Photoreaction of zinc methyl 20-substituted meso(pyro)pheophorbide-a prepared by modifying naturally occurring chlorophyll-a in the presence of oxygen molecules gave its C19-C20 oxidative cleavage (1-carbonyl-19-oxo-bilatrienes) as the major products and the regioisomeric C1-C20 cleavage (19-carbonyl-1-oxo-bilatrienes) as the minor products. The resulting zinc complexes of linear tetrapyrroles ...

Kinetic data on the rates of quinolinium dichromate oxidation of a series of aliphatic aldehydes have been determined and discussed with reference to aldehyde hydration equilibria. Kinetic results support a pathway proceeding via a rate-determining oxidative decomposition of a chromate ester of an aldehyde hydrate. A cyclic transition state is suggested; being a Hückel-type system (4n + 2), thi...

Background: The detrimental effects of persistent stimulation with hCG were investigated in rat Leydig cells in vitro. Materials and Methods: Oxidative stress parameters such as lipid peroxidation, Reactive oxygen species(ROS), Total antioxidant capcity (TAC) and activities of antioxidant enzymes were assessed in the treated cells. Apoptosis amongest the trearted cells were detected by in situ ...

The oxidative cleavage of vicinal diols to carboxylic acids was investigated over heterogeneous Fe/MFI catalysts in aqueous medium, with green oxidant H2O2 and mild reaction conditions. High conversions selectivities (X=90 %, S=79 %) were achieved for the ethylene glycol. Further substrates also tested broadening relevance this catalyst. employment non-noble abundant Fe as active metal MFI-type...

The structure of uleine type alkaloids is characterized by the presence a bridged tetracyclic hexahydro-1H-1,5-methanoazocino[4,3-b]indole ring system 1. Various strategies have been developed to access this polycyclic structural motif. We report herein one-step conversion appropriately functionalized 1,3,4-trisubstituted cyclopent-1-ene 1 way an integrated oxidation/reduction/cyclization (iORC...

The divalent metal-isocitrate site of pig heart NADP-specific isocitrate dehydrogenase can be located by affinity cleavage of the enzyme by Fe(2+)-isocitrate in the presence of O2, in analogy to the "chemical nuclease" action of DNA-binding drugs linked to Fe-EDTA. The enzyme is irreversibly inactivated and cleaved by Fe(2+)-isocitrate more rapidly than by Fe2+. Mn2+ prevents inactivation and c...