RESUMO
A novel flavonol glycoside, 7-O-methylmearnsitrin (7,4'-O-dimethylmyricetin 3-O-alpha-L-rhamnopyranoside), and myricetrin, kaempferol 3-O-alpha-L-rhamnopyranoside, europetin 3-O-alpha-L-rhamnoside, and 7-O-methyl quercetin 3-O-alpha-L-rhamnopyranoside were isolated from the leaves of Sageretia theezans, and their chemical structures were identified by spectroscopic analyses including two-dimensional NMR (HSQC, HMBC). Whereas myricetrin, europetin 3-O-alpha-L-rhamnoside, and 7-O-methylquercetin 3-O-alpha-L-rhamnopyranoside showed stronger activities than ascorbic acid and alpha-tocopherol, 7-O-methylmearnsitrin showed very weak antioxidant activities by ESR and LDL oxidation inhibition tests.
Assuntos
Antioxidantes/isolamento & purificação , Flavonoides/isolamento & purificação , Flavonóis/isolamento & purificação , Folhas de Planta/química , Rhamnaceae/química , Antioxidantes/farmacologia , Espectroscopia de Ressonância de Spin Eletrônica , Flavonoides/farmacologia , Flavonóis/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Lipoproteínas/química , Espectroscopia de Ressonância MagnéticaRESUMO
Investigation on the structure--antioxidative activity relationships of derivatives based on garcinoic acid from Garcinia kola (Guttiferae) led to discovery of a powerful antioxidative agent.
