Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• with substrates, typically oxygen, to produce reactive oxygen species. The competitive complexation can not only be applied in diagnosis via the aforementioned IDA but also be engaged in therapy. We proposed a host–guest strategy for activatable phototheranostics termed biomarker displacement

• activation (BDA) [27]. In that work, we employed the four PSs and studied their host–guest complexation with GC5A. Each PS has a strong binding affinity upon 1:1 complexation with GC5A (Table 1), accompanied by a drastic annihilation of both fluorescence and photoactivity (reactive oxygen species generation

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• oxygen species (ROS) were detected in the cells irradiated in the 2a-containing medium, but not in the non-irradiated cells in 2a-containing medium or the irradiated cells without 2a-containing medium (Figure 6). Thus, the preliminary analyses indicated that the photochemical generation of radicals from

• also observed (Figure 5). To evaluate whether the cytocidal effect was due to photochemical radical generation, cells exposed to 360 nm light for 1 min and the unexposed congeners were stained by using a ROS-ID oxidative stress detection kit (Enzo Life Sciences, Farmingdale, NY, U.S.A.). Reactive

Synthesis and biological investigation of (+)-3-hydroxymethylartemisinin

• Toni Smeilus,
• Farnoush Mousavizadeh,
• Johannes Krieger,
• Xingzhao Tu,
• Marcel Kaiser and
• Athanassios Giannis

Beilstein J. Org. Chem. 2019, 15, 567–570, doi:10.3762/bjoc.15.51

• the past it has been postulated that artemisinins kill intraerythrocytic parasites such as P. falciparum in the presence of Fe2+ forming reactive oxygen species (ROS) [4]. As artemisinin and similar derivatives are destroyed by Fe2+ in vitro (Fenton reaction), it is difficult for us to explain their

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• oxidant that would be compatible with the chemistry of the radical intermediates, would not generate any highly reactive oxygen species, and would not produce toxic or chromatographically problematic byproducts. As a starting point for our optimization studies, we examined the intramolecular oxyamination

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• by pqs QS, pyocyanin is one of the most prominent. This redox-active pigment is responsible for the greenish-blueish colour of P. aeruginosa cultures. It seems that generation of reactive oxygen species is a major mechanism of pyocyanin cytotoxicity [41]. This tricyclic compound is known to induce

Impact of Pseudomonas aeruginosa quorum sensing signaling molecules on adhesion and inflammatory markers in endothelial cells

• Carmen Curutiu,
• Florin Iordache,
• Veronica Lazar,
• Aurelia Magdalena Pisoschi,
• Aneta Pop,
• Mariana Carmen Chifiriuc and
• Alina Maria Hoban

Beilstein J. Org. Chem. 2018, 14, 2580–2588, doi:10.3762/bjoc.14.235

• of reactive oxygen species by diminishing the bacterial clearance process by macrophages. For these reasons, both PGE2 and COX-2 have been proposed as future therapeutic targets for the treatment of severe pneumonia produced by P. aeruginosa [18]. Another signaling molecule produced by P. aeruginosa

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• upon light irradiation. Two types of photooxidative damages can be induced: (i) by photosensitization of singlet oxygen and subsequent generation of highly reactive oxygen species (ROS) (type I photosensitization) or (ii) by direct oxidative electron transfer to biological molecules such as DNA or

• reactive-oxygen-species-dependent apoptosis. Another strategy for the design of cell penetrating photoreactive RuII complexes consists of tethering the complex to a vector that allows a cellular uptake. In this context, OsII, RhIII and RuII complexes were anchored to cell penetrating peptides (CPP) such as

On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

• ]. Overwhelming production of stimulus agents and enzymes [21]. For instance, many types of cancer show enhanced levels of reactive oxygen species (ROS) which are reactive molecules and play a crucial role in cell proliferation [22]. The slightly acidic pH of the tumor microenvironment [23] (Warburg effect

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• cytokines, chemokines, prostaglandins and reactive oxygen species which manifest an acute inflammatory response to infection. The “endotoxic principle” of LPS resides in its amphiphilic membrane-bound fragment glycophospholipid lipid A which directly binds to the TLR4·MD-2 receptor complex. The lipid A

• response, whereas H. pylori LPS-dependent activation of monocytes and gastric epithelial cells leads to the production of several pro-inflammatory cytokines and reactive oxygen species (ROS) [81]. The mechanism by which H. pylori induces chronic inflammation and injury of gastric tissue is not fully

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• into cancer cells and kills them by reactive oxygen species with cytotoxicity generated by light irradiation [94][95]. In addition to reducing the psychological burden of the patients because this process does not require surgical operation, damage to normal cells can be minimized by irradiating the

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• -disubstituted isoxazoles on nitric oxide and reactive oxygen species generation in Arabidopsis tissues was studied using specific diaminofluoresceine dyes as fluorescence indicators. Keywords: chemical elicitor; 1,3-dipolar cycloaddition; isoxazole; nitric oxide; nitrile oxide; reactive oxygen species

• scaffolds respectively, as well as their inductor effect on the generation of nitric oxide and reactive oxygen species in plant tissues. The benzo[1,3]dioxole framework is a constituent of some fragrances and flavors [44], and several bioactive compounds with a broad spectrum of applications [45][46][47][48

• reactive oxygen species (ROS) production in plant tissues. Usually, NO and ROS, such as O2−, OH· and H2O2, together are required to induce the activation of various defense-related enzymes in plants [55]. Plant cells contain oxygen radical detoxifying enzymes and nonenzymatic antioxidants which have an

Synthesis and evaluation of anti-oxidant and cytotoxic activities of novel 10-undecenoic acid methyl ester based lipoconjugates of phenolic acids

• Naganna Narra,
• Shiva Shanker Kaki,
• Rachapudi Badari Narayana Prasad,
• Sunil Misra,
• Koude Dhevendar,
• Venkateshwarlu Kontham and
• Padmaja V. Korlipara

Beilstein J. Org. Chem. 2017, 13, 26–32, doi:10.3762/bjoc.13.4

• vitro anti-oxidant activity against many reactive oxygen species and to protect neuronal cells against various types of oxidative damage [2][3]. To increase the effectiveness of phenolic compounds, their lipophilization has been the choice of derivatization as it provides beneficial effects of both the

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• ]. The type I mechanism describes a direct interaction between the PS and the surrounding cell material. Electrons are transferred onto the cell material, causing the production of radicals that then react with oxygen to form reactive oxygen species. The type II mechanism, however, describes the

• interference of the PS with the triplet ground state of oxygen, leading to the production of singlet oxygen. In both mechanisms, the PS harvests the energy of incident light to form reactive oxygen species or singlet oxygen, which are highly cytotoxic [6][7]. Most clinically used PSs are based on porphyrins

• leads to aggregation and inactivation under physiological conditions, causing a reduced production of reactive oxygen species [26]. To overcome this drawback, we considered to immobilize the squaraines onto a platform that provides spatial separation (Figure 1). Our platforms of choice are vesicles self

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu²⁺

• Rahman Hosseinzadeh,
• Mohammad Nemati,
• Reza Zadmard and
• Maryam Mohadjerani

Beilstein J. Org. Chem. 2016, 12, 1749–1757, doi:10.3762/bjoc.12.163

• amounts of Cu2+ are hazardous, due to generate reactive oxygen species (ROS) that disturbs cellular metabolism [10][11]. On the other hand, its deficiency may cause haematological and neurological diseases [12]. Therefore, the selective and sensitive measurement of Cu2+ ions – either as significant

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Biradical vs singlet oxygen photogeneration in suprofen–cholesterol systems

• Fabrizio Palumbo,
• Francisco Bosca,
• Isabel M. Morera,
• Inmaculada Andreu and
• Miguel A. Miranda

Beilstein J. Org. Chem. 2016, 12, 1196–1202, doi:10.3762/bjoc.12.115

• assess the capability of dyads 1–3 to photosensitize the production of excited singlet molecular oxygen (1O2 or 1Δg), time-resolved near infrared emission studies were carried out in dichloromethane using perinaphthenone (PN) as standard. The formation of this reactive oxygen species was detected by its

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• chestnut) showed antioxidant activity [28]. Testing urolithins A, B, C, D (23–26) in an assay using myelomonocytic HL-60 cells showed antioxidant activities for 23, 25 and 26. These three derivatives inhibited the reactive oxygen species (ROS)-dependent oxygenation of the non-fluorescent 2’,7

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• several clinical diseases [12][21]. One of the most commonly used thiobase for PDT applications is S4TdR, whose triplet state is generated upon photoexcitation with a quantum yield of one [22][23][24][25][26]. Under these conditions the production of reactive oxygen species (ROS), well-known toxic agents

• potential method to improve/change the photochemical behavior of the thiobase. In particular, the protection of S4TdR, as photosensitizer, from degradation through reactive oxygen species during photodynamic therapy applications could be attained in the presence of all analyzed CDs. A study in this

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• oxygen species generated through side reactions between Cu(I) and O2. a) Molecular structure of 4 (a THF molecule present in the unit cell is not shown). Cu, green; C, grey; O, red; H, white; b) Molecular structure of 1 (asymmetric unit) showing the intermolecular (dashed red lines) and intramolecular

• bubbling. Copper(I)-catalyzed processes, in particular for application in click bioconjugations, should be conducted under deaerated conditions in order to reduce copper loading due to fast Cu(I) to Cu(II) oxidation process mediated by O2, and also to limit addition of trapping agents to capture reactive

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• be suggested as being partly responsible for the activity. Furthermore, cytotoxic modes of action of pyridoacridine alkaloids include DNA-binding properties, topoisomerase (TOPO) inhibition [91] or the production of reactive oxygen species (ROS) [92][93]. It was shown that planar iminoquinone

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• ) when hydrogen peroxide was combined with superoxide solution in water matrix. The authors suggested that under these conditions the rate of the disproportionation reaction of superoxide radical anion is increased, and the formation of more reactive oxygen species such as hydroxyl radical or singlet

• expected to contribute to clinical chemistry. Conclusion Cholesterol has been regarded as an electrochemically inactive compound for a long time. Since the 1990s several methods have been developed for the indirect oxidation of cholesterol. The active species in these methods were different reactive oxygen

• species, various hypervalent transition metal–oxo and metal–peroxo species, dihalogens, hypohalites, and enzymes. The first direct electrochemical oxidation was reported only in 2005. The electrochemical oxidation of cholesterol may occur at the C3-hydroxy group, at the C5–C6 double bond, at the allylic

Synthesis and biological activity of N-substituted-tetrahydro-γ-carbolines containing peptide residues

• Nadezhda V. Sokolova,
• Valentine G. Nenajdenko,
• Vladimir B. Sokolov,
• Daria V. Vinogradova,
• Elena F. Shevtsova,
• Ludmila G. Dubova and
• Sergey O. Bachurin

Beilstein J. Org. Chem. 2014, 10, 155–162, doi:10.3762/bjoc.10.13

• ] (Figure 1). These peptides were found to scavenge hydrogen peroxide and peroxynitrite and inhibit lipid peroxidation in vitro. By reducing mitochondrial reactive oxygen species, they inhibit MPT and cytochrome c release, thus protecting cells from oxidative cell death [11]. We expected that the

Studies on the photodegradation of red, green and blue phosphorescent OLED emitters

• Susanna Schmidbauer,
• Andreas Hohenleutner and
• Burkhard König

Beilstein J. Org. Chem. 2013, 9, 2088–2096, doi:10.3762/bjoc.9.245

• , possibly competing with the above mentioned reactive oxygen species-induced degradation route may proceed via the excited state of the emitter molecule. This might be due to instability of the excited molecule itself, via interaction of the excited molecule with its local environment or even other excited

• exclusion of oxygen, however, the degradation is suppressed significantly. Therefore, reactive oxygen species are likely responsible for the decomposition of Ir(piq)3. Experiments in deuterated benzene under atmospheric conditions support this assumption showing more than 80% decrease in the complex

• that the emitters can be very susceptible to singlet oxygen-induced degradation depending on their structure. This pathway was identified as the predominant degradation mechanism for the red emitting Ir(piq)3. Ir(Me-ppy)3 also showed sensitivity towards reactive oxygen species and an oxidized

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• neurons and acetylcholine (ACh) levels, plaques caused by aggregation of the protein fragment amyloid-β (Aβ), tangles associated with irregular phosphorylation of tau protein, inflammation and increased oxidative stress from reactive oxygen species (ROS), as well as dyshomeostasis and

Synthesis of meso-substituted dihydro-1,3-oxazinoporphyrins

• Satyasheel Sharma and
• Mahendra Nath

Beilstein J. Org. Chem. 2013, 9, 496–502, doi:10.3762/bjoc.9.53

• tissue, and efficiency in generating reactive oxygen species by the absorption of photons in the visible or near IR region make them ideal candidates for developing effective photodynamic agents. These findings have encouraged researchers to design and synthesize potential targeting anticancer drugs