Purification and n-terminal sequencing of two presynaptic neurotoxic PLA2, neuwieditoxin-I and neuwieditoxin-II, from Bothrops neuwiedi pauloensis (jararaca pintada) venom

Two presynaptic phospholipases A2 (PLA2), neuwieditoxin-I (NeuTX-I) and neuwieditoxin-II (NeuTX-II), were isolated from the venom of Bothrops neuwiedi pauloensis (BNP). The venom was fractionated using molecular exclusion HPLC (Protein-Pak 300SW column), followed by reverse phase HPLC (æBondapak C18 column). Tricine-SDS-PAGE in the presence or absence of dithiothreitol showed that NeuTX-I and NeuTX-II had a molecular mass of approximately 14 kDa and 28kDa, respectively. At 10æg/ml, both toxins produced complete neuromuscular blockade in indirectly stimulated chick biventer cervicis isolated preparation without inhibiting the response to acetylcholine, but NeuTX-II reduced the response to KCl by 67.0±8.0 percent (n=3; p<0.05). NeuTX-I and NeuTX-II are probably responsible for the presynaptic neurotoxicity of BNP venom in vitro. In fact, using loose patch clamp technique for mouse phrenic nerve-diaphragm preparation, NeuTX-I produced a calcium-dependent blockade of acetylcholine release and caused appearance of giant miniature end-plate potentials (mepps), indicating a pure presynaptic action. The N-terminal sequence of NeuTX-I was DLVQFGQMILKVAGRSLPKSYGAYGCYCGWGGRGK (71 percent homology with bothropstoxin-II and 54 percent homology with caudoxin) and that of NeuTX-II was SLFEFAKMILEETKRLPFPYYGAYGCYCGWGGQGQPKDAT (92 percent homology with Basp-III and 62 percent homology with crotoxin PLA2). The fact that NeuTX-I has Q-4 (Gln-4) and both toxins have F-5 (Phe-5) and Y-28 (Tyr-28) strongly suggests that NeuTX-I and NeuTX-II are Asp49 PLA2.

Efecto hepatoprotector inducido por el flavonoide Astilbina frente a un modelo animal tratado con tetracloruro de carbono / Astilbina flavonoid-induced hepatoprotective effect versus an animal model given carbon tetrachloride

En este estudio los niveles de Malonildialdehído, Transaminasa Glutámico Pirúvica y la Fosfolipasa A2 se determinaron en homogenato de hígado de ratas hembras para comprobar el posible efecto antilipoperoxidativo del flavonoide Astilbina (40 mg/g) frente al modelo de toxicidad de Tetracloruro de Carbono (0,001 ml/g), considerándose también el peso corporal y del hígado al sacrificar los animales. Los resultados preliminares obtenidos después de 18 h de cada tratamiento sugieren un efecto hepatoprotector del flavonoide, dado por la disminución de los niveles de lipoperóxidos, de la Transaminasa Glutámico Pirúvica y la Fosfolipasa A2 para a < 0,05 contra la toxina utilizada