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Blood brain barrier (BBB) is a dynamic interface responsible for proper functioning of brain, but also a major obstacle for effective treatment of neurological diseases. Increased levels of free radicals, in high ferrous and high lipid content surrounding, induce lipid peroxidation, leading to production of 4-hydroxynonenal (HNE). HNE modifies all key proteins responsible for proper brain functioning thus playing a major role in the onset of neurological diseases. To investigate HNE effects on BBB permeability, we developed two in vitro BBB models–'physiological' and 'pathological'. The latter mimicked HNE modified extracellular matrix under oxidative stress conditions in brain pathologies. We showed that exogenous HNE induce activation of antioxidative defense systems by increasing catalase activity and glutathione content as well as reducing lipid peroxide levels in endothelial cells and astrocytes of 'physiological' model. While in 'pathological' model, exogenous HNE further increased lipid peroxidation levels of endothelial cells and astrocytes, followed by increase in Nrf2 and glutathione levels in endothelial cells. At lipid composition level, HNE caused increase in ω3 polyunsaturated fatty acid (PUFA) level in endothelial cells, followed by decrease in ω3 PUFA level and increase in monounsaturated fatty acid level in astrocytes. Using these models, we showed for the first time that HNE in 'pathological' model can reduce BBB permeability. [ABSTRACT FROM AUTHOR]

The photochemical reactivity and photophysical and electrochemical properties of a series of N-adamantylphthalimides bearing carboxylic functional groups were investigated. Upon irradiation (with or without a triplet sensitizer), the compounds undergo decarboxylation via photoinduced electron transfer (PET) from the carboxylate to the phthalimide. UV-vis and fluorescence pH titrations were used to determine pKa values for the prototropic forms, which were put in connection with the quantum yields of the reaction (ΦR). The compounds bearing electron donors OH and OCH3 at the phthalimide 4 position are fluorescent (ΦF = 0.02–0.49) and PET takes place from both singlet and triplet excited states. The estimated rate constants for PET in the singlet excited states for the methoxy- and amino-substituted phthalimides are (2.0 ± 0.1) × 109 s−1 and (3.4 ± 1.0) × 107 s−1, respectively. Laser flash photolysis (LFP) was conducted to characterize the triplet excited states, which are populated less efficiently for compounds with electron donors. The PET is reversible and the overall ΦR depends on the rates for back electron transfer, protonation of the phthalimide radical anion and decarboxylation. The plausible photochemical and photophysical pathways depend on the phthalimide substituents, which is important for the use of phthalimide derivatives in organic synthesis and photocatalysis. [ABSTRACT FROM AUTHOR]

A porous surface of tantalum and molybdenum plates has been formed by a nanosecond laser-matter interaction in the “semiconfined configuration,” in which the laser plasma is trapped between the target and the transparent cover plate. The evolution of the plasma cloud and the pressure above the surface induce a superheated state in the liquid surface layer. Explosion of the plasma disk and formation of a cylindrical blast wave drive the superheated metastable fluid toward the spinodal, i.e., to the point of absolute thermodynamic instability. Phase explosion of a spinodal fluid occurs through the cascade of bubblings and generates a very porous spongelike surface ∼5–7 μm thick (in some cases even ∼10 μm), which stays frozen permanently because of ultrafast cooling at the end of the laser pulse. The total area of the porous surface is enlarged ∼104 times at the microscale range. At even larger magnification, a different, nanoscale-type porosity has been observed. [ABSTRACT FROM AUTHOR]

One of the pathways for excessive production of free radicals is the decomposition of lipid hydroperoxides catalyzed by iron. A number of hydroperoxides of unsaturated fatty acids (LOOH), some prepared in our laboratory and others extracted from biological materials, were used to determine the rate constants of Fe2+ oxidation by measuring the formation rate of Fe3+ ions in the presence of simple unidentate ligands, chloride, and thiocyanate as the [FeCl]2+ and [FeNCS]2+ complexes, in a deoxygenated dichloromethane:methanol (2:1, v/v) mixture. The rates of Fe2+ oxidation with prepared LOOHs via the [FeNCS]2+ complex were approximately the same‐the average second‐order reaction rate constant was 1390 ± 340 dm3 mol−1 s−1; the rate constants of LOOHs from different biological materials were in the same range. The rates measured as the [FeNCS]2+ complex were somewhat higher than the rates measured as the [FeCl]2+ complex, indicating that ligands could interact in the transition state, thus affecting the disruption of the intermediate complex. Since there were no significant differences in the activation thermodynamic parameters for reactions within the reaction series of studied hydroperoxides, it was assumed that the oxidation proceeded by an inner sphere mechanism, considering that the breakdown of the successor inner sphere complex with the homolytic cleavage of peroxide bonds of hydroperoxides forming reactive alkoxyl radicals was the rate‐limiting step. Based on this research, an indirect spectrophotometric method for quantitative determination of LOOH was reestimated. The microprocedure proposed for the lipid hydroperoxide assay could be applied to follow the early stages of lipid peroxidation processes in real biological samples. [ABSTRACT FROM AUTHOR]

Toxicity of gamma irradiated mycotoxins aflatoxin B1 (AFB1) and ochratoxin A (OTA) was investigated in vitro. AFB1 and OTA stock solutions (50 mM, in methanol) were gamma irradiated (5 and 10 kGy) and non-irradiated and irradiated mycotoxins solutions were tested for cytotoxicity on Pk15, HepG2 and SH-SY5Y cell lines (MTT assay, 1–500 μM concentration range; 24 h exposure). Degradation of mycotoxin molecules was examined by liquid chromatography tandem mass spectrometry (HPLC-MS/MS). AFB1 and OTA radiolytic products were less toxic than the parent mycotoxins to all of the tested cell lines. Gamma irradiation even at 5 kGy had effect on AFB1 and OTA molecules however, this effect was dependent on chemical structure of mycotoxin. Since gamma irradiation at low dose reduced initial level of both mycotoxins, and gamma irradiated mycotoxins had lower toxicity in comparison to non-irradiated mycotoxins, it can be concluded that gamma irradiation could be used as decontamination method. [ABSTRACT FROM AUTHOR]

Self-assembled molecules (SAMs) form layers on copper that have an advantage compared to traditional corrosion inhibitors because of the significant decrease of chemical application. The protective properties of such films can be improved by different procedures of application of the SAM layer. In this work, a SAM layer of elaidic acid, a monounsaturated long-chain fatty acid with trans geometrical configuration, was applied on copper surface. Gamma irradiation was used to improve the protective properties of the SAM layer toward corrosion in 3% NaCl. Influence of gamma irradiation on such layer's properties was studied by different electrochemical techniques (polarization measurements, EIS), contact angle measurements and FTIR analysis. The results have shown that gamma irradiation at doses 0.5-5 kGy improves the protective properties of the SAM. The surface film became thinner due to stronger adsorption and resulted in better ordering of molecules on the surface of the oxide film although the polymerization involving the participation of oxygen molecules has been initiated by irradiation. [ABSTRACT FROM AUTHOR]

Background/Aims: Tff3 protein plays a well recognized role in the protection of gastrointestinal mucosa. The role of Tff3 in the metabolism is a new aspect of its function. Tff3 is one of the most affected liver genes in early diabetes and fatty liver rodent models. The aim of this study was to investigate the effect of Tff3 deficiency on lipid and carbohydrate metabolism and on markers of oxidative stress that accompanies metabolic deregulation. Methods: Specific markers of health status were determined in sera of Tff3 deficient mice, including glucose level, functional glucose and insulin tolerance. Composition of fatty acids (FAs) was determined in liver and blood serum by using gas chromatography. Oxidative stress parameters were determined: lipid peroxidation level via determination of lipid hydroperoxide and thiobarbituric acid reactive substances (TBARS), antioxidative capacity (FRAP) and specific antioxidative enzyme activity. The expression of several genes and proteins related to the metabolism of lipids, carbohydrates and oxidative stress (CAT, GPx1, SOD2, PPARα, PPARg, PPARδ, HNF4α and SIRT1) was determined. Results: Tff3 deficient mice showed better glucose utilization in the glucose and insulin test. Liver lipid metabolism is affected and increased formation of small lipid vesicles is noticed. Formation of lipid droplets is not accompanied by increased liver oxidative stress, although expression/activity of monitored enzymes is deregulated when compared with wild type mice. Tff3 deficient mice exhibit reduced expression of metabolism relevant SIRT1 and PPARg genes. Conclusion: Tff3 deficiency affects the profile and accumulation of FAs in the liver, with no obvious oxidative stress increase, although expression/activity of monitored enzymes is changed as well as the level of SIRT1 and PPARg protein. Considering the strong downregulation of liver Tff3 in diabetic/obese mice, presence in circulation and regulation by food/insulin, Tff3 is an interesting novel candidate in metabolism relevant conditions. [ABSTRACT FROM AUTHOR]

Reactive oxygen species, especially hydrogen peroxide (H2O2), contribute to functional molecular impairment and cellular damage, but also are necessary in normal cellular metabolism, and in low doses play stimulatory role in cell proliferation and stress resistance. In parallel, reactive aldehydes such as 4-hydroxynonenal (HNE), are lipid peroxidation breakdown products which also contribute to regulation of numerous cellular processes. Recently, channeling of H2O2 by some mammalian aquaporin isoforms has been reported and suggested to contribute to aquaporin involvement in cancer malignancies, although the mechanism by which these membrane water channels are implicated in oxidative stress is not clear. In this study, two yeast models with increased levels of membrane polyunsaturated fatty acids (PUFAs) and aquaporin AQY1 overexpression, respectively, were used to evaluate their interplay in cell's oxidative status. In particular, the aim of the study was to investigate if HNE accumulation could affect aquaporin function with an outcome in oxidative stress response. The data showed that induction of aquaporin expression by PUFAs results in increased water permeability in yeast membranes and that AQY1 activity is impaired by HNE. Moreover, AQY1 expression increases cellular sensitivity to oxidative stress by facilitating H2O2 influx. On the other hand, AQY1 expression has no influence on the cellular antioxidant GSH levels and catalase activity. These results strongly suggest that aquaporins are important players in oxidative stress response and could contribute to regulation of cellular processes by regulation of H2O2 influx. © 2017 IUBMB Life, 69(5):355-362, 2017 [ABSTRACT FROM AUTHOR]

Polyunsaturated fatty acid (PUFA) oxidation by thiyl radicals (RS • ) is believed to be responsible for some of the biological radiation damage. At the same time, RS • can cause isomerization of PUFA double bonds with the formation of trans isomers. The aim of this study was to better understand the competition between lipid peroxidation and geometrical isomerization processes in biomimetic model system of linoleic acid in the presence of 2-mercaptoethanol using irradiation as a method for free radicals generation. In air-equilibrated conditions the propagation of lipid peroxidation was dominant up to the dose of 400 Gy, after which at higher doses up to 10 kGy the termination occurred with the predominance of geometrical isomerization. This study revealed that undesirable and permanent lipid modifications are possible at higher irradiation doses which should be considered in the planning of irradiation treatment of foods and feeds with high content of lipids and sulfur compounds. [ABSTRACT FROM AUTHOR]

Detailed investigation on the effect of gamma (γ) irradiation on germination, sporulation, and growth of aflatoxigenic moulds ( Aspergillus parasiticus 2999, Aspergillus flavus 305, and Aspergillus niger 388), as well as on the reduction of aflatoxin B 1 (AFB 1 ) level in artificially and naturally contaminated maize/feed samples was performed. The results of in vitro and in situ experiments with aflatoxigenic moulds demonstrated that 5 kGy-γ irradiation manages to prevent sporulation, germination and growth of the tested moulds both when in form of a pure and when in form of a mixed culture. In the feed samples artificially contaminated with AFB 1 (50 μg kg −1 ) 5 kGy-γ irradiation reduced AFB 1 level by around 60%, while 10 kGy-dose reduce it for around 85%. Similarly, in feed samples spiked with AFB 1 in the concentrations of 100 μg kg −1 5 kGy-dose reduced the AFB 1 level by approximately 70%, while the dose of 10 kGy reduced it by approximately 90%. The experiments on naturally contaminated maize samples (n = 30) confirmed these observations; following a 5 kGy-irradiation, the overall mean AFB 1 reduction equalled to 69.8%, while the irradiation with a 10 kGy-dose achieved the overall mean toxin reduction of 94.5%. The obtained results indicate that γ irradiation can be used to prevent the growth of aflatoxigenic moulds and to reduce the AFB 1 levels in various goods intended for animal and human consumption, thus minimizing the animal and human exposure to this carcinogenic mycotoxin. [ABSTRACT FROM AUTHOR]

This study investigated the efficiency of gamma (γ)-irradiation in the reduction of ochratoxin A (OTA) present in dry-cured meat products prepared from intentionally contaminated raw materials from OTA-treated pigs. OTA concentrations determined in the samples (n = 24) ranged from 25.8 μg kg–1in bacon to 17.8 μg kg–1in smoked ham. After γ-irradiation at doses of 3, 7 and 10 kGy (i.e. the doses used in the food industry), a dose-depended OTA reduction was observed; however, it was not statistically significant. The mean OTA reduction achieved with 3-, 7- and 10-kGy γ-doses was approximated to 8.5%, 13.9% and 22.5%, respectively. The storage of irradiated samples (1 month, 4°C) did not significantly affect OTA levels. Based on the correlation between the OTA reduction level and basic chemical composition of dry-cured meat samples, OTA reduction may be linked to the samples’ fat content. The results indicate that γ-irradiation can reduce OTA levels in dry-cured meat products, but only to a limited extent due to the complexity of the matrix. [ABSTRACT FROM PUBLISHER]

Different types of lipid aggregations, such as micelles and liposomes, can be used as biomimetic models. The uses of γ-irradiation as a valid methodology for simulating the biological generation of thiyl radicals in these models are summarized and, in particular, thiyl radical catalyzed cis trans isomerization of unsaturated lipids is underlined. The efficiency of antioxidants against lipid isomerization assayed by biomimetic models and the importance of trans lipids as novel biomarkers of radical stress are also described. [ABSTRACT FROM AUTHOR]

The effect of molecular environment on the peroxidation of linoleic acid (LA), a polyunsaturated fatty acid (PUFA), initiated by ferrous ions was investigated in acidic and neutral pH conditions. Mixed nonionic surfactants TWEEN®-20/LA micelles were established as a model system to obtain a surfactant-in-lipid aqueous system at high acidity level. The peroxidation of LA was induced by ferrous ions and the kinetics of the produced conjugated dienes was followed by UV measurements and the ferric thiocynate method. Ferrous ions were oxidized only by the preformed LA hydroperoxides, which under established conditions produced lipid alkoxyl and peroxyl radicals as the sole initiators of propagation. The results revealed the LA peroxidation process remained mainly unaffected within the 2.5

Rosuvastatin, a member of the statin family of drugs, is used to regulate high cholesterol levels in the human body. Moreover, rosuvastatin and other statins demonstrate a protective role against free radical-induced oxidative stress. Our research aimed to investigate the end-products of free radical-induced degradation of rosuvastatin. To induce the radical degradation, an aqueous solution of rosuvastatin was irradiated using different doses of gamma radiation (50–1000 Gy) under oxidative conditions. Rosuvastatin and related degradation products were separated on nanoC18 column under gradient elution, and identification was carried out on hyphenated nanoUPLC and nanoESI-QTOF mass spectrometer system. Elemental composition analysis using highly accurate mass measurements together with isotope fitting algorithm identified nine major degradation products. This is the first study of gamma radiation-induced degradation of rosuvastatin, where chemical structures, MS/MS fragmentation pathways and formation mechanisms of the resulting degradation products are detailly described. The presented results contribute to the understanding of the degradation pathway of rosuvastatin and possibly other statins under gamma radiation conditions. [ABSTRACT FROM AUTHOR]

A series of tripeptides TrpTrpPhe (1), TrpTrpTyr (2), and TrpTrpTyr[CH2N(CH3)2] (3) were synthesized, and their photophysical properties and non-covalent binding to polynucleotides were investigated. Fluorescent Trp residues (quantum yield in aqueous solvent ΦF = 0.03–0.06), allowed for the fluorometric study of non-covalent binding to DNA and RNA. Moreover, high and similar affinities of 2×HCl and 3×HCl to all studied double stranded (ds)-polynucleotides were found (logKa = 6.0–6.8). However, the fluorescence spectral responses were strongly dependent on base pair composition: the GC-containing polynucleotides efficiently quenched Trp emission, at variance to AT- or AU-polynucleotides, which induced bisignate response. Namely, addition of AT(U) polynucleotides at excess over studied peptide induced the quenching (attributed to aggregation in the grooves of polynucleotides), whereas at excess of DNA/RNA over peptide the fluorescence increase of Trp was observed. The thermal denaturation and circular dichroism (CD) experiments supported peptides binding within the grooves of polynucleotides. The photogenerated quinone methide (QM) reacts with nucleophiles giving adducts, as demonstrated by the photomethanolysis (quantum yield ΦR = 0.11–0.13). Furthermore, we have demonstrated photoalkylation of AT oligonucleotides by QM, at variance to previous reports describing the highest reactivity of QMs with the GC reach regions of polynucleotides. Our investigations show a proof of principle that QM precursor can be imbedded into a peptide and used as a photochemical switch to enable alkylation of polynucleotides, enabling further applications in chemistry and biology. [ABSTRACT FROM AUTHOR]

Quinone methide precursors 1a–e, with different alkyl linkers between the naphthol and the naphthalimide chromophore, were synthesized. Their photophysical properties and photochemical reactivity were investigated and connected with biological activity. Upon excitation of the naphthol, Förster resonance energy transfer (FRET) to the naphthalimide takes place and the quantum yields of fluorescence are low (ΦF ≈ 10−2). Due to FRET, photodehydration of naphthols to QMs takes place inefficiently (ΦR ≈ 10−5). However, the formation of QMs can also be initiated upon excitation of naphthalimide, the lower energy chromophore, in a process that involves photoinduced electron transfer (PET) from the naphthol to the naphthalimide. Fluorescence titrations revealed that 1a and 1e form complexes with ct-DNA with moderate association constants Ka ≈ 105–106 M−1, as well as with bovine serum albumin (BSA) Ka ≈ 105 M−1 (1:1 complex). The irradiation of the complex 1e@BSA resulted in the alkylation of the protein, probably via QM. The antiproliferative activity of 1a–e against two human cancer cell lines (H460 and MCF 7) was investigated with the cells kept in the dark or irradiated at 350 nm, whereupon cytotoxicity increased, particularly for 1e (>100 times). Although the enhancement of this activity upon UV irradiation has no imminent therapeutic application, the results presented have importance in the rational design of new generations of anticancer phototherapeutics that absorb visible light. [ABSTRACT FROM AUTHOR]

The biomimetic model of micelles of linoleic acid containing 2-mercaptoethanol and the antioxidant was examined under gamma irradiation up to 400 Gy in aerobic or deoxygenated conditions where thiyl radicals are the main reactive species. Lipid peroxidation was retarded by ascorbic acid and α-tocopherol, whereas this process was strongly inhibited by resveratrol as effectively as the ascorbic acid/α-tocopherol mixture. Furthermore, antioxidants have a much stronger inhibitory effect on the peroxidation in the presence of 2-mercaptoethanol, and at the same time show protective properties of the double bond, decreasing thecis–transisomerization. Under anaerobic conditions,cis–transisomerization occurred and antioxidants efficiency increased along the series: resveratrol < α-tocopherol < ascorbic acid. This result is explained taking into account the double bond localization in the hydrophobic core of the micelle and the need of co-localization of the antioxidant in order to get an anti-isomerizing activity and protection of the natural lipid geometry. [ABSTRACT FROM AUTHOR]

Photophysical and photochemical properties of trans -resveratrol ( trans -3,5,4′-trihydroxystilbene, ArOH) were investigated in water and acetonitrile (ACN). S 1 –S n transient absorption spectrum with a peak around 530 nm was observed by a femtosecond transient absorption technique for ArOH in ACN. The excited singlet state lifetime was determined to be 28.6 ps. The radical cation of resveratrol (ArOH + ) was generated by resonant two photon ionization in ACN using nanosecond Nd:YAG laser pulses at 355 nm with an energy of 50 mJ. The molar absorption coefficient of ArOH + was determined to be, ϵ (ArOH + , 500 nm, ACN) = 33400 M −1 cm −1 . The transient ArOH + deprotonated yielding the long lived phenoxyl radical (ArO ) with a peak at 390 nm. This deprotonation was found to occur rapidly in the presence of water. The rate constant for the deprotonation of ArOH + in ACN, by the addition of small amounts of water (0.10–0.75%), was estimated to be around 1 × 10 8 M −1 s −1 . In comparison with molar absorption coefficients of the other phenoxyl radicals, an unexpectedly large value of the molar absorption coefficient of phenoxyl radicals of resveratrol was determined, ϵ (ArO , 390 nm, ACN) = 15200 M −1 cm −1 . The spectral properties of ArO were confirmed with pulse radiolysis, and the value of the molar absorption coefficient obtained by laser flash photolysis was found to be in a good agreement with the value obtained by pulse radiolysis, ϵ (ArO , 410 nm, H 2 O) = 14600 M −1 s −1 . These spectral and kinetic data of the transients could contribute to the understanding of mechanisms of resveratrol reactions with biologically relevant radical species. [ABSTRACT FROM AUTHOR]

Abstract: The rate constant for the reaction of t-butoxyl radicals with resveratrol was studied under pseudo-first order conditions. The rate constant was determined by measuring the phenoxyl radical formation rate at 390nm as function of resveratrol concentration in acetonitrile. The rate constant was determined to be 6.5×108 M−1s−1. This high value indicates the high reactivity consistent with the strong antioxidant activity of resveratrol. [Copyright &y& Elsevier]

• Sodium copper chlorophyllin (CHL) shows many beneficial properties. • CHL pre-treated whole blood samples were irradiated with 5 Gy. • CHL pre-treated irradiated samples showed dose-dependent decrease in DNA damage. • Malondialdehyde levels were lower upon pre-treatment and irradiation. • CHL alone did not show any negative effects toward blood cells. Sodium copper chlorophyllin (CHL) is a food colorant that exhibits many beneficial properties, including potential for use in radiotherapy. Nevertheless, genotoxicity studies investigating radioprotective properties against γ-radiation on human cells are rather scarce. The aim of this study was to assess the cytotoxicity, genotoxicity and induction of malondialdehyde formation on CHL pre-treated whole blood cells after an absorbed dose of 5 Gy γ-radiation. Irradiated whole blood cells pre-treated with 100, 500, and 1000 μg/mL CHL showed less DNA-strand breaks (10.92 ± 0.74%, 10.69 ± 0.68%, and 8.81 ± 0.69%, respectively) than untreated irradiated cells (12.58 ± 0.88%). At the same time, the level of malondialdehyde was lower in CHL pre-treated samples with 100, 500, and 1000 μg/mL CHL (14.11 ± 0.43, 16.35 ± 2.82, and 13.08 ± 1.03 μmol/L, respectively) compared to untreated irradiated samples (24.11 ± 0.25 μmol/L). Regarding cytotoxicity, no changes were observed in the samples tested. Another important finding is that CHL had no cyto/genotoxic properties toward human blood cells. Taken together, since CHL had no cyto/genotoxic effects and showed good radioprotective properties in human blood cells, further studies should be conducted in order to find its possible application in radiotherapy. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 4-Amino -N- adamantylphthalimide (1) is a fluorescent dye (Φ F = 0.15–0.80) that exhibits fluorosolvatochromic properties. • The dye stains artificial membranes in liposomes. • The dye stains intracellular lipid droplets and mitochondrial membranes. • The dye allows the simultaneous visualization of mitochondria in green and intracellular lipid droplets in blue emission channel. Abstract 4-Amino- N -adamantylphthalimide (1) is a dye with moderate absorptivity (in CH 3 CN ε 363 = 4200 M−1 cm−1) and high quantum yield of fluorescence (Φ F = 0.15–0.80) that exhibits fluorosolvatochromic properties. The dye can be excited at 405 nm and the position of fluorescence maximum and the Stokes shift are well correlated with the E T (30) parameter. The excitation in the near-visible part of the spectrum and low cytotoxicity allow use of the dye in live cell microscopy. Due to its amphiphilic character, the dye stains artificial membranes in liposomes. Using confocal microscopy on two human cancer cell lines, we have shown that 1 stains primarily intracellular lipid droplets. Colocalization experiments with different organelle markers indicated that 1 additionally stains mitochondrial membranes. The fluorosolvatochromism of 1 allows the simultaneous visualization of mitochondria and intracellular lipid droplets in two separate emission channels, which has a potential use in cells and tissues exhibiting intense oxidative metabolism of lipids. [ABSTRACT FROM AUTHOR]

Abstract Merlot and Traminer (Vitis vinifera L.) grapes were subjected to gamma irradiation at the panoramic 60Co source at four doses (670, 1300, 2000, 2700 Gy) and wines were produced from the irradiated grapes. HPLC analysis of musts have shown a negative impact of irradiation on the amino acids content. However, Merlot wines produced from irradiated grapes demonstrated better extraction of the coloring matter. The concentrations of anthocyanins increased with the increasing absorbed irradiation dose, while flavonols and flavanols were not affected by irradiation. Irradiation with doses up to 2000 Gy increased concentrations of fruity-floral aroma compounds, especially monoterpens and C13 norisoprenoids in wines, while a maximal dose of 2700 Gy expressed more the toasty and caramel notes due to higher concentrations of furfural and furfuryl alcohols. Results obtained suggest that ionizing irradiation might be a suitable method for grape treatment since better chemical properties in wine could be achieved. Highlights • Gamma irradiation had negative impact on amino acids content in grapes. • Better extraction of coloring matter was obtained from irradiated grapes. • Flavonols and flavan-3-ols were not affected by irradiation. • Aroma profile of wines from irradiated grapes was enhanced. • The irradiation dose up to 2000 Gy increased fruity-floral aroma in wine. [ABSTRACT FROM AUTHOR]

Abstract The finding of heavily damaged historic silks prompted this study to answer the title question on possible unwanted effects of fungal decontamination by gamma-irradiation. Although silk fiber constitutes of relatively stable protein fibroin heritage silk textiles need protection from biodegradation. Low-dose (0.5−2 kGy) gamma-irradiation is already recognized as a fast, temperature independent method of insect eradication. For fungal decontamination, somewhat higher absorbed doses are needed. Since possible unwanted side effects to already damaged material must be excluded, model samples were prepared by aging contemporary silk. Some of the unaged and aged samples were irradiated to 6 kGy and other to a much higher dose of 120 kGy to identify radiation-specific damage, if any. In order to achieve detectable damage selected irradiated and non-irradiated model samples were subjected to further artificial aging. None of the assessment methods used (ATR-FTIR, SEM thermal analysis) revealed any radiation-specific change. Provided that the fibroin conformations are identified and analyzed separately, FTIR is the method of choice for monitoring the effects caused by any treatment of silk. An increase in the amide I/II absorption intensity ratio is a sensitive though ambiguous indicator of silk degradation. Transformation of more stable beta-sheet to alpha/random coil fibroin conformation is a definite proof of degradation. It occurred exclusively on artificial aging of model silks and was accompanied by pronounced morphology changes confirming the role of conformation on silk stability. In non-treated historic silks the fraction of more stable beta-sheet conformation was unexpectedly high as was the iron content that likely protected silk structure. Since irradiation produced insignificant and likely partially reversible effects radiation treatment of silk textile is deemed safe beyond the absorbed dose proposed as an upper limit for fungal decontamination, 8 ± 2 kGy. Highlights • γ-irradiation of fungi on silk is safe to even above the D = 8 ± 2 kGy limit. • unlike artificial aging γ-radiation causes almost no change even to historic silk. • fibroin conformation stability differs so their response must be analyzed separately. • β-sheet fibroin conformation variations were the most revealing FTIR indicators. • on heavy degradation α/random coil fibroin conformation becomes predominant. [ABSTRACT FROM AUTHOR]

Thiols are well known for their role in cellular redox homeostasis, while aromatic amines and phenols are the best known classes of chain-breaking antioxidants. On the other hand, thiyl radicals are known to catalyse the double bond isomerization in PUFA. We investigated the role and interplay of 2-mercaptoethanol and diphenylamine in the parallel processes of peroxidation and cis–trans isomerization of linoleic acid (LA) during gamma radiolysis, both in solution and micelles. Both compounds, used alone were able to protect LA from oxidation; however pro-oxidant activity and enhanced isomerization was observed when they were used together, depending on the experimental settings. Instead, α-tocopherol protected LA from both oxidation and isomerization in the presence of thiols under any tested settings. The mechanistic scenario is discussed highlighting the role of diphenylaminyl radicals in promoting thiyl-radical-induced cis–trans isomerization in the presence of oxygen. [ABSTRACT FROM AUTHOR]

Abstract: Somatic embryogenesis in pumpkin can be induced on auxin-containing medium and also on hormone-free medium containing 1mM ammonium (NH4 +) as the sole source of nitrogen. Growth of NH4 +-induced embryogenic tissue was slow and caused considerable acidification of the culture medium. Small spherical cells with dense cytoplasma formed proembryogenic cell clusters that could not develop into late stage embryos. Buffering of NH4 + medium with 25mM 2-(N-morpholino)-ethane-sulfonic acid enhanced tissue proliferation, but no further differentiation was observed. Later stage embryos developed only after re-supply of nitrogen in form of nitrate or l-glutamine. Effects of nitrogen status and pH of culture media on ammonium assimilation were analyzed by following the activity of glutamine synthetase (GS) in relation to phenylalanine ammonia-lyase (PAL). Increased activity of GS and PAL in NH4 + induced tissue coincided with significantly higher activity of stress-related enzymes superoxide dismutase (SOD) and soluble peroxidase (POD), indicating oxidative stress response of embryogenic tissue to NH4 + as the sole source of nitrogen. In addition, considerable increase was observed in callose accumulation and esterase activity, the early markers of somatic embryogenesis. Activity of stress-related enzymes decreased after the re-supply of nitrate (20mM) or Gln (10mM) in combination with NH4 + (1mM), which subsequently triggered globular embryo development. Together, these results suggest that stress responses, as affected by nitrogen supply, contribute to the regulation of embryogenic competence in pumpkin. [Copyright &y& Elsevier]

[Display omitted] • Diarylethene triazoles undergo E-Z photoisomerization via distinctly different pathways. • Elucidation of substituent dependent reaction mechanism. • Adiabatic singlet excited state reaction or triplet excited state driven by the nitro group. • Experiments are in an excellent agreement with quantum-chemical calculations. Photochemical reactivity in the Z-E isomerization for two heterostilbene derivatives containing 1,2,3-triazole unit were investigated theoretically and experimentally by irradiation experiments, fluorescence and laser flash photolysis (LFP). The molecules were designed to probe the effect of the para -nitro group in 1 on the photochemical E-Z pathways, as well as to investigate the steric effect of the ortho -methyl group in 2. The quantum yield for the Z → E isomerization for both cis -isomers is 0.42, and for the E → Z is somewhat lower 0.16 and 0.12, respectively. Furthermore, fluorescence measurements for the ortho -methyl derivative indicated that the Z → E isomerization takes place in an adiabatic reaction on the potential energy surface of the S 1 state. On the contrary, the para -nitro derivative undergoes the Z → E isomerization via a triplet excited state, which was detected by LFP. For both cis - and trans -isomers of the nitro derivative a transient was detected absorbing with a maximum at 520 nm, which was assigned to the triplet excited state of the trans -isomer. All experimental observations were corroborated by computations. The stationary points were computed at the PBE50/6-31++G** level of theory, whereas potential energy surfaces were obtained by linear interpolation and computations at the SF-TDDFT/PBE50/6-31++G** level of theory. The mechanistic investigation presented gives insight in the fundamental and simple Z → E isomerization and provides new findings which are important in the rational design of different photoreactive diarylethene derivatives used in different fields of science. [ABSTRACT FROM AUTHOR]

The paper presents the dose mapping of the panoramic 60Co gamma irradiation facility at the Ruđer Bošković Institute in Croatia. Both experimental (using ionisation chamber) and simulation (using the Geant4 Monte Carlo code) studies have been performed and compared. Measured and simulation dose rates are found to be in very good agreement and can be used for the absorbed dose determination in the irradiation chamber in everyday work. In order to get a complete description of the dose distribution in the facility, the transit dose, which has to be taken into consideration at low doses, was also experimentally determined. • Dose mapping of the panoramic 60Co gamma irradiation facility was performed. • Geant4 Monte Carlo simulation was validated. • Transit doses were experimentally determined. • Results enable realistic calculation of the dose for any date and irradiation time. [ABSTRACT FROM AUTHOR]