The component of Carica papaya seed toxic to A-aegypti and the identification of tegupain, the enzyme that generates it

Author(s)

Nunes, Natalia N. dos S. ^[1] ; Santana, Lucimeire A. ^[1] ; Sampaio, Misako U. ^[1] ; Lemos, Francisco J. A. ^[2] ; Oliva, Maria Luiza ^[1]

Affiliation

^[1] Univ Fed Sao Paulo, Dept Bioquim, BR-04044020 Sao Paulo - Brazil

^[2] Univ Estadual Norte Fluminense, Biotechnol Lab, Campos Dos Goytacazes, RJ - Brazil

• Document type: Journal article
• Source: Chemosphere; v. 92, n. 4, p. 413-420, JUL 2013.
• Web of Science Citations: 8

Abstract

As Aedes aegypti transmits the etiologic agents of both yellow and dengue fever; vector control is considered essential to minimise their incidence. The aim of this work was to identify the component of Carica papaya seed toxic to A. aegypti, and the identification of tegupain, the enzyme that generates it. Aqueous extracts (1%, w/v) of the seed tegument and cotyledon of C. papaya are not larvicidal isolately. However, a mixture of 17 mu g mL(-1) tegument extract and 27 mu g mL(-1) cotyledon extract caused 100% larval mortality in a bioassay. The mixture was no longer larvicidal after the tegument extract was pre-treated at 100 degrees C for 10 min. The enzyme tegupain efficiently hydrolysed the substrate Z-Phe-Arg-pNan (K-m 58.8 mu M, K-cat 28020 s(-1), K-cat/K-m 5 x 10(8) M-1 s(-1)), and its activity increased with 2 mM dithiothreitol (DTT), at 37 degrees C, pH 5.0. The chelating agent EDTA did not modify the enzyme activity. Inhibition of tegupain by cystatin (K-iapp 2.43 nM), E64 (3.64 nM, 83% inhibition), and the propeptide N-terminal sequence indicate that the toxic activity is due to a novel cysteine proteinase-like enzyme, rendered active upon the hydrolysis of a cotyledon component of C. papaya seeds. (c) 2013 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 09/17058-6 - Purification and characterization of compounds isolated from plants with larvicidal activity.
• Grantee: Natalia Neto dos Santos Nunes
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 09/53766-5 - Proteins from plant source with selectivity for inhibition of mammalian enzymes and their role as an anti-inflammatory, antithrombotic, anti-diabetic and anti-tumor agent
• Grantee: Maria Luiza Vilela Oliva
• Support Opportunities: Research Projects - Thematic Grants