosphatidic acid, alkyl-glycerophosphate, crocin, arjunolic acid, α-lipoic acid, and FS oil are involved in the management of diabetes and its cardiac complications. Furthermore, in two clinical trials, R-(+)-lipoic acid (RLA) in combination with hyperbaric oxygenation therapy (HBOT) for treatment of chronic wound healing in DM patients, as well as supplementation with DHA plus antioxidants along with intravitreal ranibizumab were investigated for its effects on diabetic macular edema.

CONCLUSION

Proof-of-concept studies presented here seem to well shed light on the anti-diabetic effects of lipids via modulation of angiogenesis.

Highly sensitive determination of α-lipoic acid in pharmaceuticals on a boron-doped diamond electrode

A simple, highly sensitive, and selective differential pulse voltammetry method for the determination of α-lipoic acid (LA) in pharmaceutical preparations was developed and validated. The method is based on a quasi-reversible, diffusion-controlled, one-electron anodic oxidation of LA on a boron-doped diamond electrode (BDDE) in a McIlvaine (citrate-phosphate, C-PB) buffer solution at pH 3.0. For the first time, this environment was used for LA determination. A linear calibration curve was obtained within the concentration range 5.82 × 10−8 to 4.00 × 10−4 mol L−1 with a correlation coefficient of 0.9999. The limits of detection was estimated to be 1.94 × 10−8 mol L−1, which is one of the lowest values characteristic of voltammetric and chromatographic methods of LA determination. The proposed procedure is sensitive, accurate, and precise. Its utility was demonstrated in the determination of LA in pharmaceuticals without the need for its separation from the matrices. The results were comparable to those obtained by high performance liquid chromatography reference method and were in good accordance with the once declared by manufacturers. Thus, our method can be considered as an alternative to the dominant chromatographic determinations of α-LA in real samples.

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.

Evaluation of total phenols content, anti-DPPH activity and the content of selected antioxidants in the honeybee drone brood homogenate

The subject of the present research is the evaluation of health-promoting properties caused by the presence of some vitamins as well as the antioxidative potential of the honeybee drone brood homogenate (DBH). The study used 139 homogenate samples obtained from various apiaries and collected over 3 years, three times during each beekeeping season. Samples differed in terms of varroa infestation, stage of brood development, location of the apiary, and the degree of environmental contamination. The content of ascorbic acid, α-tocopherol, all-trans-retinol, and coenzyme Q₁₀ in the tested samples was determined through the application of HPLC/DAD/UV and LC/QQQ/MS methods. The antioxidant potential of samples was assessed using the Folin-Ciocalteu and DPPH methods.

Protective effects of alpha-lipoic acid on hair cell damage in diabetic zebrafish model

Hearing impairment is one of the complications in diabetes mellitus; however, there are very few therapeutic studies on it. In this study, we investigated the protective effect of alpha-lipoic acid (ALA) on hearing loss in diabetic transgenic zebrafish and confirmed that ALA protects the loss of hair cells (HCs) caused by hyperglycemia. The data indicated that ALA has a protective effect on the damage to HCs in diabetic zebrafish.

Natural Antioxidant Application on Fat Accumulation: Preclinical Evidence

Obesity represents one of the most important challenges in the contemporary world that must be overcome. Different pathological consequences of these physical conditions have been studied for more than 30 years. The most nagging effects were found early in the cardiovascular system. However, later, its negative impact was also investigated in several other organs. Damage at cellular structures due to overexpression of reactive oxygen species together with mechanisms that cause under-production of antioxidants leads to the development of obesity-related complications. In this view, the negative results of oxidant molecules due to obesity were studied in various districts of the body. In the last ten years, scientific literature has reported reasonable evidence regarding natural and synthetic compounds' supplementation, which showed benefits in reducing oxidative stress and inflammatory processes in animal models of obesity. This article attempts to clarify the role of oxidative stress due to obesity and the opposing role of antioxidants to counter it, reported in preclinical studies. This analysis aims to clear-up different mechanisms that lead to the build-up of pro-oxidants during obesity and how various molecules of different origins hinder this phenomenon, behaving as antioxidants.

Alpha-Lipoic Acid as a Nutritive Supplement for Humans and Animals: An Overview of Its Use in Dog Food

Simple Summary

A review of human and animal studies involving alpha-lipoic acid supplementation was conducted to determine the utility of alpha-lipoic acid in dog food. The present literature shows that alpha-lipoic acid has utility as a nutritive additive at concentrations of 2.7–4.94 mg/kg body weight/day and improves antioxidant capacity in dogs.

Abstract

Alpha-lipoic acid (a-LA) is used as a nutritive additive in dog food. Therefore, we performed a systematic review of studies published to date in PubMed, Google Scholar, Cochrane Library and MedlinePlus involving alpha-lipoic acid supplementation, which included human clinical trials as well as animal studies, to evaluate its utility as a supplement in foods for healthy, adult dogs. While an upper limit of alpha-lipoic acid intake in humans has not been conclusively determined, the levels for oral intake of a-LA have been better defined in animals, and distinct differences based on species have been described. The maximum tolerated oral dose of a-LA in dogs has been reported as 126 mg/kg body weight and the LD₅₀ as 400 to 500 mg/kg body weight. The antioxidant, anti-inflammatory and neuro-protective benefits of alpha-lipoic acid in dogs were observed at concentrations much lower than the maximum tolerated dose or proposed LD₅₀. At concentrations of 2.7–4.94 mg/kg body weight/day, alpha-lipoic acid is well tolerated and posed no health risks to dogs while providing improved antioxidant capacity. This review thereby supports the utility of alpha-lipoic acid as an effective nutritive additive in dog food.

Rational Design and Experimental Research on the Self-Assembled System of Thermosensitive Molecularly Imprinted Polymers Formed by α-Lipoic Acid and N-Vinyl Caprolactam

In this paper, the main work was to study the theoretical self-assembly process of thermosensitive molecularly imprinted polymers (MIPs) for α-lipoic acid and to investigate thermosensitive functional monomers through density functional theory calculations (DFT) and intermolecular weak interaction analysis. The M06-2X/6-311+G (d, p) level was used to study the structural parameters, bonding sites, natural population analysis, binding energies ( $\Delta E$ ), atom in molecules (AIM), independent gradient model (IGM), and imprinted molar ratio. The results revealed that α-lipoic acid mainly interacted with N-vinyl caprolactam (NVCL) by weak hydrogen bonds, and the best conditions for MIP synthesis were an optimum molar ratio of 1 : 4 (α-lipoic acid/NVCL). The thermosensitive properties showed that the highest adsorption was at 40°C and the lowest adsorption was at 20°C; also, the MIPs released the intercepted α-lipoic acid inside polymers, and the lower critical solution temperatures (LCST) of MIPs and nonimprinted polymers (NIPs) are 25.7°C and 19.4°C, respectively. In this study, the thermosensitive MIPs displayed a different adsorption capacity towards NVCL, which could be applied for controlled separation and release of α-lipoic acid in different temperatures in a complex matrix.

The effect of Alpha-lipoic acid supplementation on endothelial function: A systematic review and meta-analysis

There is evidence that alpha-lipoic acid (ALA) supplementation plays an important role in preventing cardiovascular diseases. However, its effect, specifically, on endothelial function (EF) is unclear. Therefore, this systematic review and meta-analysis aimed to evaluate the effects of ALA supplementation on EF. Databases including PubMed/Medline, Scopus, and ISI Web of Science were searched to identify eligible publications from inception up to April 2020. Randomized controlled trials assessing the effect of ALA supplementation on flow-mediated dilation (FMD) levels in adults were included. The pooled results were obtained using the random-effects model and are expressed as weighted mean differences (WMD) with 95% confidence intervals (CI). Five studies including six effect sizes and 300 participants were included. ALA supplementation significantly increased FMD levels by 2.36% (95% CI: 1.21-3.51; p < .001), compared with the control. Subgroup analyses suggested that the effects of ALA on FMD could be changed by age and health status of the participants. Dose-response analysis also showed that ALA dosage had a significant non-linear effect on FMD levels. The results showed that ALA supplementation appears to improve the EF. However, the role of ALA supplementation in improving other biomarkers of EF requires further research.

Reactive Oxygen Species and Their Involvement in Red Blood Cell Damage in Chronic Kidney Disease

Reactive oxygen species (ROS) released in cells are signaling molecules but can also modify signaling proteins. Red blood cells perform a major role in maintaining the balance of the redox in the blood. The main cytosolic protein of RBC is hemoglobin (Hb), which accounts for 95-97%. Most other proteins are involved in protecting the blood cell from oxidative stress. Hemoglobin is a major factor in initiating oxidative stress within the erythrocyte. RBCs can also be damaged by exogenous oxidants. Hb autoxidation leads to the generation of a superoxide radical, of which the catalyzed or spontaneous dismutation produces hydrogen peroxide. Both oxidants induce hemichrome formation, heme degradation, and release of free iron which is a catalyst for free radical reactions. To maintain the redox balance, appropriate antioxidants are present in the cytosol, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and peroxiredoxin 2 (PRDX2), as well as low molecular weight antioxidants: glutathione, ascorbic acid, lipoic acid, α-tocopherol, β-carotene, and others. Redox imbalance leads to oxidative stress and may be associated with overproduction of ROS and/or insufficient capacity of the antioxidant system. Oxidative stress performs a key role in CKD as evidenced by the high level of markers associated with oxidative damage to proteins, lipids, and DNA in vivo. In addition to the overproduction of ROS, a reduced antioxidant capacity is observed, associated with a decrease in the activity of SOD, GPx, PRDX2, and low molecular weight antioxidants. In addition, hemodialysis is accompanied by oxidative stress in which low-biocompatibility dialysis membranes activate phagocytic cells, especially neutrophils and monocytes, leading to a respiratory burst. This review shows the production of ROS under normal conditions and CKD and its impact on disease progression. Oxidative damage to red blood cells (RBCs) in CKD and their contribution to cardiovascular disease are also discussed.

The Role of Alpha-lipoic Acid Supplementation in the Prevention of Diabetes Complications: A Comprehensive Review of Clinical Trials

Alpha-lipoic acid (ALA) is a substantial antioxidant in the prevention of diabetes and diabetes complications. It can regenerate other antioxidants like vitamin E, vitamin C, Coenzyme Q10 and glutathione and is often known as a universal antioxidant. Antioxidants play a role in diabetes treatment due to hyperglycemia-induced stimulation of the polyol pathway and formation of advanced glycation end products (AGE) and reactive oxygen species (ROS). Clinical trials examining alpha-lipoic acid supplementation on diabetic neuropathy, nephropathy, cardiomyopathy and erectile dysfunction display positive results, particularly in pain amelioration in neuropathy, asymmetric dimethylarginine reductions in nephropathy and improved oscillatory potential and contrast sensitivity in retinopathy. In diabetic cardiomyopathy (DCM), ALA offers protection through inhibition of NF-kB activation, reduction of fas-ligand and decrease in matrix metalloproteinase-2. This comprehensive review summarises and provides an understanding of the importance of alpha- lipoic acid supplementation to prevent diabetes complications.

The effects of alpha lipoic acid on muscle strength recovery after a single and a short-term chronic supplementation - a study in healthy well-trained individuals after intensive resistance and endurance training

Background

Alpha lipoic acid (ALA) has been demonstrated to have anti-inflammatory activity and was tested as a drug for the treatment of various diseases. ALA is also frequently used as a nutrition supplement, in healthy individuals or in competitive athletes. However, information from intervention studies investigating physiological effects of an ALA in athletes after exercise is limited. Therefore, the aim of this study was to investigate the effects of single and short-term chronic ALA supplementation on the muscle strength recovery and performance of athletes after intensive exercise.

Methods

In a double-blind, randomised, controlled trial in cross-over design, 17 male resistance and endurance-experienced athletes successfully participated. The subjects were divided into two groups (ALA and Placebo) and underwent a standardized single training session and a high intense training week. At certain time points (T0, T1a (+ 3 h), T1b (+ 24 h) and T2 (+7d)) blood samples were taken and markers for muscle damage, inflammation and oxidative stress were investigated. In addition, the maximum performance in the back squat was measured at all time points.

Results

In the chronic training experiment, a moderate inhibition of muscle damage and inflammation could be observed in the ALA-group. Performance in the back squat was significantly reduced in the placebo-group, but not in the ALA-group. No anti-oxidative effects could be observed.

Conclusions

Our data indicate possible effects of ALA supplementation, during intensive training periods result in a reduction of muscle damage, inflammation and an increase of recovery. Whether ALA supplementation in general may enhance performance and the exact training / supplementation scenarios needs to be investigated in future studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12970-020-00389-y.

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.

An updated systematic review and dose-response meta-analysis of the effects of α-lipoic acid supplementation on glycemic markers in adults

This systematic review and dose-response meta-analysis was conducted to summarize data from available clinical trials on the effects of α-lipoic acid (ALA) supplementation on glycemic markers including glucose, hemoglobin A_1c (HbA_1c), insulin, homeostatic model assessment of insulin resistance (HOMA-IR), HOMA-β, and quantitative insulin check index in adults. A comprehensive literature search was conducted in the electronic databases of PubMed, Web of Science, ProQuest, Embase and SCOPUS from inception to February 2020. Among all of the eligible studies, 28 articles were selected. The weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated to evaluate the pooled effect size. Between-study heterogeneity was evaluated using Cochran's Q test and I². Subgroup analysis was done to evaluate the potential sources of heterogeneity. The dose-response relationship was evaluated using fractional polynomial modeling. Twenty eight eligible studies with a total sample size of 1,016 participants were included in the current meta-analysis. The findings of the meta-analysis showed that ALA supplementation significantly reduced insulin (WMD: -0.64; CI: -1.287 to 0.004, P = .04), HOMA-IR (WMD: -0.48; 95% CI: -0.79 to -0.16; P = .002). No change in glucose or HbA1C was reported. Moreover, the effect of ALA on insulin was duration-dependent (P_{non-linearity} = 0.04). No evidence of departure from linearity was observed between dose and duration of the ALA supplementation on other markers. The subgrouping revealed that ALA dosage and duration of ALA supplementation, health status of participants, geographic locations and the studies' quality are possible sources of heterogeneity. In summary, ALA supplementation improves serum insulin and insulin resistance in a two-class and duration dependent non-linear analysis.

Alpha lipoic acid antagonizes cytotoxicity of cobalt nanoparticles by inhibiting ferroptosis-like cell death

As a main element in the hard metal industry, cobalt is one of the major components of human metal implants. Cobalt-containing implants, especially joint prostheses used for artificial joint replacement, can be corroded due to the complex physiological environment in vivo, producing a large number of nanoscale cobalt particles (Cobalt Nanoparticles, CoNPs). These CoNPs can be first accumulated around the implant to cause adverse local reactions and then enter into the blood vessels followed by reaching the liver, heart, brain, kidney, and other organs through systematic circulation, which leads to multi-system toxicity symptoms. To ensure the long-term existence of cobalt-containing implants in the body, it is urgently required to find out a safe and effective detoxification drug. Herein, we have demonstrated that CoNPs could induce the ferroptosis-like cell death through the enhancement of intracellular reactive oxygen species (ROS) level, cytoplasmic Fe²⁺ level, lipid peroxidation, and consumption of reduced glutathione (GSH) as well as inhibition of glutathione peroxidase 4 (GPX4) activity. Importantly, α-lipoic acid (ALA), a natural antioxidant with the capability to scavenge free radicals and chelate toxic metals, was found to efficiently alleviate the adverse effects of CoNPs. The present study illustrates a new mechanism of CoNPs mediated by ferroptosis-like cytotoxicity and discloses an effective method for the detoxification of CoNPs by employing the natural antioxidant of ALA, providing a basis for further in vivo detoxification study.

Aging-Related Disorders and Mitochondrial Dysfunction: A Critical Review for Prospect Mitoprotective Strategies Based on Mitochondrial Nutrient Mixtures

A number of aging-related disorders (ARD) have been related to oxidative stress (OS) and mitochondrial dysfunction (MDF) in a well-established body of literature. Most studies focused on cardiovascular disorders (CVD), type 2 diabetes (T2D), and neurodegenerative disorders. Counteracting OS and MDF has been envisaged to improve the clinical management of ARD, and major roles have been assigned to three mitochondrial cofactors, also termed mitochondrial nutrients (MNs), i.e., α-lipoic acid (ALA), Coenzyme Q10 (CoQ10), and carnitine (CARN). These cofactors exert essential–and distinct—roles in mitochondrial machineries, along with strong antioxidant properties. Clinical trials have mostly relied on the use of only one MN to ARD-affected patients as, e.g., in the case of CoQ10 in CVD, or of ALA in T2D, possibly with the addition of other antioxidants. Only a few clinical and pre-clinical studies reported on the administration of two MNs, with beneficial outcomes, while no available studies reported on the combined administration of three MNs. Based on the literature also from pre-clinical studies, the present review is to recommend the design of clinical trials based on combinations of the three MNs.

Antiswelling and Durable Adhesion Biodegradable Hydrogels for Tissue Repairs and Strain Sensors

Adhesive hydrogels have gained great interest for biomedical applications, because of their great adhesion, tunable structure, high water content, and biocompatibility. However, it is still challenging to engineer hydrogel materials combining tissue repairs and strain sensors. In this work, poly(thioctic acid) (PTA) is used as a skeleton structure and mixed with polydopamine (PDA), resulting in hydrogels with excellent stretchability, resilience, and adhesion, which can adhere to various organic (porcine skin) and inorganic materials (ceramic, wood, glass, etc.) in both dry and wet environments. The hydrogels also exhibit antiswelling behavior, self-healing, and repeatable adhesion capacity (seven times), which are meaningful for bioapplications and show satisfactory biocompatibility, biodegradation, cell affinity, and ability to limit apoptosis in both in vitro and in vivo experiments. In the full-thickness skin defect model, the hydrogels can accelerate the wound healing process. The introduction of Fe³⁺ can significantly enhance the conductivity of the hydrogels, making it possible for the hydrogels to be used as strain sensors. This functional hydrogel may find an appealing application as an antiswelling and durability adhesive for strain sensors.