RESUMO
O extrato éter de petróleo das raízes de Lonchocarpus muehlbergianus foi submetido a sucessivas análises cromatográficas (CC, CCD e CDC preparativa) levando ao isolamento de nove flavonóides (1-9) dos quais seis são inéditos na literatura (1-6) destacando-se as quatro flavanas 2,4-dioxigenadas (1-4) que representam uma nova classe de flavonóides. As estruturas moleculares foram determinadas através da análise dos respectivos espectros de RMN 1H, RMN 13C e DEPT, RMN-2D (COSY, HETCOR e COLOC), NOE, IV, UV e EM. A análise quantitativa por CLAE, mostrou que a nova flavana 1 é o flavonóide que ocorre em maior abundância no extrato.
Assuntos
Fabaceae , Flavonoides , Estrutura Molecular , Extratos Vegetais , Raízes de PlantasRESUMO
The light petroleum extract from the roots of Lonchocarpus muehlbergianus Hassl contained nine flavonoids, including six new ones. These are 2,4-cis-2,4,5,8-tetramethoxy-(2'',3'':6,7)-furanoflavan; 2,4-cis-4-hydroxy-2,5,8-trimethoxy-(2'',3'':6,7)-furanoflavan; 2,4-cis-2-prenyloxy-4,5,8-trimethoxy-(2'',3'':6,7)-furanoflavan; 2,4-cis-2-prenyloxy-4-hydroxy-5,8-dimethoxy-(2'',3'':6,7)-furanoflavan; 2',5',6'-trimethoxy-9-(1,1-dimethylallyoxy)-[2'',3'':3',4']-furanochalcone; 5,6-dimethoxy-(2'',3'':7,8)-furanoflavone, identified by analysis of their spectral data (UV, IR, 1H and 13C NMR, 2D-NMR, NOE and MS). The natural occurrence of 2,4-dioxygenated flavan derivatives is being reported for the first time. Quantitative analysis of the petrol extract, by using reversed-phase HPLC, showed that the most abundant flavonoid in the extract is 2,4-cis-2,4,5,8- tetramethoxy-(2'',3'':6,7)-furanoflavan.
