The Protective Action of Coutarea hexandra (Rubiaceae) on the Neuromuscular Blockade Induced by Lachesis muta muta (Viperidae: Crotalinae) Venom.

Envenomations by snakes represent a neglected health problem in tropical and subtropical countries. In South America, Lachesis muta occasionally causes severe human envenomation, with treatment being conditioned to an unspecific antivenom. In this work, we examined the neutralizing ability of Coutarea hexandra stem bark hydroalcoholic extract (Ch-E), including the commercial phytochemicals coumarin and quinine, on the neuromuscular blockade induced by L. m. muta venom in mouse phrenic nerve-diaphragm preparation. Biological assays were performed following conventional myographic technique ex vivo. Ch-E was phytochemically characterized to detect the presence of coumarin and quinine using analytical methods. Ch-E and commercial phytochemicals were tested separately or combined under pre- and post-venom incubation protocols. Ch-E attenuated the venom-induced neuromuscular blockade only under the pre-venom incubation protocol. Quinine was not detected in Ch-E. Commercial coumarin and quinine exhibited a concentration-dependent counteracting effect on the venom-induced neuromuscular blockade. The pre-venom incubation protocol showed to be efficient in attenuating the L. m. muta venom-induced neuromuscular blockade, most likely due to the presence of coumarin derivatives and unknown alkaloids in this extract.