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Open AccessArticle

Chemical and Pharmacological Screening of Rhinella icterica (Spix 1824) Toad Parotoid Secretion in Avian Preparations

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Laboratório de Neurobiologia e Toxinologia, Programa de Pós-Graduação em Ciências Biológicas (PPGCB), Universidade Federal do Pampa (UNIPAMPA), Avenida Antônio Trilha 1847, São Gabriel RS 97300-000, Brazil
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Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica (PPGBTox), Universidade Federal de Santa Maria (UFSM), Avenida Roraima 1000, Santa Maria RS 97105-900, Brazil
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Laboratório de Biotecnologia de Produtos Naturais e Sintéticos, Instituto de Biotecnologia, Universidade de Caxias do Sul (UCS), Rua Francisco Getúlio Vargas 1130, Caxias do Sul RS 95070-560, Brazil
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Departamento de Ciências BioMoleculares, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo (USP), Avenida do Café, s/n, Ribeirão Preto SP 14.040-903, Brazil
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Laboratório de Estudos em Biodiversidade Pampiana, Universidade Federal do Pampa (UNIPAMPA), Avenida Antônio Trilha 1847, São Gabriel RS 97300-000, Brazil
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Departamento de Farmacologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária Zeferino Vaz, Campinas SP 13083-887, Brazil
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Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo (USP), Avenida Bandeirantes 3900, Ribeirão Preto SP 14040-030, Brazil
*
Authors to whom correspondence should be addressed.
Toxins 2020, 12(6), 396; https://doi.org/10.3390/toxins12060396
Received: 23 April 2020 / Revised: 12 May 2020 / Accepted: 22 May 2020 / Published: 15 June 2020
(This article belongs to the Special Issue Animal Venoms and Their Components: Molecular Mechanisms of Action)
The biological activity of Rhinella icterica parotoid secretion (RIPS) and some of its chromatographic fractions (RI18, RI19, RI23, and RI24) was evaluated in the current study. Mass spectrometry of these fractions indicated the presence of sarmentogenin, argentinogenin, (5β,12β)-12,14-dihydroxy-11-oxobufa-3,20,22-trienolide, marinobufagin, bufogenin B, 11α,19-dihydroxy-telocinobufagin, bufotalin, monohydroxylbufotalin, 19-oxo-cinobufagin, 3α,12β,25,26-tetrahydroxy-7-oxo-5β-cholestane-26-O-sulfate, and cinobufagin-3-hemisuberate that were identified as alkaloid and steroid compounds, in addition to marinoic acid and N-methyl-5-hydroxy-tryptamine. In chick brain slices, all fractions caused a slight decrease in cell viability, as also seen with the highest concentration of RIPS tested. In chick biventer cervicis neuromuscular preparations, RIPS and all four fractions significantly inhibited junctional acetylcholinesterase (AChE) activity. In this preparation, only fraction RI23 completely mimicked the pharmacological profile of RIPS, which included a transient facilitation in the amplitude of muscle twitches followed by progressive and complete neuromuscular blockade. Mass spectrometric analysis showed that RI23 consisted predominantly of bufogenins, a class of steroidal compounds known for their cardiotonic activity mediated by a digoxin- or ouabain-like action and the blockade of voltage-dependent L-type calcium channels. These findings indicate that the pharmacological activities of RI23 (and RIPS) are probably mediated by: (1) inhibition of AChE activity that increases the junctional content of Ach; (2) inhibition of neuronal Na+/K+-ATPase, leading to facilitation followed by neuromuscular blockade; and (3) blockade of voltage-dependent Ca2+ channels, leading to stabilization of the motor endplate membrane. View Full-Text
Keywords: Anti-AChE activity; avian; chick neurobiological preparations; cytotoxicity; neuromuscular blockade; toad poison Anti-AChE activity; avian; chick neurobiological preparations; cytotoxicity; neuromuscular blockade; toad poison
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Oliveira, R.S.; Borges, B.T.; Leal, A.P.; Lailowski, M.M.; Bordon, K.C.F.; Souza, V.Q.; Vinadé, L.; Santos, T.G.; Hyslop, S.; Moura, S.; Arantes, E.C.; Corrado, A.P.; Dal Belo, C.A. Chemical and Pharmacological Screening of Rhinella icterica (Spix 1824) Toad Parotoid Secretion in Avian Preparations. Toxins 2020, 12, 396.

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