Oxygen in human health from life to death--An approach to teaching redox biology and signaling to graduate and medical students

Moringa oleifera leaf extracts improve exercise performance in young male adults: A pilot study

BACKGROUND

Moringa oleifera leaves are rich in bioactive substances.

PURPOSE

The purpose of this study was to evaluate the effects of Moringa oleifera leaf aqueous extract supplements on energy metabolism and antioxidant function in young male adults.

METHODS

Forty-four young male adults (26.3 ± 3.5 years) were randomly assigned to two groups: a supplement group (n = 23) receiving aqueous extract of Moringa oleifera leaves and a placebo group (n = 21). The supplementation period lasted for 30 days. Baseline measurements were taken at the beginning of the study, and further measurements were taken at the end of the supplementation period. Changes in upper- and lower-body strength, treadmill endurance, and certain blood biochemical parameters were evaluated.

RESULTS

After 30 days of supplementation, participants in the supplement group exhibited enhanced performance in push-ups and treadmill exhaustion tests compared to the placebo group. Levels of glucose, urea, malondialdehyde, and glutathione peroxidase activity in serum were also improved in the supplement group.

CONCLUSION

The findings suggest that Moringa oleifera leaf aqueous extracts have the potential to improve post-exercise energy metabolism and antioxidant function in young male adults.

Caenorhabditis elegans as an in vivo model for the identification of natural antioxidants with anti-aging actions

Natural antioxidants have recently emerged as a highly exciting and significant topic in anti-aging research. Diverse organism models present a viable protocol for future research. Notably, many breakthroughs on natural antioxidants have been achieved in the nematode Caenorhabditis elegans, an animal model frequently utilized for the study of aging research and anti-aging drugs in vivo. Due to the conservation of signaling pathways on oxidative stress resistance, lifespan regulation, and aging disease between C. elegans and multiple high-level organisms (humans), as well as the low and controllable cost of time and labor, it gradually develops into a trustworthy in vivo model for high-throughput screening and validation of natural antioxidants with anti-aging actions. First, information and models on free radicals and aging are presented in this review. We also describe indexes, detection methods, and molecular mechanisms for studying the in vivo antioxidant and anti-aging effects of natural antioxidants using C. elegans. It includes lifespan, physiological aging processes, oxidative stress levels, antioxidant enzyme activation, and anti-aging pathways. Furthermore, oxidative stress and healthspan improvement induced by natural antioxidants in humans and C. elegans are compared, to understand the potential and limitations of the screening model in preclinical studies. Finally, we emphasize that C. elegans is a useful model for exploring more natural antioxidant resources and uncovering the mechanisms underlying aging-related risk factors and diseases.

The innate immune system and fever under redox control: A Narrative Review

ABSTRACT:

In living cells, redox potential is vitally important for normal physiological processes that are closely regulated by antioxidants, free amino acids and proteins that either have reactive oxygen and nitrogen species capture capability or can be compartmentalized. Although hundreds of experiments support the regulatory role of free radicals and their derivatives, several authors continue to claim that these perform only harmful and non-regulatory functions. In this paper we show that countless intracellular and extracellular signal pathways are directly or indirectly linked to regulated redox processes. We also briefly discuss how artificial oxidative stress can have important therapeutic potential and the possible negative effects of popular antioxidant supplements.

Effect of chronic alcohol consumption on myocardial apoptosis in the rat model of isoproterenol-induced myocardial injury and investigation on the cardioprotective role of calpain inhibitor 1

We investigated the presence of myocardial apoptosis on isoproterenol (ISO)-induced myocardial injury (MI) after long-term high dose alcohol consumption and examined the antiapoptotic role of calpain inhibitor 1. Male Wistar Albino rats (n = 108) were divided into six groups: Control, alcohol (ethanol was given during 30 days for chronic alcohol consumption), MI (150 mg/kg ISO injection at last two days of alcohol consumption), alcohol + MI, alcohol + MI + calpain inhibitor 1 (10 mg/kg inhibitor was injected at 15 min before ISO injections) and Dimethyl Sulfoxide (DMSO) groups. Biochemical, histological, and morphometric methods determined apoptosis levels in the heart tissue of rats. Cytochrome c, caspase 3, and calpain levels were significantly high in alcohol, MI, and alcohol + MI groups. In contrast, mitochondrial cardiolipin content was found to be low in alcohol, MI, and alcohol + MI groups. These parameters were close to the control group in the therapy group. Histological and morphometric data have supported biochemical results. As a result of our biochemical data, myocardial apoptosis was seen in the alcohol, MI, and especially alcohol after MI groups. Calpain inhibitor 1 reduced apoptotic cell death and prevented myocardial tissue injury in these groups. The efficiency of calpain inhibitor was very marked in MI after long-term high dose alcohol consumption.

Alterations in the Plasma and Red Blood Cell Properties in Patients with Varicose Vein: A Pilot Study

The varicose vein results from the inefficient functioning of the valves in the lower limb veins, making the blood flow slow down and leading to blood stasis and hypoxia. This type of vein dysfunction might be a result of the development of oxidative stress. We compared oxidative stress markers in the plasma and erythrocytes obtained from peripheral veins and varicose veins in the same patients (glutathione, nonenzymatic antioxidant capacity (NEAC), catalase (CAT) and acetylcholinesterase (AChE) activity, thiols, thiobarbituric acid-reactive substance (TBARS), and protein carbonyls). We found a decrease in NEAC in the plasma obtained from the varicose veins compared to the peripheral veins. We detected a decrease in thiols in the plasma, hemolysate, and plasma membranes and increase in protein carbonyl compounds and TBARS levels in the varicose veins. These changes were accompanied by a decrease in CAT and AChE activity. For the first time, our results show changes in the plasma, erythrocyte membrane, and hemolysate protein properties in varicose vein blood in contrast to the plasma and erythrocytes in peripheral vein blood from the same patients. The increased oxidative stress accompanying varicose vein disease might result from the local inefficiency of the antioxidant defense system.

Therapeutic Potential of Hemoglobin Derived from the Marine Worm Arenicola marina (M101): A Literature Review of a Breakthrough Innovation

Oxygen (O₂) is indispensable for aerobic respiration and cellular metabolism. In case of injury, reactive oxygen species are produced, causing oxidative stress, which triggers cell damaging chemical mediators leading to ischemic reperfusion injuries (IRI). Sufficient tissue oxygenation is necessary for optimal wound healing. In this context, several hemoglobin-based oxygen carriers have been developed and tested, especially as graft preservatives for transplant procedures. However, most of the commercially available O₂ carriers increase oxidative stress and show some adverse effects. Interestingly, the hemoglobin derived from the marine lugworm Arenicola marina (M101) has been presented as an efficient therapeutic O₂ carrier with potential anti-inflammatory, anti-bacterial, and antioxidant properties. Furthermore, it has demonstrated promise as a supplement to conventional organ preservatives by reducing IRI. This review summarizes the properties and various applications of M101. M101 is an innovative oxygen carrier with several beneficial therapeutic properties, and further research must be carried out to determine its efficacy in the management of different pathologies.

Genome-wide analysis of DNA methylation identifies the apoptosis-related gene UQCRH as a tumor suppressor in renal cancer

DNA hypermethylation is frequently observed in clear cell renal cell carcinoma (ccRCC) and correlates with poor clinical outcomes. However, the detailed function of DNA hypermethylation in ccRCC has not been fully uncovered. Here, we show the role of DNA methylation in ccRCC progression through the identification of a target(s) of DNA methyltransferases (DNMT). Our preclinical model of ccRCC using the serial orthotopic inoculation model showed the upregulation of DNMT3B in advanced ccRCC. Pretreatment of advanced ccRCC cells with 5-aza-deoxycytidine, a DNMT inhibitor, attenuated the formation of primary tumors through the induction of apoptosis. DNA methylated sites were analyzed genome-wide using methylation array in reference to RNA-sequencing data. The gene encoding ubiquinol cytochrome c reductase hinge protein (UQCRH), one of the components of mitochondrial complex III, was extracted as a methylation target in advanced ccRCC. Immunohistochemical analysis revealed that the expression of UQCRH in human ccRCC tissues was lower than normal adjacent tissues. Silencing of UQCRH attenuated the cytochrome c release in response to apoptotic stimuli and resulted in enhancement of primary tumor formation in vivo, implying the tumor-suppressive role of UQCRH. Moreover, 5-aza-deoxycytidine enhanced the therapeutic efficiency of mammalian target of rapamycin inhibitor everolimus in vivo. These findings suggested that the DNMT3B-induced methylation of UQCRH may contribute to renal cancer progression and implicated clinical significance of DNMT inhibitor as a therapeutic option for ccRCC.

Hypoxia-mediated alterations in pulmonary surfactant protein expressions: Beneficial effects of quercetin prophylaxis

We have compared the prophylactic efficacies of quercetin and salbutamol in preventing pulmonary surfactants oxidation under hypoxia. Male SD rats supplemented orally with quercetin (50 mg/Kg BW) and salbutamol (2 mg/Kg BW) were exposed to hypobaric hypoxia (7,620 m for 6 h). Hypoxia-mediated elevation in oxidative stress, inflammation, and extravasations of LDH & albumin content in BALF of rats were assessed. Western blotting and mRNA studies determined the differential expressions of Nrf-2, HO-1, and associated surfactant proteins (SP-A, SP-B, SP-C, & SP-D) in rat lungs. Later, the lung configuration under hypoxia was assessed histopathologically. Quercetin and salbutamol pretreatment considerably restored the expressions of Nrf-2, HO-1, and surfactant proteins to normal by attenuating the increase in oxidative stress, inflammation, and extravasations of plasma proteins in the animals under hypoxia. The histopathology has also evidenced the protective effect of quercetin in retaining normal lung architecture under hypoxia over salbutamol. The present study indicates the effectiveness of quercetin prophylaxis in preventing pulmonary surfactants oxidation under hypoxia over salbutamol.

Lipid Peroxidation Assay Using BODIPY-Phenylbutadiene Probes: A Methodological Overview

The assessment of reactive oxygen species has increasing importance in biomedical sciences, due to their biological role in signaling pathways and induction of cell damage at low and high concentrations, respectively. Detection of lipid peroxidation with sensing probes such as some BODIPY dyes has now wide application in studies using fluorescent microplate readers, flow cytometry, and fluorescence microscopy. Two phenylbutadiene derivatives of BODIPY are commonly used as peroxidation probes, non-oxidized probes and oxidized products giving red and green fluorescence, respectively. Peculiar features of lipoperoxidation and BODIPY dye properties make this assessment a rather complex process, not exempt of doubts and troubles. Color changes and fluorescence fading that are not due to lipid peroxidation must be taken into account to avoid misleading results. As a characteristic feature of lipoperoxidation is the propagation of peroxyl radicals, pitfalls and advantages of a delayed detection by BODIPY probes should be considered.

A Comparative Study on the Oxidation of Label-Free Silver Triangular Nanoplates by Peroxides: Main Effects and Sensing Applications

Nowadays, analytical systems based on silver triangular nanoplates (AgTNPs) have been shown as good prospects for chemical sensing. However, they still remain relatively poorly studied as colorimetric probes for sensing various classes of compounds. This study shows that these nanoparticles are capable of being oxidized by peroxides, including both hydrogen peroxide and its organic derivatives. The oxidation was found to result in a decrease in the AgTNPs' local surface plasmon resonance band intensity at 620 nm. This was proposed for peroxide-sensitive spectrophotometric determination. Five peroxides differing in their structure and number of functional groups were tested. Three of them easily oxidized AgTNPs. The effects of a structure of analytes and main exterior factors on the oxidation are discussed. The detection limits of peroxides in the selected conditions increased in the series peracetic acid < hydrogen peroxide < tert-butyl hydroperoxide, coming to 0.08, 1.6 and 24 μmol L^-1, respectively. tert-Butyl peroxybenzoate and di-tert-butyl peroxide were found to have no effect on the spectral characteristics of AgTNPs. By the example of hydrogen peroxide, it was found that the determination does not interfere with 100-4000-fold quantities of common inorganic ions. The proposed approach was successfully applied to the analysis of drugs, cosmetics and model mixtures.

Redox Regulation and Oxidative Stress: The Particular Case of the Stallion Spermatozoa

Redox regulation and oxidative stress have become areas of major interest in spermatology. Alteration of redox homeostasis is recognized as a significant cause of male factor infertility and is behind the damage that spermatozoa experience after freezing and thawing or conservation in a liquid state. While for a long time, oxidative stress was just considered an overproduction of reactive oxygen species, nowadays it is considered as a consequence of redox deregulation. Many essential aspects of spermatozoa functionality are redox regulated, with reversible oxidation of thiols in cysteine residues of key proteins acting as an “on–off” switch controlling sperm function. However, if deregulation occurs, these residues may experience irreversible oxidation and oxidative stress, leading to malfunction and ultimately death of the spermatozoa. Stallion spermatozoa are “professional producers” of reactive oxygen species due to their intense mitochondrial activity, and thus sophisticated systems to control redox homeostasis are also characteristic of the spermatozoa in the horse. As a result, and combined with the fact that embryos can easily be collected in this species, horses are a good model for the study of redox biology in the spermatozoa and its impact on the embryo.

Therapeutic potential of natural compounds in inflammation and chronic venous insufficiency

The term varicose vein refers to the twisted and swollen vein visible under the skin surface which occurs most commonly in the leg. Epidemiological studies report a varying percentage of incidences from 2 to 56% in men and <1-60% in women. Venous insufficiency is most often caused by the damage to the valves and walls of the veins. The mechanism of varicose vein formation is complex. It is, however, based on hypotensive blood vessels, hypoxia, and other mechanisms associated with inflammation. This work describes mechanisms related to the formation and development of the varicose vein. It discusses risk factors, pathogenesis of chronic venous disease, markers of the epithelial and leukocyte activation, state of hypoxia and inflammation, reactive oxygen species (ROS) generation, and oxidative stress. Additionally, this paper describes substances of plant origin used in the treatment of venous insufficiency. It also considers the structure of the molecules, their properties, and their mechanisms of action, the structure-activity relationship and chemical properties of flavonoids and other substances. The flavonoids include quercetin derivatives, micronized purified flavonoid fraction (Daflon), natural pine bark extract (Pycnogenol), and others such as triterpene saponine, extracts from Ruscus aculeatus and Centella asiatica, Ginkgo biloba extract, coumarin dereivatives that are used in chronic venous insufficiency. Flavonoids are natural substances found in plants, including fruits, vegetables, flowers, and others. They are important to the circulatory system and critical to blood vessels and the blood flow. Additionally, they have antioxidant, antiinflammatory properties.

Cancer cells change their glucose metabolism to overcome increased ROS: One step from cancer cell to cancer stem cell?

Cancer cells can adapt to low energy sources in the face of ATP depletion as well as to their high levels of ROS by altering their metabolism and energy production networks which might also have a role in determining cell fate and developing drug resistance. Cancer cells are generally characterized by increased glycolysis. This is while; cancer stem cells (CSCs) exhibit an enhanced pentose phosphate pathway (PPP) metabolism. Based on the current literature, we suggest that cancer cells when encountering ROS, first increase the glycolysis rate and then following the continuation of oxidative stress, the metabolic balance is skewed from glycolysis to PPP. Therefore, we hypothesize in this review that in cancer cells this metabolic deviation during persistent oxidative stress might be a sign of cancer cells' shift towards CSCs, an issue that might be pivotal in more effective targeting of cancer cells and CSCs.

Corilagin induces apoptosis, autophagy and ROS generation in gastric cancer cells in vitro

Corilagin, a unique component of the tannin family, has been identified in several medicinal plants. In previous literature, corilagin exhibited a marked anticancer property in a variety of human cancer cells. However, the biological effects of corilagin on gastric cancer and the mechanisms involved remain to be fully elucidated. In the present study, it was reported that corilagin induced inhibition of cell growth in SGC7901 and BGC823 cells in a concentration-dependent manner. It was found that corilagin exhibited less toxicity towards normal GES-1 cells. Furthermore, the study showed that corilagin induced the apoptosis of gastric cancer cells mainly via activating caspase-8, -9, -3 and poly ADP-ribose polymerase proteins. Simultaneously, it was verified that corilagin triggered autophagy in gastric cancer cells and the inhibition of autophagy improved the activity of corilagin on cell growth suppression. In addition, corilagin significantly increased intracellular reactive oxygen species production, which is important in inhibiting the growth of gastric cancer cells. Finally, it was shown that necroptosis cannot be induced by corilagin-incubation in SGC7901 and BGC823 cell lines. Consequently, these findings indicate that corilagin may be developed as a potential therapeutic drug for gastric cancer.

Determination of the volatile and polyphenol constituents and the antimicrobial, antioxidant, and tyrosinase inhibitory activities of the bioactive compounds from the by-product of Rosa rugosa Thunb. var. plena Regal tea

Background

The phytochemical constituents and biological activities of Rosa rugosa Thunb. var. plena Regal flower cell sap (RFCS) were investigated.

Methods

Volatile constituent, such as linalool, phenylethyl alcohol, citronellol, α-bisabolol, were identified by GC-MS. The contents of hyperoside, kaempferol-3-O-rutinosid, rutin, and luteolin as well as the total flavonoid content in RFCS were determined by HPLC and HPLC-MS. The total polyphenol content was evaluated by the Folin-Ciocalteu colorimetric method. The antioxidant activities of RFCS and the standards were evaluated by DPPH and ABTS radical scavenging assays. The tyrosinase inhibitory activities of the rose samples and standard substance were determined by a spectrophotometric method. The antimicrobial effects of RFCS were evaluated in terms of minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) or minimum Fungicidal concentrations (MFCs).

Results

The rose fraction exhibited a high content of biologically active ingredients. The total content of volatile compounds in RFCS was approximately 48.21 ± 2.76 ng/mL. The total phenolic acid content and total flavonoid content were 0.31 ± 0.01 mg/mL and 0.43 ± 0.01 mg/mL, respectively. Its IC₅₀ value in the DPPH assay was 1120 ± 42 μg/mL, and its IC₅₀ value for ABTS radical scavenging activity was 1430 ± 42 μg/mL.RFCS strongly inhibited L-tyrosine oxidation with an IC₅₀ value of 570 ± 21 μg/mL. Every compound identified in RFCS exhibited broad-spectrum antimicrobial activity. F. nucleatum was most susceptible to RFCS with an MIC of 64 μg/mL and MBC of 250 μg/mL.

Conclusions

Due to its rose-like aroma, phenylethyl alcohol may be combined with linalool for use as a natural skin-whitening agent and skin care additive in the and pharmaceutical industries.

Oxygen, evolution and redox signalling in the human brain; quantum in the quotidian

Rising atmospheric oxygen (O₂ ) levels provided a selective pressure for the evolution of O₂ -dependent micro-organisms that began with the autotrophic eukaryotes. Since these primordial times, the respiring mammalian cell has become entirely dependent on the constancy of electron flow, with molecular O₂ serving as the terminal electron acceptor in mitochondrial oxidative phosphorylation. Indeed, the ability to 'sense' O₂ and maintain homeostasis is considered one of the most important roles of the central nervous system (CNS) and probably represented a major driving force in the evolution of the human brain. Today, modern humans have evolved with an oversized brain committed to a continually active state and, as a consequence, paradoxically vulnerable to failure if the O₂ supply is interrupted. However, our pre-occupation with O₂ , the elixir of life, obscures the fact that it is a gas with a Janus face, capable of sustaining life in physiologically controlled amounts yet paradoxically deadly to the CNS when in excess. A closer look at its quantum structure reveals precisely why; the triplet ground state diatomic O₂ molecule is paramagnetic and exists in air as a free radical, constrained from reacting aggressively with the brain's organic molecules due to its 'spin restriction', a thermodynamic quirk of evolutionary fate. By further exploring O₂ 's free radical 'quantum quirkiness', including emergent (quantum) physiological phenomena, our understanding of precisely how the human brain senses O₂ deprivation (hypoxia) and the elaborate redox-signalling defence mechanisms that defend O₂ homeostasis has the potential to offer unique insights into the pathophysiology and treatment of human brain disease.

RETRACTED ARTICLE: The quantum physiology of oxygen; from electrons to the evolution of redox signaling in the human brain

Rising atmospheric oxygen (O₂) levels provided a selective pressure for the evolution of O₂-dependent micro-organisms that began with the autotrophic eukaryotes. Since these primordial times, the respiring mammalian cell has become entirely dependent on the constancy of electron flow with molecular O₂ serving as the terminal electron acceptor in mitochondrial oxidative phosphorylation. Indeed, the ability to “sense” O₂ and maintain homeostasis is considered one of the most important roles of the central nervous system (CNS) and likely represented a major driving force in the evolution of the human brain. Today, modern humans have evolved with an oversized brain committed to a continually active state and as a consequence, paradoxically vulnerable to failure if the O₂ supply is interrupted. However, our pre-occupation with O₂, the elixir of life, obscures the fact that it is a gas with a Janus Face, capable of sustaining life in physiologically controlled amounts yet paradoxically deadly to the CNS when in excess. A closer look at its quantum structure reveals precisely why; the triplet ground state diatomic O₂ molecule is paramagnetic and exists in air as a free radical, constrained from reacting aggressively with the brain’s organic molecules due to its “spin restriction”, a thermodynamic quirk of evolutionary fate. By further exploring O₂’s free radical “quantum quirkiness” including emergent quantum physiological phenomena, our understanding of precisely how the human brain senses O₂ deprivation (hypoxia) and the elaborate redox-signaling defense mechanisms that defend O₂ homeostasis has the potential to offer unique insights into the pathophysiology and treatment of human brain disease.

Identification of a functional antioxidant response element at the HIF1A locus

Reactive oxygen species (ROS), which are a byproduct of oxidative metabolism, serve as signaling molecules in a number of physiological settings. However, if their levels are not tightly maintained, excess ROS lead to potentially cytotoxic oxidative stress. Accordingly, several transcriptional regulatory networks have evolved to include components that are highly ROS-responsive. Depending on the context, these regulatory networks can leverage ROS to respond to nutrient conditions, metabolism, or other physiological signals, or to respond to oxidative stress. However, ROS signaling is complex, so regulatory interactions between various ROS-responsive transcription factors are still being mapped out. Here we show that the transcription factor NRF2, a key regulator of the adaptive response to oxidative stress, directly regulates expression of HIF1A, which encodes HIF1α, a key transcriptional regulator of the adaptive response to hypoxia. We used an integrative genomics approach to identify HIF1A as a ROS-responsive transcript and we found an NRF2-bound antioxidant response element (ARE) approximately 30 kilobases upstream of HIF1A. This ARE sequence is deeply conserved, and we verified that it is directly bound and activated by NRF2. In addition, we found that HIF1A is upregulated in breast and bladder tumors with high NRF2 activity. Taken together, our results demonstrate that NRF2 targets a functional ARE at the HIF1A locus, and reveal a direct regulatory connection between two important oxygen responsive transcription factors.

Neuronal-like differentiated SH-SY5Y cells adaptation to a mild and transient H2 O2 -induced oxidative stress

Preconditioning (PC) is a cell adaptive response to oxidative stress and, with regard to neurons, can be considered as a neuroprotective strategy. The aim of the present study was to verify how neuronal-like differentiated SH-SY5Y cells adapt to a mild and transient H₂ O₂ -induced oxidative stress and, hence, whether may be considered as more sensitive cell model to study PC pathways. A first screening allowed to define H₂ O₂ concentrations for PC (10μM-50μM), applied before damage(100μM H₂ O₂ ). Cell viability measured 24 hours after 100μM H₂ O₂ -induced damage was ameliorated by 24-hour pre-exposure to low-concentration H₂ O₂ (10μM-30μM) with cell size as well restored. Markers for apoptosis (Bcl-2 and Bad), inflammation (iNOS), and redox system (MnSOD) were also determined, showing that, in cells pre-exposed to 10μM H₂ O₂ and then submitted to 100μM H₂ O₂ , Bcl-2 levels were higher, Bad and iNOS levels were lower than those observed in damaged cells, and MnSOD levels were unchanged. Such findings show that (1) neuronal-like differentiated SH-SY5Y cells are a suitable model to investigate PC response and more sensitive to the effect of a mild and transient H₂ O₂ -induced oxidative stress with respect to other neuronal cells; (2) 10μM H₂ O₂ -induced PC is mediated by apoptotic and inflammatory pathways, unlike antioxidant system; (3) such neuroprotective strategy and underlying signals proven in neuronal-like differentiated SH-SY5Y cells may contribute to understand in vivo PC mechanisms and to define a window for pharmacological intervention, namely, related to ischemic brain damage.

SIGNIFICANCE OF THE STUDY

Neuronal-like differentiated SH-SY5Y cells are a suitable model to investigate PC, an endogenous neuroprotective response to a mild and transient H₂ O₂ -induced oxidative stress, elicited by 24-hour exposure to very low H₂ O₂ concentrations and mediated by both apoptotic and inflammatory pathways. This model reflects in vivo PC mechanisms occurring after brain trauma and provides novel information about pathways and time of protection useful for an appropriate pharmacological intervention.

The Interplay of Reactive Oxygen Species, Hypoxia, Inflammation, and Sirtuins in Cancer Initiation and Progression

The presence of ROS is a constant feature in living cells metabolizing O2. ROS concentration and compartmentation determine their physiological or pathological effects. ROS overproduction is a feature of cancer cells and plays several roles during the natural history of malignant tumor. ROS continuously contribute to each step of cancerogenesis, from the initiation to the malignant progression, acting directly or indirectly. In this review, we will (a) underline the role of ROS in the pathway leading a normal cell to tumor transformation and progression, (b) define the multiple roles of ROS during the natural history of a tumor, (c) conciliate many conflicting data about harmful or beneficial effects of ROS, (d) rethink the importance of oncogene and tumor suppressor gene mutations in relation to the malignant progression, and (e) collocate all the cancer hallmarks in a mechanistic sequence which could represent a "physiological" response to the initial growth of a transformed stem/pluripotent cell, defining also the role of ROS in each hallmark. We will provide a simplified sketch about the relationships between ROS and cancer. The attention will be focused on the contribution of ROS to the signaling of HIF, NFκB, and Sirtuins as a leitmotif of cancer initiation and progression.

Evaluation of the Antioxidant Activities and Tyrosinase Inhibitory Property from Mycelium Culture Extracts

Since mushrooms have many bioactive components, they have been used as components in folk medicine. Because mycelium has an advantage when it comes to large-scale production, this study aimed to evaluate the antioxidant properties and anti-tyrosinase activity from 55 mycelia in culture media. Relatively high 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity was detected from the ethanol extract of culture media including mycelium (EECiM) of Morchella esculenta var. esculenta (MEVE), Auricularia polytricha (APO), Tremella aurantia (TAU), Volvariella bombycina (VBO), and Oudemansiella sp. (Osp), which also showed strong reducing power and inhibitory activity in relation to the thiobarbituric acid (TBA) value. On the other hand, relatively high tyrosinase inhibitory activity was detected in Inonotus mikadoi (IMI), Coriolus versicolor (CVE), Volvariella volvacea (VVO), Panellus serotinus (PSE), Auricularia auricula (AAU), and Fomitopsis sp. (Fsp). Interestingly, the APO EECiM exhibited the highest DPPH radical scavenging rate (77.5 ± 4.3%) and reducing power (1.18 ± 0.041), while the highest inhibitory power of the TBA value and antityrosinase activity were detected in that of TAU (64.5 ± 4.1%) and IMI (46.0 ± 7.5%), respectively. Overall, our study suggested potential candidates for EECiMs that exhibited powerful antioxidant and tyrosinase inhibitory properties and might be used as natural antioxidant tyrosinase inhibitor.

The redox biology network in cancer pathophysiology and therapeutics

The review pinpoints operational concepts related to the redox biology network applied to the pathophysiology and therapeutics of solid tumors. A sophisticated network of intrinsic and extrinsic cues, integrated in the tumor niche, drives tumorigenesis and tumor progression. Critical mutations and distorted redox signaling pathways orchestrate pathologic events inside cancer cells, resulting in resistance to stress and death signals, aberrant proliferation and efficient repair mechanisms. Additionally, the complex inter-cellular crosstalk within the tumor niche, mediated by cytokines, redox-sensitive danger signals (HMGB1) and exosomes, under the pressure of multiple stresses (oxidative, inflammatory, metabolic), greatly contributes to the malignant phenotype. The tumor-associated inflammatory stress and its suppressive action on the anti-tumor immune response are highlighted. We further emphasize that ROS may act either as supporter or enemy of cancer cells, depending on the context. Oxidative stress-based therapies, such as radiotherapy and photodynamic therapy, take advantage of the cytotoxic face of ROS for killing tumor cells by a non-physiologically sudden, localized and intense oxidative burst. The type of tumor cell death elicited by these therapies is discussed. Therapy outcome depends on the differential sensitivity to oxidative stress of particular tumor cells, such as cancer stem cells, and therefore co-therapies that transiently down-regulate their intrinsic antioxidant system hold great promise. We draw attention on the consequences of the damage signals delivered by oxidative stress-injured cells to neighboring and distant cells, and emphasize the benefits of therapeutically triggered immunologic cell death in metastatic cancer. An integrative approach should be applied when designing therapeutic strategies in cancer, taking into consideration the mutational, metabolic, inflammatory and oxidative status of tumor cells, cellular heterogeneity and the hypoxia map in the tumor niche, along with the adjoining and systemic effects of oxidative stress-based therapies.

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Critical point mutations and distorted redox-sensitive signaling pathways underlie the tumorigenic phenotype.

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Inter-cellular crosstalk under stress conditions in the tumor niche drives the behavior of tumor cells.

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ROS may act as either as supporter or enemy of tumor cells, depending on the context.

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Oxidative stress-injured cells deliver danger signals to neighboring and distant cells, hence dictating the outcome of therapy in cancer.