Peroxyl Radicals Research Articles

An evolutionary conserved detoxification system for membrane lipid-derived peroxyl radicals in Gram-negative bacteria.

How double-membraned Gram-negative bacteria overcome lipid peroxidation is virtually unknown. Bactericidal antibiotics and superoxide ion stress stimulate the transcription of the Burkholderia cenocepacia bcnA gene that encodes a secreted lipocalin. bcnA gene orthologs are conserved in bacteria and generally linked to a conserved upstream gene encoding a cytochrome b561 membrane protein (herein named lcoA, lipocalin-associated cytochrome oxidase gene). Mutants in bcnA, lcoA, and in a gene encoding a conserved cytoplasmic aldehyde reductase (peroxidative stress-associated aldehyde reductase gene, psrA) display enhanced membrane lipid peroxidation. Compared to wild type, the levels of the peroxidation biomarker malondialdehyde (MDA) increase in the mutants upon exposure to sublethal concentrations of the bactericidal antibiotics polymyxin B and norfloxacin. Microscopy with lipid peroxidation-sensitive fluorescent probes shows that lipid peroxyl radicals accumulate at the bacterial cell poles and septum and peroxidation is associated with a redistribution of anionic phospholipids and reduced antimicrobial resistance in the mutants. We conclude that BcnA, LcoA, and PsrA are components of an evolutionary conserved, hitherto unrecognized peroxidation detoxification system that protects the bacterial cell envelope from lipid peroxyl radicals.

СПЕЦИФИЧЕСКАЯ РОЛЬ ИОНА ЦИНКА ПРИ ПЕРЕНОСЕ ЭЛЕКТРОНА В МЕДНО-ЦИНКОВОЙ СУПЕРОКСИДДИСМУТАЗЕ

The interaction of the superoxide radical ion O2– with the active center of Cu,Zn-superoxide dismutase was studied by computer simulation using the ORCA software package version 5.0.2. at the level of density functional theory using the PBE functional. The main characteristics for two processes of electron transfer in the catalytic cycle of deactivation of the radical ion are obtained. The variable factor in the modeling was the presence of the Zn2+ ion in the active site of the enzyme. It has been established that the presence of the Zn2+ ion contributes to a large extent only to the second electron transfer from the Cu+ ion to the protonated form of the radical ion, to the hydroperoxide radical HO2

Role of antioxidant in the regulation of blood glucose level

Antioxidants play important role in the prevention of free radical formation and helps in reducing various disorders such as cancer, aging, cardiovascular disease, cataracts, immune system decline, and brain dysfunction. There are several foods such as fruits, green leafy vegetables, tea, coffee, nuts and oilseeds which have been found to have good antioxidants potential. These dietary antioxidants such as vitamin A, vitamin C, vitamin E, carotenoids, phytochemicals etc. are found to have various disease preventive capacities. These antioxidants play an important role in protection against photo oxidative processes by acting as oxygen and peroxyl radical scavengers. These have the capacities of preventing cardiovascular diseases include atherosclerosis, coronary heart disease, arterial hypertension, and heart failure. Antioxidants stimulate the immune system by enhancing T-lymphocyte proliferation in response to infection increasing cytokine production and synthesis of immunoglobulin and protect membrane stability, including quenching or scavenging Reactive Oxygen Species. The present review highlights the health benefits of antioxidants with supporting evidence from animal studies and humans.

Antioxidant activity of delphinidin and pelargonidin: Theory and practice.

The quantum chemical density functional theory and in vitro chemical-based antioxidant assays were used to research the reaction mechanism of delphinidin/pelargonidin with free radicals including superoxide anion radicals (O2 - ∙) and hydroperoxide radicals (OOH∙). The geometric configuration, bond dissociation energy, PCM (polarizable continuum model) solvent model reaction enthalpy changes were studied to explain the transition states, and the reaction enthalpy change value was calculated to determine the active site. From the results of spatial configuration, delphinidin showed a stronger conjugation effect than that of pelargonidin. The dihedral angle between the three rings of delphinidin was almost 180°, and the angle between the B and C rings was only -2.81868°. Both coplanar and antioxidant activity of delphinidin was better than pelargonidin. The consequences of reaction enthalpy change in PCM were consistent with the bond dissociation energy. The phenolic hydroxyl bond dissociation energy of delphinidin was slightly smaller than that of pelargonidin. Moreover, the C4' site of delphinidin and the C3 site of pelargonidin were the active sites for scavenging free radicals. The free radical scavenging ability of delphinidin was marginally higher than that of pelargonidin. On the other hand, in vitro antioxidant results proved the scavenging ability of delphinidin and pelargonidin on superoxide anions, DPPH, and ABTS∙+ free radicals. It was shown that the chemical-based antioxidant activity was consistent with the theoretical calculation results, with delphinidin showing greater antioxidant activity. These results could explain the antioxidant mechanism of delphinidin/pelargonidin in scavenging free radicals from chemical reactions. PRACTICAL APPLICATIONS: This manuscript explained the antioxidant mechanism of delphinidin/pelargonidin in scavenging free radicals through the analysis of the geometric configuration of delphinidin/pelargonidin and the theoretical calculation of the reaction transition state. It could also speculate on the possible reaction sites, and provide a basis for judging how to efficiently select antioxidants with great antioxidant activity.

Radical-Mediated C-C Coupling of Alcohols Induced by Plasmonic Hot Carriers.

The C-C coupling reactions of aliphatic alcohols to aromatics and larger-mass compounds have large endothermicities and activation energies, calling for catalysts operating at high temperatures. Here, we demonstrate that plasmon-excited nanoparticles catalyze the C-C coupling of aliphatic alcohols at room temperature to produce polyaromatic hydrocarbons and graphene oxide. The conversion is quenched by radical and electron scavengers and by the surface passivation of metals, suggesting that the reaction proceeds through alkoxy, peroxyl, hydroxyalkyl, and alkyl radical intermediates created by the metal to molecule transfer of plasmonic hot carriers. Besides being the first realization of C-C coupling of aliphatic alcohols at room temperature, the result constitutes a rare example of an endothermic plasmon-induced reaction producing new bonds and a new method for photogenerating graphene derivatives. More importantly, the result demonstrates the facile generation of organic radicals directly from alcohols, which may be used as precursors for radical-based organic reactions.

The Antioxidant, Anti-Inflammatory and Immunomodulatory Effects of Camel Milk

Camel milk (CM) has been found to have several health benefits, including antiviral, antibacterial, anti-tumor, anti-fungal, antioxidant, hypoglycaemic and anti-cancer activities. In addition, CM can counter signs of aging and may be a useful naturopathic treatment for autoimmune diseases. The composition of CM varies with geographic origin, feeding conditions, seasonal and physiological changes, genetics and camel health status. In the present review, we collate the diverse scientific literature studying antioxidant, anti-inflammatory and immunomodulatory effects of CM and its bioactive compounds. The databases Scopus, PubMed, and Web of Science were searched until the end of September 2021 using the keywords: camel milk, antioxidant, anti-inflammatory, immunomodulatory. The anti-inflammatory mechanism of CM in various inflammatory disorders was consistently reported to be through modulating inflammatory cells and mediators. The common anti-inflammatory bioactive components of CM seem to be lactoferrin. The antioxidant effects of α-lactalbumin, β-caseins and vitamin C of CM work by reducing or inhibiting the production of reactive oxygen species (ROS), hydroxyl radicals, nitric oxide (NO), superoxide anions and peroxyl radicals, likely alleviating oxidative stress. Higher levels of protective proteins such as lysozyme, IgG and secretory IgA compared to cow’s milk, and insulin-like protein activity of CM on ß cells appear to be responsible for the immunomodulatory properties of CM. The evidence indicates that CM and its bioactive components has the potential to be a therapeutic value for diseases that are caused by inflammation, oxidative stress and/or immune-dysregulation.

Peroxyl radicals from diketones enhanced the indirect photochemical transformation of carbamazepine: Kinetics, mechanisms, and products

In surface waters, photogenerated transients (e.g., hydroxyl radicals, carbonate radicals, singlet oxygen and the triplet states of dissolved organic matter) are known to play a role in the transformation of biorecalcitrant carbamazepine (CBZ). Small diketones, such as acetylacetone (AcAc) and butanedione (BD), are naturally abundant and have been proven to be effective precursors of carbon and oxygen centered radicals. However, the photochemical kinetics and mechanisms of coexisting diketones and CBZ are barely known. Herein, the effects of AcAc and BD on the photochemical conversion of CBZ were investigated compared with H2O2 which was the main ·OH precursor in the environment. An enhancing effect was observed for the degradation of CBZ by the addition of diketones. The enhancing effect of diketones was pH-dependent and much more significant than H2O2 under simulated solar irradiation. On the basis of the identification of transient species and the competition kinetic model, organic peroxyl radicals were found to play a dominant role in CBZ photodegradation, and the second-order rate constants of the reaction between CBZ and peroxyl radicals were determined to be approximately 107–108 M–1s–1. Furthermore, mutagenic acridine was found to be the major cumulative intermediate with a yield of > 30% in the presence of diketones, which might be an environmental concern. This work indicates that the coexistence of diketones and persistent organic pollutants might lead to some detrimental effects on aquatic environments if the water is exposed to sunlight.

On ‘Is vitamin E the only lipid-soluble, chain-breaking antioxidant in human blood plasma and erythrocyte membranes?’ by Graham W. Burton, Anne Joyce, Keith U. Ingold

Application of a time-tested quantitative method of measuring peroxyl radical production in conjunction with the determination of the stoichiometry of the reaction of peroxyl radicals with α-tocopherol has permitted the conclusion that α-tocopherol is the major lipid-soluble chain-breaking antioxidant in human plasma and red cell membranes.

Peroxyl radical induced membrane instability of giant unilamellar vesicles and anti-lipooxidation protection

The present work is intended to investigate the morphological instability of lipid membrane induced by peroxyl radical (ROO•) and the underlying mechanism. To this end, the giant unilamellar vesicle (GUV) made from phosphatidylcholine was employed as a membrane model, and the azo compounds 2,2′-azobis(2,4-dimethylvaleronitrile) (AMVN) and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) were used as the precursors of ROO•. Upon mild pyrolysis, the GUV immobilized in agarose gel was followed by conventional optical microscopy in real time, and the morphological variation was quantified by the image heterogeneity, perimeter and area all as a function of time for up to an hour. Lipid oxidation initiated from lipid phase with AMVN and from aqueous phase with AAPH led to different types of morphological changes, i.e. membrane coarsening and vesicle deformation/budding, respectively. Based on the compositional analysis of lipid oxidation products, we propose that ROO• as the primary radical initiator is responsible for the morphological changes of the GUV-AMVN while both ROO• and RO• are responsible for the morphological changes of the GUV-AAPH system. Lipophilic β-carotene and amphipathic plant phenols as antioxidants are found to be able to stabilize the membrane integrity effectively, in corroboration with the proposed mechanisms for membrane destruction.

Structure–antioxidant activity (oxygen radical absorbance capacity) relationships of phenolic compounds

Antioxidant capacity is the extent to which a compound can eliminate reactive oxygen species, and in vitro methods for its chemical evaluation have been proposed. Among these methods, the oxygen radical absorbance capacity (ORAC) assay comes close to the oxidation reaction in the living body because it generates radical species that mimic the lipid peroxyl radical involved in the peroxidation reaction of biological components and react in a phosphate buffer. In this study, PM7, a semi-empirical molecular orbital method, was used to calculate the thermodynamic properties (bond dissociation enthalpy, ionisation potential and proton affinity) associated with ORAC. We also applied the clusterwise linear regression analysis as a statistical method for grouping the antioxidants by structure. By analysing the data for antioxidants, the trend in the hydrophilic ORAC values was determined using the calculated structures and bond dissociation enthalpies of the groups classified according to the presence or absence of oxygen functional groups in the ortho position of phenol. Further studies of indicators other than bond dissociation enthalpy are needed to predict the ORAC of other antioxidants such as flavonoids and indoles.

Impact of malathion toxicity on the oxidative stress parameters of the black soldier fly Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae)

The black soldier fly larvae (BSFL) may serve as a promising tool in the animals feed production industry. The input organic wastes may be contaminated by insecticides that affect both the insect’s mass rearing, and the animals feed process. Therefore, in the current study the assessment of oxidative stress parameters of the black soldier fly (BSF) were investigated to quantify the deleterious effect of malathion-contaminated kitchen waste (1:1 vegetable: fruit waste) container on the insect. The different developmental stages of insect (adult and larva) were exposed to different concentrations (0, 0.005, 0.01, 0.015, and 0.02 mg/mL) of malathion. The results showed that the mean value of the reactive oxygen species (ROS), which included hydrogen peroxide (H2O2) and superoxide anion radicals (O2•-) concentrations were lower in larval stage than in adults, in all treated groups (0, 0.005, 0.01, 0.015, and 0.02 mg/mL malathion concentration). Also, the protein carbonyls amount and lipid peroxides levels were decreased in the 0.02 mg/mL Malathion compared to the control values. However, the cluster analysis revealed slight dissimilar patterns for control insects and the highest malathion concentration (0.02 mg/ml). These stage-related differences could occur from the different growth dynamic functions of larvae and adults. The larvae were distinguished by robust growth, and significant oxygen consumption. The results verified that oxidative stress parameters, especially protein carbonyls and α, α-diphenyl-β-picrylhydrazyl (DPPH) were promising, cheap, quick and cost-effective applications for determining the macromolecules damage, and antioxidant ability of H. illucens enclosed with malathion exposure. These findings described that malathion application induces macromolecules damage mediated through oxidative stress injury.

New Insights in Biological Development of Novel Varieties with Antioxidant, Antimicrobial, Antiparasitic, DNA Protection Activities and Future Perspectives

Medicinal plants are most valuable source of different natural compounds and safer than the chemicals that directly used for the treatment of high risk diseases. The compounds that present in the medicinal plants are monoterpenes, flavonoids, and phenolics. The ultimate goal of the using of medicinal herbs are inhibiting the growth of the infectious particles that causing variety of diseases. Medicinal plants have been used in order to control the growth of infectious bacteria in as some of them deviling the resistance due to changing endearments for example, Enterococcus faecium and Klebsiella pneumonia. Many of the plant extracts such as N.sativa seeds have been used as natural booster for targeting the lethal pathogens and causing the cellular toxicities While, Commelina africana L and Elephantorrhiza elephantine that binds with living cells by damaging’s the membranes of the toxic pathogens. The production of the free radicals due to stress or any environmental conditions may increase the risk of damage to DNA molecules. These free radicals binds to the double binds of the DNA molecule inhibit their functions in order to replicate for further central dogma processing. It give rise the production of peroxyl radicals species due to consecutive attack to the DNA molecule.

Honeybee Pollen From Southern Chile: Phenolic Profile, Antioxidant Capacity, Bioaccessibility, and Inhibition of DNA Damage.

Honeybee pollen (HBP) chemical composition is highly variable conforming to the floral and geographical origin of the pollen grains. The beneficial effects and functional properties of the HBP are well-known and have been mainly attributed to their high content of antioxidant polyphenols. In this work, twelve HBPs samples from the Southern region of Chile (X Región de Los Lagos) were characterized for the first time according to their botanical origin, phenolic composition, and antioxidant activity. The in vitro gastrointestinal digestion assay was done to simulate the human upper digestive tract. Selected honeybee pollen extracts (HBPEs) were assessed as bioaccessible fractions during an in vitro gastrointestinal digestion. Contents of phenolic compounds, antioxidant capacity, and recovery index of quercetin, myricetin, and cinnamic acid were monitored in different steps of gastrointestinal digestion. Furthermore, the protective effect of in vitro digested HBP towards DNA damage induced by peroxyl radicals was evaluated. The introduced species Brassica rapa L. (Brassicaceae), Lotus pedunculatus Cav. (Fabaceae), and Ulex europaeus L. (Fabaceae) predominated in all the HBPs analyzed, while the native species Buddleja globosa Hope (Scrophulariaceae), Luma apiculata (DC.) Burret (Myrtaceae), Embothrium coccineum J.R. Forst. & G. Forst. (Proteaceae) and Eucryphia cordifolia Cav. (Cunoniaceae) appeared less frequently. The content of polyphenols and antioxidant capacity in HBPEs achieved full bioaccessibility at the end of the intestinal digestion step. However, results obtained by a state-of-the-art technique (i.e. HPLC-DAD) demonstrated relatively low values of bioaccessible quercetin and cinnamic acid after the digestion process. In contrast, myricetin showed a high bioaccessibility in the intestinal digestion steps. The protective effect of in vitro digested HBP towards DNA damage induced by peroxyl radicals showed promising results (up to 91.2% protection). In conclusion, HBPs from the X Region de Los Lagos are rich sources of phenolic antioxidants that protect DNA from strand breakage. Therefore, the potential of HBPEs in preventing gastric and/or intestinal cancer should be further considered.

Visible light driven instantaneous photocatalytic degradation of aniline blue (AB) and methyl violet (MV) by strontium ferrite nanoparticles

AbstractToxic organic dyes released into aquatic sources as a result of industrial activities pose a significant threat to the environment. The removal of such dyes from water sources is a challenging task in the context of environmental emergencies. In this present effort, the strontium ferrite nanoparticles were synthesized by coprecipitation followed by a calcination method and is applied for photocatalytic degradation of such organic dyes. The ferrite nanoparticles were characterized by FTIR, XRD, VSM, SEM‐EDX, TEM, and HR‐TEM studies. In the existence of H2O2 under visible light, the catalyst performs efficient degradation of aniline blue (AB) and methyl violet (MV) dyes in a remarkably short interval of time. The superparamagnetic performance of the catalyst was confirmed by VSM, and thus it can be easily recovered from the degraded dye by applying an external magnet. The Fenton mechanism justifies the elevated rate of photo degradation, which generates hydroxyl and perhydroxyl radicals in the progress of the reaction.

Efficacy of Propyl Selenoethers Against Peroxyl Radical Induced Protein Damage: Effect of Functional Group Substitution

Background: Proteins are the critical bio-molecules for cellular function and are also considered to be highly susceptible to reactive oxygen species (ROS)-induced oxidative damages. Methods: The present study aimed to evaluate some simple water-soluble aliphatic organoselenium compounds bearing different functional groups but of similar carbon chain (propyl) length for a protective effect against 2,2’-azobis-(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative damage using mitochondria as an in vitro model. Results: The results indicated that APPH (20 mM) treatment of mitochondrial fraction induced protein carbonylation, leading to inactivation of redox enzymes and electron transport chain (ETC) and, ultimately the mitochondrial dysfunction. On the other hand, treatment with 0.5 mM of monoselenobutyric acid (SeBA) and monoselenopropyl alcohol (SePOH) significantly prevented APPH-induced protein carbonylation in mitochondrial fraction and restored activities of mitochondrial proteins. On the contrary, monoselenopropyl amine (SePAm) treatment at identical concentrations did not show significant protection to mitochondrial activity from AAPH-induced oxidative damages. The above results concur with the reported peroxyl radical scavenging activities of the above molecules. Conclusion: In conclusion, SeBA and SePOH are potential candidate molecules to protect proteins from oxidative damage and, therefore, can be useful for managing oxidative stress in cellular models.

Effect of immersion time of dried scallop on amino acids, antioxidant and ACE inhibitory activities in Japanese traditional Dashi

The dried adductor muscle of scallop (Mizuhopecten yessoensis) has been used as a material for “dashi.” To prepare dashi, the dried scallop must be soaked in water before boiling. Although dashi recipes using dried scallops have been passed down for many generations as a local food, the optimum immersion time prior to cooking has not been elucidated. Thus, the objective of the present study was to determine the optimum immersion time of dried scallops for the preparation of dashi from the viewpoint of components and biological activities.Immersion of dried scallops changed the L * (lightness), a* (redness), and b* (yellowness) of dashi, and subsequent heat treatment led to evident changes in these values. Glycine (Gly), taurine (Tau), and arginine (Arg) are the major components of dashi, accounting for approximately 62%, 15%, and 11% of the total free amino acids, respectively. When the immersion time was 8 h and more, these major amino acids were significantly increased in dashi with or without heating compared to that after 1 h of immersion without heating.Heat treatment significantly decreased maltose in dashi prepared after 8 h of immersion. Dashi prepared following 4 h or more of immersion had significantly enhanced peroxyl radical scavenging and angiotensin converting enzyme (ACE) inhibitory activities compared to those prepared following 1 h of immersion.A minimum of 8 h of immersion appears to be necessary for preparing dashi rich in umami, sweetness, and antioxidant and ACE inhibitory activities. An extended immersion time (12 h) caused evident progress in the Maillard reaction. The soluble and aromatic compounds of the reaction products may affect the taste and functionality of dashi.

Spectroscopic characterization of two peroxyl radicals during the O2-oxidation of the methylthio radical

The atmospheric oxidation of dimethyl sulfide (DMS) yields sulfuric acid and methane sulfonic acid (MSA), which are key precursors to new particles formed via homogeneous nucleation and further cluster growth in air masses. Comprehensive experimental and theoretical studies have suggested that the oxidation of DMS involves the formation of the methylthio radical (CH3S•), followed by its O2-oxidation reaction via the intermediacy of free radicals CH3SOx• (x = 1–4). Therefore, capturing these transient radicals and disclosing their reactivity are of vital importance in understanding the complex mechanism. Here, we report an optimized method for efficient gas-phase generation of CH3S• through flash pyrolysis of S-nitrosothiol CH3SNO, enabling us to study the O2-oxidation of CH3S• by combining matrix-isolation spectroscopy (IR and UV–vis) with quantum chemical computations at the CCSD(T)/aug-cc-pV(X + d)Z (X = D and T) level of theory. As the key intermediate for the initial oxidation of CH3S•, the peroxyl radical CH3SOO• forms by reacting with O2. Upon irradiation at 830 nm, CH3SOO• undergoes isomerization to the sulfonyl radical CH3SO2• in cryogenic matrixes (Ar, Ne, and N2), and the latter can further combine with O2 to yield another peroxyl radical CH3S(O)2OO• upon further irradiation at 440 nm. Subsequent UV-light irradiation (266 nm) causes dissociation of CH3S(O)2OO• to CH3SO2•, CH2O, SO2, and SO3. The IR spectroscopic identification of the two peroxyl radicals CH3SOO• and CH3S(O)2OO• is also supported by 18O- and 13C-isotope labeling experiments.

High‐efficient surface tailoring via reverse atom transfer radical polymerization and reversible addition‐fragmentation chain‐transfer polymerization in an aqueous system initiated by a monocenter redox pair

AbstractThe commonly used multi‐center initiation methods always lead to the formation of quantities of homopolymer in the surface tailoring based on reverse atom transfer radical polymerization (ATRP) and reversible addition‐fragmentation chain‐transfer (RAFT) polymerization. In this study, a monocenter redox pair constructed of silica bearing tert‐butyl hydroperoxide groups and ascorbic acid (SiO2‐TBHP/AsAc) was applied to substitute the commonly used initiation method of R‐supported RAFT grafting polymerization. All the propagating radicals were restricted on the surface of solid particles during the whole procedure theoretically, resulting in a higher grafting efficiency of 95.1% combined with the “controllable” feature at 10 h. This redox pair was also used to initiate the reverse ATRP in miniemulsion successfully with a grafting efficiency of 86.3% at 10 h. The grafting efficiency obtained under this monocenter initiation method was significantly higher than that of the frequently reported surface modification by reverse ATRP and RAFT polymerization. In addition, the high‐efficient surface tailoring was traced and confirmed by nuclear magnetic resonance, Fourier transform infrared, X‐ray photoelectron spectroscopy, thermogravimetric analysis, transmission electron microscopy, and other analysis tests. The advantage of this monocenter redox pair will open a new avenue for the potential “high‐efficient” surface tailoring of various materials.

RETRACTED ARTICLE: Cirsilineol inhibits cell growth and induces apoptosis in glioma C6 cells via inhibiting MAPK and PI3K/Akt/mTOR signaling pathways

BackgroundGlioma is a major type of brain cancer and responsible for high death rate worldwide due to the delayed diagnosis and chemo-resistance. It is responsible for nearly 16% of all brain cancer incidences with increased prevalence globally.ObjectiveThe present research study deals with discovering the in vitro anticancer potential of cirsilineol on the rat glioma C6 cells through the inhibition of PI3K/Akt/mTOR and MAPK signaling pathways.MethodologyThe in vitro antioxidant potential of cirsilineol was examined by different free radical scavenging analyses. The effects of cirsilineol on the cell viability of C6 and normal Vero cells were investigated by MTT assay. The intracellular ROS production and apoptotic cell death in the cirsilineol-administered C6 cells were scrutinized by fluorescent staining techniques. The contents of TBARS and GSH, SOD and caspase activity were examined using assay kits. The PI3K, mTOR, Akt, ERK1/2, JNK1/2, and p38 expressions in the cirsilineol-supplemented C6 cells were examined by RT-PCR study.ResultsThe cirsilineol treatment appreciably scavenged the DPPH, superoxide, and peroxyl radicals. The cell viability of C6 cells was markedly reduced by the cirsilineol; however, it does not affected the Vero cell viability. The cirsilineol treatment demonstrated the augmented ROS production and apoptosis in the C6 cells. The TBARS level and caspase activity were improved, and GSH level and SOD activity were depleted by the cirsilineol. Cirsilineol effectively inhibited PI3K, mTOR, Akt, ERK1/2, JNK1/2, and p38 expressions in the C6 cells.ConclusionOur findings confirmed that the cirsilineol inhibited cell growth and induced apoptosis in C6 cells by inhibiting the PI3K/Akt/mTOR and MAPK signaling cascades. Hence, it can be a potential candidate to treat the glioma in the future.

Antioxidant Activity of Diatomic Phenols

Nine compounds are studied for antioxidant activity, including those from the class of catecholamines containing 3,4-hydroxyphenyl (catechol) as a common structural fragment, which imparts antioxidant properties to the compounds in the reactions of hydrocarbon substrate oxidation. The antiradical activity is determined by the chemiluminescent method by the interception of peroxyl radicals in the model reaction of the initiated oxidation of ethylbenzene (RH). The mechanism of the inhibition of chain oxidation processes by diatomic phenol compounds is provided by the presence of two active hydroxy groups with a possible intramolecular hydrogen bond, leading to a weakening of the О–Н bond and a high rate constant of hydrogen abstraction in the reaction with peroxyl radicals (kinh). This reaction is dominant and determines the inhibitory activity of antioxidants in oxidation processes. The maximum inhibitory activity is shown by 3,5- and 3,6-di-tert-butylpyrocatechins, dopamine, and epicatechin.