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A trypsin inhibitor purified from Cassia leiandra seeds has insecticidal activity against Aedes aegypti

2017; Elsevier BV; Volume: 57; Linguagem: Inglês

10.1016/j.procbio.2017.03.015

1873-3298

Lucas Pinheiro Dias, José T.A. Oliveira, Lady Clarissa Brito da Rocha-Bezerra, Daniele O.B. Sousa, Helen Paula Silva da Costa, Nadine Monteiro Salgueiro Araújo, Ana Fontenele Urano Carvalho, Pedro MS Tabosa, Ana Cristina de Oliveira Monteiro‐Moreira, Marina Duarte Pinto Lobo, Frederico Bruno Mendes Batista Moreno, B.A.M. Rocha, José Luiz de Souza Lopes, Leila Maria Beltramini, Ilka M. Vasconcelos,

Insect Pest Control Strategies

A trypsin inhibitor from Cassia leiandra seeds, named ClTI, was purified, characterized, and its insecticidal activity against Aedes aegypti evaluated. ClTI was purified by DEAE-Cellulose and trypsin-Sepharose 4B chromatography, with a 15.5-fold purification and 2.4% yield. ClTI is composed of a 19,484 Da polypeptide chain as revealed by mass spectrometry, it is not a glycoprotein, its amino acid sequence is similar to other Kunitz-type inhibitors, and it comprises 35% β-sheets, 14% β-turns, and 50% disordered secondary structures. ClTI is an uncompetitive inhibitor of bovine trypsin (IC50 of 33.81 × 10−8 M, Ki of 6.25 × 10−8 M) stable over a broad range of pHs (2.2–10.0) and temperatures (30–70 °C), but dithiothreitol led to a partial loss of the inhibitory activity. ClTI, at 4.65 × 10−6 M, reduced in 50% the activity of the Ae. aegypti midgut proteases. ClTI also promoted acute toxicity on the 3rd instar larvae of Ae. aegypti, with an LC50 of 2.28 × 10−2 M. Moreover, it caused a 24-h delay of the larvae development and 44% mortality after ten days of exposure. Altogether, these results suggest that ClTI has potential as a natural compound to control Ae. aegypti, a vector of several infection diseases.