Atividade do extrato de frutos de Pterodon emarginatus contra o estresse oxidativo e nitrosativo induzido por exercicio agudo em ratos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

High-intensity exercise can cause muscle damage. Evidences point to a strong association between physical exercise-induced muscle damage and reactive oxygen (ROS) and nitrogen (RNS) species. Animal studies have shown that phytochemical antioxidants, such as terpens and phenols are capable of removing free radicals. Previous chemical analysis of the hexane crude extract (HCE) of Peterodon emarginatus showed the presence of the acid 6?, 7?-dihydroxyvouacapane-17?-oic (diterpenoid), ?-cariophilene, ?-pinene, myrcene, eugenol and geraniol. The aim of the present work was to evaluate the effect of HCE in oxidative and nitrosative stress induced by intense exercise in brain, liver and tibialis anterior muscle of rats. Adult male Wistar rats were submitted to standardized contractions by functional electrical stimulation (FES) of the anterior tibialis muscles (50 Hz, 15 min). Animals were subjected to one doses (30 min before or 30 min after exercise) or three doses (24h, 12h and 30 min before exercise) of 498 mg/kg HCE oral administration. Serum creatine kinase (CK) activities were measured by kinetic method. Lipoperoxidation was estimated by measuring of thiobarbituric acid-reactive substances (TBARS). NO production was evaluated by measuring nitrite formation, using Griess reagent and tyrosine nitration was assessed by western blot analysis. In vitro studies demonstrated that HCE inhibited guaiacol oxidation (IC50=19,8?g/mL) as well as brain and muscle lipid peroxidation with IC50 of 16,2 ?g/mL and 26,7?g/mL, respectively. The extract affected nitric oxide synthase (NOS) activity in brain (IC50=49?g/mL) and muscle (IC50=42,3?g/mL) homogenates of adult Wistar rats. Nitrite production in brain and muscle tissue homogenates decreased in the presence of NOS inhibitors (NG-nitro-L-arginine methyl ester and aminoguanidine) and was even lower in the presence of HCE. The in vivo studies demonstrated that serum CK activities in the controls (111U/L) increased after 1h FES (443U/L). Intense exercise also increased the lipid peroxidation in the brain (108,9%), liver (55,5%) and tibialis anterior muscle (967%), and also nitrite levels in 90,5%, 30,7%, 60%, respectively. The tyrosine nitration induced by exercise was identified in these tissues. Previous treatment with HCE decreased the lipoperoxidation, nitrite production and also the tyrosine nitration leading to the levels of controls. This effect could be explained by the chemical composition of this extract, that has phenols and terpens, which exhibit free radical scavenging activity and the present results also indicate that EHB has also NOS inhibitory properties

ASSUNTO(S)

musculos - ferimentos e lesões estresse oxidativo

ACESSO AO ARTIGO

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