Estudo fitoquímico e bioatividade de Diplotropis purpurea e Deguelia duckeana

Abstract

The present phytochemical study describes the isolation and identification of nine compounds from the roots dichloromethanic and branches hexanic extracts of Deguelia duckeana and three compounds from the leaves of Diplotropis purpurea hexanic extract, both species belonging to the Fabaceae family. The compounds from Deguelia duckeana were identified as stilbene (3,5,4’-trimethoxy-4- prenylstilbene), chalcones (4-methoxylonchocarpin and 4-methoxyderricidin), flavanones (5-hydroxy-4’,7-dimethoxy-6-prenylflavanone, 5-hydroxy-4’- methoxyisolonchocarpin), flavones (3’,4’-methylenedioxy-7-methoxyflavone, 3’,4’,7- trimethoxyflavone, racemoflavone) and one lignan (yangambin). Unprecedentedly, this study describes flavanone 5-hydroxy-4’,7-dimethoxy-6-prenylflavanone as a natural product at the literature. Other compounds as chalcone 4- methoxylonchocarpin, flavone racemoflavone and the lignan are also described by Deguelia without have been reported so far. The compounds of Diplotropis purpurea were identified as triterpenes lupeol, taraxerol and β-amirin which are also first reported by Diplotropis, except lupeol. All the compounds were identified using 1H and 13C-NMR and LC/MS. In order to find active compounds, the extracts and isolated compounds from Deguelia duckeana were assayed for anticancer potential in neuroblastoma cells (SK-N-SH), among them one chalcone 4-hydroxylonchocarpin and one flavanone 4-hydroxyisolonchocarpin showed cytotoxicity by lactate dehydrogenase (LDH) assay. These two compounds also activated caspase-3, which indicate cell death via necrose and apoptosis. The other flavonoids induced phosphorylation of the eukaryotic elongation factor 2 (eEF2) and one flavone also induced AMP-activated protein kinase (AMPK). These results suggest that flavonoids have anticancer potential due to their effect on protein synthesis. Another biological activity examined in the present study was antibacterial activity of Diplotropis purpurea extracts and the most active was the methanolic extract from leaves, against three bacterial strains: Serratia marcescens (MIC at 250 mg/mL), Bacillus cereus (MIC at 1000 mg/mL) inhibiting 66% of bacterial growth in comparison with positive control and Providencia rettgeri (MIC at 250 mg/mL) with 69.5% of inhibition in comparison with positive control. The present study contributes to Deguelia duckeana and Diplotropis purpurea species chemical studies, due to their biological activities and description of six compounds on the genus are described by the first time at the literature. Among those compounds, one of them is also reported by the first time as a natural product.