Oxidative modification of collagen by malondialdehyde in porcine skin

Human skin is exposed to various physical and chemical stress factors, which commonly cause the oxidation of lipids and proteins. In this study, azo initiator AAPH [2,2' -azobis(2-methylpropionamidine) dihydrochloride] was employed to initiate lipid peroxidation in porcine skin as an ex vivo model for human skin. We demonstrate that malondialdehyde (MDA), a secondary product of lipid peroxidation, is covalently bound to collagen in the dermis, forming MDA-collagen adducts. The binding of MDA to collagen results in an unfolding of the collagen triple helix, formation of the dimer of α-chains of collagen, and fragmentation of the collagen α-chain. It is proposed here that the MDA is bound to the lysine residues of α-chain collagen, which are involved in electrostatic interaction and hydrogen bonding with the glutamate and aspartate of other α-chains of the triple helix. Our data provide crucial information about the MDA binding topology in the skin, which is necessary to understand better the various types of skin-related diseases and the aging process in the skin under stress.

Aminochalcones Attenuate Neuronal Cell Death under Oxidative Damage via Sirtuin 1 Activity

Encouraged by the lack of effective treatments and the dramatic growth in the global prevalence of neurodegenerative diseases along with various pharmacological properties of chalcone pharmacophores, this study focused on the development of aminochalcone-based compounds, organic molecules characterized by a chalcone backbone (consisting of two aromatic rings connected by a three-carbon α,β-unsaturated carbonyl system) with an amino group attached to one of the aromatic rings, as potential neuroprotective agents. Thus, the aminochalcone-based compounds in this study were designed by bearing a -OCH3 moiety at different positions on the ring and synthesized by the Claisen-Schmidt condensation. The compounds exhibited strong neuroprotective effects against hydrogen peroxide-induced neuronal death in the human neuroblastoma (SH-SY5Y) cell line (i.e., by improving cell survival, reducing reactive oxygen species production, maintaining mitochondrial function, and preventing cell membrane damage). The aminochalcone-based compounds showed mild toxicity toward a normal embryonic lung cell line (MRC-5) and a human neuroblastoma cell line, and were predicted to have preferable pharmacokinetic profiles with potential for oral administration. Molecular docking simulation indicated that the studied aminochalcones may act as competitive activators of the well-known protective protein, SIRT1, and provided beneficial knowledge regarding the essential key chemical moieties and interacting amino acid residues. Collectively, this work provides a series of four promising candidate agents that could be developed for neuroprotection.

Multi-Target Mechanisms of Phytochemicals in Alzheimer’s Disease: Effects on Oxidative Stress, Neuroinflammation and Protein Aggregation

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by a tangle-shaped accumulation of beta-amyloid peptide fragments and Tau protein in brain neurons. The pathophysiological mechanism involves the presence of Aβ-amyloid peptide, Tau protein, oxidative stress, and an exacerbated neuro-inflammatory response. This review aims to offer an updated compendium of the most recent and promising advances in AD treatment through the administration of phytochemicals. The literature survey was carried out by electronic search in the following specialized databases PubMed/Medline, Embase, TRIP database, Google Scholar, Wiley, and Web of Science regarding published works that included molecular mechanisms and signaling pathways targeted by phytochemicals in various experimental models of Alzheimer’s disease in vitro and in vivo. The results of the studies showed that the use of phytochemicals against AD has gained relevance due to their antioxidant, anti-neuroinflammatory, anti-amyloid, and anti-hyperphosphorylation properties of Tau protein. Some bioactive compounds from plants have been shown to have the ability to prevent and stop the progression of Alzheimer’s.

Simultaneous Quantification of Four Marker Compounds in Bauhinia coccinea Extract and Their Potential Inhibitory Effects on Alzheimer's Disease Biomarkers

Bauhinia coccinea is a tropical woody plant widely distributed in Vietnam and Unnan in southern China. Although many studies have shown the biological activities of extracts from various other species in the genus, no studies have investigated the effects of B. coccinea extracts on biological systems. In the present study, a quantitative analysis of four marker compounds of ethanol extracts of B. coccinea branches (EEBC) was performed using the high performance liquid chromatography (HPLC)-photodiode array (PDA) method. Among gallic acid, (+)-catechin, ellagic acid, and quercitrin contained in EEBC, the most abundant compound was (+)-catechin (18.736 mg/g). In addition, we investigated the EEBC on neuroprotection, antioxidation, and Alzheimer’s disease (AD) marker molecules, acetylcholinesterase (AChE), and amyloid-β (Aβ). EEBC significantly inhibited hydrogen peroxide (H₂O₂)-induced cell death in a HT22 neuronal cell line and increased 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl scavenging activity markedly. EEBC also inhibited AChE and Aβ aggregation. Among the four compounds, gallic acid exhibited strong inhibitory effects against AChE activation. In the Aβ aggregation assay, the four marker compounds exhibited inhibitory effects lower than 30%. According to the results, EEBC could exert anti-AChE activation and Aβ aggregation activities based on the interactive effects of the marker compounds. Our findings suggest that EEBC are sources of therapeutic candidates for application in the development of AD medication based on AChE and Aβ dual targeting.

Antioxidant lipoic acid ligand-shell gold nanoconjugates against oxidative stress caused by α-synuclein aggregates

Gold nanoparticles are becoming a promising platform for the delivery of drugs to treat neurodegenerative diseases. Parkinson's disease, associated with the aggregation of α-synuclein, is a condition that results in dysfunctional neuronal cells leading to their degeneration and death. Oxidative stress has been strongly implicated as a common feature in this process. The limited efficacy of the traditional therapies and the development of associated severe side effects present an unmet need for preventive and adjuvant therapies. The organosulfur compound lipoic acid, naturally located in the mitochondria, plays a powerful antioxidative role against oxidative stress. However, the efficacy is limited by its low physiological concentration, and the administration is affected by its short half-life and bioavailability due to hepatic degradation. Here we exploited the drug delivery potential of gold nanoparticles to assemble lipoic acid, and administered the system into SH-SY5Y cells, a cellular model commonly used to study Parkinson's disease. We tested the nanoconjugates of GNPs-LA, under an oxidative environment induced by gold nanoparticle/α-synuclein conjugates (GNPs-α-Syn). GNPs-LA were found to be biocompatible and capable of restoring the cell damage caused by high-level reactive oxygen species generated by excessive oxidative stress in the cellular environment. We conclude that GNPs-LA may serve as promising drug delivery vehicles conveying antioxidant molecules for the treatment of Parkinson's disease.

Neuroprotective Effects of Phlorotannin-Rich Extract from Brown Seaweed Ecklonia cava on Neuronal PC-12 and SH-SY5Y Cells with Oxidative Stress

Neurodegenerative disorders in the elderly are characterized by gradual loss of memory and cognitive function. Oxidative stress caused by reactive oxygen species is associated with progressive neuronal cell damage and death in Alzheimer's disease, one of the most common neurodegenerative disorders. An edible brown seaweed, Ecklonia cava, contains a variety of biologically active compounds such as phlorotannins. In this study, we comparatively evaluated the total phenolic content, antioxidant capacity, and neuroprotective effects of the phlorotannin-rich extract from E. cava (PEEC). The total phenolic content of PEEC and dieckol was 810.8 mg gallic acid equivalents (GAE)/g and 996.6 mg GAE/g, respectively. Antioxidant capacity of PEEC was 1,233.8 mg vitamin C equivalents (VCE)/g and 392.1 mg VCE/g determined using ABTS and DPPH assays, respectively, while those of dieckol were 2,238.4 mg VCE/g and 817.7 mg VCE/g. High-performance liquid chromatography results revealed 48.08 ± 0.67 mg dieckol/g of PEEC. PEEC had neuroprotective effects in pheochromocytoma (PC-12) and human neuroblastoma (SH-SY5Y) cells against H₂O₂- and AAPH-induced oxidative damage, partly due to reduced intracellular oxidative stress. PEEC treatment inhibited acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner. Taken together, these findings suggest that PEEC is a good source of antioxidants and neuroprotective materials.

Protective effects of diarylpropionitrile against hydrogen peroxide-induced damage in human neuroblastoma SH-SY5Y cells

Oxidative stress is implicated in pathogenesis of neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. The study demonstrates diarylpropionitrile (DPN), an antioxidant selective agonist of estrogen receptor β, protected human neuroblastoma SH-SY5Y cells against H₂O₂-induced toxicity by attenuating production of reactive oxygen species, apoptosis, autophagy, NF-κB activation, MAPK p38, JNK and ERK 1/2 signaling pathways, and β-site amyloid precursor protein cleaving enzyme level, but, interestingly, stimulating Akt pathway. These findings indicate the important potential of DPN to ameliorate oxidative stress-associated damage in neurodegenerative disorders.

Cladophora glomerata methanolic extract decreases oxidative stress and improves viability and mitochondrial potential in equine adipose derived mesenchymal stem cells (ASCs)

Reactive oxygen species (ROS) are key mediators of several cellular damage and thus associated with equine diseases such as inflammation and metabolic syndrome. This study aimed to evaluate the protective and antioxidant activities of methanolic extract prepared from Cladophora glomerata (C. glomerata) biomass, on equine adipose derived mesenchymal stem cells (EqASCs), under experimental oxidative stress induced by H₂O₂. Pre-treatment of EqASCs cells with different concentrations of C. glomerata methanolic extract (1% and 5%) provided a clear protection against cellular damage triggered by H₂O₂. The cell's apoptotic status was significantly regulated, with promotion of cell viability, down-regulation of pro-apoptotic (p21, p53, Bax and Casp-9) genes expression, concomitant to up-regulation of the survival gene Bcl-2, this being supported by a mitigation of the endoplasmic reticulum (ER) stress and significant minimization of mitochondrial dysfunction. The results also showed that C. glomerata extract significantly increased the antioxidant enzymes Superoxide dismutase (SOD) and Catalase (CAT) activities, positively regulated the enzymes genes expression, and markedly reduced the protein carbonyls derivatives production. Finally, RT-qPCR analysis of the inflammatory related genes allowed to highlight a promising anti-inflammatory and immunomodulatory effect of this extract. Due to the valuable antioxidant and anti-inflammatory activities, C. glomerata may have potential benefits for the prevention of equine diseases associated with oxidative stress, including metabolic syndrome.

Oxidative stress differentially impacts male and female bovine embryos depending on the culture medium and the stress condition

Male and female embryos are known to differ for their metabolism and response to environmental factors very early in development. The present study aimed to evaluate the response to oxidative stress of male and female bovine embryos at the morula-blastocyst stages in terms of developmental rates, total cell number and apoptotic rates in two culture conditions. Embryos where cultured in a medium supplemented with either 5% fetal calf serum (FCS) or 4 mg/mL bovine serum albumin and a mixture of insulin, transferrin and selenium (BSA-ITS). Oxidative stress was applied at Day-5 post insemination (pi) by adding either AAPH or menadione to the culture medium, and blastocysts were analyzed at Day-7pi. The impact on development and blastocyst quality was dependent on the culture medium and the stress inducer but differed between male and female embryos. Male embryos resisted better to oxidative stress in FCS supplemented medium, no matter the stress inducer. Accordingly, the impact on blastocyst cell number tended to be higher in female blastocysts after stress induction with AAPH in FCS supplemented medium. On the other hand, in BSA-ITS supplemented medium, female embryos were more resistant to AAPH induced stress, while menadione had no impact on sex ratio. The weaker resistance of males to AAPH in this medium is in accordance with their trend to show a higher increase in apoptotic rates than females in this condition. In conclusion, this study shows that oxidative stress has differential impact on male and female bovine blastocysts depending on the culture condition and on the way oxidative stress is induced.

Effects of electromagnetic fields exposure on the antioxidant defense system

Technological devices have become essential components of daily life. However, their deleterious effects on the body, particularly on the nervous system, are well known. Electromagnetic fields (EMF) have various chemical effects, including causing deterioration in large molecules in cells and imbalance in ionic equilibrium. Despite being essential for life, oxygen molecules can lead to the generation of hazardous by-products, known as reactive oxygen species (ROS), during biological reactions. These reactive oxygen species can damage cellular components such as proteins, lipids and DNA. Antioxidant defense systems exist in order to keep free radical formation under control and to prevent their harmful effects on the biological system. Free radical formation can take place in various ways, including ultraviolet light, drugs, lipid oxidation, immunological reactions, radiation, stress, smoking, alcohol and biochemical redox reactions. Oxidative stress occurs if the antioxidant defense system is unable to prevent the harmful effects of free radicals. Several studies have reported that exposure to EMF results in oxidative stress in many tissues of the body. Exposure to EMF is known to increase free radical concentrations and traceability and can affect the radical couple recombination. The purpose of this review was to highlight the impact of oxidative stress on antioxidant systems. Abbreviations: EMF, electromagnetic fields; RF, radiofrequency; ROS, reactive oxygen species; GSH, glutathione; GPx, glutathione peroxidase; GR, glutathione reductase; GST, glutathione S-transferase; CAT, catalase; SOD, superoxide dismutase; HSP, heat shock protein; EMF/RFR, electromagnetic frequency and radiofrequency exposures; ELF-EMFs, exposure to extremely low frequency; MEL, melatonin; FA, folic acid; MDA, malondialdehyde.

Water-soluble fractions from defatted sesame seeds protect human neuroblast cells against peroxyl radicals and hydrogen peroxide-induced oxidative stress

Oxidative stress is involved in the development of aging-related diseases, such as neurodegenerative diseases. Dietary antioxidants that can protect neuronal cells from oxidative damage play an important role in preventing such diseases. Previously, we reported that water-soluble fractions purified from defatted sesame seed flour exhibit good antioxidant activity in vitro. In the present study, we investigated the protective effects of white and gold sesame seed water-soluble fractions (WS-wsf and GS-wsf, respectively) against 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) and hydrogen peroxide (H2O2) induced oxidative stress in human neuroblast SH-SY5Y cells. Pretreatment with WS-wsf and GS-wsf did not protect cells against AAPH-induced cytotoxicity, while simultaneous co-treatment with AAPH significantly improved cell viability and inhibited membrane lipid peroxidation. These results suggest that WS-wsf and GS-wsf protect cells from AAPH-induced extracellular oxidative damage via direct scavenging of peroxyl radicals. When oxidative stress was induced by H2O2, pretreatment WS-wsf and GS-wsf significantly enhanced cell viability. These results suggest that in addition to radical scavenging, WS-wsf and GS-wsf enhance cellular resistance to intracellular oxidative stress by activation of the Nrf-2/ARE pathway as confirmed by the increased Nrf2 protein level in the nucleus and increased heme oxygenase 1 (HO-1) mRNA expression. The roles of ferulic and vanillic acids as bioactive antioxidants in these fractions were also confirmed. In conclusion, our results indicated that WS-wsf and GS-wsf, which showed antioxidant activity in vitro, are also efficient antioxidants in a cell system protecting SH-SY5Y cells against both extracellular and intracellular oxidative stress.