Identificação molecular e caracterização estrutural de ciclotídeo de palicourea rígida com potencial inseticida

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

11/11/2010

RESUMO

Over the years, there have been several discoveries of peptides containing a cyclic structural fold. Among these molecules the cyclotides family was reported, being composed of small cyclic peptides containing 6 (six) conserved cysteine residues, connected by disulfide bonds forming a cysteine binding cyclic structure also known as "Cyclic Cysteine Knot" (CCK), responsible for enhanced structural stability against chemical, thermal and proteolytic degradation. Due to this stability, grouving interests in discovering the structural characteristics and biological function of this family have been observed. In this way, this work aims to isolate and characterize a cyclotide from Palicourea rigida (Rubiaceae), popularly known as the bate-caixa, with insecticidal and hemolytical activities. For this, leaves of P. rigida were crushed with extraction solution dichloromethane/methanol (1:1). After extraction, the crude extract was purified in multiple steps, including size exclusion chromatography by using a Sephadex G-10 resin, followed by reverse-phase chromatography HPLC and UFLC. Mass spectrometry analysis (MALDI-ToF/ToF and LC-MS/MS) indicated that the molecular mass of Parigidina-br 1 is 3.278 Da. Moreover, the sequence clearly indicated that this peptide is a member of the family of Bracelets cyclotides, now named Parigidina-br 1. In addition, the antimicrobial activity of Parigidina-br 1 was evaluated against Gram-negative bacteria (Escherichia coli) and Gram-positive (Staphylococcus aureus) showing a negative result for inhibition the growth of these bacteria. This same peptide was also challenged in vivo against neonate larvae of Lepidoptera (Diatraea saccharalis), and against insect SF-9 cells, showing remarkable insecticide and cytotoxic activities. Finally, the peptide citotoxicity against mammalian cells was also performed; causing a 41 % of hematocrit disruption. In conclusion, the results herein reported indicate that in the near future, the Parigidina-br 1 may be used in the development of new biopesticides.

ASSUNTO(S)

estrutura molecular inseticidas genética genetica cyclic peptide cyclotides palicourea rígida insecticide

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