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.