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The integration of photovoltaic technologies within agricultural settings, also known as agrivoltaics, is attracting increasing attention as a sustainable approach to ensure both clean energy and food supply. The success of this strategy relies on the development of innovative materials that can selectively convert specific wavelengths into energy while being transparent to photosynthetically relevant light. To this aim, here we report our endeavors in the synthesis of a new class of D‐π‐A‐π‐D quinoxaline fluorophores and their use in the preparation of wavelength‐selective luminescent solar concentrators. The dyes were expeditiously prepared following a direct arylation protocol and extensively characterized by spectroscopic analyses and computational studies. They present high light harvesting ability in the green region of the visible spectrum and good emission properties, which were fully retained in the solid state when embedded into a poly methyl methacrylate (PMMA) matrix. These materials were employed to construct LSC devices of promising efficiency, fostering further developments for the use of wavelength‐selective LSC in agrivoltaic systems. [ABSTRACT FROM AUTHOR]

Here, we report a general approach to the synthesis of the difluoroalkyl bicycloalkanes (CF2‐BCAs), as structural surrogates of aryl ketones and ethers. The chemistry is driven by a dihydrobenzoacridine photocatalyst, that engages in a catalytic electron‐donor acceptor (EDA) complex, or directly reduces the fluorinated substrate. These two convergent manifolds lead to the generation of the R‐CF2 radical, that reacts with the [1.1.1]‐ or [3.1.1.]‐propellane. The method is extremely general, and extendable to complex bioactive molecules (30 examples, up to 87 % yield). The structural features of the CF2‐BCP hybrid bioisostere were investigated by single crystal X‐ray. Finally, we synthesised a CF2‐BCP analogue of a Leukotriene A4 hydrolase inhibitor, replacing the original aryl ether motif. In silico docking studies indicated that this new analogue maintains the same arrangement within the enzyme pocket, profiling the use of the CF2‐BCA hybrid bioisostere in medicinal chemistry settings. [ABSTRACT FROM AUTHOR]

Piperidine‐based photoswitchable derivatives have been developed as putative pharmacological chaperones for glucocerebrosidase (GCase), the defective enzyme in Gaucher disease (GD). The structure‐activity study revealed that both the iminosugar and the light‐sensitive azobenzene are essential features to exert inhibitory activity towards human GCase and a system with the correct inhibition trend (IC50 of the light‐activated form lower than IC50 of the dark form) was identified. Kinetic analyses showed that all compounds are non‐competitive inhibitors (mixed or pure) of GCase and the enzyme allosteric site involved in the interaction was identified by means of MD simulations. A moderate activity enhancement of mutant GCase assessed in GD patients' fibroblasts (ex vivo experiments) carrying the most common mutation was recorded. This promising observation paves the way for further studies to improve the benefit of the light‐to‐dark thermal conversion for chaperoning activity. [ABSTRACT FROM AUTHOR]

The synthesis of four membered heterocycles usually requires multi‐step procedures and prefunctionalized reactants. A straightforward alternative is the photochemical [2+2]‐heterocycloaddition between an alkene and a carbonyl derivative, conventionally based on the photoexcitation of this latter. However, this approach is limited by the absorption profile of the carbonyl, requiring in most of the cases the use of high‐energy UV‐light, that often results in undesired side reactions and/or the degradation of the reaction components. The development of new and milder visible light‐driven [2+2]‐heterocycloadditions is, therefore, highly desirable. In this Review, we highlight the most relevant achievements in the development of [2+2]‐heterocycloadditions promoted by visible light, with a particular emphasis on the involved reaction mechanisms. The open challenges will also be discussed, suggesting new possible evolutions, and stimulating new methodological developments in the field. [ABSTRACT FROM AUTHOR]

Glycosylamine derivatives are biologically relevant compounds widespread in Nature, but the synthesis of this motif has been little addressed and its access with control of configuration at the anomeric carbon is challenging. Glycals substituted at C‐3 with a carbamate group undergo, upon dehydration, a prompt allyl cyanate to isocyanate rearrangement to the isomeric N‐glycosyl isocyanates, which can be conveniently trapped by one‐pot nucleophilic addition with alcohols or amines to afford N‐glycosyl carbamates and ureas, respectively. The rearrangement follows a [3,3]‐sigmatropic pericyclic mechanism as illustrated by the stereospecificity of the reaction, with nitrogen being delivered at the anomeric position to the same face from which the oxygen at C‐3 has departed. Thus, glucal and galactal give β‐N‐glycosides exclusively while allal furnishes α‐N‐glycosides. cis‐Dihydroxylation of the synthesized unsaturated N‐glycosides afford different 1‐aminosugars with good selectivity.Glycals substituted at C‐3 with a carbamate group undergo, upon dehydration, a prompt allyl cyanate to isocyanate rearrangement to the isomeric N‐glycosyl isocyanates, which give N‐glycosyl carbamates and ureas by one‐pot addition of alcohols or amines. The rearrangement occurs with complete stereoselectivity via a [3,3]‐sigmatropic mechanism, affording α‐ or β‐linked amines depending on the configuration at C‐3 of the carbohydrate. [ABSTRACT FROM AUTHOR]

Multivalent ligands of the C‐type lectin receptor DC‐SIGN have emerged as effective antiadhesive agents against various pathogens. Some years ago, we described a hexavalent DC‐SIGN ligand, Polyman‐26, designed to bridge two of the four binding sites displayed by the receptor. In this work, we present our efforts to accomplish simultaneous coordination of all four carbohydrate binding sites of DC‐SIGN through the synthesis of cross‐shaped glycodendrimers. The tailored rigid scaffold allowed multivalent presentation of glycomimetics in a spatially defined fashion, while providing good water solubility to the constructs. Evaluation of the biological activity by SPR assays revealed strong binding avidity towards DC‐SIGN and increased selectivity over langerin. Inhibition of DC‐SIGN binding to SARS‐CoV‐2 spike protein and of DC‐SIGN mediated Ebola virus trans‐infection testifies for the glycodendrimers potential application in infection diseases. The tetravalent platform described here is easily accessible and can be used in modular fashion with different ligands, thus lending itself to multiple applications. [ABSTRACT FROM AUTHOR]

The article titled "Front Cover: Green Light-Responsive D-A-D Quinoxaline Emitters for Luminescent Solar Concentrators: Potential Integration in Agrivoltaic Systems" discusses the use of polymeric films doped with quinoxaline-based emitters for luminescent solar concentrators. These materials selectively absorb green light, which is non-productive for plant photosynthesis, making them suitable for integrating photovoltaic technologies in agricultural settings. The authors suggest that this approach can provide both clean energy and food simultaneously. The article is authored by Giulio Goti, Gianna Reginato, Carmen Coppola, Alessio Dessì, Daniele Franchi, Alessandro Mordini, Alberto Picchi, Andrea Pucci, Adalgisa Sinicropi, Lorenzo Zani, and Massimo Calamante. [Extracted from the article]

Organic Near‐Infrared luminophores have found broad application as functional materials, but the development of efficient NIR emitters is still a challenging goal. Here we report on a new class of thieno[3,4‐b]pyrazine‐based NIR emitting materials with Aggregation Induced Emission (AIE) properties. The dyes feature a donor–acceptor–donor (D−A−D) structure, with a thienopyrazine acceptor core connected to two triarylamine donor groups bearing a tetraphenylethylene (TPE) moiety. Fast and efficient synthesis allowed the modular preparation of three dyes of tunable absorption and emission profiles. These constructs were extensively characterized by spectroscopic studies in different solvents, which revealed intense light‐harvesting ability and emissions in the deep‐red and NIR region with large Stokes shift values. Remarkably, the dyes exhibited AIE properties, retaining emissive ability in the aggregate state, thus emerging as attractive materials for their potential application in the development of luminescent devices.Novel NIR‐emitting organic dyes with aggregation‐induced emission (AIE) properties are described. The thienopyrazine‐based donor‐acceptor‐donor structure allows for easy tuning of the photophysical properties. The intense light absorption ability and the emission in the red/NIR region, both in solution and in the aggregate phase, make them attractive for potential use as functional organic materials in the development of luminescent devices. [ABSTRACT FROM AUTHOR]

Carbonic Anhydrases (CAs; EC 4.2.1.1) are zinc metalloenzymes which play a pivotal role both in physiological and pathological processes in humans (h). Therefore, modulation of the activity of hCAs represents an appealing target for drug development, which is highly challenging due to the large number of isozymes expressed and the requirement in discovery of selective inhibitors. By following the "sugar approach" and in light of our recent disclosure of two selective hCAs inhibitors based on nitrogen containing glycomimetic-sulfonamide conjugates, twelve new azasugar􀀀 benzenesulfonamides have been synthesized. These compounds were prepared by connecting several benzenesulfonamides to a triazole armed azasugar, varying in the chain length and type of linking moiety (ureido, amido or thioureido) to probe their influence on the inhibition profile. The in vitro biological assays highlighted that such structural changes have remarkable effects on the hCAs inhibition profile. Several new compounds behave as selective inhibitors, and four of them are particularly effective on the therapeutically relevant hCAs II and VII isoforms. [ABSTRACT FROM AUTHOR]

Due to their interactions with C‐type lectin receptors (CLRs), glycans from the helminth Schistosoma mansoni represent promising leads for treatment of autoimmune diseases, allergies or cancer. We chemo‐enzymatically synthesized nine O‐glycans based on the two predominant O‐glycan cores observed in the infectious stages of schistosomiasis, the mucin core 2 and the S. mansoni core. The O‐glycans were fucosylated next to a selection of N‐glycans directly on a microarray slide using a recombinant fucosyltransferase and GDP‐fucose or GDP‐6‐azidofucose as donor. Binding assays with fluorescently labelled human CLRs DC‐SIGN, DC‐SIGNR and MGL revealed the novel O‐glycan O8 as the best ligand for MGL from our panel. Significant binding to DC‐SIGN was also found for azido‐fucosylated glycans. Contrasting binding specificities were observed between the monovalent carbohydrate recognition domain (CRD) and the tetravalent extracellular domain (ECD) of DC‐SIGNR. [ABSTRACT FROM AUTHOR]

Gaucher disease is caused by mutations in human acid β‐glucosidase or glucocerebrosidase (GCase), the enzyme responsible for hydrolysis of glucosyl ceramide in the lysosomes. Imino‐ and azasugars such as 1‐deoxynojirimycin and isofagomine are strong inhibitors of the enzyme and are of interest in pharmacological chaperone therapy of the disease. Despite several crystal structures of the enzyme with the imino‐ and azasugars bound in the active site having been resolved, the actual acid–base chemistry of the binding is not known. In this study we show, using photoinduced electron transfer (PET), that 1‐deoxynojirimycin and isofagomine derivatives are protonated by human acid β‐glucosidase when bound, even if they are completely unprotonated outside the enzyme. While isofagomine derivative protonation to some degree was foreshadowed by earlier crystal structures, 1‐deoxynojirimycin derivatives were not believed to act as basic amines in the enzyme. [ABSTRACT FROM AUTHOR]

Reported herein is a visible‐light‐mediated radical approach to the α‐alkylation of ketones. This method exploits the ability of a nucleophilic organocatalyst to generate radicals upon SN2‐based activation of alkyl halides and blue light irradiation. The resulting open‐shell intermediates are then intercepted by weakly nucleophilic silyl enol ethers, which would be unable to directly attack the alkyl halides through a traditional two‐electron path. The mild reaction conditions allowed functionalization of the α position of ketones with functional groups that are not compatible with classical anionic strategies. In addition, the redox‐neutral nature of this process makes it compatible with a cinchona‐based primary amine catalyst, which was used to develop a rare example of enantioselective organocatalytic radical α‐alkylation of ketones. [ABSTRACT FROM AUTHOR]

Indium(0)‐mediated reductions have been reported for the transformation of several functional groups (imines, oximes, nitro groups, isoxazolidines, and conjugated alkenes, among others), prompted by the opportunity of performing the reactions in aqueous media and green conditions. We describe here the comparison of several reactions using indium or the less expensive zinc, carried out in order to evaluate the effective advantages brought about indium metal. We found some reactions for which use of In is mandatory and others where Zn worked equally well or even better. The reduction of hydroxylamines to the corresponding amines was the only reduction for which use of In provided much better results than Zn and was also possible to apply an efficient catalytic version with use of 2–5 mol‐% In in the presence of stoichiometric Zn. Applicability of this catalytic reduction to "one‐pot" model processes is also demonstrated. [ABSTRACT FROM AUTHOR]

Multivalent iminosugars have gained the attention of the research community in the last ten years. We report herein the proof of principle for an original synthetic strategy to build multivalent iminosugars based on the natural DAB‐1 moiety as the bioactive epitope. The synthesis relies on the iteration of three selective and high‐yielding steps (1,3‐dipolar cycloaddition to nitrone 1, N‐O bond cleavage of the adduct and selective N‐ and/or O‐allylation), and allows the preparation of different topologies of the final DAB‐1 clusters. [ABSTRACT FROM AUTHOR]

We report a visible‐light‐mediated organocatalytic strategy for the enantioselective acyl radical conjugate addition to enals, leading to valuable 1,4‐dicarbonyl compounds. The process capitalizes upon the excited‐state reactivity of 4‐acyl‐1,4‐dihydropyridines that, upon visible‐light absorption, can trigger the generation of acyl radicals. By means of a chiral amine catalyst, iminium ion activation of enals ensures a stereoselective radical trap. We also demonstrate how the combination of this acylation process with a second catalyst‐controlled bond‐forming event allows to selectively access the full matrix of all possible stereoisomers of the resulting 2,3‐substituted 1,4‐dicarbonyl products. [ABSTRACT FROM AUTHOR]

A new green method for the preparation of nitrones through the aerobic oxidation of the corresponding N,N-disubstituted hydroxylamines has been developed upon exploring the catalytic activity of a diruthenium catalyst, that is, [Ru2(OAc)4Cl]), in aqueous or alcoholic solution under mild reaction conditions (0.1 to 1 mol % catalyst, air, 50 °C) and reasonable reaction times. Notably, the catalytic activity of the dimetallic centre is retained after its binding to the small protein lysozyme. Interestingly, this new artificial metalloenzyme conferred complete chemoselectivity to the oxidation of cyclic hydroxylamines, in contrast to the diruthenium catalyst. [ABSTRACT FROM AUTHOR]

The scientific community and regulatory bodies worldwide, currently promote the development of non-experimental tests that produce reliable data for pesticide risk assessment. The use of standard quantum chemistry methods could allow the development of tools to perform a first screening of compounds to be considered for the experimental studies, improving the risk assessment. This fact results in a better distribution of resources and in better planning, allowing a more exhaustive study of the pesticides and their metabolic products. The current paper explores the potential of quantum chemistry in modelling toxicity and environmental behaviour of pesticides and their by-products by using electronic descriptors obtained computationally. Quantum chemistry has potential to estimate the physico-chemical properties of pesticides, including certain chemical reaction mechanisms and their degradation pathways, allowing modelling of the environmental behaviour of both pesticides and their by-products. In this sense, theoretical methods can contribute to performing a more focused risk assessment of pesticides used in the market, and may lead to higher quality and safer agricultural products. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Novel pyrrolidine-based multivalent iminosugars, synthesized by a CuAAC approach, have shown remarkable multivalent effects towards jack bean α-mannosidase and a Golgi α-mannosidase from Drosophila melanogaster, as well as a good selectivity with respect to a lysosomal α-mannosidase, which is important for anticancer applications. STD NMR and molecular modeling studies supported a multivalent mechanism with specific interactions of the bioactive iminosugars with Jack bean α-mannosidase. TEM studies suggested a binding mode that involves the formation of aggregates, which result from the intermolecular cross-linked network of interactions between the multivalent inhibitors and two or more dimers of JBMan heterodimeric subunits. [ABSTRACT FROM AUTHOR]

Corrigendum: Mechanisms and Synthetic Strategies in Visible Light-Driven [2+2]-Heterocycloadditions In order to better represent the work of the Schindler and Sivaguru groups a sentence on page 13 of this Review article should be modified as shown below. "Their strategy relied on the selective activation of the alkene functionality within the oxime substrate B 80 b , while avoiding the excitation of the imine moiety." should be corrected to "As previously demonstrated by Sivaguru and co-workers SP 57i sp for UV-light PB reactions, it was possible to rely on the selective activation of the alkene functionality within the oxime substrate B 80 b , while avoiding the excitation of the imine moiety". [Extracted from the article]

In order to better represent the work of the Schindler and Sivaguru groups a sentence on page 13 of this Review article should be modified as shown below. "Their strategy relied on the selective activation of the alkene functionality within the oxime substrate B 80 b , while avoiding the excitation of the imine moiety." should be corrected to "As previously demonstrated by Sivaguru and co-workers SP 57i sp for UV-light PB reactions, it was possible to rely on the selective activation of the alkene functionality within the oxime substrate B 80 b , while avoiding the excitation of the imine moiety". [Extracted from the article]

Allegorically, the Old Bridge reflecting on the water surface represents the two faces of the sugar derivative on which the rearrangement may take place: from top (the Old Bridge) or bottom (the mirrored Old Bridge). B The Front Cover b exhibits a photo of the famous Ponte Vecchio (Old Bridge) on the Arno River, as a tribute to the city of Florence and its University, where all the research has been carried out. Front Cover: Stereospecific Access to - and -N-Glycosylamine Derivatives by a Metal Free O-to-N [3,3]-Sigmatropic Rearrangement (Eur. J. Org. [Extracted from the article]

Hsp90 is a molecular chaperone that plays a pivotal role in the cell life cycle. ATP-regulated internal dynamics are critical to Hsp90 function and we recently demonstrated that these dynamics can be modulated in an allosteric fashion; the protein C-terminal domain (CTD) can be effectively targeted with a family of 2-phenyl-benzofuran derivatives. Here we describe the expansion of the initial library, reporting 28 new derivatives that explore the chemical space at opposite ends of the benzofuran scaffold. Interactions of the compounds with a full-length protein homolog were explored by Saturation Transfer Difference (STD) NMR spectroscopy. In this context we also report the interaction epitope of Novobiocin, a known CTD inhibitor. [ABSTRACT FROM AUTHOR]

Antagonists of mannose binding lectin (MBL) have shown a protective role against brain reperfusion damage after acute ischemic stroke. Here we describe the design and streamlined synthesis of glycomimetic MBL antagonists based on a new tetravalent dendron scaffold. The dendron was developed by optimisation of a known polyester structure previously demonstrated to be very efficient for ligand presentation to MBL. Replacement of a labile succinyl ester bond with a more robust amide functionality, use of a longer and more hydrophilic linker, fast modular synthesis and orthogonal functionalisation at the focal point are the main features of the new scaffold. The glycoconjugate constructs become stable to silica gel chromatography and to water solutions at physiological pH, while preserving water solubility and activity in an SPR assay against the murine MBL-C isoform. Higher-order constructs were easily assembled, as demonstrated by the synthesis of a 16-valent dendrimer, which leads to two orders of magnitude increase in activity over the tetravalent version against MBL-C. [ABSTRACT FROM AUTHOR]

The 1,3 dipolar cycloaddition reactions of three pentose-derived pyrroline N-oxides with mono- and disubstituted alkenes are reported. A strong dependence of the diastereoselectivity of the cycloadditions on the relative configuration of the nitrone stereocentres was observed. Further transformation of the reaction products allowed the synthesis of four new tetrahydroxylated indolizidines. Their activity as glycosidase inhibitors was evaluated against a panel of commercially available glycosidases. The specificity of inhibitory activity against amyloglucosidase and α-mannosidases depends on the configuration at C-2 of the indolizidine moiety. [ABSTRACT FROM AUTHOR]

Keywords: Carbohydrates; DC-SIGN; Dendrimers; Glycomimetics; Langerin EN Carbohydrates DC-SIGN Dendrimers Glycomimetics Langerin 1 1 1 08/09/22 20220805 NES 220805 B The Front Cover b shows a blueprint for the design of a multivalent ligand of the C-type lectin receptor DC-SIGN. This molecular architecture achieves strong binding avidity towards DC-SIGN and increased selectivity over the C-type lectin langerin, which is characterized by a distinct spatial arrangement of the carbohydrate recognition domains. Carbohydrates, DC-SIGN, Dendrimers, Glycomimetics, Langerin. [Extracted from the article]

A new method for the preparation of nitrones through the aerobic oxidation of the corresponding N, N-disubstituted hydroxylamines has been developed by exploring a new catalytic reactivity of gold supported on silica. The oxidation occurs under very mild conditions (flux of air, methanol or water, room temperature). The oxidation of a range of highly functionalized hydroxylamines with complete conversions and excellent yields of nitrones illustrates the selectivity, efficiency, and reliability of this practical method. The oxidation was shown to take place chemoselectively in competition experiments with benzyl alcohol and dibutylamine. [ABSTRACT FROM AUTHOR]

A general strategy for the synthesis of diversely substituted 3,4,5-trihydroxypiperidines (including two natural products), 5-amino-3,4-dihydroxypiperidines, 3,4,5-trihydroxypipecolic acids, and 2-(aminomethyl)-3,4,5-trihydroxypiperidines is reported. The procedure used a double reductive amination or a Strecker reaction, starting from differently protected aldehydes readily synthesized on a gram scale from D-mannose. The biological activities of the target compounds were evaluated, and some of them showed moderate inhibition of α- L-fucosidase and β-glucosidase. [ABSTRACT FROM AUTHOR]

BACKGROUND The European Pesticide Regulation ( EC) No. 1107/2009 encourages the use of less harmful active substances. Two main concerns involve the application of cut-off criteria for pesticides without losing tools for future agriculture (especially for minor uses) and the implementation of zonal evaluations. Biopesticides are considered to have lower risks than synthetic pesticides; consequently, there is strong interest for their use in integrated pest management practices. RESULTS This paper provides an analysis of the current European situation, starting with the first attempts to regulate the use of plant protection products and focusing on the implications of the new legislative criteria for biopesticides. CONCLUSION It is important to be aware that biopesticides are still pesticides and fall under the same regulations as their synthetic counterparts. Although manufacturers are still reluctant to commit to such alternatives due to difficulties with approval and registration, biopesticides could be alternatives for traditional plant protection products, either as a base for the synthesis of new products or integrated with traditional plant protection products. In addition, biopesticides have to be used only as indicated on the label, which provides critical information about how to safely handle and use plant protection products. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The synthesis of three tetrahydroxyindolizidines and one tetrahydroxypyrrolizidine related to natural hyacinthacines B and their biological evaluation as glycosidase inhibitors is reported. The target molecules were obtained through highly stereoselective cycloadditions between sugriched allylic and homoallylic alcohols. This allowed the installation of a methyl group at C5 - a common feature of many natural hyacinthacines - with high control over the stereoselectivity. The new compounds inhibit amyloglucosidase from Aspergillus niger and β-glucosidase from almonds. Compound 1 is a competitive inhibitor of amyloglucosidase and shows a fair selectivity towards this enzyme. The presence of C5-Me substitution in indolizidines 2 and 3 slightly diminishes the inhibitory activity towards amyloglucosidase whereas it improves the inhibitory properties towards β-glucosidase. [ABSTRACT FROM AUTHOR]

Addition of lithiated 1-benzyloxyallene to a D-arabinose-derived cyclic nitrone occurred with perfect diastereoselectivity furnishing a bicyclic 1,2-oxazine derivative, which is an excellent precursor for pyrrolizidine alkaloids hydroxylated at C-7 with optional configuration at this stereogenic center. Depending on the stage of the NO bond cleavage and ring re-closure, 7-hydroxypyrrolizidines with 7 R or 7 S configuration were obtained, as a result of completely selective addition reactions occurring complementarily at the bottom or top face of the endocyclic CC double bond in six- and five-membered B rings, respectively. Applicability of these stereodivergent routes to obtain polyhydroxy pyrrolizidine alkaloids is demonstrated by the efficient syntheses of casuarine and australine as examples of the two classes of diversely configured 7-hydroxypyrrolizidine alkaloids. An alternative synthesis of australine and two strategies for the preparation of 7- epi-australine are also reported, which demonstrate that the stereoselectivity of hydride reduction of an exocyclic CO double bond is independent of the ring size, occurring preferentially from the top face either in a six- or five-membered ring. [ABSTRACT FROM AUTHOR]

UV-induced toxicity is characterized by marked oxidative stress, accompanied by the depletion of key cellular antioxidants, particularly glutathione ( GSH). Replenishing cellular GSH may represent a means of counteracting UV-induced toxicity: however, treatment with free GSH is not therapeutically effective due to its unfavorable pharmacokinetic properties. In this study, we show that S-acyl-glutathione (acyl- SG) derivatives, which consist of an acyl chain (of variable length and saturation) linked via a thioester bond to GSH, increase intracellular levels of reduced GSH in primary skin fibroblasts, adenocarcinoma HeLa and neuroblastoma SH- SY5Y cells. Consistent with this, acyl- SG derivatives protect against UV-induced reactive oxygen species ( ROS) production and UV-B/C-mediated lipid peroxidation and caspase-3 activation in the analyzed cell lines, with unsaturated thioesters displaying a significantly greater protective effect. Taken together, our findings suggest that acyl- SG thioesters may be therapeutically effective in the treatment of UV-related skin disorders and oxidative stress-mediated conditions in general. [ABSTRACT FROM AUTHOR]

• The hypothesis was tested that flavonoids may scavenge singlet oxygen (1O2) in mesophyll cells of Phillyrea latifolia exposed to excess-light stress. • In cross-sections taken from leaves developed at 10% (shade) or 100% (sun) solar irradiance, we evaluated the excess photosynthetically active radiation (PAR)-induced accumulation of 1O2 in mesophyll cells by imaging the fluorescence quenching of the specific 1O2 probe N-[2-(diethylamino)ethyl]- N-[(2,5-dihydro-2,2,5,5-tetramethyl-1 H-pyrrol-3-yl)methyl]-5-(dimethylamino)-1-naphthalenesulfonamide (DanePy). The intracellular location of flavonoids was also analyzed using three-dimensional deconvolution microscopy. • Photo-induced quenching of DanePy fluorescence was markedly greater in the mesophyll of shade leaves than in that of sun leaves, the former showing a negligible accumulation of mesophyll flavonoids. The photo-induced generation of 1O2 was inversely related to the content of flavonoids in the mesophyll cells of sun leaves. Flavonoids were located in the chloroplasts, and were likely associated with the chloroplast envelope. • Here we provide relevant evidence for the potential scavenger activity of chloroplast-located flavonoids against 1O2 and new insights into the photo-protective role of flavonoids in higher plants. [ABSTRACT FROM AUTHOR]

As in other phagocytic cells, the NADPH-oxidase system in microglia is thought to be primarily responsible for the production of superoxide anion radicals (O[sub 2][sup -]·), a potentially cytotoxic reactive oxygen species. The assembly of a functional NADPH-oxidase complex at the plasma membrane depends on the phosphorylation and subsequent translocation of several cytosolic subunits. Immunocytochemical and subcellular fractionation experiments performed during the present study revealed that the NADPH-oxidase subunit p67[sup phox] translocates from the cytosol to the plasma membrane upon stimulation. Pre-incubation of microglia in α-tocopherol (αTocH) containing medium decreased O[sub 2][sup -]· production in a time- and concentration-dependent manner, findings attributed to attenuated p67[sup phox] translocation to the plasma membrane. Moreover, αTocH-supplementation of the culture medium resulted in decreased microglial protein kinase C (PKC) activities, an effect that could be partially or completely reversed by the addition of protein phosphatase inhibitors (okadaic acid and calyculin A). The addition of the PKC-inhibitor staurosporine inhibited the microglial respiratory burst in a manner comparable to αTocH. The addition of okadaic acid or calyculin A completely restored O[sub 2][sup -]· production in αTocH-supplemented cells. The present findings suggest that αTocH inactivates PKC via a PP1 or PP2A-mediated pathway and, as a consequence, blocks the phosphorylation-dependent translocation of p67[sup phox] to the plasma membrane. As a result, O[sub 2][sup -]· production by the microglial NADPH-oxidase system is substantially inhibited. [ABSTRACT FROM AUTHOR]