Enzymatic Antioxidant Capacity Research Articles

Facing climate change: plant stress mitigation strategies in agriculture.

Climate change poses significant challenges to global agriculture, with rising temperatures, altered precipitation patterns, and increased frequency of extreme weather events threatening crop yields. These changes exceed the adaptability thresholds of many crops, decreasing their yield and threatening food security. At plant physiological levels, climate change-induced stressors disrupt photosynthesis, growth, and reproductive processes, contributing to a reduced productivity. Furthermore, the negative impacts of climate change on agriculture are exacerbated by anthropogenic factors, with agriculture itself contributing significantly to greenhouse gas emissions. To mitigate these challenges, various approaches have been explored. This work reviews the most important physical, chemical, and biological strategies most commonly used in a broad range of agricultural crops. Among physical strategies, increasing water use efficiency without yield reduction through different irrigation strategies, and the use of foliar treatments with reflective properties to mitigate the negative effects of different stresses have been proven to be effective. Concerning chemical approaches, the exogenous treatment of plants with chemicals induces existing molecular and physiological plant defense mechanisms, enhancing abiotic stress tolerance. Regarding biological treatments, plant inoculation with mycorrhiza and plant growth-promoting rhizobacteria (PGPR) can improve enzymatic antioxidant capacity and mineral solubilization, favoring root and plant growth and enhance plant performance under stressful conditions. While these strategies provide valuable short- to medium-term solutions, there is a pressing need for new biotechnological approaches aimed at developing genotypes resistant to stressful conditions. Collaborative efforts among researchers, policymakers, and agricultural stakeholders are essential to ensure global food security in the face of ongoing climate challenges.

Evaluation of maize varieties via multivariate analysis: Roles of ionome, antioxidants, and autophagy in salt tolerance.

Salt stress presents a major obstacle to maize (Zea mays L.) production globally, impeding its growth and development. In this study, we aimed to identify salt-tolerant maize varieties through evaluation using multivariate analysis and shed light on the role of ionome, antioxidant capacity, and autophagy in salt tolerance. We investigated multiple growth indices, including shoot fresh weight, shoot dry weight, plant height, chlorophyll content, electrolyte leakage, potassium and sodium contents, and potassium-to-sodium ratio in 20 maize varieties at the V3 stage under salt stress (200 mM NaCl). The results showed significant differences in the growth indices, accompanied by a wide range in their coefficient of variation, suggesting their suitability for screening salt tolerance. Based on D values, clustering analysis categorized the 20 varieties into four distinct groups. TG88, KN20, and LR888 (group I) emerged as the most salt-tolerant varieties, while YD9, XD903, and LH151 (group IV) were identified as the most sensitive. TG88 showcased nutrient preservation and redistribution under salt stress, surpassing YD9. It maintained nitrogen and iron levels in roots while YD9 experienced decreases. TG88 redistributed more nitrogen, zinc, and potassium to its leaves, outperforming YD9. TG88 preserved sulfur levels in both roots and leaves, unlike YD9. Additionally, TG88 demonstrated higher enzymatic antioxidant capacity (SOD, POD, APX, and GR) both at the enzyme and gene expression levels, upregulation of autophagy-related (ATG) genes (ZmATG6, ZmATG8a, and ZmATG10), and increased autophagic activity. Overall, this study offers insights into accurate maize varieties evaluation methods and the physiological mechanisms underlying salt tolerance and identifies promising materials for further research.

The Protective Effects of Taurine, a Non-essential Amino Acid, Against Metals Toxicities: A Review Article.

Taurine is a non-proteinogenic amino acid derived from cysteine. It is involved in several phenomena such as the regulation of growth and differentiation, osmoregulation, neurohormonal modulation, and lipid metabolism. Taurine is important because of its high levels in several tissues such as the central nervous system (CNS), heart, skeletal muscles, retinal membranes, and platelets. In this report, we present the functional properties of taurine indicating that it has potential effects on various metal toxicities. Therefore, a comprehensive literature review was performed using the Scopus, PubMed, and Web of Science databases. According to the search keywords, 61 articles were included in the study. The results indicate that taurine protects tissues against metal toxicity through enhancement of enzymatic and non-enzymatic antioxidant capacity, modulation of oxidative stress, anti-inflammatory and anti-apoptotic effects, involvement in different molecular pathways, and interference with the activity of various enzymes. Taken together, taurine is a natural supplement that presents antitoxic effects against many types of compounds, especially metals, suggesting public consumption of this amino acid as a prophylactic agent against the incidence of metal toxicity.

Effect of N-Acetylcysteine on Cisplatin Toxicity: A Review of the Literature.

N-acetylcysteine (NAC) is a membrane-permeable cysteine precursor capable of enhancing the intracellular cysteine pool, enhancing cellular glutathione (GSH) synthesis, and thus potentiating the endogenous antioxidant mechanism. Late administration of NAC after cisplatin has been shown in different in vivo studies to reduce the side effects caused by various toxicities at different levels without affecting the antitumor efficacy of platinum, improving total and enzymatic antioxidant capacity and decreasing oxidative stress markers. These characteristics provide NAC with a rationale as a potentially effective chemo protectant in cisplatin-based therapeutic cycles. NAC represents a potential candidate as a chemoprotective agent to decrease toxicities secondary to cisplatin treatment. It suggests that it could be used in clinical trials, whereby the effective dose, timing, and route should be adjusted to optimize chemoprotection. This review provides an overview of the effect of NAC on cisplatin toxicity, a drug widely used in the clinic in adults and children.

Probing the binding mechanism of tea polyphenols from different processing methods to anti-obesity and TMAO production-related enzymes through in silico molecular docking

Tea polyphenols possess anti-obesity properties and reduce TMAO levels. However, the variability of tea polyphenols under different processing methods and their preventive efficacy requires further exploration. This study systematically evaluated the antioxidant, hypoglycemic, and hypolipotropic enzyme capacities of GT, YT and DT through UPLC-ESI-MS/MS analysis of catechin profiles. OPLS, correlation analysis, and molecular docking were employed to investigate the compounds and inhibitory mechanisms targeting hypoglycemic, hypolipidemic, and TMAO-producing enzymes. GT exhibited significantly lower IC50 values for biological activity and higher catechins contents compared to YT and DT (p < 0.05). Strong positive correlations were observed between EGCG, CG, and ECG and biological activities (r ≥ 7.4, p < 0.001). Molecular docking results highlighted the establishment of stable hydrogen bonds and hydrophobic interactions between EGCG, CG, ECG, and the receptor. These findings contribute novel insights into the mechanisms by which tea polyphenols prevent obesity and inhibit TMAO production.

Comprehensive structural analysis of polyphenols and their enzymatic inhibition activities and antioxidant capacity of black mulberry (Morus nigra L.).

In this paper, the structures of polyphenols and their bioactivity of black mulberry (Morus nigra L.) cv. 'Heisang No. 1' were comprehensively analyzed. The 11 anthocyanins and 20 non-anthocyanin phenolic compounds were identified and quantified by liquid chromatography high-resolution time-of-flight mass spectrometry (LC-HR-TOF/MS2). The cyanidin-3-glucoside and cyanidin-3-rutinoside were the major anthocyanins in the black mulberry. In addition, the black mulberry showed potent antioxidant capacity as assessed by DPPH, ABTS, and FRAP assays. Black mulberry anthocyanins exhibited stronger inhibition activities against α-amylase, α-glucosidase, and lipase compared to non-anthocyanin polyphenols, with IC50 values of 1.10, 4.36, and 9.18mg/mL, respectively. The total anthocyanin content of black mulberry crude extracts and anthocyanins was 570.10±77.09 and 1278.23±117.60mg C3GE/100g DW, respectively. Black mulberry may be a rich source of polyphenols, natural antioxidants, and effective antidiabetic substances with great potential in the food industry.

Ammonium to total nitrogen ratio affects the purslane (Portulaca oleracea L.) growth, nutritional, and antioxidant status

Purslane (Portulaca oleracea L.) is a widespread weed, which is greatly appreciated for its high nutritional value. The present work evaluated the effect of different ammonium/total nitrogen ratios (NH4/Total N: Nr 0.01–0.15) on growth, physiological and biochemical parameters, and nutrient accumulation in different plant parts of hydroponically grown purslane, under two growing seasons, spring and autumn. Young seedlings of purslane were transferred to a Nutrient Film Technique (NFT) system and they were exposed to different Nr levels. The pH and the electrical conductivity of the nutrient solution were kept constant at 5.8 and 2.3 mS cm−1, respectively. After the end of the cultivation periods (19 days for spring and 22 days for autumn), a series of assessments (growth parameters, mineral content in different plant organs, antioxidant status of the plant, etc.) were done. Plant height, leaf number, root fresh weight and plant biomass revealed decreased trends at the higher NH4/total N ratios, especially during the autumn growing season. Total phenols, flavonoids and antioxidant capacity appeared increased at Nr ≤ 0.10 during both seasons (autumn and spring), revealing higher nitrogen accumulation rates and increased water and nutrient use efficiency. Purslane plants grown in Nr 0.05–0.10 revealed a less intense oxidative stress, with decreased lipid peroxidation levels that was the result of the activation of both enzymatic (superoxide dismutase, catalase and peroxidase) and non-enzymatic (ascorbic acid) antioxidant capacity of the plant. Increased Nr resulted in the accumulation of potassium, while calcium and magnesium levels in leaves were decreased. Additionally, the greater water use efficiency was measured for plants grown under Nr 0.01–0.05. Therefore, the recommended ammonium/total nitrogen ratio for purslane production of increased yield, improved nutritional value and efficient use of water and nitrogen sources is to employ Nr of 0.05, while additional care should be addressed during autumn periods as plants are subjected to greater impacts of the Nr ratio.

Redox-active metals and oxidative stress-mediated myopathies in Callinectes amnicola, blue crab populations from impacted sites of the Lagos Lagoon: inferences for adverse ecological outcomes.

While oxidative stress pathways are associated with a wide variety of tissue pathologies, its applications for evaluating and discerning ecological risks are limited. This study seeks to associate trends of lipid peroxidation and oxidative stress to risks of muscle pathologies in blue crabs inhabiting regions of the Lagos Lagoon. Crab samples (n = 520) were selected from pollution-impacted sites of the lagoon at Iddo, Ajah, Okobaba, Makoko, and the mid-lagoon area (control site). Antioxidant enzyme capacity, i.e., superoxide dismutase, catalase, glutathione peroxidase (GPx), and glutathione-S-transferase, and lipid peroxidation were evaluated in the muscle tissue of the blue crabs. The study findings showed distinct patterns of metal uptake in muscle, with redox-active metals (Cu and Zn) and redox-inactive metals (Pb and Cd) exhibiting site-specific differences. Additionally, there were changes in antioxidant modulation, lipid peroxidation, and the presence of associated myopathies. Blue crabs from sites (Makoko and Ajah) with greater uptake of redox-active metals (Cu and Zn) in muscle tissue showed higher trends of lipid peroxidation and the most prevalence of severe regression-type myopathies. Sites with lower uptake of redox-active metals showed the predominance of circulatory-type myopathies. This study also provides evidence of severe necrosis and myositis associated with digenean parasite cysts in crab muscle. Pathological evidence of severe skeletal muscle deterioration in the presence of greater lipid peroxidation could have implications for motor-neuron activity and reduced force-generating capacity necessary for adaptive responses in the wild. We conclude that elevated uptake of redox metals could aggravate the onset of myopathies in wild populations.

Exhaustive exercise alters native and site-specific H2O2 emission in red and white skeletal muscle mitochondria

Mitochondrial reactive oxygen species (ROS) homeostasis is intricately linked to energy conversion reactions and entails regulation of the mechanisms of ROS production and removal. However, there is limited understanding of how energy demand modulates ROS balance. Skeletal muscle experiences a wide range of energy requirements depending on the intensity and duration of exercise and therefore is an excellent model to probe the effect of altered energy demand on mitochondrial ROS production. Because in most fish skeletal muscle exists essentially as pure spatially distinct slow-twitch red oxidative and fast-twitch white glycolytic fibers, it provides a natural system for investigating how functional specialization affects ROS homeostasis. We tested the hypothesis that acute increase in energy demand imposed by exhaustive exercise will increase mitochondrial H2O2 emission to a greater extent in red muscle mitochondria (RMM) compared with white muscle mitochondria (WMM). We found that native H2O2 emission rates varied by up to 6-fold depending on the substrate being oxidized and muscle fiber type, with RMM emitting at higher rates with glutamate-malate and palmitoylcarnitine while WMM emitted at higher rates with succinate and glyceral-3-phosphate. Exhaustive exercise increased the native and site-specific H2O2 emission rates; however, the maximal emission rates depended on the substrate, fiber type and redox site. The H2O2 consumption capacity and activities of individual antioxidant enzymes including the glutathione- and thioredoxin-dependent peroxidases as well as catalase were higher in RMM compared with WMM indicating that the activity of antioxidant defense system does not explain the differences in H2O2 emission rates in RMM and WMM. Overall, our study suggests that substrate selection and oxidation may be the key factors determining the rates of ROS production in RMM and WMM following exhaustive exercise.

Multi-biomarker approach for the (eco)toxicity of UV-filter environmental pollution on the Mediterranean mussel Mytilus galloprovincialis in a multiple stressor context. The case of 4-MBC under salinity shifts.

Marine-coastal ecosystems are rapidly transforming because of climate change (CC). At the same time, the impacts of emerging organic contaminants (i.e., organic UV-filters) on these ecosystems are intensifying. In the Mediterranean, the consequences of these disturbances are occurring at a fast pace making this area a potential sentinel site to be investigated. While singular effects of organic UV-filters or CC-related factors on marine biota have been relatively described, their combined impact is still largely unknown. Thus, the objective of this study was to assess the long-term responses of the Mediterranean mussel Mytilus galloprovincialis towards anticipated salinity changes (decreases-S20 or increases-S40) when exposed to environmentally relevant concentrations of the UV-filter 4-methylbenzylidene camphor (4-MBC). An integrated multi-biomarker approach was applied, featuring general and oxidative stress, antioxidant and biotransformation enzyme capacity, energy metabolism, genotoxicity, and neurotoxicity biomarkers. Results showed that both projected salinities, considered separately, exerted non-negligible impacts on mussels' health status, with greater biological impairments found at S 40. Combining both stressors resulted in an evident increase in mussels' susceptibility to the UV-filter, which exacerbated the toxicity of 4-MBC. The dominant influence of salinity in the climate change-contaminant interaction played a crucial role in this outcome. The most severe scenario occurred when S 20 was combined with 4-MBC. In this situation, mussels exhibited a decrease in filtration rate, metabolic capacity and deployment of energy reserves increased, with an upregulation of biotransformation and inhibition of antioxidant enzyme activities. This exposure also led to the observation of cellular and DNA damage, as well as an increase in AChE activity. Furthermore, salinity-dependent bioaccumulation patterns were evaluated revealing that the lowest values in contaminated mussels are found at S 20. Overall, the present findings provide evidence that projected CC/pollutant scenarios may represent high risks for mussels’ populations, with global relevant implications for the ecosystem level.

Chronic Thermal Acclimation Effects on Critical Thermal Maxima (CTmax) and Oxidative Stress Differences in White Epaxial Muscle between Surface and Cave Morphotypes of the Mexican Cavefish (Astyanax mexicanus).

AbstractIn the face of increasing environmental temperatures, operative differences between mitochondrial function and whole-animal phenotypic response to the environment are underrepresented in research, especially in subtemperate ectothermic vertebrates. A novel approach to exploring this connection is to examine model species that are genetically similar but that have different whole-animal phenotypes, each of which inhabits different environments. The blind Mexican cavefish (Astyanax mexicanus) has the following two morphotypes: a surface form found in aboveground rivers and an obligate cave-dwelling form. Each morphotype inhabits vastly different thermal and oxygen environments. Whole-animal and mitochondrial responses to thermal acclimation and oxidative stress, with respect to increasing temperatures, have not been previously determined in either morphotype of this species. Here, we chronically acclimated both morphotypes to three temperatures (14°C, 25°C, and 31°C) to establish potential for acclimation and critical thermal maxima (CTmax) for each morphotype of this species. After measuring CTmax in six cohorts, we additionally measured enzymatic antioxidant capacity (catalase, superoxide dismutase, and glutathione peroxidase activities), peroxyl scavenging capacity, and lipid peroxidation damage in white epaxial muscle for each individual. We found a significant effect of acclimation temperature on CTmax (, ) but no effect of morphotype on CTmax (, ). Additionally, we found that morphotype had a significant effect on glutathione peroxidase activity, with the surface morphotype having increased glutathione peroxidase activity compared with the cave morphotype (, ). No other oxidative stress variable demonstrated significant differences. Increases in CTmax with chronic thermal acclimation to higher temperatures suggests that there is some degree of phenotypic plasticity in this species that nominally occupies thermally stable environments. The decreased glutathione peroxidase activity in the cave morphotype may be related to decreased environmental oxygen concentration and decreased metabolic rate in this environmentally constrained morphotype compared to in its surface-living counterparts.

1,3-Butanediol Administration Increases β-Hydroxybutyrate Plasma Levels and Affects Redox Homeostasis, Endoplasmic Reticulum Stress, and Adipokine Production in Rat Gonadal Adipose Tissue.

Ketone bodies (KBs) are an alternative energy source under starvation and play multiple roles as signaling molecules regulating energy and metabolic homeostasis. The mechanism by which KBs influence visceral white adipose tissue physiology is only partially known, and our study aimed to shed light on the effects they exert on such tissue. To this aim, we administered 1,3-butanediol (BD) to rats since it rapidly enhances β-hydroxybutyrate serum levels, and we evaluated the effect it induces within 3 h or after 14 days of treatment. After 14 days of treatment, rats showed a decrease in body weight gain, energy intake, gonadal-WAT (gWAT) weight, and adipocyte size compared to the control. BD exerted a pronounced antioxidant effect and directed redox homeostasis toward reductive stress, already evident within 3 h after its administration. BD lowered tissue ROS levels and oxidative damage to lipids and proteins and enhanced tissue soluble and enzymatic antioxidant capacity as well as nuclear erythroid factor-2 protein levels. BD also reduced specific mitochondrial maximal oxidative capacity and induced endoplasmic reticulum stress as well as interrelated processes, leading to changes in the level of adipokines/cytokines involved in inflammation, macrophage infiltration into gWAT, adipocyte differentiation, and lipolysis.

Polyphosphate fertilizer impacts the enzymatic and non-enzymatic antioxidant capacity of wheat plants grown under salinity

By 2050, the predicted global population is set to reach 9.6 billion highlighting the urgent need to increase crop productivity to meet the growing demand for food. This is becoming increasingly challenging when soils are saline and/or deficient in phosphorus (P). The synergic effect of P deficiency and salinity causes a series of secondary stresses including oxidative stress. Reactive Oxygen Species (ROS) production and oxidative damage in plants caused either by P limitation or by salt stress may restrict the overall plant performances leading to a decline in crop yield. However, the P application in adequate forms and doses could positively impact the growth of plants and enhances their tolerance to salinity. In our investigation, we evaluated the effect of different P fertilizers forms (Ortho-A, Ortho-B and Poly-B) and increasing P rates (0, 30 and 45 ppm) on the plant's antioxidant system and P uptake of durum wheat (Karim cultivar) grown under salinity (EC = 3.003 dS/m). Our results demonstrated that salinity caused a series of variations in the antioxidant capacity of wheat plants, at both, enzymatic and non-enzymatic levels. Remarkably, a strong correlation was observed between P uptake, biomass, various antioxidant system parameters and P rates and sources. Soluble P fertilizers considerably enhanced the total plant performances under salt stress compared with control plants grown under salinity and P deficiency (C+). Indeed, salt-stressed and fertilized plants exhibited a robust antioxidant system revealed by the increase in enzymatic activities of Catalase (CAT) and Ascorbate peroxidase (APX) and a significant accumulation of Proline, total polyphenols content (TPC) and soluble sugars (SS) as well as increased biomass, Chlorophyll content (CCI), leaf protein content and P uptake compared to unfertilized plants. Compared to OrthoP fertilizers at 45 ppm P, Poly-B fertilizer showed significant positive responses at 30 ppm P where the increase reached + 18.2% in protein content, + 156.8% in shoot biomass, + 93% in CCI, + 84% in shoot P content, + 51% in CAT activity, + 79% in APX activity, + 93% in TPC and + 40% in SS compared to C+. This implies that PolyP fertilizers might be an alternative for the suitable management of phosphorus fertilization under salinity.

L-quebrachitol extracted from industrial rubber serum: a study on its antioxidant activities and bone mineral density enhancing functions

In Southeast Asia, the natural rubber (Hevea brasiliensis) industry has expanded dramatically, and throughout the production process, a sizeable portion of industrial rubber serum is treated as effluent. L-quebrachitol has been proved as a natural product abundantly present in natural rubber serum. In order to improve the utilization rate of natural rubber, a method was provided to extract L-quebrachitol from industrial rubber serum, and the yield was 0.1∼0.2%. By using mass spectrometer, Fourier transform infrared, and nuclear magnetic resonance spectroscopy, the isolated molecule was identified as L-quebrachitol. Meanwhile, there is a lack of complete research on the antioxidant capacity of L-quebrachitol, and the effect of L-quebrachitol on bone mineral density remains at the cellular level. In this work, L-quebrachitol was confirmed to have a great ability to scavenge free radicals, especially at a concentration of 0.5 mg/mL. The protective capacity of antioxidant enzymes (catalase, total glutathione peroxidase, and superoxide dismutase) and the ability to inhibit lipid peroxidation of L-quebrachitol at concentrations of 50 and 100 μg/mL was remarkable. Furthermore, animal experiment showed that L-quebrachitol at 125 mg/kg·bw can significantly reduce weight gain, increase bone mineral density and bone calcium content of ovariectomized rats. Consequently, L-quebrachitol could be used as a novel antioxidant to prevent oxidative stress-related diseases or as an agent to increase bone density to prevent osteoporosis.

Oxidative Stress and MicroRNAs in Endothelial Cells under Metabolic Disorders.

Reactive oxygen species (ROS) are radical oxygen intermediates that serve as important second messengers in signal transduction. However, when the accumulation of these molecules exceeds the buffering capacity of antioxidant enzymes, oxidative stress and endothelial cell (EC) dysfunction occur. EC dysfunction shifts the vascular system into a pro-coagulative, proinflammatory state, thereby increasing the risk of developing cardiovascular (CV) diseases and metabolic disorders. Studies have turned to the investigation of microRNA treatment for CV risk factors, as these post-transcription regulators are known to co-regulate ROS. In this review, we will discuss ROS pathways and generation, normal endothelial cell physiology and ROS-induced dysfunction, and the current knowledge of common metabolic disorders and their connection to oxidative stress. Therapeutic strategies based on microRNAs in response to oxidative stress and microRNA's regulatory roles in controlling ROS will also be explored. It is important to gain an in-depth comprehension of the mechanisms generating ROS and how manipulating these enzymatic byproducts can protect endothelial cell function from oxidative stress and prevent the development of vascular disorders.

Three thermal treated methods improve physicochemical and functional properties of wheat bran-germ and the bran-germ containing products.

To fully investigate the effect of different stabilization methods on WBG in the same environment, we studied the effect of microwaving, baking, and extrusion on the nutritional, physicochemical, and processability properties of WBG and whole wheat bran-germ noodle (WBGN). Principal component analysis was used to comprehensively evaluate the qualities of WBG and WBGN. Machine learning-based research was conducted to predict the quality of WBGN based on the features of WBG. The results showed that three methods improved antioxidant ability, bound flavonoids, bound and total phenolics, and the processing properties in WBG (P < 0.05). Extruded-WBG showed a lower polyphenol oxidase activity, lipase activity (35.02 ± 2.02 U and 20.29 ± 0.47 mg g-1 ) and particle size (54.08 ± 0.38 μm), and higher water hold capacity (2.60 ± 0.68%) and bound phenolic levels. The enhanced quantity of bound polyphenols had a major role in the increased antioxidant potential of WBGN. Extruded-WBGN showed higher antioxidant ability for 2,2-diphenyl-1-picrylhydrazyl (171.28 ± 3.16 μmol Trolox eq kg-1 ). The extruded-WBGN had high concentrations of WBG aroma compounds, and low contents of bitterness and raw bran-germ flavor compounds. Next, the enzymatic activity, powder properties, color, and antioxidant capacity of WBG were further utilized to predict the polyphenolic, flavonoids, flavor compounds, and antioxidant capacities of WBGN, where the R2 value of the model exceeded 0.90. The best comprehensive quality modification method of the WBG and WBGN was extrusion, followed by baking and microwaving. The present study shows that extrusion is a promising way to improve WBG into a nutritious and flavorful cereal food ingredient. © 2023 Society of Chemical Industry.

A Diet Containing Rutin Ameliorates Brain Intracellular Redox Homeostasis in a Mouse Model of Alzheimer’s Disease

Quercetin has been studied extensively for its anti-Alzheimer's disease (AD) and anti-aging effects. Our previous studies have found that quercetin and in its glycoside form, rutin, can modulate the proteasome function in neuroblastoma cells. We aimed to explore the effects of quercetin and rutin on intracellular redox homeostasis of the brain (reduced glutathione/oxidized glutathione, GSH/GSSG), its correlation with β-site APP cleaving enzyme 1 (BACE1) activity, and amyloid precursor protein (APP) expression in transgenic TgAPP mice (bearing human Swedish mutation APP transgene, APPswe). On the basis that BACE1 protein and APP processing are regulated by the ubiquitin-proteasome pathway and that supplementation with GSH protects neurons from proteasome inhibition, we investigated whether a diet containing quercetin or rutin (30 mg/kg/day, 4 weeks) diminishes several early signs of AD. Genotyping analyses of animals were carried out by PCR. In order to determine intracellular redox homeostasis, spectrofluorometric methods were adopted to quantify GSH and GSSG levels using o-phthalaldehyde and the GSH/GSSG ratio was ascertained. Levels of TBARS were determined as a marker of lipid peroxidation. Enzyme activities of SOD, CAT, GR, and GPx were determined in the cortex and hippocampus. ΒACE1 activity was measured by a secretase-specific substrate conjugated to two reporter molecules (EDANS and DABCYL). Gene expression of the main antioxidant enzymes: APP, BACE1, a Disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), caspase-3, caspase-6, and inflammatory cytokines were determined by RT-PCR. First, overexpression of APPswe in TgAPP mice decreased GSH/GSSG ratio, increased malonaldehyde (MDA) levels, and, overall, decreased the main antioxidant enzyme activities in comparison to wild-type (WT) mice. Treatment of TgAPP mice with quercetin or rutin increased GSH/GSSG, diminished MDA levels, and favored the enzyme antioxidant capacity, particularly with rutin. Secondly, both APP expression and BACE1 activity were diminished with quercetin or rutin in TgAPP mice. Regarding ADAM10, it tended to increase in TgAPP mice with rutin treatment. As for caspase-3 expression, TgAPP displayed an increase which was the opposite with rutin. Finally, the increase in expression of the inflammatory markers IL-1β and IFN-γ in TgAPP mice was lowered by both quercetin and rutin. Collectively, these findings suggest that, of the two flavonoids, rutin may be included in a day-to-day diet as a form of adjuvant therapy in AD.

L-Arginine Alleviates the Reduction in Photosynthesis and Antioxidant Activity Induced by Drought Stress in Maize Seedlings.

Maize (Zea mays L.) is one of the most important food crops in the world. Drought is currently the most important abiotic factor affecting maize yield. L-arginine has emerged as a nontoxic plant growth regulator that enhances the tolerance of plants to drought. An experiment was conducted to examine the role of L-arginine in alleviating the inhibitory effects of drought on the photosynthetic capacity and activities of antioxidant enzymes when the plants were subjected to drought stress. The results showed that the biomass of maize seedlings decreased significantly under a 20% polyethylene glycol-simulated water deficit compared with the control treatment. However, the exogenous application of L-arginine alleviated the inhibition of maize growth induced by drought stress. Further analysis of the photosynthetic parameters showed that L-arginine partially restored the chloroplasts' structure under drought stress and increased the contents of chlorophyll, the performance index on an adsorption basis, and Fv/Fm by 151.3%, 105.5%, and 37.1%, respectively. Supplementation with L-arginine also reduced the oxidative damage caused by hydrogen peroxide, malondialdehyde, and superoxide ions by 27.2%, 10.0%, and 31.9%, respectively. Accordingly, the activities of ascorbate peroxidase, catalase, glutathione S-transferase, glutathione reductase, peroxidase, and superoxide dismutase increased by 11.6%, 108.5%, 104.4%, 181.1%, 18.3%, and 46.1%, respectively, under drought. Thus, these findings suggest that L-arginine can improve the drought resistance of maize seedlings by upregulating their rate of photosynthesis and their antioxidant capacity.

Effects of torularhodin against acetaminophen induced liver injury base on antioxidation, anti-inflammation and anti-apoptosis

Oxidative stress, inflammatory, and excessive apoptosis are the crucial culprits of drug-induced liver injury (DILI). Torularhodin was judged to have good potential to intervene DILI due to its antioxidant and immunomodulation activity. The aim of this study was to clarify the preventive effect of torularhodin on hepatic injury caused by acetaminophen (APAP) and its mechanism in mice. The liver injury model of mice was established by injecting APAP into the tail's veins to evaluate the intervention effect of torularhodin on liver injury. The mechanisms involved were investigated using Western blot and transcriptome analysis. The results reflected that torularhodin significantly increased antioxidant enzyme capacities (Compared with the group Dam, the activities of SOD and GSH-Px in the group TorH increased by2.47 and 3.79 times, and the content of MDA decreased by 58.78%, respectively p < 0.05), alleviated inflammation (Compared with the group Dam, the contents of TNF-α, IL-1β and IL-6 in the group TorH increased by 61.98%, 64.93% and 58.49, respectively, p < 0.05) and improved the pathological condition of liver in mice. Transcriptomic result indicated that differential genes caused by the intervention of torularhodin were mainly involved in cell metabolism processes, immunomodulation and apoptosis. Western blot results confirmed that torularhodin could inhibit hepatocyte apoptosis by regulating signaling pathways including PI3K/Akt/mTOR and Nrf2/HO-1 to increase antioxidant enzyme activity, thus intervening in DILI. It suggested that torularhodin might provide a promising preventive strategy for DILI.

Adaptive Responses of Four Medicinal Plants to High Altitude Oxidative Stresses through the Regulation of Antioxidants and Secondary Metabolites

The conservation of medicinal plants, particularly endangered or endemic species, is of the utmost importance, especially in light of inevitable climate change and its consequences. Species inhabiting high altitudes adopt exceptional defense mechanisms in response to abiotic stresses as a survival strategy. The objective of the current study was to investigate the effects of altitudinal variations on secondary metabolite accumulation and antioxidant enzyme capacity in four plants (Cotoneaster orbicularis, Crataegus x sinaica, Echinops spinosissimus subsp. Spinosissimus, and Tanacetum sinaicum) growing naturally on the Sinai Peninsula’s high mountains. Plant leaves and soil samples were collected from three altitudes between 1500 and 2250 m a.s.l. to evaluate the adaptive responses of these species in relation to high-altitude oxidative stresses. The results showed that at higher altitudes, the electrical conductivity and the micronutrient contents of the soil decreased, which may be due to the prevalence of silt and clay decreasing at higher altitudes. Chlorophyll a, chlorophyll b, ascorbic acid, and total soluble protein showed similar results in relation to higher altitudes for all species. On the other hand, proline, total soluble sugars, carotenoids, phenols, tannins, and flavonoids increased in response to high altitudes. The activity levels of catalase and ascorbic acid peroxidase showed a significant increase aligned with higher altitudes, while a significant decrease in activity levels was obtained for polyphenol oxidase. In conclusion, the present findings showed that Cotoneaster orbicularis exhibited the maximum response for coping with high-altitude stresses, followed by the remaining three species regarding the level of biochemical and physiological responses. The present work will help formulate conservation plans for important medicinal species.