Sialic acid associated with oxidative stress and total antioxidant capacity (TAC) expression level as a predictive indicator in moderate to severe Alzheimer's disease

Dermatoprotective effect of Moringa oleifera leaf extract on sodium valproate-induced skin damage in rats

Valproic acid is an antiepileptic drug associated with skin-related issues like excessive hair growth, hair loss, and skin rashes. In contrast, Moringa oleifera, rich in nutrients and antioxidants, is gaining popularity worldwide for its medicinal properties. The protective properties of M. oleifera extract against skin-related side effects caused by valproic acid were investigated. Female rats were divided into control groups and experimental groups such as moringa, sodium valproate, and sodium valproate + moringa groups. A 70% ethanolic extract of moringa (0.3 g/kg/day) was given to moringa groups, and a single dose of sodium valproate (0.5 g/kg/day) was given to valproate groups for 15 days. In the skin samples, antioxidant parameters (such as glutathione, glutathione-S-transferase, superoxide dismutase, catalase, and total antioxidant capacity), as well as oxidant parameters representing oxidative stress (i.e. lipid peroxidation, sialic acid, nitric oxide, reactive oxygen species, and total oxidant capacity), were examined. Additionally, boron, hydroxyproline, sodium-potassium ATPase, and tissue factor values were determined. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was also carried out for protein analysis in the skin samples. The results showed that moringa could increase glutathione, total antioxidant capacity, sodium-potassium ATPase, and boron levels, while decreasing lipid peroxidation, sialic acid, nitric oxide, total oxidant capacity, reactive oxygen species, hydroxyproline, and tissue factor levels. These findings imply that moringa possesses the potential to mitigate dermatological side effects.

Distinct patterns of plaque and microglia glycosylation in Alzheimer's disease

Glycosylation is the most common form of post-translational modification in the brain. Aberrant glycosylation has been observed in cerebrospinal fluid and brain tissue of Alzheimer's disease (AD) cases, including dysregulation of terminal sialic acid (SA) modifications. While alterations in sialylation have been identified in AD, the localization of SA modifications on cellular or aggregate-associated glycans is largely unknown because of limited spatial resolution of commonly utilized methods. The present study aims to overcome these limitations with novel combinations of histologic techniques to characterize the sialylation landscape of O- and N-linked glycans in autopsy-confirmed AD post-mortem brain tissue. Sialylated glycans facilitate important cellular functions including cell-to-cell interaction, cell migration, cell adhesion, immune regulation, and membrane excitability. Previous studies have not investigated both N- and O-linked sialylated glycans in neurodegeneration. In this study, the location and distribution of sialylated glycans were evaluated in three brain regions (frontal cortex, hippocampus, and cerebellum) from 10 AD cases using quantitative digital pathology techniques. Notably, we found significantly greater N-sialylation of the Aβ plaque microenvironment compared with O-sialylation. Plaque-associated microglia displayed the most intense N-sialylation proximal to plaque pathology. Further analyses revealed distinct differences in the levels of N- and O-sialylation between cored and diffuse Aβ plaque morphologies. Interestingly, phosphorylated tau pathology led to a slight increase in N-sialylation and no influence of O-sialylation in these AD brains. Confirming our previous observations in mice with novel histologic approach, these findings support microglia sialylation appears to have a relationship with AD protein aggregates while providing potential targets for therapeutic strategies.

Biochemical and Histological Effects of Moringa oleifera Extract against Valproate-Induced Kidney Damage

Valproic acid is an effective treatment for generalized seizure and related neurological defects. Despite its efficacy and acceptability, its use is associated with adverse drug effects. Moringa oleifera leaves are rich in phytochemical and nutritional components. It has excellent antioxidant and ethnobotanical benefits, thus popular among folk medicines and nutraceuticals. In the present study, 70% ethanol extract of moringa leaves was assessed for its in vivo biochemical and histological effects against valproate-induced kidney damage. Female Sprague-Dawley rats were randomly divided into four groups: Group I: control animals given physiological saline (n = 8); Group II: Moringa extract-administered group (0.3 g/kg b.w./day, n = 8); Group III: valproate-administered animals (0.5 g/kg b.w./day, n = 15); and Group IV: valproate + moringa extract (given similar doses of both valproate and moringa extract, n = 12) administered group. Treatments were administered orally for 15 days, the animals were fasted overnight, anesthetized, and then tissue samples harvested. In the valproate-administered experimental group, serum urea and uric acid were elevated. In the kidney tissue of the valproate rats, glutathione was depleted, antioxidant enzyme activities (superoxide dismutase, catalase, glutathione reductase, glutathione S-transferase, and glutathione peroxidase) disrupted, while oxidative stress biomarker, inflammatory proteins (Tumor necrosis factor-alpha and interleukin-6), histological damage scores, and the number of PCNA-positive cells were elevated. M. oleifera attenuated all these biochemical defects through its plethora of diverse antioxidant and therapeutic properties.

Reversal of Valproate-Induced Major Salivary Gland Changes By Moringa Oleifera Extract in Rats

This study aimed to explore the potential protective impacts of Moringa oleifera extract on major alteration in salivary glands of rats exposed to sodium valproate (VA). Groups were defined as control, control+moringa extract, sodium valproate, and sodium valproate+moringa extract. Antioxidant and oxidant status, activities of digestive and metabolic enzymes were examined. VA treatment led to various biochemical changes in the salivary glands, including decreased levels of antioxidants like glutathione, glutathione-S-transferase, and superoxide dismutase (except for sublingual superoxide dismutase). Conversely, a decrease in alpha-amylase, alkaline and acid phosphatase, lactate dehydrogenase, protease, and maltase activities were observed. The study also demonstrated that VA induces oxidative stress, increases lipid peroxidation, sialic acid, and nitric oxide levels in the salivary glands. Total oxidant capacity was raised in all glands except in the sublingual gland. The electrophoretic patterns of proteins were similar. Moringa oleifera extract exhibited protective properties, reversing these VA-induced biochemical changes due to its antioxidant and therapeutic attributes. This research suggests that moringa extract might serve as an alternative treatment approach for individuals using VA and experiencing salivary gland issues, although further research is necessary to confirm these findings in human subjects.

Fakhri M, T. Salim E, Subramaniam S. Exploring faradaic and non-faradaic electrochemical impedance spectroscopy approaches in Parkinson's disease diagnosis

Parkinson's disease is a neurodegenerative condition defined by the progressive death of dopaminergic neurons in the brain. The diagnosis of Parkinson's disease often uses time-consuming clinical evaluations and subjective assessments. Electrochemical Impedance Spectroscopy (EIS) is a useful technique for electroanalytical devices due to its label-free performance, in-situ measurements, and low cost. The development of reliable diagnostic tools for Parkinson's disease can be significantly enhanced by exploring novel techniques like faradaic and non-faradaic EIS detection methods. These techniques have the ability to identify specific biomarkers or changes in electrochemical properties linked to Parkinson's disease, allowing for an early and accurate diagnosis. Faradaic EIS detection methods utilize redox processes on the electrode surface, while non-faradaic EIS methods rely on charge transfer or capacitive properties. EIS can identify biomarkers or changes in electrical properties as indicators of Parkinson's disease by measuring impedance at different frequencies. By combining both faradaic and non-faradaic EIS approaches, it may be possible to obtain a comprehensive understanding of the electrochemical changes occurring in Parkinson's disease patients. This may lead to the development of more effective diagnostic techniques and potentially opening up new avenues for personalized treatment strategies. This review explores the current research on faradaic and non-faradaic EIS approaches for diagnosing Parkinson's disease using electrochemical impedance spectroscopy.

Insights into the Structure, Metabolism, Biological Functions and Molecular Mechanisms of Sialic Acid: A Review

Sialic acid (SA) is a kind of functional monosaccharide which exists widely in edible bird's nest (EBN), milk, meat, mucous membrane surface, etc. SA is an important functional component in promoting brain development, anti-oxidation, anti-inflammation, anti-virus, anti-tumor and immune regulation. The intestinal mucosa covers the microbial community that has a significant impact on health. In the gut, SA can also regulate gut microbiota and metabolites, participating in different biological functions. The structure, source and physiological functions of SA were reviewed in this paper. The biological functions of SA through regulating key signaling pathways and target genes were discussed. In summary, SA can modulate gut microbiota and metabolites, which affect gene expressions and exert its biological activities. It is helpful to provide scientific reference for the further investigation of SA in the functional foods.

Effect of Moringa oleifera leaf extract on valproate-induced oxidative damage in muscle

Valproic acid (VPA) is a drug used for the treatment of epilepsy worldwide. Depending on usage, it can cause complications such as coagulopathies, hepatotoxicity, and encephalopathy. Moringa oleifera has been shown to have antitumor, anti-inflammatory, antiulcer, antispasmodic, diuretic, antihypertensive, antidiabetic, and hepatoprotective activities. The current study investigated the effects of Moringa leaves extract (70% ethanol) on antioxidant systems against valproate-induced oxidative damage in muscle tissues of rats. Female Sprague Dawley rats were randomly divided into four groups. Group I: control group; Group II: animals given only Moringa extract; Group III: animals that received only sodium valproate; Group IV: animals administered with sodium valproate + Moringa extract. Moringa extract and sodium valproate were administered orally. Muscle tissues were collected after sacrificing the animals. Biochemical analysis of muscle tissue homogenates of the valproate group revealed elevated levels/activities of lipid peroxidation, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, catalase, glutathione reductase, glutathione-S-transferase, reactive oxygen species, total oxidant status, oxidative stress index, glucose-6-phosphate dehydrogenase, sialic acid, protein carbonyl, nitric oxide, and myeloperoxidase. While glutathione, superoxide dismutase, glutathione peroxidase, total antioxidant status, aryl esterase and sodium/potassium ATPase were decreased. The administration of Moringa extract reversed these biochemical changes. These results indicate that Moringa leaves extract had a protective effect on muscle tissues against valproate-induced damage.

Recent advances on N-acetylneuraminic acid: Physiological roles, applications, and biosynthesis

N-Acetylneuraminic acid (Neu5Ac), the most common type of Sia, generally acts as the terminal sugar in cell surface glycans, glycoconjugates, oligosaccharides, lipo-oligosaccharides, and polysaccharides, thus exerting numerous physiological functions. The extensive applications of Neu5Ac in the food, cosmetic, and pharmaceutical industries make large-scale production of this chemical desirable. Biosynthesis which is associated with important application potential and environmental friendliness has become an indispensable approach for large-scale synthesis of Neu5Ac. In this review, the physiological roles of Neu5Ac was first summarized in detail. Second, the safety evaluation, regulatory status, and applications of Neu5Ac were discussed. Third, enzyme-catalyzed preparation, whole-cell biocatalysis, and microbial de novo synthesis of Neu5Ac were comprehensively reviewed. In addition, we discussed the main challenges of Neu5Ac de novo biosynthesis, such as screening and engineering of key enzymes, identifying exporters of intermediates and Neu5Ac, and balancing cell growth and biosynthesis. The corresponding strategies and systematic strategies were proposed to overcome these challenges and facilitate Neu5Ac industrial-scale production.

The Therapeutic Potential of Hydroxycinnamic Acid Derivatives in Parkinson's Disease: Focus on In Vivo Research Advancements

Hydroxycinnamic acid derivatives (HCDs) are polyphenols that are abundant in cereals, coffee, tea, wine, fruits, vegetables, and other plant-based foods. To aid in the clinical prevention and treatment of Parkinson's disease (PD), we evaluated in vivo investigations of the pharmacological properties of HCDs relevant to PD, and their pharmacokinetic and safety aspects. An extensive search of published journals was conducted using several literature databases, including PubMed, Google Scholar, and the Web of Science. The search terms included "hydroxycinnamic acid derivatives," "ferulic acid," "caffeic acid," "sinapic acid," "p-coumaric acid," "Parkinson's disease," and combinations of these keywords. As of April 2023, 455 preclinical studies were retrieved, of which 364 were in vivo studies; we included 17 of these articles on the pharmaceutics of HCDs in PD. Available evidence supports the protective effects of HCDs in PD due to their anti-inflammatory, antioxidant, as well as antiapoptotic physiological activities. Studies have identified possible molecular targets and pathways for the protective actions of HCDs in PD. However, the paucity of studies on these compounds in PD, and the risk of toxicity induced with high-dose applications, limits their use. Thus, multifaceted studies of HCDs in vitro and in vivo are needed.

N-acetylneuraminic acid links immune exhaustion and accelerated memory deficit in diet-induced obese Alzheimer's disease mouse model

Systemic immunity supports lifelong brain function. Obesity posits a chronic burden on systemic immunity. Independently, obesity was shown as a risk factor for Alzheimer's disease (AD). Here we show that high-fat obesogenic diet accelerated recognition-memory impairment in an AD mouse model (5xFAD). In obese 5xFAD mice, hippocampal cells displayed only minor diet-related transcriptional changes, whereas the splenic immune landscape exhibited aging-like CD4+ T-cell deregulation. Following plasma metabolite profiling, we identified free N-acetylneuraminic acid (NANA), the predominant sialic acid, as the metabolite linking recognition-memory impairment to increased splenic immune-suppressive cells in mice. Single-nucleus RNA-sequencing revealed mouse visceral adipose macrophages as a potential source of NANA. In vitro, NANA reduced CD4+ T-cell proliferation, tested in both mouse and human. In vivo, NANA administration to standard diet-fed mice recapitulated high-fat diet effects on CD4+ T cells and accelerated recognition-memory impairment in 5xFAD mice. We suggest that obesity accelerates disease manifestation in a mouse model of AD via systemic immune exhaustion.

Sialic acid biosensing by post-printing modification of PEDOT:PSS with pyridylboronic acid

A poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based conducting polymer, which has biorecognition capabilities, has promising biosensing applications. Previously, we developed a facile method for post-printing chemical modification of PEDOT:PSS thin films from commercial sources. Molecular recognition elements were directly introduced into the PSS side chain by a two-step chemical reaction: introduction of an ethylenediamine linker via an acid chloride reaction of the sulfonate moiety, and subsequent receptor attachment to the linker via amine coupling. In this study, the same method was used to introduce 6-carboxypyridine-3-boronic acid (carboxy-PyBA) into the linker for specifically detecting N-acetylneuraminic acid (sialic acid, SA), as a cancer biomarker. The surface-modified PEDOT:PSS films were characterized by X-ray photoelectron spectroscopy, attenuated total reflection Fourier-transform infrared spectroscopy, and static water contact angle and conductivity measurements. The specific interaction between PyBA and SA was detected by label-free reagent-free potentiometry. The SA-specific negative potential responses of modified PEDOT:PSS electrodes, which was ascribed to an SA carboxyl anion, were observed in a physiologically relevant SA range (1.6-2.9 mM) at pH 5, in a concentration-dependent manner even in the presence of 10% fetal bovine serum. The sensitivity was -2.9 mV/mM in 1-5 mM SA with a limit of detection of 0.7 mM. The sensing performances were almost equivalent to those of existing graphene-based electrical SA sensors. These results show that our chemical derivatization method for printing PEDOT:PSS thin films will have applications in SA clinical diagnostics.

Blood-Based Biomarkers for Alzheimer's Disease Diagnosis and Progression: An Overview

Alzheimer's Disease (AD) is a progressive neurodegenerative disease characterized by amyloid-β (Aβ) plaque deposition and neurofibrillary tangle accumulation in the brain. Although several studies have been conducted to unravel the complex and interconnected pathophysiology of AD, clinical trial failure rates have been high, and no disease-modifying therapies are presently available. Fluid biomarker discovery for AD is a rapidly expanding field of research aimed at anticipating disease diagnosis and following disease progression over time. Currently, Aβ1-42, phosphorylated tau, and total tau levels in the cerebrospinal fluid are the best-studied fluid biomarkers for AD, but the need for novel, cheap, less-invasive, easily detectable, and more-accessible markers has recently led to the search for new blood-based molecules. However, despite considerable research activity, a comprehensive and up-to-date overview of the main blood-based biomarker candidates is still lacking. In this narrative review, we discuss the role of proteins, lipids, metabolites, oxidative-stress-related molecules, and cytokines as possible disease biomarkers. Furthermore, we highlight the potential of the emerging miRNAs and long non-coding RNAs (lncRNAs) as diagnostic tools, and we briefly present the role of vitamins and gut-microbiome-related molecules as novel candidates for AD detection and monitoring, thus offering new insights into the diagnosis and progression of this devastating disease.

Edible bird's nest protects histomorphology of rat's uterus against cadmium (Cd) toxicity through a reduction of Cd deposition and enhanced antioxidant activity

Cadmium (Cd) is often associated with reproductive disorders of mammals. Edible bird's nest (EBN) is a natural food product made of swiftlet's salivary secretion used to make their nests and it has been consumed as a tonic food for decades. This research aimed to study the protective effects of EBN against Cd-induced uterine toxicity in Sprague Dawley rats. Thirty (30) female Sprague Dawley rats were assigned into five groups as follows: group 1- negative control (NC) received distilled water; group 2 - positive control (PC) administered with CdCl₂, 5 mg/kg BW; while groups EBN-1, EBN-2, and EBN-3 received CdCl₂ (5 mg/kg BW) plus graded concentrations of 60, 90 and 120 mg/kg BW of EBN, respectively. After four weeks of daily oral treatment, rats were euthanized to collect the uterus for evluations of histopathological changes, Cd concentrations and Metallothionein (MT) expressions using H&E stain, inductive coupled plasma mass spectrometry (ICP-MS) and immunohistochemistry, respectively. Blood samples were collected for superoxide dismutase (SOD) analysis using SOD assay kit. Results revealed that the CdCl₂ without EBN supplement (PC) group had elevated levels of Cd in the uterus along with increased MT expressions and decreased SOD enzyme activity as compared to the NC group. Moreover, uterine histopathological changes, including glandular cysts and loss of normal structure of luminal epithelium (LE) and glandular epithelium (GE) were found in the PC group. Interestingly, groups treated with CdCl₂ along with EBN (EBN1, EBN2, EBN3) showed lower levels of uterine tissue Cd deposition and MT expression, lower degenerative changes with normal histomorphology of glands, and increased SOD activity as compared to the PC group. Overall, the findings revealed that oral exposure to Cd at a dose of 5 mg/kg BW resulted in significant alterations in the rat's uterus. However, the toxicity effect was averted by EBN treatment in a dose dependant manner; highest protection achieved with EBN 120 mg/kg BW, through a possible detoxification mechanism and prevention of Cd deposition.

Cellular and molecular influencers of neuroinflammation in Alzheimer's disease: Recent concepts & roles

Alzheimer's disease (AD), an extremely common neurodegenerative disorder of the older generation, is one of the leading causes of death globally. Besides the conventional hallmarks i.e. Amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs), neuroinflammation also serves as a major contributing factor in the pathogenesis of AD. There are mounting evidences to support the fundamental role of cellular (microglia, astrocytes, mast cells, and T-cells) and molecular (cytokines, chemokines, caspases, and complement proteins) influencers of neuroinflammation in producing/promoting neurodegeneration and dementia in AD. Genome-wide association studies (GWAS) have revealed the involvement of various single nucleotide polymorphisms (SNPs) of genes related to neuroinflammation with the risk of developing AD. Modulating the release of the neuroinflammatory molecules and targeting their relevant mechanisms may have beneficial effects on the onset, progress and severity of the disease. Here, we review the distinct role of various mediators and modulators of neuroinflammation that impact the pathogenesis and progression of AD as well as incite further research efforts for the treatment of AD through a neuroinflammatory approach.

Can keto/amino acids reduce oxidative stress in peritoneal dialysis patients with hypoalbuminemia?

INTRODUCTION

There is no consensus on an ideal marker of oxidative stress (OS). Disruption of the balance between free radical and antioxidant activity production by increasing oxidative markers results in OS. In this study, we aimed to investigate how OS, which increases mortality and morbidity due to various reasons, is affected by keto/amino therapy in patients with hypoalbuminemia undergoing peritoneal dialysis.

MATERIALS AND METHOD

Twenty patients who underwent peritoneal dialysis were included in the study. Before starting keto/amino acid therapy, primary kidney diseases were determined, body mass indexes, serum total protein, albumin, C-reactive protein, ferritin, calcium, phosphorus, parathyroid hormone, paraoxonase-1 (PON-1), sialic acid levels, arylesterase (ARE) activities, and malondialdehyde (MDA) levels were measured, and Kt/V values were calculated. Keto/amino acid treatment was initiated for those with an albumin level of <3.5 g/dL. The same parameters of the patients, followed up for 3 months, were checked again at the end of the third month.

RESULTS

Paraoxonase-1 and ARE activities, which are antioxidant enzyme activities, were found to be statistically significantly increased compared to the initial period (59 ± 59, 135 ± 69, 15.8 ± 19.7, and 44.7 ± 16.4, respectively; p < 0.00). MDA and sialic acid levels were significantly lower than the initial values (109 ± 99, 23 ± 9, 2.26 ± 0.44, and 2.04 ± 0.39, respectively; p < 0.01).

CONCLUSION

In our study, after the initiation of keto/amino acid treatment, PON-1, which is a significant antioxidant marker, and ARE plasma activities increased and tissue destruction product MDA and sialic acid significantly decreased. In the light of all these data, we think that this treatment can reduce OS, improve hypoalbuminemia, which causes both mortality and morbidity in patients, improve survival in PD patients, and may be an antioxidant treatment in suitable patients.