Single and double reduction of C\u3csub\u3e60\u3c/sub\u3e in 2:1 γ-cyclodextrin/[60]fullerene inclusion complexes by cyclodextrin radicals

Spectroscopic and chemical properties of γ-CD• radicals, resulting from the abstraction by HO• radicals of hydrogen atoms, have been investigated using pulse radiolysis. The reactions of γ-CD• radicals with C60 in 2:1 γ-CD/C60 inclusion complexes have been studied in aqueous solutions. It has been demonstrated that the γ-CD_ radicals are reducing species producing C60•— monoanion radicals, as well as doubly reduced C602— , well characterized by their absorption spectra in the near IR. The oxidation potential of γ-CD• radical is estimated to be more negative than –390 mV vs. NHE. The kinetics of the C60 reduction by γ-CD• radicals have been determined and compared with kinetics by other reducing species including the solvated electron (e—aq) and CO2•— radicals. It was observed that the method of preparation of the 2:1 γ-CD/C60 inclusion complexes modifies the C60 reduction mechanism

Réactions induites par les rayonnements, étudiées en France du XIXe siècle à nos jours

Abréviations et acronymes : CNRS : Centre national de la recherche scientifique CEA : Commissariat à l’énergie atomique, devenu en 2010 Commissariat à l’énergie atomique et aux énergies alternatives (CEAEA) Inra : Institut national de la recherche agronomique ISMO : Institut des sciences moléculaires d’Orsay MNHN : Muséum national d’histoire naturelle SIRLaF : Société internationale de radiobiologie de langue française ERO : Espèces réactives de l’oxygène ROS : Reactive Oxygen Species Genèse ..

Photophysical properties in aqueous solutions of C60_{60} embedded in 2:1 γ\gamma-cyclodextrin/[60]fullerene inclusion complexes

International audienceTo resolve conflicting results in the literature, we determine quantitatively the properties of the lowest triplet excited state of water soluble 2:1 host:guest complexes of C$_{60}$ embedded in $\gamma$-cyclodextrin ($\gamma$-CD/C$_{60}$) using laser flash photolysis. The results show that the triplet excited state characteristics of $\gamma$-CD/C$_{60}$ in aqueous solutions are very similar to those observed for C$_{60}$ in organic solvents. Moreover oxygen, in contrast with non-gaseous solutes, can reach the proximity of C$_{60}$ embedded in 2:1 $\gamma$-CD inclusion complexes. In addition, photodestruction quantum yields have been determined for C$_{60}$ in toluene and for C$_{60}$ in $\gamma$-CD inclusion complexes in water

Potency ranking of triterpenoids as inducers of a cytoprotective enzyme and as inhibitors of a cellular inflammatory response via their electron affinity and their electrophilicity index

Electron affinity (EA) and electrophilicity index (omega) of 16 synthetic triterpenoids (TP), previously identified as inducers of cytoprotective enzymes and as inhibitors of cellular inflammatory responses, have been calculated by the molecular orbital method. Linear correlations were obtained by plotting the values of EA, as well as those of omega versus (i) the potencies of induction of NAD(P)H quinone reductase (NQO1, EC 1.6.99.2), a cytoprotective enzyme, expressed via the concentration of TP required to double the specific activity of NQO1 (CD value) and (ii) the values of their anti-inflammatory activity expressed via the IC-50 of TP for suppression of upregulation of inducible nitric oxide synthase (iNOS, EC 1.14.13.39), both previously experimentally determined. The observed correlations demonstrate quantitatively for a series of triterpenoids that their electrophilicity is a major factor determining their potency as inducers of the cytoprotective phase 2 response and as inhibitors of inflammatory processes