Isolation of a haemorrhagic protein toxin (SA-HT) from the Indian venomous butterfish (Scatophagus argus, Linn) sting extract.

A haemorrhagic protein toxin (SA-HT) was isolated and purified from the spine extract of the Indian venomous butterfish, S. argus Linn, by two step ion exchange chromatography. The toxin was homogeneous in native and SDS-PAGE gel. SDS-molecular weight of the toxin was found to be 18.1 +/- 0.09 kDa. SA-HT produced severe haemorrhage on stomach wall but devoid of cutaneous haemorrhage. UV, EDTA, trypsin, protease, cyproheptadine, indomethacin, acetylsalicylic acid and BW755C treatment significantly antagonized the haemorrhagic activity of SA-HT. The toxin produced dose and time dependent oedema on mice hind paw, which was significantly encountered by cyproheptadine, indomethacin and BW755C. SA-HT increased capillary permeability on guinea pig dorsal flank. On isolated guineapig ileum, rat fundus and uterus, SA-HT produced slow contraction which was completely antagonised by prostaglandin blocker SC19220. On isolated rat duodenum, SA-HT produced slow relaxation. SA-HT significantly increased plasma plasmin, serum MDA level and decreased serum SOD level indicating the possible involvement of cyclooxygenase and lipooxygenase pathway.

A lethal cardiotoxic protein isolated from Bidder's organ of common Indian toad, Bufo melanostictus Schneider.

A lethal cardiotoxic (BO-CT; Bidder's organ cardiotoxin) protein was purified from the Bidder's organ of the common Indian toad B. melanostictus by gel filtration on Sephadex G-200. The homogeneity of cardiotoxin was tested by gel electrophoresis. The molecular weight of lethal BO-CT was 62 KDa and was devoid of glycoprotein. LD50 of the BO-CT was 50 micrograms/20 g (i.v.) in male albino mice. On isolated heart and auricle BO-CT initially increased the rate and amplitude of contraction and finally produced irreversible blockade of contraction. BO-CT induced auricular blockade, was not influenced by verapamil, propranolol and atropine. On isolated chick biventer cervicis preparation BO-CT produced irreversible blockade of electrically induced twitch response followed by contracture. This action was not antagonized by 4-aminopyridine and neostigmine. BO-CT induced contracture on chick biventer cervicis was increased by Ca2+, decreased by Na+ and abolished by K+. Cardiotoxic and neuromuscular activity of BO-CT was heat stable and abolished by proteolytic enzyme.

A lethal protein toxin (toxin-PC) from the Indian catfish (Plotosus canius, Hamilton) venom.

Isolation and purification of a lethal protein toxin from the Indian catfish Plotosus canius, Hamilton, venom is described. The purification procedure involved ammonium sulfate precipitate of crude venom followed by DEAE-ion exchange chromatography. The purified toxin (toxin-PC) was homogeneous on one-dimensional PAGE and PAS-negative, and had a molecular weight 15 Kd. Toxin-PC was lethal (LD50 225 micrograms/kg, intravenous, in mice) and cardiotoxic, having neuromuscular blocking activity. Toxin-PC produced cardiac arrest on isolated toad and guinea pig hearts. Prior administration of atropine and propanolol failed to counteract toxin activity on isolated heart preparations. On isolated chick biventer cervicis, toxin-PC produced total blockage of electrically-induced twitch response without affecting carbachol- and acetylcholine-induced contraction. The tension developed by the muscle was Ca++ ion-dependent. Neuromuscular blocking time was reduced when K+ ion concentration was increased in the medium. Antiserum raised against toxin-PC failed to antagonize lethal activity of toxin-PC in mice. Toxin-PC probably represents a major toxic component of catfish venom (P. canius), and was responsible for the pathophysiological changes.