In Vitro Antiophidian Mechanisms of Hypericum brasiliense Choisy Standardized Extract: Quercetin-Dependent Neuroprotection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The neuroprotection induced by Hypericum brasiliense Choisy extract (HBE) and its main active polyphenol compound quercetin, against Crotalus durissus terrificus (Cdt) venom and crotoxin and crotamine, was enquired at both central and peripheral mammal nervous system. Cdt venom (10 mu g/mL) or crotoxin (1 mu g/mL) incubated at mouse phrenic nerve-diaphragm preparation (PND) induced an irreversible and complete neuromuscular blockade, respectively. Crotamine (1 mu g/mL) only induced an increase of muscle strength at PND preparations. At mouse brain slices, Cdt venom (1, 5, and 10 mu g/mL) decreased cell viability. HBE (100 mu g/mL) inhibited significantly the facilitatory action of crotamine (1 mu g/mL) and was partially active against the neuromuscular blockade of crotoxin (1 mu g/mL) (data not shown). Quercetin (10 mu g/mL) mimicked the neuromuscular protection of HBE (100 mu g/mL), by inhibiting almost completely the neurotoxic effect induced by crotoxin (1 mu g/mL) and crotamine (1 mu g/mL). HBE (100 mu g/mL) and quercetin (10 mu g/mL) also increased cell viability in mice brain slices. Quercetin (10 mu g/mL) was more effective than HBE (100 mu g/mL) in counteracting the cell lysis induced by Cdt venom (1 and 10 mu g/mL, resp.). These results and a further phytochemical and toxicological investigations could open new perspectives towards therapeutic use of Hypericum brasiliense standardized extract and quercetin, especially to counteract the neurotoxic effect induced by snake neurotoxic venoms.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundo de Apoio ao Ensino, a Pesquisa e Extensao (FAEPEX)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES [063/2010