RESUMO
Two highly oxygenated nortriterpenes, picraviane A and B, were isolated from the ethanolic extract of Picramnia glazioviana Engl. The structures were determined by analysis of HRMS and 2D NMR spectroscopic data. Single-crystal X-ray diffraction data was also obtained for picraviane B. The absolute configuration of both compounds were assigned by comparison of experimental and calculated vibrational and electronic circular dichroism spectroscopy, respectively. Picraviane A showed a moderate cytotoxic activity against the triple negative MDA-MB-231 breast cancer cell line. These compounds represent an undescribed class of natural products with limonoid-like skeletons containing a heptanolide as the E-ring.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Produtos Biológicos/farmacologia , Simaroubaceae/química , Triterpenos/farmacologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Produtos Biológicos/química , Produtos Biológicos/isolamento & purificação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Modelos Moleculares , Conformação Molecular , Estereoisomerismo , Relação Estrutura-Atividade , Triterpenos/química , Triterpenos/isolamento & purificaçãoRESUMO
The trypanocidal activity of crude extracts and fractions from the leaves and stems of Peperomia obtusifolia (Piperaceae) was evaluated in vitro against the epimastigote forms of Trypanosoma cruzi. Bioactivity-guided fractionation of the most active extracts afforded seven known compounds, including three chromanes, two furofuran lignans and two flavone C-diglycosides. The most active compounds were the chromanes peperobtusin A and 3,4-dihydro-5-hydroxy-2,7-dimethyl-8-(2''-methyl-2''-butenyl)-2-(4'-methyl-1',3'-pentadienyl)-2 H-1-benzopyran-6-carboxylic acid, with IC (50) values of 3.1 microM (almost three times more active than the positive control benznidazole, IC (50) 10.4 microM) and 27.0 microM, respectively. Cytotoxicity assays using peritoneal murine macrophages indicated that the chromanes were not toxic at the level of the IC (50) for trypanocidal activity. This is the first report on the trypanocidal activity besides unspecific cytotoxicity of chromanes from Peperomia species. Additionally it represents the first time isolation of 3,4-dihydro-5-hydroxy-2,7-dimethyl-8-(2''-methyl-2''-butenyl)-2-(4'-methyl-1',3'-pentadienyl)-2 H-1-benzopyran-6-carboxylic acid from P. obtusifolia.
