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Characterization of a Bioactive Acyclotide from Palicourea rigida

Pinto, Michelle F. S., Silva, Osmar N., Viana, Juliane C., Porto, William F., Migliolo, Ludovico, B. da Cunha, Nicolau, Gomes, Nelson, Fensterseifer, Isabel C. M., Colgrave, Michelle L., Craik, David J., Dias, Simoni C., Franco, Octavio L.
Journal of natural products 2016 v.79 no.11 pp. 2767-2773
Palicourea, adenocarcinoma, anticarcinogenic activity, breast neoplasms, cytotoxicity, genes, hemolysis, inhibitory concentration 50, leaves, neoplasm cells
The extraction and purification of parigidin-br3, a cyclotide analogue belonging to the “bracelet” subfamily, from Palicourea rigida leaves is discussed. Unlike conventional cyclotides, parigidin-br3 has free N- and C-termini, as identified by MALDI-TOF/TOF analysis and confirmed by gene structure elucidation, and is one of a small number of acyclotides discovered during recent years. Parigidin-br3 showed cytotoxic activity against MCF-7 (breast cancer) and CACO2 (colorectal adenocarcinoma) cells, with IC₅₀ values of ∼2.5 μM and less than 10% hemolytic activity. Overall, parigidin-br3 is a promising new molecule with cytotoxic properties against tumor cell lines and, unlike many synthetic acyclic analogues, demonstrates that cytotoxic activity is not limited to conventional (i.e., cyclic) cyclotides.