Sequence analysis of the cDNA encoding for SpCTx: a lethal factor from scorpionfish venom ( Scorpaena plumieri )

Background: Lethal factors are multifunctional oligomeric proteins found in the venomous apparatus of Scorpaeniformes fish. These toxins elicit not only an array of biological responses in vitro but also cardiovascular disorders and strong hemolytic, nociceptive and edematogenic activities in vivo. This work describes the cloning and molecular identification of two toxin subunits, denominated Sp-CTx- and Sp-CTx-, from scorpionfish venom ( Scorpaena plumieri ). Methods: The primary structures were deduced after cDNA amplification by PCR with primers from conserved sequences described in Scorpaeniformes toxins. Following DNA sequencing and bioinformatic analysis, the tridimensional structures of both subunits were modeled. Results: The translated sequences (702 amino acids, each subunit) show homology with other lethal factors, while alignment between Sp-CTx- and Sp-CTx- shows 54% identity. The subunits lack N-terminal signal sequences and display masses of approximately 80 kDa each. Both Sp-CTx subunits display a B30.2/SPRY domain at the C-terminal region with typically conserved motifs as described in these toxins. Secondary structure prediction identified six -helices 18 residues long in both and subunits, some of them amphiphilic with their N-terminal flanked by many basic residues, creating a cationic site associated with the cytolytic activity of these toxins. Antimicrobial potential sites were identified in Sp-CTx and share some features with other peptides presenting variable and broad-spectrum activity...

A review on the Scorpaena plumieri fish venom and its bioactive compounds

The most poisonous fish species found along the Brazilian coast is the spotted scorpionfish Scorpaena plumieri. Though hardly ever life-threatening to humans, envenomation by S. plumieri can be quite hazardous, provoking extreme pain and imposing significant socioeconomic costs, as the victims may require days to weeks to recover from their injuries. In this review we will walk the reader through the biological features that distinguish this species as well as the current epidemiological knowledge related to the envenomation and its consequences. But above all, we will discuss the challenges involved in the biochemical characterization of the S. plumieri venom and its compounds, focusing then on the successful isolation and pharmacological analysis of some of the bioactive molecules responsible for the effects observed upon envenomation as well as on experimental models. Despite the achievement of considerable progress, much remains to be done, particularly in relation to the non-proteinaceous components of the venom. Therefore, further studies are necessary in order to provide a more complete picture of the venoms chemical composition and physiological effects. Given that fish venoms remain considerably less studied when compared to terrestrial venoms, the exploration of their full potential opens a myriad of possibilities for the development of new drug leads and tools for elucidating the complex physiological processes.

Lethal, oedema, haemorrhagic activity of spotted butterfish (Scatophagus argus, Linn) sting extract and its neutralization by antiserum and pharmacological antagonists.

An attempt has been made in this communication to develop antiserum in rabbit against Scatophagus. argus sting extract. Antiserum did not neutralized the sting extract induced proinflammatory and haemorrhagic activity but successfully neutralized lethality upto 2LD50. Cyproheptadine, indomethacin and BW 755C pretreatment significantly reduced sting extract induced proinflammatory activity. The haemorrhagic activity of sting extract was significantly inhibited by temperature, UV-exposure, EDTA, cyproheptadine, indomethacin and BW 755C pretreatment. The results conclude that the local effects of S.argus venom is likely to be mediated through release of mediators and may be encountered by pharmacological antagonists better than the antiserum.

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.

Isolation and partial structural evaluation of a cardiotoxic factor from Indian common murrel (Channa striatus L.) skin extract.

It was earlier reported from this laboratory that, Channa striatus, L a common edible fish, whose skin extract (CSSE) was pharmacologicaclly potent and contains several bioactive compounds. In the present communication a cardiotoxic factor was isolated and purified by thin layer chromatography followed by silica gel and neutral alumina column chromatography. Spectroscopic studies (UV, IR, 1H and 13C NMR, FAB-MS) indicated that the lethal cardiotoxic factor (CSS-CTF II) was an aromatic alkaloid compound with -NH, > C = C < and -OH functional groups. The molecular weight was found to be 413 dalton. LD50 of CSS-CTF II was found to be 42.5 mg/kg (i.v) in Swiss albino male mice. Pharmacological studies showed that CSS-CTF II possesses hypotensive and cardiotoxic activities and produced death through apnoea in experimental animals but had no effect on nerve muscle preparations. The haematological and biochemical data also indicated the toxic nature of CSS-CTF II, through significant fall in haemoglobin, total RBC, WBC, platelet count and increased cardiac marker enzyme CPK and CPK-MB value in experimental animals. The present investigation thus established the toxic nature of CSS-CTF II isolated from edible fish C. striatus skin extract. Further work is needed to identify CSS-CTF II's mechanism of action and its antagonism for therapeutic purpose.