RESUMO
Four cyclic octapeptides, squamins C-F, were isolated from the seeds of Annona globiflora Schltdl. These compounds share part of their amino acid sequence, -Pro-Met(O)-Tyr-Gly-Thr-, with previously reported squamins A and B. Their structures were determined using NMR spectroscopic techniques together with quantum mechanical calculations (QM-NMR), ESI-HRMS data and a modified version of Marfey's chromatographic method. All compounds showed cytotoxic activity against DU-145 (human prostate cancer) and HeLa (human cervical carcinoma) cell lines. Clearly, A. globiflora is an important source of bioactive molecules, which could promote the sustainable exploitation of this undervalued specie.
Assuntos
Annona , Antineoplásicos Fitogênicos/farmacologia , Peptídeos Cíclicos/farmacologia , Sequência de Aminoácidos , Annona/química , Células HeLa , Humanos , Compostos Fitoquímicos/farmacologia , Sementes/químicaRESUMO
A new cyclic heptapeptide, ectyoplasin (1), was isolated from a methanol extract of the sponge Ectyoplasia ferox. The planar structure of 1, cyclo(-Leu1-Asn2-Ala3-Val4-Thr5-Pro6-Gly7-), was determined by one and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry. Its absolute stereochemistry was solved by Marfey's method. The in vitro assays show that ectyoplasin (1) possess significant cytotoxic activity (2.9 - 23.5 µM) against the cell lines, DU-145 (human prostate cancer), Jurkat (human T-cell acute leukaemia), MM144 (human multiple myeloma), HeLa (human cervical carcinoma) and CADO-ES1 (human Ewing's sarcoma). The DU-145 cell line showed apoptotic cell death in response to ectyoplasin (1) treatment.
Assuntos
Antineoplásicos , Poríferos , Animais , Antineoplásicos/farmacologia , Linhagem Celular , Humanos , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologia , Espectrometria de Massas em TandemRESUMO
Two novel natural metabolites, 3-O-butyl-(-)-epicatechin (1) and 3-O-butyl-(-)-epigallocatechin (2), as well as several known substances, (-)-epicatechin (3), (+)-gallocatechin (4), (-)-epigallocatechin (5), azadirachtin A (6), trilinolein (7) and octadecanoic acid-tetrahydrofuran-3,4-diyl ester (8), were isolated from the bark of Azadirachta indica. The structures of all compounds were established by comprehensive and comparative spectroscopic analysis of NMR and ESI-HRMS data. The new metabolites 1 and 2 represent one of the few examples of natural compounds with a butyl ether group moiety. The acaricidal activity of the compounds was tested using a standard Shaw larval immersion assay. All the compounds, except 7, possess a LD50 value less than or equal to 7.2 mM.
