RESUMO
A short, convergent synthesis of the mushroom pigment norbadione A is described. The construction of an appropriately substituted naphtholactone intermediate involved a regioselective Diels-Alder reaction between a bis(triisopropylsilyloxy)diene and 2,6-dichlorobenzo-1,4-quinone. A double Suzuki-Miyaura cross-coupling between a diboronate and two identical enol triflates was another key feature of the synthesis.
Assuntos
4-Butirolactona/análogos & derivados , Fenilacetatos/síntese química , 4-Butirolactona/síntese química , 4-Butirolactona/química , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Fenilacetatos/química , EstereoisomerismoRESUMO
A recently reported high-throughput screening strategy has been applied to the rapid selection of new water-soluble antioxidants that display strong protective activities. Based on a competitive immunoassay, a triple-screening procedure was used to evaluate the ability of different compounds to protect thymidine under different oxidative stresses. The pro-oxidant effect of norbadione A in the presence of iron was observed, while some pulvinic acid derivatives proved strongly protective during gamma radiolysis, UV irradiation, and Fenton-like oxidation.
Assuntos
Antioxidantes/química , Antioxidantes/farmacologia , Flavonoides/química , Oxidantes/química , Fenóis/química , Timidina/química , 4-Butirolactona/análogos & derivados , 4-Butirolactona/química , Ácidos Carboxílicos/química , Cromatografia Líquida de Alta Pressão , Estudos de Avaliação como Assunto , Flavonoides/fisiologia , Imunoensaio , Lactonas/química , Oxidantes/farmacologia , Estresse Oxidativo , Fenilacetatos/química , Polifenóis , Quercetina/química , Espécies Reativas de OxigênioRESUMO
We present a new high-throughput screening method for the selection of powerful water-soluble antiradiation compounds. This method, which uses conventional immunoassay techniques, allowed the capacity of a given compound to protect thymidine from irradiation to be evaluated. By applying this assay to an antioxidant library, we showed for the first time that norbadione A, a well-known mushroom pigment, has pronounced atypical antiradiation properties.
Assuntos
4-Butirolactona/análogos & derivados , 4-Butirolactona/farmacologia , Avaliação Pré-Clínica de Medicamentos/métodos , Imunoensaio/métodos , Fenilacetatos/farmacologia , Protetores contra Radiação/farmacologia , Timidina/química , 4-Butirolactona/química , Agaricales/química , Antioxidantes/química , Antioxidantes/classificação , Antioxidantes/farmacologia , Fatores Biológicos/química , Fatores Biológicos/farmacologia , DNA/efeitos da radiação , Relação Dose-Resposta a Droga , Estudos de Avaliação como Assunto , Fenilacetatos/química , Extratos Vegetais/química , Protetores contra Radiação/química , Solubilidade , Timidina/efeitos da radiação , Fatores de TempoRESUMO
The alkylation of the lithium enolate of enantiopure alpha-cyclohexylsulfinyl thioacetamide 1 with allyl bromides 5 possessing an electron-withdrawing group at the vinylic position does not occur at the sulfur center - as expected in the sulfur series - but at the carbon center through conjugate addition followed by bromide elimination. The modest to excellent 1,2-asymmetric induction achieved by the alkylsulfinyl group (dr up to 100:0) is explained by an electronic model.