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

The biological activity of 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, (5 ,12 )-12,14-dihydroxy-11-oxobufa-3,20,22-tr...

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Published in:	Toxins Vol. 12; no. 6; p. 396
Main Authors:	Oliveira, Raquel Soares, Borges, Bruna Trindade, Leal, Allan Pinto, Lailowski, Manuela Merlin, Bordon, Karla de Castro Figueiredo, Souza, Velci Queiróz de, Vinadé, Lúcia, Santos, Tiago Gomes Dos, Hyslop, Stephen, Moura, Sidnei, Arantes, Eliane Candiani, Corrado, Alexandre Pinto, Dal Belo, Cháriston A
Format:	Journal Article
Language:	English
Published:	Switzerland MDPI AG 15-06-2020 MDPI
Subjects:	Acetylcholinesterase Animals Anti-AChE activity avian Biological activity Brain - drug effects Brain - metabolism Brain - pathology Brain slice preparation Bufanolides - isolation & purification Bufanolides - toxicity Bufonidae Calcium Channel Blockers - isolation & purification Calcium Channel Blockers - toxicity Calcium channels Calcium channels (L-type) Calcium channels (voltage-gated) Calcium ions Cell Survival - drug effects Cell viability Channels chick neurobiological preparations Chickens Cholinesterase Inhibitors - isolation & purification Cholinesterase Inhibitors - toxicity cytotoxicity Digoxin Dose-Response Relationship, Drug Electric potential Mass spectrometry Mass spectroscopy Muscles Na+/K+-exchanging ATPase neuromuscular blockade Neuromuscular Junction - drug effects Neuromuscular Junction - metabolism Neuromuscular junctions Neurotoxins - isolation & purification Neurotoxins - toxicity Ouabain Parotid Gland - chemistry Pharmacology Proteins Rhinella icterica Secretion Secretory Pathway Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors Sodium-Potassium-Exchanging ATPase - metabolism Steroids Sulfates toad poison Toads Tryptamine Tryptamines Voltage Brazil chick neurobiological preparations neuromuscular blockade Anti-AChE activity toad poison cytotoxicity avian
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Summary:	The biological activity of 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, (5 ,12 )-12,14-dihydroxy-11-oxobufa-3,20,22-trienolide, marinobufagin, bufogenin B, 11α,19-dihydroxy-telocinobufagin, bufotalin, monohydroxylbufotalin, 19-oxo-cinobufagin, 3α,12 ,25,26-tetrahydroxy-7-oxo-5 -cholestane-26- -sulfate, and cinobufagin-3-hemisuberate that were identified as alkaloid and steroid compounds, in addition to marinoic acid and -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 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 Ca channels, leading to stabilization of the motor endplate membrane.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	2072-6651 2072-6651
DOI:	10.3390/toxins12060396