Estudo químico das espécies Kielmeyera argentea e K. lathrophyton (Calophyllaceae) e avaliação da atividade citotóxica de 4-fenil e 4-alquilcumarinas frente a células de glioblastoma humano

Abstract

The present work describes the chemical study of hexanic extract of the roots of Kielmeyera argentea and of the stems of K. lathrophyton (Calophyllaceae) as well as the evaluation of the cytotoxic activity in vitro of 4-phenyl and 4-alkylcoumarins against U251 cell line of human glioblastoma. The compounds mammea B/BA, mammea B/BA cycle F, ferruol A and mammea A/BB were isolated from hexanic extract of K. argentea through successive chromatographic processes for the first time in the genus Kielmeyera. The presence of 4-alkylcoumarins mammea B/AB cycle D and mammea B/AA cycle D were also observed in addition to the substances friedelin and -tocotrienol. The xanthones 1-hydroxy-3,6-dimethoxy-8-methylxanthone and 1,8-dihydroxy-3-methoxy-6-xanthones as well as the compound methyl 2,4-dihydroxy-3,6-dimethylbenzoate were isolated from the hexanic extract of K. lathrophyton and these is reported for the first time in the Calophyllaceae family. In addition, the compounds 7-methoxy-2,2-dimethyl-6-(2-methylbutanoyl)-10-phenyl-2H-8H-benzo[1,2-b:3,4-b']dipyran-8-one, 1-hydroxy-7-methoxystatin, friedelin and epifriedelanol were also isolated. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic analysis and by comparison with literature data. The biological assay showed that the 4-alkylcoumarin mammea B/BA exhibited significtive actived with an IC50 value of 6.60μM while the compounds mammea B/BA cycle F (IC50 = 52,26 μM), ferruol A (IC50 =37,07 μM) and mammea A/BB (IC50 = 27,00 μM) showed moderate activity against the tumor cells.