Antiophidian Mechanisms Of Medicinal Plants

Vegetal extracts usually have a large diversity of bioactive compounds showingseveral pharmacological activities, including antiophidian properties. In this study, bothcoumarin and tannic acid (100 μg/mL) showed no changes in the basal response oftwitches in mouse nerve phrenic diaphragm preparations. In opposite, Crotalus durissusterrificus (Cdt 15 μg/mL) or Bothrops jararacussu (Bjssu 40 μg/mL) venoms causedirreversible neuromuscular blockade. Tannic acid (preincubated with the venoms), butnot coumarin, was able to significantly inhibit (p<0.05) the impairment of the musclestrength induced by Cdt (88 ± 8%) and Bjssu (79 ± 7.5%), respectively. A remarkableprecipitation was observed when the venoms were preincubated with tannic acid, but notwith coumarin. Plathymenia reticulata is a good source of tannins and flavonoidswhereas Mikania laevigata contain high amounts of coumarin. P. reticulata (PrHE, 0.06mg/mL) and M. laevigata (MlHE, 1 mg/mL) hydroalcoholic extracts were assayed withor without Bjssu or Cdt venoms. Both PrHE and MlHE showed protection against Bjssu(79.3 ± 9.5% and 65 ± 8%, respectively) and Cdt (73.2 ± 6.7% and 95 ± 7%,respectively) neuromuscular blockade. In order to observe if the protective mechanismcould be induced by protein precipitation, tannins were eliminated from both extracts andthe assay was repeated. MlHE protected against the blockade induced by Bjssu (57.2 ±6.7%), but not against Cdt. We concluded that plants containing tannins could induce theprecipitation of venoms' proteins and plants containing coumarin showed activity againstBothrops venoms, but not against Crotalus venoms. We also concluded that the use ofisolated bioactive compounds could not represent the better strategy against ophidianvenoms, since the purification may exclude some bioactive components resulting in aloss of antivenom activity. In addition, M. laevigata showed better antiophidian activitythan P. reticulata. © 2009 Nova Science Publishers, Inc. All rights reserved.