RESUMO
Examination of Dracaena loureiri, a Thai medicinal plant possessing anti-bacterial activity, has led to the isolation of two new representatives, 1 and 2, of a rare skeleton of homoisoflavans. Proton assignments of the two isolates were aided by extensive 2D-homonuclear chemical shift correlation and nOe difference spectroscopy. Carbon assignments were completed through the utilization of simple and sensitive one-dimensional techniques such as selective population transfer via one-bond (CSCM 1D) and selective polarization transfer via long range coupling (selective INEPT) experiments. Conformational assignments were proposed through nOe difference spectroscopy and have been established by X-ray crystallography. The absolute configuration is proposed based on the octant rule and a biogenetic pathway for this type of homoisoflavan is briefly discussed.
Assuntos
Antibacterianos/isolamento & purificação , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Cromonas , Plantas Medicinais/análise , Antibacterianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Espectrofotometria Infravermelho , Staphylococcus aureus/efeitos dos fármacos , TailândiaRESUMO
Five isoflavonoids, including the new isoflavone quinone, 5-hydroxybowdichione [2], were isolated from the heartwood of Dalbergia candenatensis through bioactivity-directed fractionation.