Inhibitory effects of flavonoids on several venom hyaluronidases

In vitro studies showed that the flavonoid aglycones apigenin, luteolin and kaempferol inhibited the hyaluronidase activity of five different venoms dose-dependently. They were also able to delay the venom action when injected into mice. Naringenin, catechin and flavonoid glycosides had no effect. The flavonoids with unsubstituted hydroxyl groups at C-positions 5, 7 and 4′, a double bond between carbons 2 and 3, as well as a ketone group at position 4, exhibited potent inhibitory actions on the venom hyaluronidases.     

Molecular basis of cardiotoxicity upon cobra envenomation

Various clinical manifestations leading to death have been documented in most cases of bites caused by venomous snakes. Cobra envenomation is an extremely variable process and known to cause profound neurological abnormalities. The complexity of cobra venom can induce multiple-organ failure, leading to death in case of severe envenomation. Intramuscular administration of Malayan spitting cobra (Naja sputatrix) crude venom at 1 g/g dose caused death in mice in approximately 3 h. Analysis of gene expression profiles in the heart, brain, kidney, liver and lung revealed 203 genes whose expression was altered by at least 3-fold in response to venom treatment. Of these, 50% were differentially expressed in the heart and included genes involved in inflammation, apoptosis, ion transport and energy metabolism. Electrocardiogram recordings and serum troponin T measurements indicated declining cardiac function and myocardial damage. This not only sheds light on the cardiotoxicity of cobra venom but also reveals the molecular networks affected during envenomation.Received 7 August 2004; received after revision 11 October 2004; accepted 4 November 2004     

The scorpine family of defensins: gene structure,alternative polyadenylation and fold recognition

Small cationic antimicrobial peptides (SCAMPs) as effectors of animal innate immunity provide the first defense against infectious pathogens. This class of molecules exists widely in invertebrate hemolymph and vertebrate skin secretion, but animal venoms are emerging as a new rich resource. Scorpine is a unique scorpion venom defensin peptide that has an extended amino-terminal sequence similar to cecropins. From the African scorpion Opistophthalmus carinatus venom gland, we isolated and identified several cDNAs encoding four new homologs of scorpine (named opiscorpines 1–4). Importantly, we show for the first time the existence of multiple opiscorpine mRNAs with variable 3 untranslated regions (UTRs) in the venom gland, which may be generated by alternative usage of polyadenylation signals. The complete opiscorpine gene structure including its promoter region is determined by genomic DNA amplification. Two large introns were found to be located within the 5 UTR and at the boundary of the mature peptide-coding region. Such a gene structure is distinct, when compared with other scorpion venom peptide genes. However, a comparative promoter analysis revealed that both opiscorpine and scorpion venom neurotoxins share a similar promoter organization. Sequence analysis and structural modeling allow us to group the scorpines and scorpion long-chain K-channel toxins together into one family that shares a similar fold with two distinct domains. The N-terminal cecropin-like domain displaying a clear antimicrobial activity implies that the scorpine family represents a group of real naturally occurring hybrids. Based on the phylogenetic analysis, a possible cooperative interaction between the N and C domains is elucidated, which provides an evolutionary basis for the design of a new class of anti-infectious drugs.Received 5 April 2004; accepted 17 May 2004     

Antimicrobial and cytolytic peptides of venomous arthropods

As a response to invading microorganisms, the innate immune system of arthropods has evolved a complex arrangement of constitutive and inducible antimicrobial peptides that immediately destroy a large variety of pathogens. At the same time, venomous arthropods have developed an additional offensive system in their venom glands to subdue their prey items. In this complex venom system, several enzymes, low-molecular-mass compounds, neurotoxins, antimicrobial and cytolytic peptides interact together, resulting in extremely rapid immobilization and/or killing of prey or aggressors. This review provides an overview of antimicrobial peptides identified in the hemolymph of venomous arthropods, and especially of cytolytic peptides in their venom. For these peptides a dual role is proposed: acting as antimicrobials as well as increasing the potency of the venom by influencing excitable cells.Received 17 March 2003; received after revision 11 June 2003; accepted 17 June 2003     

Protein complexes in snake venom

Snake venom contains mixture of bioactive proteins and polypeptides. Most of these proteins and polypeptides exist as monomers, but some of them form complexes in the venom. These complexes exhibit much higher levels of pharmacological activity compared to individual components and play an important role in pathophysiological effects during envenomation. They are formed through covalent and/or non-covalent interactions. The subunits of the complexes are either identical (homodimers) or dissimilar (heterodimers; in some cases subunits belong to different families of proteins). The formation of complexes, at times, eliminates the non-specific binding and enhances the binding to the target molecule. On several occasions, it also leads to recognition of new targets as protein-protein interaction in complexes exposes the critical amino acid residues buried in the monomers. Here, we describe the structure and function of various protein complexes of snake venoms and their role in snake venom toxicity.     

Snake venom action: are enzymes involved in it?

Enzymes were the first clearly recognized components of snake venoms. When several more were discovered, attempts were made to correlate venom action with enzymic functions. The last few years have seen most successful efforts in the identification, isolation and structrual elucidation of highly toxic polypeptides present in snake venoms, in particular of 'neurotoxins' and membrane-active toxins. Following this development the polypeptides were called the true toxic components and the enzymes lost their previous central position in venom pharmacology. The time, therefore, has come re-evaluate the role of enzymes in the complex interaction between snake and prey. While highly active polypeptides indeed dominate the actionof hydrophiid venoms, they appear to play a lesser role in crotalid venom action as compared with enzyme components. Enzymes are involved in many levels of venom action, e.g. by serving as spreading factors, of by producing very active agents, such as bradykinin and lysolecithins in tissues of preys or predators. Some toxins, e.g. the membrane-active polypeptides appear to participate in the interaction between membrane phospholipids and venom phospholipases. The classical neurotoxin, beta-bungarotoxin, has been recognized as a powerful phospholipase. Several instances are known which indicate that some enzymes potentiate the toxic action of others; the analysis of a single enzyme may, therefore, not fully reveal its biofunction. For 3 enzymes,ophidian L-amino acid oxicase, ATPpyrophosphatase, and acetylcholinesterase, some of the problems pertaining to venom toxicity are discussed.     

The isolation,identification and synthesis of the alarm pheromone ofVespula squamosa (Drury) (Hymenoptera: Vespidae) and associated behavior

Summary A material that elicits alarm and attack behavior byVespula squamosa (Drury) workers was isolated from venom extracts and identified by spectroscopic methods as N-3-methylbutylacetamide. This compound elicited attack responses from worker wasps identical to those responses observed when venom was applied at the same dosage. This is the first behavioral role reported for this compound.The authors thank E. Adamak, R. Murphy and F. Takken for technical assistance. This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or the recommendation for its use by USDA.     

Myotoxic phospholipases A from snake venom,Pseudechis colletti,producing myoglobinuria in mice

Summary 2 proteins producing myoglobinuria in mice were isolated from the venom of the Australian elapid snakePseudechis colletti and identified as phospholipases A showing close similarities in amino acid composition to a similarly acting enzyme from a sea snake venom (Enhydrina schistosa).     

Snake venom action: Are enzymes involved in it?

Summary Enzymes were the first clearly recognized components of snake venoms. When several more were discovered, attempts were made to correlate venom action with enzymic functions. The last few years have seen most successful efforts in the identification, isolation and structural elucidation of highly toxic polypeptides present in snake venoms, in particular of neurotoxins and membrane-active toxins. Following this development the polypeptides were called the true toxic components and the enzymes lost their previous central position in venom pharmacology. The time, therefore, has come to re-evaluate the role of enzymes in the complex interaction between snake and prey. While highly active polypeptides indeed dominate the action of hydrophiid venoms, they appear to play a lesser role in crotalid venom action as compared with enzyme components. Enzymes are involved in many levels of venom action, e. g. by serving as spreading factors, of by producing very active agents, such as bradykinin and lysolecithins in tissues of preys or predators. Some toxins, e. g. the membrane-active polypeptides appear to participate in the interaction between membrane phospholipids and venom phospholipases. The classical neurotoxin, -bungarotoxin, has been recognized as a powerful phospholipase. Several instances are known which indicate that some enzymes potentiate the toxic action of others; the analysis of a single enzyme may, therefore, not fully reveal its biofunction. For 3 enzymes, ophidianl-amino acid oxidase, ATPpyrophosphatase, and acetylcholinesterase, some of the problems pertaining to venom toxicity are discussed.     

Isolation of the major toxic protein from the skin venom of the crested newt, Triturus cristatus

A new protein, of molecular weight 160,000, was isolated from the skin venom of the crested newt and partially characterized by bioassays and biochemical methods. This protein shows the same functional properties as the crude venom, which produces convulsions in mice and is cytotoxic.     

Anticholinesterase-like activity by oriental hornet (Vespa orientalis) venom and venom sac extract.

Oriental hornet venom or venom sac extract produces pharmacological and toxicological effects typical of anticholinesterase agents. The effects produced in animals can be counteracted by atropine and heparin.     

Snake venom components and their applications in biomedicine

Snake envenomation is a socio-medical problem of considerable magnitude. About 2.5 million people are bitten by snakes annually, more than 100,000 fatally. However, although bites can be deadly, snake venom is a natural biological resource that contains several components of potential therapeutic value. Venom has been used in the treatment of a variety of pathophysiological conditions in Ayurveda, homeopathy and folk medicine. With the advent of biotechnology, the efficacy of such treatments has been substantiated by purifying components of venom and delineating their therapeutic properties. This review will focus on certain snake venom components and their applications in health and disease. Received 6 July 2006; received after revision 14 August 2006; accepted 28 September 2006     

Anticholinesterase-like activity by oriental hornet (Vespa orientalis) venom and venom sac extract

Summary Oriental hornet venom or venom sac extract produces pharmacological and toxicological effects typical of anticholinesterase agents. The effects produced in animals can be counteracted by atropine and heparin.     

Effect of scorpion venom (Androctonus australis) on neuromuscular transmission inhibited by botulinum toxin in the frog]

We have shown that Scorpion venom restores the neuro-muscular transmission inhibited by Botulinum toxin in the Frog. The effectiveness of Scorpion venom was antagonized by excess magnesium.     

The occurrence of arachidonic acid in the venom duct of the marine snailConus textile

Summary A crude extract of the venom of the marine snailConus textile Linné caused a powerful contraction in the guinea-pig isolated ileum. The extract of the venom has been fractionated, and the fractions monitored by the contractile effect. Arachidonic acid was shown to be present as an active substance.Acknowledgment. We are grateful to Mr Z. Nagahama of Okinawa island for suppling specimens ofC. textile and to Dr T. Higashijima and Prof. T. Miyazawa (Department of Biophysics and Biochemistry, Tokyo University) for 270 MHz¹H-NMR-measurements.     

Basic phospholipase of Naja nigricollis venom]

It is confirmed that N. nigricollis venom contains several phospholipases one of these is a basic phospholipase A. This enzyme is toxic for mice when injected intravenously. In vitro it reacts on egg yolk lecithin producing lysolecithin and prevents the phenomenon of blood clotting. An immunological identity has been established between this basic phospholipase and two acidic phospholipases present in the same venom.     

Unmasking of the fast sodium channel in less than 4 day old embryonic chicken heart by inhibitors of sodium inactivation]

Embryonic Chick hearts aged less than 4 days are not always sensitive to tetrodotoxin, an inhibitor of fast sodium channel. It is shown that in the most frequent cases, in which tetrodotoxin sensitivity is apparently absent, this sensitivity can be demonstrated after previous treatment by veratridine or by toxin II of androctonus australis Hector Scorpion venom. It is concluded that the fast tetrodotoxin-sensitive sodium channel is regularly present in the heart of Chick embryos aged 2 and 3 days, but most often in a permanently inactivated state.