Influence of Lafoensia pacari (Lythraceae) against the neuromuscular blockade-induced by bothropstoxin-I

Abstract

The Lafoensia pacari A.St.-Hil. (Lythraceae) species, popularly known as “pacari”, is native to the Cerrado and has numerous medicinal properties. On the other hand, snakebites caused by Bothrops jararacussu cause symptoms such as inflammation, oedema, necrosis in the bite region with extensive local tissue damage, haemorrhages, in vitro neurotoxic and myotoxic effects – caused by bothropstoxin-I (BthTX-I), the myotoxin which corresponds to 15% of the total snake venom. The objective of this study was to evaluate the influence of Lafoensia pacari extract on the neuroblocking effect of BthTX-I. The study was approved by the Animal Use Ethics Committee according to Protocol 159/2019. Pharmacological assays (preincubation and post-myotoxin models) were performed on mouse phrenic nerve-diaphragm preparations (ex vivo), using conventional myographic technique. The results were statistically analyzed by comparing the neutralizing capacity of pacari extract (40 µg/mL) against the neuromuscular blockade induced by BthTX-I (40 µg/mL), as well as the controls Tyrode and pacari extract and BthTX-I only. The venom alone caused a blockade of around 80% ± 8. The extract, which does not change the basal response of the neuromuscular preparation, protected against the blockade induced by myotoxin in a preincubation model (102% ± 2 of functioning fibres) and, partially, in a post-myotoxin model (60% ± 8 of functioning fibres). It is concluded that the plant extract has high antivenom potential and the participation of tannins, in addition to other constituents, in eliminating the toxic effect of neuromuscular blockade induced by BthTX-I is suggested.