Contribution de la radiolyse pulsée et de la photolyse par éclair à l'étude des formes activées de l'oxygène moléculaire présents in vivo

La radiolyse puisée et la photolyse éclair ont permis de caractériser les propriétés cinétiques et thermodynamiques de l'oxygène singulet et des radicaux libres [math]˙ et OH˙

Involvement of C60 fullerene monomers and aggregates in the photoconductivity of ultrathin bilayer lipid membranes

International audienc

Potency of inhibition of human DNA topoisomerase I by flavones assessed through physicochemical parameters.

DNA topoisomerases, enzymes involved in DNA replication and transcription, are known as targets for anticancer drugs. Among the various types of topoisomerase inhibitors, flavones (F) have been identified as promising compounds. In this study, it is shown that the potency of flavones acting as topoisomerase I inhibitors can be ranked according to their redox properties and their 3D structure. Linear correlations were observed between the topoisomerase I inhibition activity exerted by five flavones (chrysin, apigenin, kaempferol, fisetin, quercetin) and experimental and theoretical redox parameters of F. Moreover, theoretical calculations of the dihedral angle O(1)-2-1'-2' in the flavone molecules indicate the importance of their structural and steric features in their potency as topoisomerase I inhibitors. It is suggested that the flavones might interact with the DNA-topoisomerase I complex after their oxidation into quinones via autoxidation, enzymatic oxidation, or reactions with reactive oxygen species. Our investigation opens a new strategy quantitatively based on redox and 3D structural parameters in the search for the most active flavones as anticancer drug candidates inhibiting topoisomerase I

Triplet state properties of N-mTEG(60)Fulleropyrrolidine mono and bisadduct derivatives

Laser \uafash photolysis and pulse radiolysis techniques were used to determine triplet state properties of N-mTEG[60]fulleropyrrolidine mono and bisadduct derivatives (FP) mTEG CH2CH2OCH2CH2OCH2CH2OCH3 in benzene. These properties include the triplet absorption spectra between 550 and 900 nm, quantum yields of triplet photosensitized singlet oxygen production UD and triplet molar absorption coe cients eT with the assumption that the quantum yield of triplet formation UT is equal to UD. Our results demonstrate that the triplet properties depend on the number of addends and the addition pattern

Photophysical properties of C76

International audienc

Electron affinity of tricyclic, bicyclic, and monocyclic compounds containing cyanoenones correlates with their potency as inducers of a cytoprotective enzyme.

Tricyclic, bicyclic, and monocyclic compounds containing cyanoenones induce various anti-inflammatory and cytoprotective enzymes through activation of the Keap1/Nrf2/ARE (antioxidant response element) pathway. The potency of these compounds as Nrf2 activators was determined using a prototypic cytoprotective enzyme quinone oxidoreductase 1 (NQO1) in Hepa1c1c7 murine hepatoma cells. The electron affinity (EA) of the compounds, expressed as the energy of their lowest unoccupied molecular orbital [E (LUMO)], was evaluated using two types of quantum mechanical calculations: the semiempirical (AM1) and the density functional theory (DFT) methods. We observed striking linear correlations [r=0.897 (AM1) and 0.936 (DFT)] between NQO1 inducer potency of these compounds and their E (LUMO) regardless of the molecule size. Importantly and interestingly, this finding demonstrates that the EA is the essentially important factor that determines the reactivity of the cyanoenones with Keap1