Nanoparticle-conjugated venom-toxins of venomous animals and its therapeutic efficacy against emerging or neglecting diseases is a promising strategy. In this study, silver nanoparticles (AgNPs ∼50 nm, 0.081 mg mL) were studied against the neuromuscular blockade, myotoxic effects induced by Bothrops jararacussu venom (60 µg mL) and also against prokaryotic cells. The neurotoxicity was evaluated on ex vivo mouse phrenic nerve-diaphragm using traditional myographic technique, able to obtain functional contractile responses and to check the neurotransmission. The myotoxicity on mammalian cells was evaluated in muscles resulting from pharmacological assays using routine histological techniques and light microscopy. The toxicity to prokaryotic cells was evaluated on Salmonella typhimurium TA100 without metabolic activation. The in vitro preincubation model between AgNPs and venom was enough to abolish toxic effects of B. jararacussu venom, but mammalian cells were highly sensitive to AgNPs more than prokaryotic cells, by acting as dose-independently and dose-dependently parameters, respectively. These results allowed us to conclude that AgNPs showed promising activity as antivenom agent but for its safer use, the toxicity should be evaluated on experimental animals.

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The ability of Terminalia fagifolia hydroalcoholic extract (Tf-HE) to neutralise the paralysis and myotoxicity induced by Bothrops jararacussu venom was assayed using mouse phrenic nerve-diaphragm (PND) preparation and two varieties of chick biventer cervicis (BC) preparations. Tf-HE 100 μg/mL and 500 μg/mL were tested against 40 and 200 μg of venom/mL in PND and BC preparations, respectively, using pre- and post-venom incubation treatments. The effects of Tf-HE against the myotoxicity caused by venom were evaluated via histological analysis (PND) and creatine kinase (CK) release (BC). Tf-HE was able to reverse the venom paralysis in both preparation types. The contractures to exogenous ACh in BC preparations showed that Tf-HE may act on extrinsic, preserving those intrinsic postsynaptic receptors. There was a positive correlation between CK and morphological changes. The high non-hemolytic saponin content can explain the Tf-HE efficacy against the toxic effects of B. jararacussu venom in vertebrate neuromuscular preparations.

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SUMMARYVochysia haenkeana extract (Vh-E) was assessed against the neuromuscular blockade induced by Bothrops jararaca venom on chick biventer cervicis (BC) preparation. Pre-and post-venom incubation treatments (Pre-vit and Post-vit) were analysed here. Contractures ACh (110 μM) and KCl (20 mM) were evoked before and after addition of venom without stimulation. Vh-E (600 μg/mL) under Pre-vit was more effi cient to neutralize the neuromuscular blockade by venom (40 μg/mL) [72.5±4.6% (venom) vs. 45.2±14% (Vh-E) of blockade, p<0.05, n=4]. Vh-E (600 μg/mL) did not cause signifi cant changes under Post-vit [72.5±4.6% (venom) vs. 63.4±8.2% (Vh-E) of blockade, n=4]. The Pre-vit inhibited the blockade of the contracture to ACh (106±17% of response; n=4) while the Post-vit was able to attenuate the effect of the venom on this contracture (55±5% of response; n=4); related to those contractures to KCl both of treatments with Vh-E attenuated the blocker effect of the venom (62.5±7.7% and 55±5% of response for Pre-vit and Post-vit, respectively; n=4). In conclusion, Vh-E neutralizes partially the neuromuscular blockade in Pre-vit, an effect that can be related to preserved function of "extrinsic" post-synaptic receptors, by measured contractures in response to ACh. The myotoxicity of the venom was signifi cantly reduced by Vh-E in both, Pre-vit and Post-vit, by measured contractures in response to KCl.

Nephrolepis exaltata (L.) Schott decreases the heartbeats of cockroaches and it was postulated that the plant could be an anticholinesterase agent and could have effects. It was performed: (a) In vitro: hydroalcoholic extract of N. exaltata was pharmacognostically characterized, the cholinesterase activity determined with 1.0 and 3.0 mg/ml, comparing to positive control and negative control, and the preliminary toxicity was evaluated with 5 mg/plate through Salmonella/microsome assay using TA100 strain; (b) Ex vivo: 2, 5, or 10 mg of extract was assayed on mouse phrenic nerve-diaphragm preparation using conventional myographic technique; and (c) In vivo: 2.0, 1.0 or 0.5 g of extract was exposed to Allium cepa root cells, using onions bulbs for further measuring and microscopic analysis. The cholinesterase activities (U/L, n=3) of 1.0 and 3.0 mg/mL fern extract were of 2,866.6 ± 200.7 and 3,092.9 ± 214.2, respectively, versus 87.1 ± 58.1 (p<0.05) for positive control. The extract showed the absence of micronucleus and inhibited the root growth reaching 100% at 2 mg. The plant has no anticholinesterase activity, it is not toxic on bacterial reverse mutation or nerve-muscle parameters and is not genotoxic on A. cepa assay, but inhibits the root growth of A. cepa.