Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase

This study analyses venom from the elapid krait snake Bungarus sindanus, which contains a high level of acetylcholinesterase (AChE) activity. The enzyme showed optimum activity at alkaline pH (8.5) and 45ºC. Krait venom AChE was inhibited by substrate. Inhibition was significantly reduced by using a high ionic strength buffer; low ionic strength buffer (10 mM PO4 pH 7.5) inhibited the enzyme by 1. 5mM AcSCh, while high ionic strength buffer (62 mM PO4 pH 7.5) inhibited it by 1 mM AcSCh. Venom acetylcholinesterase was also found to be thermally stable at 45ºC; it only lost 5% of its activity after incubation at 45ºC for 40 minutes. The Michaelis-Menten constant (Km) for acetylthiocholine iodide hydrolysis was found to be 0.068 mM. Krait venom acetylcholinesterase was also inhibited by ZnCl2, CdCl2, and HgCl2 in a concentrationdependent manner. Due to the elevated levels of AChE with high catalytic activity and because it is more stable than any other sources, Bungarus sindanus venom is highly valuable for biochemical studies of this enzyme.(AU)

Peroxidação lipídica em ratos tratados com sulfato de vincristina e decanoato de nandrolona / Lipid peroxidation in rats treated with vincristine sulphate and nandrolone decanoate

Brain and serum lipid peroxidation was studied in rats treated with vincristine sulphate and different doses of nandrolone decanoate. Thirty rats were distributed into six groups (n=5). The treatments were applied once a week for two weeks. Sample collection was performed in the third week. Treatments during the first week were: G1 (control) - physiologic solution, G2 - vincristine sulphate (4mg/m²), G3 - physiologic solution, G4 - physiologic solution, G5- vincristine sulphate (4mg/m²), and G6 - vincristine sulphate (4mg/m²). In the second week, they were: G1 (control) - physiologic solution, G2- physiologic solution, G3 - nandrolone decanoate (1.8mg/kg-1), G4 - nandrolone decanoate (10mg/kg-1), G5 - nandrolone decanoate (1.8mg/kg-1), and G6 - nandrolone decanoate (10mg/kg-1). Lipid peroxidation increased with the isolated use of vincristine and nandrolone decanoate, and with vincristine associated to the highest dose of the ester as well. These results suggest that vincristine sulphate and nandrolone decanoate increase free radical production. Therapeutic dose of nandrolone decanoate when associated with vincristine sulphate proved to be beneficial, as it was able to protect the organism from damaging processes involved in free radical production.

Este estudo teve por objetivo detectar a peroxidação lipídica presente no cérebro e no soro de ratos tratados com sulfato de vincristina e diferentes doses de decanoato de nandrolona. Trinta ratos foram distribuídos em seis grupos (n=5). Os tratamentos foram aplicados uma vez por semana, durante duas semanas, e a coleta de amostras foi realizada na terceira semana. Na primeira semana, os tratamentos consistiram de: G1(controle) - solução fisiológica; G2 - sulfato de vincristina (4mg/m 2 ); G3 - solução fisiológica; G4 - solução fisiológica; G5 - sulfato de vincristina (4mg/m 2 ) e G6 - sulfato de vincristina (4mg/m 2 ). Na segunda semana: G1(controle) - solução fisiológica; G2 - solução fisiológica; G3 - decanoato de nandrolona (1.8mg/kg-1 ); G4 - decanoato de nandrolona (10mg/kg-1 ); G5 - decanoato de nandrolona (1.8mg/kg-1 ) e G6 - decanoato de nandrolona (10mg/kg-1 ). A peroxidação lipídica aumentou com o uso isolado tanto da vincristina quanto do decanoato de nandrolona e com a associação da vincristina à dose mais alta do éster. Estes resultados sugerem que o sulfato de vincristina e o decanoato de nandrolona aumentam a produção de radicais livres. A dose terapêutica do decanoato de nandrolona, quando associada ao sulfato de vincristina, provou ser benéfica, já que foi capaz de proteger o organismo dos processos prejudiciais induzidos pela produção de radicais livres.