Human erythrocytes as a system for evaluating the antioxidant capacity of vegetable extracts

From microbes to molecules: a review of microbial-driven antioxidant peptide generation

Oxidative stress, arising from excess reactive oxygen species (ROS) or insufficient antioxidant defenses, can damage cellular components, such as lipids, proteins, and nucleic acids, resulting in cellular dysfunction. The relationship between oxidative stress and various health disorders has prompted investigations into potent antioxidants that counteract ROS's detrimental impacts. In this context, antioxidant peptides, composed of two to twenty amino acids, have emerged as a unique group of antioxidants and have found applications in food, nutraceuticals, and pharmaceuticals. Antioxidant peptides are sourced from natural ingredients, mainly proteins derived from foods like milk, eggs, meat, fish, and plants. These peptides can be freed from their precursor proteins through enzymatic hydrolysis, fermentation, or gastrointestinal digestion. Previously published studies focused on the origin and production methods of antioxidant peptides, describing their structure-activity relationship and the mechanisms of food-derived antioxidant peptides. Yet, the role of microorganisms hasn't been sufficiently explored, even though the production of antioxidant peptides frequently employs a variety of microorganisms, such as bacteria, fungi, and yeasts, which are recognized for producing specific proteases. This review aims to provide a comprehensive overview of microorganisms and their proteases participating in enzymatic hydrolysis and microbial fermentation to produce antioxidant peptides. This review also covers endogenous peptides originating from microorganisms. The information obtained from this review might guide the discovery of novel organisms adept at generating antioxidant peptides.

Acarbose Mitigates Age-Dependent Alterations in Erythrocyte Membrane Transporters During Aging in Rats

Acarbose (ACA), a well-studied and effective inhibitor of α-amylase and α-glucosidase, is a postprandial-acting antidiabetic medicine. The membrane of the erythrocyte is an excellent tool for analyzing different physiological and biochemical activities since it experiences a range of metabolic alterations throughout aging. It is uncertain if ACA modulates erythrocyte membrane activities in an age-dependent manner. As a result, the current study was conducted to explore the influence of ACA on age-dependent deteriorated functions of transporters/exchangers, disrupted levels of various biomarkers such as lipid hydroperoxides (LHs), protein carbonyl (PCO), sialic acid (SA), total thiol (-SH), and erythrocyte membrane osmotic fragility. In addition to a concurrent increase in Na+/H+ exchanger activity and concentration of LH, PCO, and osmotic fragility, we also detected a considerable decrease in membrane-linked activities of Ca2+-ATPase (PMCA) and Na+/K+-ATPase (NKA), as well as concentrations of SA and -SH in old-aged rats. The aging-induced impairment of the activities of membrane-bound ATPases and the changed levels of redox biomarkers were shown to be effectively restored by ACA treatment.

Red blood cell distribution width at admission predicts outcome in critically ill patients with kidney failure: a retrospective cohort study based on the MIMIC-IV database

PURPOSE

We aimed to explore whether red blood cell distribution width (RDW) could serve as a biomarker to predict outcomes in critically ill patients with kidney failure in this study.

MATERIALS AND METHODS

This retrospective study was conducted with the Medical Information Mart for Intensive Care IV (MIMIC-IV).A total of 674 patients were divided into three groups based on tertiles of RDW. We used the generalized additive model, Kaplan-Meier curve, and Cox proportional hazards models to evaluate the association between RDW and clinical outcomes. We then performed subgroup analyses to investigate the stability of the associations between RDW and all-cause mortality.

RESULTS

Nonlinear and J-shaped curves were observed in the generalized additive model. Kaplan-Meier analysis showed that patients with elevated RDW had a lower survival rate. The Cox regression model indicated that high levels of RDW were most closely associated with ICU mortality and 30-day mortality (HR = 4.71, 95% CI: 1.69-11.64 and HR = 6.62, 95% CI: 2.84-15.41). Subgroup analyses indicated that the associations between RDW and all-cause mortality were stable.

CONCLUSIONS

Elevated levels of RDW were associated with an increased risk of all-cause mortality, and RDW could be an independent prognostic factor for kidney failure.

Protective Effect of Flavonoids from Mulberry Leaf on AAPH-Induced Oxidative Damage in Sheep Erythrocytes

To evaluate the antioxidant activity of flavonoids extracted from Chinese herb mulberry leaves (ML), flavonoids from mulberry leaves (FML) were extracted and purified by using ultrasonic-assisted enzymatic extraction and D101 macroporous resin. Using LC-MS/MS-Liquid Chromatography with tandem mass spectrometry analysis, hesperidin, rutoside, hyperoside, cyanidin-3-o-glucoside, myricitrin, cyanidin, and quercetin were identified, and NMR and UV were consistent with the verification of IR flavonoid characteristics. The antioxidant activity of FML has also been evaluated as well as the protective effect on 2,2 0-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced oxidative stress. The results showed that FML exhibited powerful antioxidant activity. Moreover, FML showed dose-dependent protection against AAPH-induced sheep erythrocytes’ oxidative hemolysis. In the enzymatic antioxidant system, pretreatment with high FML maintained the balance of SOD, CAT, and GSH-Px; in the non-enzymatic antioxidant system, the content of MDA can be effectively reduced after FML treatment. This study provides a research basis for the development of natural products from mulberry leaves.

Red cell distribution width and Glasgow coma scale score as predictors of in-hospital mortality in maintenance hemodialysis patients diagnosed with spontaneous intracerebral hemorrhage

Glasgow Coma Scale (GCS) score is being widely used as a useful predictor to investigate patients with head injury. High red cell distribution width (RDW) values have been independently associated with mortality and poor neurological outcome. However, there are few data available for Spontaneous Intracerebral Hemorrhage (SIH) in maintenance hemodialysis (MHD) patients. This study aimed to evaluate the prognostic value of the combined measurement of RDW and GCS score in MHD patients with SIH. We retrospectively studied 46 MHD patients who was admitted to our hospital for nontraumatic SIH from October 2014 to May 2020. Data including demographic information, cause of renal failure, comorbidities at ESRD, clinical and laboratory parameters at admission were collected from medical records. Univariate and multivariate Logistic regression analysis were performed to identify independent risk factors of the in-hospital Mortality in Hemodialysis Patients with SIH. The receiver operating characteristic curve (ROC) and areas under the curve (AUCs) were determined. The sensitivity and specificity of independent risk factors were calculated for a range of different cutoff points. A total of 46 patients were enrolled in the study. The in-hospital mortality rate was 69.57%. We divided subjects into 2 groups based on the clinical outcomes. Compared with survivors (n = 14), non-survivors (n = 32) had longer hemodialysis vintage (P = .017), lower GCS score (P < .001), higher hemoglobin (Hb) (P = .032) and RDW (P = .009). In multivariate logistic regression analysis, GCS score (OR 0.719, 95% CI 0.546-0.946; P = .018) and RDW (OR 4.549, 95% CI 1.243-0.946; P = .018) were independent risk factors of in-hospital mortality in MHD patients with SIH. The area under the ROC curve (AUC) for GCS score was 0.849 (95% CI 0.729-0.970) while that for RDW was 0.743 (95% CI 0.596-0.891). The AUC for the combined prediction was 0.916 (95% CI 0.828-1.000), with a sensitivity of 90.63% and a specificity of 88.46%. In conclusion, high RDW and low GCS score were useful and independent poor prognostic markers for in-hospital mortality of MHD patients with SIH.

Effectiveness of 3 Polyherbal Formulations (EcXaPu, EcXa, and EcPu) on the Management of Oxidative Stress and Hyperglycemia

Oxidative stress and hyperglycemia are major disorders involved in the occurrence and severity not only of chronic non-communicable diseases but also of infectious pathologies. This study aimed to evaluate the in vitro antioxidant and antihyperglycemic properties of EcXaPu, EcXa, and EcPu. The antioxidant properties were evaluated using 3 mechanisms: radical scavenging; reducing property, and metal chelating. Finally, the antihyperglycemic properties were evaluated by 2 mechanisms: glucose adsorption and cellular glucose capture. The different formulations showed their ability to scavenge DPPH, ABTS, and NO radicals with SC₅₀ ranging from 2.75 to 3.51 mg/ml, from 2.6 to 2.76 mg/ml, and from 2.59 to 3.3 mg/ml, respectively. All the formulations also reduced MoO₄ ²⁺ and Fe³⁺ and chelated Cu²⁺ and Fe²⁺. The different formulations adsorbed the glucose with glucose adsorption rates ranging from 72.83% to 87.01%. The different formulations also stimulated cellular glucose uptake, with uptake rates ranging from 31.9% to 50.71% in yeast cells and from 21.81% to 39.45% in muscle cells. These formulations could be potential agents to prevent and/or protect against biological disorders associated with oxidative stress and hyperglycemia.

Association between red blood cell distribution width and non-valvular atrial fibrillation in hemodialysis patients: a single-center Chinese population study

Background

Red blood cell distribution width (RDW) has emerged as a prognostic marker of atrial fibrillation (AF) in various clinical settings. However, the relationship by which RDW was linked to AF in hemodialysis (HD) patients was not clear. We sought to reveal the relationship between RDW and AF occurrence in HD patients.

Methods

We enrolled 170 consecutive maintenance HD patients, including 86 AF patients and 84 non-AF patients. All participants’ medical history and detailed clinical workup were recorded before the first dialysis session of the week. Electrocardiography, laboratory and transthoracic echocardiography examination indices were compared between the AF group and non-AF group. Multivariable logistic regression analysis was performed to identify the independent predictors of AF occurrence in HD patients.

Results

There were all paroxysmal AF patients in AF group. Compared to the non-AF group, patients with AF group had a significantly older age (61.0 ± 1.48 vs. 49.71 ± 1.79, p < 0.001), lower BMI (24.3 ± 4.11 vs. 25.8 ± 3.87, p < 0.05), higher RDW (15.10 ± 0.96 vs. 14.26 ± 0.82, p < 0.001) and larger LAD (39.87 ± 3.66 vs. 37.68 ± 5.08, p < 0.05). Multivariable logistic regression analyses demonstrated that values of age (OR: 1.030, 95%CI: 1.004-1.057, per one- year increase), BMI (OR: 0.863, 95%CI: 0.782–0.952, per 1 kg/m² increase), RDW (OR: 2.917, 95%CI: 1.805–4.715, per 1% increase) and LAD (OR: 1.097, 95%CI: 1.004–1.199, per 1 mm increase) were independently associated with AF occurrence (p < 0.05, respectively). The best cutoff value of RDW to predict AF occurrence was 14.65% with a sensitivity of 68.6% and a specificity of 72.6%.

Conclusions

The increased RDW was significantly associated with the paroxysmal AF occurrence in HD patients.

Biochemical Evaluation of the Effects of Hydroxyurea in Vitro on Red Blood Cells

Hydroxyurea (HU) is a low-cost, low-toxicity drug that is often used in diseases, such as sickle cell anemia and different types of cancer. Its effects on the red blood cells (RBC) are still not fully understood. The in vitro effects of HU were evaluated on the biochemical parameters of the RBC from healthy individuals that were treated with 0.6 mM or 0.8 mM HU for 30 min and 1 h. After 30 min, there was a significant increase in almost all of the parameters analyzed in the two concentrations of HU, except for the pyruvate kinase (PK) activity. A treatment with 0.8 mM HU for 1 h resulted in a reduction of the levels of lipid peroxidation, Fe³⁺, and in the activities of some of the enzymes, such as glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD), and PK. After the incubation for 1 h, the levels of H₂O₂, lipid peroxidation, reduced glutathione (GSH), enzymatic activity (hexokinase, G6PD, and superoxide dismutase (SOD) were reduced with the treatment of 0.8 mM HU when compared with 0.6 mM. The results have suggested that a treatment with HU at a concentration of 0.8 mM seemed to be more efficient in protecting against the free radicals, as well as in treating diseases, such as sickle cell anemia. HU appears to preferentially stimulate the pentose pathway over the glycolytic pathway. Although this study was carried out with the RBC from healthy individuals, the changes described in this study may help to elucidate the mechanisms of action of HU when administered for therapeutic purposes.

Potential Hepatoprotective Effect of Cheatomorpha gracilis extract against High Fat Diet (HFD)-Induced Liver Damage, and its characterization by HPLC

The current investigation was carried out to estimate the protective effect of aqueous extract of Cheatomorpha gracilis (AEC) against High fat Diet (HFD) induced liver damage in mice. The results of the in vitro study showed that AEC have higher antioxidant capacities in the DPPH and hydroxyl radical-scavenging assays. Indeed, many phenolic compounds (gallic acid, quercetin, naringenin, apigenin, kaempferol and rutin) were identified in the AEC. In the animal studies, during 6 weeks, HFD promoted oxidative stress with a rise level of malonaldehyde (MDA), protein carbonyls (PCOs) levels and a significant decrease of the antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase. Interestingly, the treatment with AEC (250 mg/kg body weight) significantly reduced the effects of HFD disorders on some plasmatic liver biomarkers (AST, ALT and ALP) in addition to, plasmatic proteins inflammatory biomarkers (α2 and β1 decreases / β2 and γ globulins increases). It can be suggest that supplementation of MECG displays high potential to quench free radicals and attenuates high fat diet promoted liver oxidative stress and related disturbances.

Metformin protects red blood cells against rotenone induced oxidative stress and cytotoxicity

CONTEXT

The anti-diabetic medicine metformin has been reported as an anti-ageing drug candidate as it mimics the benefits of caloric restriction and reduces ageing-related oxidative stress in various experimental organisms.

OBJECTIVE

We investigated the possible anti-oxidative role of metformin against rotenone-induced oxidative stress and cytotoxicity in erythrocytes of Wistar rats. Rotenone is a well-known inducer of oxidative stress which leads to a cellular redox imbalance.

MATERIALS AND METHODS

We have co-exposed the experimental rats with rotenone (2.5 mg/kg, i.p.) and metformin (300 mg/kg, orally) for 30 days to investigate the protective effects of metformin on various rotenone-induced impaired oxidative stress biomarkers in rat erythrocytes.

RESULTS

We found that a significant alleviation in the levels of rotenone-induced pro-oxidant and anti-oxidant markers following exposure of metformin.

DISCUSSION AND CONCLUSIONS

Our findings suggest that metformin supplementation shows a protective role in against rotenone-induced redox imbalance and cytotoxicity in rat erythrocytes.

In silico, in vitro, and in vivo investigation of antioxidant potential and toxicity of ethyl ferulate

By submitting this manuscript, each author certifies that they have made a direct and substantial contribution to the work reported in the manuscript. In this manuscript the conception, design, investigation, acquisition of data and analysis, interpretation of data and writing of the article were conducted by author Camila Bomfim de Sá under the guidance of professors Margareth de Fátima Formiga Melo Diniz, Hilzeth de Luna Freire Pessôa and Caliandra Maria Bezerra Luna Lima, who also approved the final version of the manuscript. Professor Damião Pergentino de Sousa and his student Mayara Castro de Morais performed the production, synthesis and chemical characterization of ethyl ferulate (EF). Professor Abrahão Alves de Oliveira Filho assessed the in silico tests. PhD student Andressa Brito Lira participated in the critical review of the text for important intellectual content and assisted in the in vitro antioxidant activity and cytotoxicity tests. Kardilandia Mendes de Oliveira participated in acute oral toxicity tests evaluating the biochemical parameters. Students, Tafaela Dias and Cinthia Rodrigues Melo also assisted in the acute oral toxicity testing and preparing of slides for histopathological analysis. Pathologist Alexandre Rolim da Paz analyzed the histopathology results. EF, a phenolic compound of the large class of phenylpropanoids, is derived from ferulic acid and is produced both naturally and synthetically. Its principal pharmacological activities are: anti-inflammatory and antioxidant activity. This study aimed to investigate the in silico, in vitro and in vivo toxicity and antioxidant activity of EF. The in silico prediction showed more than 20 biological activities as well as good absorption at the biological membranes and no theoretical toxicity. However, EF presented high environmental toxicity. EF presented low hemolytic potential and exerted protective activity for the erythrocyte membrane for only blood type O. EF presented antioxidant activity against H₂O₂ at all concentrations and all blood types, but no effect against phenylhydrazine, being unable to prevent its oxidative effects. In the acute nonclinical toxicological trial, the treated animals presented behavioral changes (e.g., sedation). Feed intake was higher for the 2000 mg/kg group, but with no significant difference in weight change. The biochemical parameters presented no differences between treated and control animals, and the organs remained intact with no change. Thus, EF presents a low toxic profile and this study provides important information about the toxicity of this compound, suggesting future safe use.

Helix pomatia albumen gland water soluble protein extract as powerful antiaging agent

Accounting for increasingly developed population aging and dramatic elevation of aging-related severe disorders worldwide, search of the efficient antiaging agents is becoming one of the urgent problems of contemporary biomedical science. The aim of current study was to reveal the potential protective effects of water-soluble proteins extracted from albumen gland of snails against aging processes. We evaluated the antioxidant effect of the extract in 20 older adult rats in vivo and on 60 human blood samples ex vivo at the cellular level under physiological and oxidative stress conditions using the methods of spectrophotometric analysis, two-photon imaging and cell viability assay. The in vivo animal experiments showed significant increase in the levels of catalase and superoxide dismutase in treated older adult rats, compared to non-treated group. The ex vivo studies involving three human groups (young, middle aged and older adult), demonstrated that the extract has no effect on the cell viability, moreover significantly increases the number of erythrocytes, decreases age-related oxidative stress and the percentage of hemolysis of erythrocytes by aging. Thus, the snails albumen gland protein extract can be considered as effective natural antioxidative antiaging agent in prevention of aging-related pathological processes associated with oxidative stress.

Phytochemistry, antifungal and antioxidant activity, and cytotoxicity of byrsonima gardneriana (A. Juss) extract

OBJECTIVE

To determine the phytochemical composition of Byrsonima gardneriana (A. Juss) leaf extract (BGE) and its antifungal activity against Candida spp., antioxidant potential and in vitro cytotoxicity.

MATERIAL AND METHODS

BGE was obtained and submitted to Gas Chromatography Coupled to Mass Spectrometry for phytochemical analysis. The ethanolic extract was tested for its antifungal activity against C. albicans and non-albicans reference strains and clinical isolates in addition to inhibition of C. albicans growth kinetics. It was also tested for antioxidant potential in the presence of phenylhydrazine and reactive oxygen species (ROS). And cytoxicity in human erythrocytes. The data were analyzed by one-way Analysis of Variance (ANOVA) followed by Tukey's or Dunnett's post-hoc test, with α = 0.05.

RESULTS

Pyroglutamic acid (90.77 %), eucalyptol (89.61 %) and octanoic acid (76.22 %) were the major compounds detected in BGE, P (%) is the percent probability of compound identification, according to the mass spectra library. The extract showed fungistatic activity, with MIC of 125 μg/mL against most tested strains. While BGE showed low hemolytic activity on all blood types tested herein, it could not prevent osmotic stress in human erythrocytes. The extract did not have oxidizing effects in the presence of phenylhydrazine, but it showed antioxidant potential against ROS when tested at 31 μg/mL and 62 μg/mL.

CONCLUSION

B. gardneriana extract showed antifungal activity against Candida spp., demonstrated low hemolytic potential, no oxidant activity in human erythrocytes and antioxidant activity against ROS. This study opens avenues for the study of BGE as a promising biocompatible antifungal agent.

Red Blood Cell Distribution Width Is Associated with Deterioration of Renal Function and Cardiovascular Morbidity and Mortality in Patients with Diabetic Kidney Disease

We sought to investigate the possible association between Red Blood Cell Distribution Width (RDW), vascular calcification, oxidative stress and renal function and all-cause/cardiovascular (CV) mortality, CV events and progression of kidney disease in a cohort of patients with Diabetic Kidney Disease (DKD). Carotid intima media thickness (cIMT) and oxidized low-density cholesterol were measured in 104 Type 2 Diabetes Mellitus (T2DM) patients with established DKD, distributed in all five stages of kidney disease and 38 diabetics with normal renal function. All patients were followed for 7 years with end-points all-cause and CV mortality, CV events and progression to End-Stage Renal Disease (ESRD). RDW was positively correlated with diabetes duration (r = 0.19, p = 0.023) and albuminuria (r = 0.29, p = 0.002). Multivariate regression analysis revealed that RDW was a strong, independent predictor of cIMT value (β = 0.031, p = 0.012). Kaplan-Meier curves and Cox proportional hazard models revealed that after adjustment for several cofounders, RDW was a significant and independent predictor for all-cause mortality, CV mortality, CV event and progression to ESRD (HR 1.75, p = 0.001, HR 2.03, p = 0.001, HR = 1.66, p < 0.0001 and HR 2.14, p = 0.001 respectively). RDW predicts mortality, CV events and deterioration of renal function in DKD, probably reflecting atherosclerosis.

Synthesis and Antioxidative Activity of Piperine Derivatives Containing Phenolic Hydroxyl

Piperine was used in this study in its raw form, and different steps, such as amide hydrolysis and amidation, were used to synthesize piperine derivatives containing a phenolic hydroxyl group. DPPH and ABTS free radical scavenging assays were used to assess piperine derivative antioxidant activities. We constructed an AAPH oxidative stress erythrocyte model to study the effect of piperine derivatives on the hemolysis rate of oxidatively damaged erythrocytes as well as the hemoglobin oxidation rate. This AAPH model was also used to determine piperine derivative effects on antioxidant enzyme activity and malondialdehyde (MDA) content. Results showed that spectroscopic methods could synthesize and identify piperine derivatives containing phenolic hydroxyl groups (H-1∼H-3). Moreover, DPPH and ABTS assay results showed that piperine derivative free radical clearance rates were higher compared with the parent compound. Additionally, piperine derivatives (H-1∼H-3) were found to provide protection to AAPH oxidatively damaged erythrocytes in their ability to inhibit AAPH-induced erythrocyte lysis, while hemoglobin oxidation was higher compared with the parent compound. Piperine derivatives may protect intracellular glutathione peroxidase (GSH-Px) antioxidant enzyme system activities, safeguarding against oxidative damage. This study synthesized novel piperine derivatives for use as potential antioxidant agent candidates.

Effects of Pulsed Magnetic Field on the Hemolysis of Erythrocytes Exposed to Oxidative Stress

Ahematological and morphological investigation was made of the effects of pulsed magnetic field (PMF) stimulus on oxidized erythrocyte membrane using the smear method and spectroscopic measurement. Tert-butyl hydroperoxide (tBHP) was used for oxidative stress, and verapamil was used as reduction agent on red blood cells (RBCs). Our PMF stimulator system was designed to generate a maximum intensity of 0.27 T at a transition time of 0.102 ms. The morphology of oxidized RBCs, and oxidative stressed RBCs after treatment with a reducing agent were observed before and after PMF. Light absorbance of hemoglobin (Hb) was measured in the membrane as well as plasma, through hemolysis of RBCs. Absorbance for a sample exposed to PMF before the oxidation treatment was lower than that for a sample not exposed to PMF in the plasma. This means that PMF plays a role in preventing hemolysis of erythrocyte membrane from oxidative stress. Our results were confirmed using an osmotic fragility test. Hemolysis in the case of PMF treatment is 28% lower than that of non-PMF treatment. As a result, PMF stimulus is proposed to achieve an improvement of RBCs aggregation and prevent RBCs from oxidative stress, and could be used in various clinical fields related to peripheral vascular diseases. For further clinical application, we need to optimize PMF intensity and stimulated duration.

Effects of oral administration of common antioxidant supplements on the energy metabolism of red blood cells. Attenuation of oxidative stress-induced changes in Rett syndrome erythrocytes by CoQ10

Nutritional supplements are traditionally employed for overall health and for managing some health conditions, although controversies are found concerning the role of antioxidants-mediated benefits in vivo. Consistently with its critical role in systemic redox buffering, red blood cell (RBC) is recognized as a biologically relevant target to investigate the effects of oxidative stress. In RBC, reduction of the ATP levels and adenylate energy charge brings to disturbance in intracellular redox status. In the present work, several popular antioxidant supplements were orally administrated to healthy adults and examined for their ability to induce changes on the energy metabolism and oxidative status in RBC. Fifteen volunteers (3 per group) were treated for 30 days per os with epigallocatechin gallate (EGCG) (1 g green tea extract containing 50% EGCG), resveratrol (325 mg), coenzyme Q10 (CoQ10) (300 mg), vitamin C (1 g), and vitamin E (400 U.I.). Changes in the cellular levels of high-energy compounds (i.e., ATP and its catabolites, NAD and GTP), GSH, GSSG, and malondialdehyde (MDA) were simultaneously analyzed by ion-pairing HPLC. Response to oxidative stress was further investigated through the oxygen radical absorptive capacity (ORAC) assay. According to our experimental approach, (i) CoQ10 appeared to be the most effective antioxidant inducing a high increase in ATP/ADP, ATP/AMP, GSH/GSSG ratio and ORAC value and, in turn, a reduction of NAD concentration, (ii) EGCG modestly modulated the intracellular energy charge potential, while (iii) Vitamin E, vitamin C, and resveratrol exhibited very weak effects. Given that, the antioxidant potential of CoQ10 was additionally assessed in a pilot study which considered individuals suffering from Rett syndrome (RTT), a severe X-linked neuro-developmental disorder in which RBC oxidative damages provide biological markers for redox imbalance and chronic hypoxemia. RTT patients (n = 11), with the typical clinical form, were supplemented for 12 months with CoQ10 (300 mg, once daily). Level of lipid peroxidation (MDA production) and energy state of RBCs were analyzed at 2 and 12 months. Our data suggest that CoQ10 may significantly attenuate the oxidative stress-induced damage in RTT erythrocytes.

High Levels of β-Amyloid, Tau, and Phospho-Tau in Red Blood Cells as Biomarkers of Neuropathology in Senescence-Accelerated Mouse

Alzheimer's Disease (AD) is the most common Neurodegenerative Disease (ND), primarily characterised by neuroinflammation, neuronal plaques of β-amyloid (Aβ), and neurofibrillary tangles of hyperphosphorylated tau. α-Synuclein (α-syn) and its heteroaggregates with Aβ and tau have been recently included among the neuropathological elements of NDs. These pathological traits are not restricted to the brain, but they reach peripheral fluids as well. In this sense, Red Blood Cells (RBCs) are emerging as a good model to investigate the biochemical alterations of aging and NDs. Herein, the levels of homo- and heteroaggregates of ND-related proteins were analysed at different stages of disease progression. In particular, a validated animal model of AD, the SAMP8 (Senescence-Accelerated Mouse-Prone) and its control strain SAMR1 (Senescence-Accelerated Mouse-Resistant) were used in parallel experiments. The levels of the aforementioned proteins and of the inflammatory marker interleukin-1β (IL-1β) were examined in both brain and RBCs of SAMP8 and SAMR1 at 6 and 8 months. Brain Aβ, tau, and phospho-tau (p-tau) were higher in SAMP8 mice than in control mice and increased with AD progression. Similar accumulation kinetics were found in RBCs, even if slower. By contrast, α-syn and its heterocomplexes (α-syn-Aβ and α-syn-tau) displayed different accumulation kinetics between brain tissue and RBCs. Both brain and peripheral IL-1β levels were higher in SAMP8 mice, but increased sooner in RBCs, suggesting that inflammation might initiate at a peripheral level before affecting the brain. In conclusion, these results confirm RBCs as a valuable model for monitoring neurodegeneration, suggesting peripheral Aβ, tau, and p-tau as potential early biomarkers of AD.

Isopropyl Caffeate: A Caffeic Acid Derivative-Antioxidant Potential and Toxicity

Phenolic compounds, among them isopropyl caffeate, possess antioxidant potential, but not without toxicity and/or adverse effects. The present study aimed to evaluate the antioxidant activity and toxicity of isopropyl caffeate through in silico, in vitro and in vivo testing. The results showed that isopropyl caffeate presents no significant theoretical risk of toxicity, with likely moderate bioactivity: GPCR binding, ion channel modulation, nuclear receptor binding, and enzyme inhibition. Isopropyl caffeate induced hemolysis only at the concentrations of 500 and 1000 μg/ml. We observed types A and O erythrocyte protection from osmotic stress, no oxidation of erythrocytes, and even sequestrator and antioxidant behavior. However, moderate toxicity, according to the classification of GHS, was demonstrated through depressant effects on the central nervous system, though there was no influence on water and food consumption or on weight gain, and it did present possible hepatoprotection. We conclude that the effects induced by isopropyl caffeate are due to its antioxidant activity, capable of preventing production of free radicals and oxidative stress, a promising molecule with pharmacological potential.

Rapamycin mitigates erythrocyte membrane transport functions and oxidative stress during aging in rats

Erythrocyte membrane is a suitable model to study various metabolic and physiological functions as it undergoes variety of biochemical changes during aging. An age-dependent modulatory effect of rapamycin on erythrocyte membrane functions is completely unknown. Therefore, the present study was undertaken to investigate the effect of rapamycin on age-dependent impaired activities of transporters/exchangers, altered levels of redox biomarkers, viz. protein carbonyl (PC), lipid hydroperoxides (LHs), total thiol (-SH), sialic acid (SA) and intracellular calcium ion [Ca²⁺]i, and osmotic fragility of erythrocyte membrane. A significant reduction in membrane-bound activities of Na⁺/K⁺-ATPase (NKA) and Ca²⁺-ATPase (PMCA), and levels of -SH and SA was observed along with a simultaneous induction in Na⁺/H⁺ exchanger (NHE) activity and levels of [Ca²⁺]i, PC, LH and osmotic fragility in old-aged rats. Rapamycin was found to be a promising age-delaying drug that significantly reversed the aging-induced impaired activities of membrane-bound ATPases and altered levels of redox biomarkers.

Brown Algae Padina sanctae-crucis Børgesen: A Potential Nutraceutical

Padina sanctae-crucis Børgesen is distributed worldwide in tropical and subtropical seas; belongs to the Dictyotaceae family, and has proven to be an exceptional source of biologically active compounds. Four compounds were isolated and identified, namely: dolastane diterpene new for the genus Padina; phaeophytin and hidroxy-phaeophytin new for the family Dictyotaceae, and; mannitol first described in this species. Saturated fatty acids as compared to the percentages of unsaturated fatty acids were shown to be present in greater abundance. Palmitic and linolenic acid were the main saturated and unsaturated acids, respectively. Cytotoxic and antioxidant activities were evaluated using human erythrocytes. In vivo evaluations of acute toxicity and genotoxicity were performed in mice. Methanolic extract of P.sanctae-crucis presented antioxidant activity and did not induce cytotoxicity, genotoxicity or acute toxicity. Since Padina sanctae-crucis is already used as food, has essential fatty acids for the nutrition of mammals, does not present toxicity and has antioxidant activity, it can be considered as a potential nutraceutical.

Baseline red blood cell distribution width predicts long-term glycemic remission in patients with type 2 diabetes

AIMS

We explored whether red blood cell distribution width (RDW), a routinely checked item of complete blood cell counts, was an indicator of long-term euglycemia remission in patients with type 2 diabetes after short-term continuous subcutaneous insulin infusion (CSII).

METHODS

We analyzed the original data of patients enrolled in three randomized control trials from 2002 to 2014. CSII was administered to drug-naїve patients with newly diagnosed type 2 diabetes to achieve and maintain euglycemia for 2weeks.

RESULTS

A total of 185 patients were involved and 98 patients (52.97%) who achieved and maintained euglycemia for at least 12months were classified as the remission group, and the others as the non-remission group. Patients in remission group had a relatively lower value for baseline RDW (38.82±2.76vs 39.89±2.78fL, p=0.017) compared with those in non-remission group. A graded decrease of remission rate (67.50%, 55.00%, 53.66% and 30.77% for Quartile 1 to Quartile 4 respectively, P<0.05) was observed with the increasing of RDWs. The risk of hyperglycemic relapse was significantly increased for those in the highest quartile compared with the lowest (hazard ratio=2.68; 95% CI, 1.38-5.22). Those who achieved euglycemia within 7days or obtained a better fasting glucose after therapy had preferable remission rates.

CONCLUSIONS

Patients with lower baseline RDWs are more likely to maintain a one-year euglycemia remission after short-term CSII. A faster normalization of glucose during treatment and a lower fasting glucose after therapy are correlated with a long-term glucose control.

In Silico Study and Bioprospection of the Antibacterial and Antioxidant Effects of Flavone and Its Hydroxylated Derivatives

Flavonoid compounds are widely used as natural protective species, which can act as anti-inflammatory, antioxidant, anticoagulant, antihypertensive and antitumor agents. This study set out to investigate the probable pharmacological activities, along with the antibacterial and antioxidant effects, of flavone and its hydroxy derivatives: 3-hydroxyflavone, 5-hydroxyflavone and 6-hydroxyflavone. To do so, we investigated their pharmacological characteristics, using in silico tests that indicate likelihood of activity or inactivity, with the PASS online software, and the antimicrobial potential against Gram positive and Gram negative bacteria was also analyzed, including bacteria of clinical importance. We also tested for oxidant and antioxidant potential in these molecules in the presence of reactive oxygen species (ROS) and phenylhydrazine (Ph). The results revealed the following characteristics: pharmacological activities for the flavonoids as agonists of cell membrane integrity and as permeability inhibitors, as antagonists of anaphylatoxin receptors, as inhibitors of both kinase and peroxidase, and as having both antimutagenic capacity and vaso-protective potential. All of the flavonoids exhibited moderate antibacterial activity against Gram positive and Gram negative strains, with the flavones being bactericidal at 200 μg/mL for the strains of P. aeruginosa ATCC 8027, S. aureus ATCC 25619 and E. coli 104; the other flavonoids revealed bacteriostatic action. The substances did not promote erythrocyte oxidation and behaved as sequestrators and antioxidants of hydrogen peroxide (H₂O₂) and phenylhydrazine (Ph). It was concluded that the analyzed compounds have various pharmacological activities in accordance with the predictions of PASS online, as their antibacterial and antioxidant activities were confirmed. The study also helps to consolidate the use of computational chemistry in silico tools to guide new drug search and discovery protocols.

Increased membrane lipid peroxidation and decreased Na+/K+-ATPase activity in erythrocytes of patients with stable coronary artery disease

OBJECTIVES

We aimed to determine erythrocyte membrane lipid peroxidation levels and Na/K-ATPase activity in patients with and without coronary artery disease (CAD) documented by coronary angiography.

DESIGN AND METHODS

A total of 144 patients who had undergone coronary angiography were divided into a CAD group (n=82) and a non-CAD group (control group, n=62) according to the results of coronary angiography. Lipid peroxide levels in plasma and the erythrocyte membrane were measured using a fluorimetric method. Total antioxidant status and Na/K-ATPase activity in plasma were determined using spectrophotometric methods.

RESULTS

Lipid peroxidation levels were significantly higher in the erythrocyte membrane of CAD patients compared with controls, whereas Na/K-ATPase activity was significantly lower in the erythrocyte membrane of CAD patients compared with controls. The coronary artery scores were correlated positively with membrane lipid peroxidation (r=0.324, P<0.001) and negatively with Na/K-ATPase activity (r=-0.302, P<0.001).

CONCLUSION

This study shows that the levels of membrane lipid peroxidation and Na/K-ATPase activity are correlated with the severity of CAD.

Attenuation of Oxidative Stress of Erythrocytes by Plant-Derived Flavonoids, Orientin and Luteolin

Erythrocytes are easy to be injured by oxidative stress in their lifespan. Although there are several chemicals such as vitamin C (VC) that would be able to reduce oxidative stress, natural herbal products still remain an interesting research area. The current study investigated the effects of two plant-derived flavonoids, orientin and luteolin, on erythrocytes and their possible mechanisms. This experiment was divided into nine groups, which were normal group, model group, VC control group, and treated groups with different doses of orientin and luteolin (10, 20, and 40 μg/mL), respectively. Hemolysis rate was determined by spectrophotometry. Antioxidative enzyme and products were evaluated by different methods. Erythrocyte cell surface and cellular structure were observed with scanning or transmission electron microscope, respectively. Oxidative stress induced significant increase in hemolysis rate of erythrocytes. Orientin or luteolin ameliorated hemolysis of erythrocytes in oxidative stress in a dose-dependent manner. Both orientin and luteolin reduced oxidative products and increased antioxidative enzyme activities. Moreover, orientin and luteolin attenuated oxidative stress induced damage of erythrocyte cell surface morphology and cellular structure. In conclusion, orientin and luteolin could protect human erythrocytes from oxidative damage by attenuating oxidative stress, protecting antioxidative enzyme activities, and preserving integrity of erythrocyte structure.

Red Cell Distribution Width and Mortality in Hemodialysis Patients

BACKGROUND

Red cell distribution width (RDW) is an index of red blood cell volume variability that has historically been used as a marker of iron deficiency anemia. More recently, studies have shown that elevated RDW is associated with higher mortality risk in the general population. However, there is lack of data demonstrating the association between RDW and mortality risk in hemodialysis (HD) patients. We hypothesized that higher RDW is associated with higher mortality in HD patients.

STUDY DESIGN

Retrospective observational study using a large HD patient cohort.

SETTING & PARTICIPANTS

109,675 adult maintenance HD patients treated in a large dialysis organization from January 1, 2007, to December 31, 2011.

PREDICTOR

Baseline and time-varying RDW, grouped into 5 categories: <14.5%, 14.5% to <15.5%, 15.5% to <16.5%, 16.5% to <17.5%, and ≥17.5%. RDW of 15.5% to <16.5% was used as the reference category.

OUTCOME

All-cause mortality.

RESULTS

Mean age of study participants was 63±15 (SD) years and the study cohort was 44% women. In baseline and time-varying analyses, there was a graded association between higher RDW and incrementally higher mortality risk. Receiver operating characteristic, net reclassification analysis, and integrated discrimination improvement analyses demonstrated that RDW is a stronger predictor of mortality as compared with traditional markers of anemia, such as hemoglobin, ferritin, and iron saturation values.

LIMITATIONS

Lack of comprehensive data that may be associated with both RDW and HD patient outcomes, such as blood transfusion data, socioeconomic status, and other unknown confounders; therefore, the possibility of residual confounding could not be excluded. Also, lack of information for cause of death; thus, cardiovascular mortality outcomes could not be examined.

CONCLUSIONS

In HD patients, higher RDW is associated with incrementally higher mortality risk. RDW is also a stronger predictor of mortality than traditional laboratory markers of anemia. Further studies are needed to determine the mechanisms underlying the association between RDW and mortality.

Concurrent measurement of cellular turbidity and hemoglobin to evaluate the antioxidant activity of plants

In past decades, a multitude of analytical methods for measuring antioxidant activity of plant extracts has been developed. However, when using methods to determine hemoglobin released from human erythrocytes treated with ginger extracts, we found hemoglobin concentrations were significantly higher than in untreated control samples. This suggests in the presence of antioxidants that measuring hemoglobin alone is not sufficient to determine hemolysis. We show concurrent measurement of erythrocyte concentration and hemoglobin is essential in such assays, and describe a new protocol based on simultaneous measurement of cellular turbidity and hemoglobin.

Anti-Oxidative Effect of Myrtenal in Prevention and Treatment of Colon Cancer Induced by 1, 2-Dimethyl Hydrazine (DMH) in Experimental Animals

Colon cancer is considered as the precarious forms of cancer in many developed countries, with few to no symptoms; the tumor is often diagnosed in the later stages of cancer. Monoterpenes are a major part of plant essential oils found largely in fruits, vegetables and herbs. The cellular and molecular activities show therapeutic progression that may reduce the risk of developing cancer by modulating the factors responsible for colon carcinogenesis. Colon cancer was induced with DMH with a dose of (20 mg/Kg/body weight) for 15 weeks by subcutaneous injection once in a week. Myrtenal treatment was started with (230 mg/Kg/body weight) by intragastric administration, one week prior to DMH induction and continued till the experimental period of 30 weeks. The Invivo results exhibit the elevated antioxidant and lipid peroxidation levels in DMH treated animals. The Histopathological analysis of colon tissues well supported the biochemical alterations and inevitably proves the protective role of Myrtenal. Treatment with myrtenal to cancer bearing animals resulted in a remarkable increase in the inherent antioxidants and excellent modulation in the morphological and physiological nature of the colon tissue. It is thus concluded that myrtenal exhibits excellent free radical scavenging activity and anticancer activity through the suppression of colon carcinoma in Wistar albino rats.

Characterization of extra virgin olive oils produced with typical Italian varieties by their phenolic profile

Evaluation of phenolic profile, antioxidant power, and protective capacity against oxidation of red blood cells (RBCs) of olive oil phenolic extracts (OOPEs) from several Italian varieties were studied. Phenolic profiles, and quantification of seven selected bioactive compounds were performed by RP-HPLC. OOPEs exhibited high antioxidant activity, and this capacity was positively related to their phenolic amount. In particular, OOPE5 (cv Gentile di Larino, Molise region) displayed the highest phenolic and ortho-diphenolic content as well as the strongest scavenging activity determined using 2,2'-diphenyl-1-picrylhydrazyl (DPPH) (87% DPPH inhibition). Protective capacity against stressed RBCs was investigated through the evaluation of methemoglobin (MetHb) and malondialdehyde (MDA) levels. OOPE5 was the most active against methemoglobin production (53.7% reduction), whereas OOPE1 (cv Lavagnina, Liguria region) showed the highest protection toward malondialdehyde (83.3% reduction). Overall the selected oils showed qualitative and quantitative differences in phenol composition, and this variability influenced their protective effect against oxidative damages.

Biophysical mechanism of the protective effect of blue honeysuckle (Lonicera caerulea L. var. kamtschatica Sevast.) polyphenols extracts against lipid peroxidation of erythrocyte and lipid membranes

The aim of the present research was to determine the effect of blue honeysuckle fruit and leaf extracts components on the physical properties of erythrocyte and lipid membranes and assess their antioxidant properties. The HPLC analysis showed that the extracts are rich in polyphenol anthocyanins in fruits and flavonoids in leaves. The results indicate that both extracts have antioxidant activity and protect the red blood cell membrane against oxidation induced by UVC irradiation and AAPH. The extracts do not induce hemolysis and slightly increase osmotic resistance of erythrocytes. The research showed that extracts components are incorporated mainly in the external part of the erythrocyte membrane, inducing the formation of echinocytes. The values of generalized polarization and fluorescence anisotropy indicate that the extracts polyphenols alter the packing arrangement of the hydrophilic part of the erythrocyte and lipid membranes, without changing the fluidity of the hydrophobic part. The DSC results also show that the extract components do not change the main phase transition temperature of DPPC membrane. Studies of electric parameters of membranes modified by the extracts showed that they slightly stabilize lipid membranes and do not reduce their specific resistance or capacity. Examination of IR spectra indicates small changes in the degree of hydration in the hydrophilic region of liposomes under the action of the extracts. The location of polyphenolic compounds in the hydrophilic part of the membrane seems to constitute a protective shield of the cell against other substances, the reactive forms of oxygen in particular.

Hemolysis assessment and antioxidant activity evaluation modified in an oxidized erythrocyte model

Hydrogen peroxide (H₂O₂)-induced hemolysis is a commonly used model for antioxidant activity evaluation, and the hemolysis index is often presented as the absorbance of supernatant hemoglobin (Hb), which releases from injured cells. However, in previous studies, as an oxidation-sensitive protein, it has been recognized that Hb easily forms other types or substances, such as metHb, Heinz, and some fluorescent products. This study concerns whether Hb oxidation participated in H₂O₂-induced hemolysis and confirmed that the destruction of Hb under oxidizing condition had been a novel interfering factor that could reduce the absorbance in Hb quantitative detection. To correct the lower absorbance, the stable fluorescent products found in Hb degradation were selected, and the absorbance correction factor of 6.436 was drawn on the basis of the absorbance and fluorescent intensity. This correction factor obviously altered the results of both dose-dependent hemolysis of H₂O₂ and antioxidant activity. In addition, the assessment difference was innovatively discussed by altering the sequences of adding antioxidant and oxidant. These different sequences caused variations in hemolysis, indicating that multiple evaluations may be related to the antioxidant pathways which are necessary for more accurate bioactivity data.

Biological activity of blackcurrant Extracts (Ribes nigrum L.) in relation to erythrocyte membranes

Compounds contained in fruits and leaves of blackcurrant (Ribes nigrum L.) are known as agents acting preventively and therapeutically on the organism. The HPLC analysis showed they are rich in polyphenol anthocyanins in fruits and flavonoids in leaves, that have antioxidant activity and are beneficial for health. The aim of the research was to determine the effect of blackcurrant fruit and leaf extracts on the physical properties of the erythrocyte membranes and assess their antioxidant properties. The effect of the extracts on osmotic resistance, shape of erythrocytes and hemolytic and antioxidant activity of the extracts were examined with spectrophotometric methods. The FTIR investigation showed that extracts modify the erythrocyte membrane and protect it against free radicals induced by UV radiation. The results show that the extracts do not induce hemolysis and even protect erythrocytes against the harmful action of UVC radiation, while slightly strengthening the membrane and inducing echinocytes. The compounds contained in the extracts do not penetrate into the hydrophobic region, but bind to the membrane surface inducing small changes in the packing arrangement of the polar head groups of membrane lipids. The extracts have a high antioxidant activity. Their presence on the surface of the erythrocyte membrane entails protection against free radicals.

Extraction, chemical characterization and biological activity determination of broccoli health promoting compounds

Broccoli (Brassica oleracea L. var. Italica) contains substantial amount of health-promoting compounds such as vitamins, glucosinolates, phenolic compounds, and dietary essential minerals; thus, it benefits health beyond providing just basic nutrition, and consumption of broccoli has been increasing over the years. This review gives an overview on the extraction and separation techniques, as well as the biological activity of some of the above mentioned compounds which have been published in the period January 2008 to January 2013. The work has been distributed according to the different families of health promoting compounds discussing the extraction procedures and the analytical techniques employed for their characterization. Finally, information about the different biological activities of these compounds has been also provided.

Ameliorative effect of Opuntia ficus indica juice on ethanol-induced oxidative stress in rat erythrocytes

The aim of the present study was to investigate the efficacy of Opuntia ficus indica f. inermis fruit juice (OFIj) on reversing oxidative damages induced by chronic ethanol intake in rat erythrocytes. OFIj was firstly analyzed with HPLC for phenolic and flavonoids content. Secondly, 40 adult male Wistar rats were equally divided into five groups and treated for 90 days as follows: control (C), ethanol-only 3 g/kg body weight (b.w) (E), low dose of OFIj 2 ml/100 g b.w+ethanol (Ldj+E), high dose of OFIj 4 ml/100 g b.w+ethanol (Hdj+E), and only a high dose of OFIj 4 ml/100g b.w (Hdj). HPLC analysis indicated high concentrations of phenolic acids and flavonoids in OFIj. Ethanol treatment markedly decreased the activities of erythrocyte superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), and the level of reduced glutathione (GSH). Changes in the erythrocyte's antioxidant ability were accompanied by enhanced oxidative modification of lipids (increase of malondialdeyde level) and proteins (increase in carbonyl groups). Interestingly, pre-administration of either 2 ml/100 g b.w or 4 ml/100 g b.w of OFIj to ethanol-intoxicated rats significantly reversed decreases in enzymatic as well as non enzymatic antioxidants parameters in erythrocytes. Also, the administration of OFIj significantly protected lipids and proteins against ethanol-induced oxidative modifications in rat erythrocytes. The beneficial effect of OFIj can result from the inhibition of ethanol-induced free radicals chain reactions in rat erythrocytes or from the enhancement of the endogenous antioxidants activities.

Biomarkers of oxidative stress in red blood cells

BACKGROUND

Exposure to high concentrations of oxygen radicals, the lack of nucleus and mitochrondria, inability to synthesise new protein and degradation of detoxifying enzymes makes red blood cells (RBCs) uniquely vulnerable to oxidative stress. This review summarizes the changes in biochemical parameters that primarily contribute to alterations in red blood cells during oxidative stress.

METHODS

PubMed, Science Direct and Springer online databases and updates from the Indian Council of Medical Research (ICMR).

RESULTS AND CONCLUSION

As one of the first cells to be affected by changes in the redox status of the body, alterations in red blood cells are widely used in first step-diagnoses of a number of pathological conditions. The information presented in this review provides an update on biomarkers of redox balance in red blood cells. These biomarkers may be used for assessment of oxidative stress during human health and disease.