RESUMO
The isolation of 6-hydroxyluteolin-7-O-(1"-alpha-rhamnoside) from the Central American epiphyte Vriesea sanguinolenta Cogn. and Marchal (Bromeliaceae) is described here. Its stereostructure was established by spectroscopic methods and an X-ray structure analysis of its hepta-O-acetyl derivative. This flavonoid glycoside had previously been reported from some Teucrium species (Labiatae), yet without sufficient physical data and spectroscopic evidence.
Assuntos
Glicosídeos/isolamento & purificação , Luteolina , Plantas/química , Animais , Antimaláricos/química , Antimaláricos/isolamento & purificação , Cristalografia por Raios X , Glicosídeos/química , Espectroscopia de Ressonância Magnética , Folhas de Planta/química , Plantas/classificação , Plasmodium falciparum/efeitos dos fármacosRESUMO
The stereoselective total synthesis of the antimalarial korupensamines A (1a) and B (1b) by application of the "lactone method" is described. Key steps of this first atropo-selective access to 5,8'-coupled naphthylisoquinoline alkaloids were the regioselective intramolecular coupling of ester 8 to give the configurationally labile lactone-bridged biaryl 9 and its atropisomer-selective cleavage with a variety of chiral and achiral H-nucleophiles, yielding the configurationally stable P-diol 10a or, optionally, the M-product 10b. From the axially chiral phenylisoquinolines thus obtained atropo-diastereodivergently, the authentic natural naphthylisoquinolines with the respective axial configurations, korupensamines A (1a) and B (1b), were obtained by completion of the second naphthalene ring, starting from the previous "bridgehead" C1 unit.
Assuntos
Antimaláricos/síntese química , Isoquinolinas/síntese química , Naftalenos/síntese química , Catálise , Cromatografia Líquida de Alta Pressão , Lactonas/química , Espectroscopia de Ressonância Magnética , Paládio , Plantas Medicinais/química , Espectrofotometria Ultravioleta , EstereoisomerismoRESUMO
The first synthesis of an N-quaternary salt of a naphthylisoquinoline alkaloid, N,N-dimethyldioncophyllinium A iodide, is described. For this potential natural product, a degradative procedure for the unambiguous stereoanalysis of the stereogenic centers has been elaborated. It shows enhanced anti-plasmodial activity in vitro towards Plasmodium falciparum erythrocytic forms, as compared to its less methylated precursors.
