- Reactions of nitroxides. Part X: Antifungal activity of selected sulfur and selenium derivatives of 2,2,6,6-tetramethylpiperidine
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The antifungal activity of nitroxyl radicals - derivatives of 2,2,6,6-tetramethylpiperidine-1-oxyl with reactive substituents 4-isothiocyanato-, 4-isocyano-, and 4-isoselenocyanato- and of N-formyl-, N-thioformyl-, N-selenoformyl-derivatives of 2,2,6,6-tetramethylpiperidine was investigated. Those of the above compounds, which contain a sulfur or selenium atom are the most active against four fungus plant patogens: Botrytis cinerea, Fusarium culmorum, Phytophthora cactorum, Rhizoctonia solani. 4-Isoselenocyanato-2,2,6,6-tetramethylpiperidine-1-oxyl proved to be the most active compound.
- Zakrzewski, Jerzy,Krawczyk, Maria
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- EPR and affinity studies of mannose-TEMPO functionalized PAMAM dendrimers
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Mannose-TEMPO functionalized G(4)-PAMAM dendrimers with increasing mannose loadings have been synthesized and characterized by MALDI-TOF MS and EPR spectroscopy. Analysis of linebroadening effects in the EPR spectra of these dendrimers allowed us to determine the relative presentation of mannose and TEMPO on the dendrimer surface. Hemagglutination assays and affinity chromatography/EPR experiments to assess the activity of the mannose-TEMPO dendrimers with Concanavalin A are presented.
- Samuelson, Lynn E.,Sebby, Karl B.,Walter, Eric D.,Singel, David J.,Cloninger, Mary J.
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- Design, Synthesis, EPR-Studies and Conformational Bias of Novel Spin-Labeled DCC-Analogues for the Highly Regioselective Labeling of Aliphatic and Aromatic Carboxylic Acids
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Novel types of spin-labeled N,N′-dicyclohexylcarbodiimides (DCC) are reported that bear a 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) residue on one side and different aromatic and aliphatic cyclohexyl analogues on the other side of the diimide core. These readily available novel reagents add efficiently to aliphatic and aromatic carboxylic acids, forming two possible spin-labeled amide derivatives with different radical distances of the resulting amide. The addition of aromatic DCC analogues proceeds with excellent selectivity, giving amides where the carboxylic acid is exclusively connected to the aromatic residue, while little or no selectivity was observed for the aliphatic congeners. The usefulness of these adducts in structural studies was demonstrated by EPR (electron paramagnetic resonance) measurements of biradical adducts of biphenyl-4,4′-dicarboxylic acids. These analyses also reveal high degrees of conformational bias for aromatic DCC derivatives, which further underlines the powerfulness of these novel reagents. This observation was further corroborated by quantum chemical calculations, giving a detailed understanding of the structural dynamics, while detailed information on the solid state structure of all novel reagents was obtained by X-ray structure analyses.
- G?lz, Jan Philipp,NejatyJahromy, Yaser,Bauer, Mirko,Muhammad, Ashraf,Schnakenburg, Gregor,Grimme, Stefan,Schiemann, Olav,Menche, Dirk
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p. 9591 - 9598
(2016/07/14)
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- Carbonic anhydrase inhibitors: Design of spin-labeled sulfonamides incorporating TEMPO moieties as probes for cytosolic or transmembrane isozymes
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A series of spin-labeled sulfonamides incorporating TEMPO moieties were synthesized by a procedure involving the formation of a thiourea functionality between the benzenesulfonamide and free radical fragment of the molecules. The new compounds were tested as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) and showed efficient inhibition of the physiologically relevant isozymes hCA II and hCA IX (hCA IX being predominantly found in tumors) and moderate to weak inhibitory activity against hCA I. Some derivatives were also selective for inhibiting the tumor-associated isoform over the cytosolic one CA II, and presented significant changes in their ESR signals when complexed to the enzyme active site, being interesting candidates for the investigation of hypoxic tumors overexpressing CA IX by ESR techniques, as well as for imaging/treatment purposes.
- Cecchi, Alessandro,Ciani, Laura,Winum, Jean-Yves,Montero, Jean-Louis,Scozzafava, Andrea,Ristori, Sandra,Supuran, Claudiu T.
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experimental part
p. 3475 - 3480
(2009/04/04)
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- Reaction of Nitroxides with Sulfur Containing Compounds II [1]. Preparation of Nitroxides Bearing an Isothiocyanate Substituent in View of the Nitroxyl Group Reduction with Thiophosgene
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The reaction of thiophosgene with 2,2,6,6-tetramethylpiperidine-1-oxyl (used as a model nitroxyl radical) was examined. 2,2,6,6-Tetramethylpiperidine and 2,2,6,6-tetramethyl-1-hydroxypiperidine were identified as products. The reaction is not competitive with the reaction of thiophosgene with an amino group. Thus, three nitroxides with an isothiocyanate group were synthesized from thiophosgene and the nitroxides containing the amino substituent.
- Zakrzewski, Jerzy,Hupko, Jarosllaw,Kryczka, Krzysztof
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p. 843 - 850
(2007/10/03)
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- Synthesis of alpha- and beta-glycosides containing spin labels, as probes for studies of carbohydrate-protein interaction.
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Nitroxide spin-labeled alpha-D-glycopyranosides were synthesized in good yield and in a highly stereoselective manner by reaction of per-O-benzyl-alpha-D-glycopyranosyl bromides with 2,2,6,6-tetramethyl-4-piperidinol under the bromide ion-catalyzed conditions devised by Lemieux et al. After hydrogenolysis, the deblocked intermediates were oxidized to give the desired, spin-labeled alpha-D-glycopyranosides. Nitroxide spin-labeled beta-D-glycopyranosides, as well as a beta-maltoside, were synthesized by standard methods. The synthesis is also described of 2-amino-2-deoxy-D-glucose and -D-galactose derivatives having a spin label at C-2, and of the spin-labeled compound 1-[4-(beta-D-galactopyranosyloxy)phenyl]-3-(2,2,6,6-tetramethylpiperidin-1-oxyl -4-yl)-2-thiourea.
- Plessas,Goldstein
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p. 211 - 220
(2007/10/02)
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