ω-Phonetoxins inhibit voltage-gated calcium CaV2.2 ion channel splice isoforms of dorsal root ganglia.

Cell-specific alternative splicing of Cacna1b pre-mRNA generates functionally distinct voltage-gated CaV2.2 channels. CaV2.2 channels mediate the release of glutamate from nociceptor termini in the dorsal horn spinal cord and they are implicated in chronic pain. One alternatively spliced exon in Cacna1b, e37a, is highly expressed in dorsal root ganglia, relative to other regions of the nervous system, and it is particularly important in inflammatory hyperalgesia. Here we studied the effects of two ω-phonetoxins, PnTx3-4 and Phα1ß, derived from the spider Phoneutria nigriventer on CaV2.2 channel isoforms of dorsal root ganglia (CaV2.2 e37a and CaV2.2 e37b). Both PnTx3-4 and Phα1ß are known to have analgesic effects in rodent models of pain and to inhibit CaV2.2 channels. CaV2.2 e37a and CaV2.2 e37b isoforms expressed in a mammalian cell line were inhibited by PnTx3-4 and Phα1ß with similar potency and with similar timecourse, although CaV2.2 e37a currents were slightly, but consistently more sensitive to toxin inhibition compared to CaV2.2 e37b. The inhibitory effects of PnTx3-4 and Phα1ß on CaV2.2-e37a and CaV2.2-e37b channels were voltage-dependent, and both occlude the inhibitory effects of ω-conotoxin GVIA, consistent with a common site of action. The potency of PnTx3-4 and Phα1ß on both major splice isoforms in dorsal root ganglia constribute to understanding the analgesic actions of these ω-phonetoxins.

Partial characterization of Loxosceles anomala (Mello-Leitão, 1917) venom: A brown spider of potential medical concern.

The spider's genus Loxosceles (also known as "brown spiders") is one of the few ones of medical importance in Brazil, being Loxosceles anomala a species of common occurrence in the Southeast region. This species is usually smaller in size than the other members of the Loxosceles group. A single human accident involving L. anomala was reported to date and the clinical picture shared similar characteristics with accidents caused by other Loxosceles species. Despite the potential relevance of L. anomalafor loxocelism in Minas Gerais state, its venom activity has never been characterized. In this work, we provide a preliminary characterization of L. anomala venom, considering its most relevant enzymatic activities and its venom immunorecognition by current therapeutic antivenoms. The results showed that L. anomala venom is immunorecognised by therapeutic antivenoms and by anti-phospholipase D antibodies. Its venom also shows enzymatic activities (sphingomyelinase activity, fibrinogenolytic) described for other Loxosceles venoms. This work contributes to a better knowledge on the venom content and activities of synanthropic Loxosceles species that have the potential of causing relevant human accidents.

Rhomb-I, a P-I metalloproteinase from Lachesis muta rhombeata venom degrades vessel extra cellular matrix components and impairs platelet aggregation.

Rhomb-I, a 23-kDa metalloproteinase was isolated from L. m. rhombeata venom. Its dimethylcasein proteolysis was abolished by metal chelators, and slightly enhanced by Ca2+ and Mg2+ ions, but inhibited by Co2+, Zn2+ and α2-macroglobulin. In aqueous solution, rhomb-I autoproteolyzed to a 20- and 11-kDa fragments at 37 °C. The amino acid sequence showed high homology with other snake venom metalloproteinases. Rhomb-I causes hemorrhage that may be ascribed to hydrolysis of essential basement membrane, extracellular matrix and plasma proteins. It preferentially cleaves the α-chains of fibrin (ogen). Rhomb-I inhibited convulxin- and von Willebrand factor (vWF)-induced aggregation on human platelets without significant effect on collagen-stimulated aggregation or other effectors. It digests vWF into a low-molecular-mass multimers of vWF and a rvWF-A1 domain to a 27-kDa fragment as revealed by western blotting with mouse anti-rvWF A1-domain IgG. Incubation of platelets with rhomb-I resulted in adhesion to and cleavage of platelet receptors glycoprotein (GP)Ibα and GPVI to release a 55-kDa soluble form. Both membrane glycoproteins GPIbα that binds vWF, together with GPVI which binds collagen, play a key role in mediating platelet adhesion/activation and can initiate (patho)physiological thrombus formation. Conclusions: rhomb-I is implicated in the pathophysiology of Lachesis envenoming by disrupting vasculature, hemostasis and platelet aggregation through impairing vWF-GPIb axis and blocking GPVI-collagen binding.

Rhomb-I, a P–I metalloproteinase from Lachesis muta rhombeata venom degrades vessel extra cellular matrix components and impairs platelet aggregation

Rhomb-I, a 23-kDa metalloproteinase was isolated from L. m. rhombeata venom. Its dimethylcasein proteolysis was abolished by metal chelators, and slightly enhanced by Ca2+ and Mg2+ ions, but inhibited by Co2+, Zn2+ and α2-macroglobulin. In aqueous solution, rhomb-I autoproteolyzed to a 20- and 11-kDa fragments at 37 °C. The amino acid sequence showed high homology with other snake venom metalloproteinases. Rhomb-I causes hemorrhage that may be ascribed to hydrolysis of essential basement membrane, extracellular matrix and plasma proteins. It preferentially cleaves the α-chains of fibrin (ogen). Rhomb-I inhibited convulxin- and von Willebrand factor (vWF)-induced aggregation on human platelets without significant effect on collagen-stimulated aggregation or other effectors. It digests vWF into a low-molecular-mass multimers of vWF and a rvWF-A1 domain to a 27-kDa fragment as revealed by western blotting with mouse anti-rvWF A1-domain IgG. Incubation of platelets with rhomb-I resulted in adhesion to and cleavage of platelet receptors glycoprotein (GP)Ibα and GPVI to release a 55-kDa soluble form. Both membrane glycoproteins GPIbα that binds vWF, together with GPVI which binds collagen, play a key role in mediating platelet adhesion/activation and can initiate (patho)physiological thrombus formation. Conclusions: rhomb-I is implicated in the pathophysiology of Lachesis envenoming by disrupting vasculature, hemostasis and platelet aggregation through impairing vWF-GPIb axis and blocking GPVI-collagen binding.

Comparative venomic profiles of three spiders of the genus Phoneutria.

Background: Spider venoms induce different physio-pharmacological effects by binding with high affinity on molecular targets, therefore being of biotechnological interest. Some of these toxins, acting on different types of ion channels, have been identified in the venom of spiders of the genus Phoneutria, mainly from P. nigriventer. In spite of the pharmaceutical potential demonstrated by P. nigriventer toxins, there is limited information on molecules from venoms of the same genus, as their toxins remain poorly characterized. Understanding this diversity and clarifying the differences in the mechanisms of action of spider toxins is of great importance for establishing their true biotechnological potential. This prompted us to compare three different venoms of the Phoneutria genus: P. nigriventer (Pn-V), P. eickstedtae (Pe-V) and P. pertyi (Pp-V). Methods: Biochemical and functional comparison of the venoms were carried out by SDS-PAGE, HPLC, mass spectrometry, enzymatic activities and electrophysiological assays (whole-cell patch clamp). Results: The employed approach revealed that all three venoms had an overall similarity in their components, with only minor differences. The presence of a high number of similar proteins was evident, particularly toxins in the mass range of ~6.0 kDa. Hyaluronidase and proteolytic activities were detected in all venoms, in addition to isoforms of the toxins Tx1 and Tx2-6. All Tx1 isoforms blocked Nav1.6 ion currents, with slight differences. Conclusion: Our findings showed that Pn-V, Pe-V and Pp-V are highly similar concerning protein composition and enzymatic activities, containing isoforms of the same toxins sharing high sequence homology, with minor modifications. However, these structural and functional variations are very important for venom diversity. In addition, our findings will contribute to the comprehension of the molecular diversity of the venoms of the other species from Phoneutria genus, exposing their biotechnological potential as a source for searching for new active molecules.

Comparative venomic profiles of three spiders of the genus Phoneutria

Spider venoms induce different physio-pharmacological effects by binding with high affinity on molecular targets, therefore being of biotechnological interest. Some of these toxins, acting on different types of ion channels, have been identified in the venom of spiders of the genus Phoneutria, mainly from P. nigriventer. In spite of the pharmaceutical potential demonstrated by P. nigriventer toxins, there is limited information on molecules from venoms of the same genus, as their toxins remain poorly characterized. Understanding this diversity and clarifying the differences in the mechanisms of action of spider toxins is of great importance for establishing their true biotechnological potential. This prompted us to compare three different venoms of the Phoneutria genus: P. nigriventer (Pn-V), P. eickstedtae (Pe-V) and P. pertyi (Pp-V). Methods: Biochemical and functional comparison of the venoms were carried out by SDS-PAGE, HPLC, mass spectrometry, enzymatic activities and electrophysiological assays (whole-cell patch clamp). Results: The employed approach revealed that all three venoms had an overall similarity in their components, with only minor differences. The presence of a high number of similar proteins was evident, particularly toxins in the mass range of ~6.0 kDa. Hyaluronidase and proteolytic activities were detected in all venoms, in addition to isoforms of the toxins Tx1 and Tx2-6. All Tx1 isoforms blocked Nav1.6 ion currents, with slight differences. Conclusion: Our findings showed that Pn-V, Pe-V and Pp-V are highly similar concerning protein composition and enzymatic activities, containing isoforms of the same toxins sharing high sequence homology, with minor modifications. However, these structural and functional variations are very important for venom diversity. In addition, our findings will contribute to the comprehension of the molecular diversity of the venoms of the other species from Phoneutria genus, exposing their biotechnological potential as a source for searching for new active molecules.(AU)

Comparative venomic profiles of three spiders of the genus Phoneutria

Abstract Background: Spider venoms induce different physio-pharmacological effects by binding with high affinity on molecular targets, therefore being of biotechnological interest. Some of these toxins, acting on different types of ion channels, have been identified in the venom of spiders of the genus Phoneutria, mainly from P. nigriventer. In spite of the pharmaceutical potential demonstrated by P. nigriventer toxins, there is limited information on molecules from venoms of the same genus, as their toxins remain poorly characterized. Understanding this diversity and clarifying the differences in the mechanisms of action of spider toxins is of great importance for establishing their true biotechnological potential. This prompted us to compare three different venoms of the Phoneutria genus: P. nigriventer (Pn-V), P. eickstedtae (Pe-V) and P. pertyi (Pp-V). Methods: Biochemical and functional comparison of the venoms were carried out by SDS-PAGE, HPLC, mass spectrometry, enzymatic activities and electrophysiological assays (whole-cell patch clamp). Results: The employed approach revealed that all three venoms had an overall similarity in their components, with only minor differences. The presence of a high number of similar proteins was evident, particularly toxins in the mass range of ~6.0 kDa. Hyaluronidase and proteolytic activities were detected in all venoms, in addition to isoforms of the toxins Tx1 and Tx2-6. All Tx1 isoforms blocked Nav1.6 ion currents, with slight differences. Conclusion: Our findings showed that Pn-V, Pe-V and Pp-V are highly similar concerning protein composition and enzymatic activities, containing isoforms of the same toxins sharing high sequence homology, with minor modifications. However, these structural and functional variations are very important for venom diversity. In addition, our findings will contribute to the comprehension of the molecular diversity of the venoms of the other species from Phoneutria genus, exposing their biotechnological potential as a source for searching for new active molecules.

Tityus serrulatus (Scorpion): From the Crude Venom to the Construction of Synthetic Peptides and Their Possible Therapeutic Application Against Toxoplasma gondii Infection.

Toxoplasmosis, caused by Toxoplasma gondii, is a major public concern owing to its neurotropic nature and high morbidity and mortality rates in immunocompromised patients and newborns. Current treatment for this disease is inefficient and produces side effects. Inflammatory mediators produced during T. gondii infection (e.g., cytokines and nitric oxide) are crucial in controlling parasite replication. In this context, Tityus serrulatus venom (TsV) induces the production of inflammatory mediators by immune cells. Thus, this study aimed to isolate and identify the components of TsV with potential anti-T. gondii activity. TsV was extracted from scorpions and lyophilized or loaded onto a column to obtain its fractions. TsV subfractions were obtained using chromatography, and its amino acid sequence was identified and applied to peptide design using bioinformatics tools. The C57BL/6 mice and their harvested macrophages were used to test the anti-Toxoplasma activity of TsV components and peptides. TsV and its fraction F6 attenuated the replication of tachyzoites in macrophages and induced nitric oxide and cytokine (IL-12, TNF, and IL-6) production by infected cells, without host cell toxicity. Moreover, Su6-B toxin, a subfraction of F6, demonstrated anti-T. gondii activity. The partially elucidated and characterized amino acid sequence of Sub6-B demonstrated 93% similarity with T. serrulatus 2 toxin (Ts2). Ts2 mimetic peptides ("Pep1," "Pep2a," and "Pep2b") were designed and synthesized. Pep1 and Pep2a, but not Pep2b, reduced the replication of tachyzoites in macrophages. In vivo, treatment of T. gondii-infected mice with Pep1, Pep2a, or Pep2b decreased the number of cerebral cysts and did not induce hepatotoxicity in the animals. Taken together, our data show promising immunomodulatory and antiparasitic activity of TsV that could be explored and applied in future therapies for treating infectious parasitic diseases such as toxoplasmosis.

Tityus serrulatus scorpion venom as a potential drug source for Chagas' disease: Trypanocidal and immunomodulatory activity.

Current chemical therapies for Chagas Disease (CD) lack ability to clear Trypanosoma cruzi (Tc) parasites and cause severe side effects, making search for new strategies extremely necessary. We evaluated the action of Tityus serrulatus venom (TsV) components during Tc infection. TsV treatment increased nitric oxide and pro-inflammatory cytokine production by Tc-infected macrophages (MØ), decreased intracellular parasite replication and trypomastigotes release, also triggering ERK1/2, JNK1/2 and p38 activation. Ts7 demonstrated the highest anti-Tc activity, inducing high levels of TNF and IL-6 in infected MØ. TsV/Ts7 presented synergistic effect on p38 activation when incubated with Tc antigen. KPP-treatment of MØ also decreased trypomastigotes releasing, partially due to p38 activation. TsV/Ts7-pre-incubation of Tc demonstrated a direct effect on parasite decreasing MØ-trypomastigotes releasing. In vivo KPP-treatment of Tc-infected mice resulted in decreased parasitemia. Summarizing, this study opens perspectives for new bioactive molecules as CD-therapeutic treatment, demonstrating the TsV/Ts7/KPP-trypanocidal and immunomodulatory activity during Tc infection.

Mapping of Brain Activity in the Analgesia Induced by Phα1ß and Morphine.

Preclinical evidence suggests the potential of Phα1ß, a toxin obtained from the venom of spider Phoneutria nigriventer, as a new analgesic drug. Molecular brain imaging techniques have afforded exciting opportunities to examine brain processes in clinical pain conditions. This paper aims to study the brain regions involved in the analgesic effects of Phα1ß compared with Morphine, in a model of acute pain induced by formalin in Sprague Dawley rats. We used 18F-fluorodeoxyglucose as a metabolic radiotracer to perform brain imaging of rats pretreated with Phα1ß or Morphine in a model of acute inflammatory pain caused by intraplantar injection of formalin. The rats' hind paw's formalin stimulation resulted in a brain metabolic increase at the bilateral motor cortex, visual cortex, somatosensory cortex, thalamus, and cingulate cortex.In rats treated with Phα1ß, selective inhibition of unilateral motor cortex and cingulate cortex was observed. Morphine treatment leads to small and selective inhibition at the bilateral amygdala striatum and accumbens. Our results indicate that the analgesic effect of Phα1ß and Morphine possesses a differential profile of central processing in the pain state.

Calcium channels blockers toxins attenuate abdominal hyperalgesia and inflammatory response associated with the cerulein-induced acute pancreatitis in rats.

Agents that modulate the activity of high-voltage gated calcium channels (HVCCs) exhibit experimentally and clinically significant effect by relieving visceral pain. Among these agents, the toxins Phα1ß and ω-conotoxin MVIIA effectively reduce chronic pain in rodent models. The molecular mechanisms underlying the chronic pain associated with acute pancreatitis (AP) are poorly understood. Hypercalcemia is a risk factor; the role of cytosolic calcium is considered to be a modulator of pancreatitis. Blockade of Ca2+ signals may be useful as a prophylactic treatment of pancreatitis. We explored the pathophysiological roles of three peptide toxins: Phα1ß and its recombinant form CTK 01512-2-blockers of TRPA1 receptor and HVCCs and ω-conotoxin MVIIA, a specific blocker of N-type calcium channels in cerulein-induced AP. Cerulein injection elicits AP in rats, evidenced by an increase in hyperalgesic pain, inflammatory infiltration, amylase and lipase secretion, and reactive oxygen species, TNF-α, and p65 NF-κB levels. These effects of cerulein-induced AP were abolished by Phα1ß and its recombinant form CTK 01512-2, whereas ω-conotoxin MVIIA had no effect on the induced increase in pancreatic enzyme secretion. Our results demonstrate that Phα1ß and CTK 01512-2 toxins-antagonists of HVCCs and TRPA1 receptor presented an effective response profile, in the control of nociception and inflammatory process in the AP model in rats, without causing changes in spontaneous locomotion of the rats.

Funcionalização do polietilenoglicol metil éter via reação de bromoacetilação: ativação, caracterização por MALDI-TOF e mecanismo de reação / Poly(ethylene glycol) methyl ether functionalization by bromoacetylation reaction: Activation, characterization by MALDI-TOF and reaction mechanism / Funcionalización de polietilenglicol metil éter mediante reacción de bromoacetilación: activación, caracterización por MALDI-TOF y mecanismo de reacción

Resumo A PEGuilação, reação química de conjugação com a molécula de polietilenoglicol (PEG) ou polietilenoglicol metil éter (mPEG), tem sido amplamente aplicada pelas indústrias farmacêuticas como estratégia de melhoria das propriedades farmaco-cinéticas de compostos bioativos. O PEG é um polímero que possui um esqueleto de poliéter quimicamente inerte e que apresenta grupos hidroxilas (-OH) em suas extremidades. Assim, o PEG para tornar-se apto como reagente de conjugação deve ser ativado com um grupo funcional que seja reativo. Nesse sentido, a bromoaceti-lação apresenta-se como uma alternativa para a funcionalização do PEG. Portanto, nesse trabalho objetivamos descrever em detalhes os procedimentos e o mecanismo de reação envolvida na funcionalização do mPEG, através da reação de bromoacetilação. Além do mais, estudamos a aplicação do MALDI-ToF para a caracterização do produto ativado. Após a bromoacetilação, por um procedimento adaptado, obteve-se o bromoacetil-mPEG-éster, com rendimento bruto de 56,78%. Análises posteriores, por espectrometria de massas por MALDI-ToF, possibilitaram identificar e caracterizar o produto bromoacetilado. Entre as condições de reação, o controle de temperatura (-10 °C a 0 °C) mostrou-se eficaz favorecendo a adição nucleofílica essencial à bromoacetilação. Assim, concluímos que o controle da baixa temperatura reacional é um fator chave para o favorecimento da adição nucleofílica à carbonila e, portanto, essencial na obtenção do mPEG funcionalizado via bromoacetilação. Estudos posteriores serão necessários, no entanto, para confirmar se o mPEG esterificado, nessas condições, poderá ser utilizado na conjugação com moléculas de natureza proteica ou peptídica, por meio de substituição nucleofílica bimolecular.

SUMMARY PEGylation, a chemical reaction of conjugation with the polyethylene glycol molecule (PEG), has been widely applied by the pharmaceutical industries as a strategy to improve the pharmacokinetic properties of bioactive compounds. PEG is a polymer that has a chemically inert polyether backbone and hydroxyl groups (-OH) at its ends. Thus, PEG to become fit as a reagent for conjugation must be activated with a functional group that is reactive. In this sense, bromoacetylation presents itself as an alternative for the functionalization of PEG. Therefore, in this study we aim to describe in detail the procedures and reaction mechanism involved in the functionalization of mPEG through the bromoacetylation reaction. In addition, we used the spectrometric technique, by MALDI-ToF, for the characterization of the activated product. After applying an adapted bromoacetylation procedure, bromoacetyl-mPEG-ester was obtained with a yield of 56.78%. Subsequent analyzes of MALDI-ToF mass spectrometry were able to correctly identify and characterize the bromoacety-lated product. Among the reaction conditions, temperature control (from -10 °C to 0 °C) was effective in favoring the essential nucleophilic addition to bromoacetylation. Thus, we conclude that the control of the low reaction temperature is a key factor in favoring the nucleophilic addition to carbonyl and, therefore, obtaining a favorable conversion to functionalized PEG via bromoacetylation. Further studies, however, will be necessary to confirm whether PEG esterified with these conditions can be used in conjunction with molecules of a protein or peptide nature by means of bimolecular nucleophilic substitution.

RESUMEN La PEGilación, una reacción química de conjugación con la molécula de polietilenglicol (PEG), ha sido ampliamente aplicada por las industrias farmacéuticas como una estrategia para mejorar las propiedades farmacocinéticas de los compuestos bioactivos. El PEG es un polímero formado por un esqueleto de poliéter químicamente inerte con grupos hidroxilo (-OH) en sus extremos. Por lo tanto, para usar el PEG como reactivo de conjugación debe activarse con un grupo funcional que sea reactivo. En este sentido, la bromoacetilación es una alternativa para la funcionalización de PEG. De esta manera, en este trabajo nuestro objetivo es describir en detalle los procedimientos y el mecanismo de reacción involucrados en la funcionalización de PEG a través de la reacción de bromoacetilación. Además, estudiamos la aplicación de MALDI-ToF para la caracterización del producto activado. Después de aplicar un procedimiento de bromoacetilación adaptado, se obtuvo bromoacetil-mPEG-éster con un rendimiento bruto de 56,78%. Los análisis posteriores de espectrometría de masas por MALDI-ToF pudieron identificar y caracterizar correctamente el producto bromoacetilado. Entre las condiciones de reacción, el control de la temperatura (desde -10 °C hasta 0 °C) fue eficaz para favorecer la adición nucleofílica esencial a la bromoacetilación. Así, concluimos que el control de la baja temperatura de reacción es un factor clave para favorecer la adición nucleofílica al carbonilo y, por lo tanto, esencial para obtener el mPEG funcionalizado mediante la bromoacetilación. Sin embargo, serán necesarios más estudios para confirmar si el mPEG esterificado en estas condiciones puede usarse junto con moléculas de naturaleza proteica o peptídica por medio de la sustitución nucleófila bimolecular.

GiTx1(ß/κ-theraphotoxin-Gi1a), a novel toxin from the venom of Brazilian tarantula Grammostola iheringi (Mygalomorphae, Theraphosidae): Isolation, structural assessments and activity on voltage-gated ion channels.

Spider venoms, despite their toxicity, represent rich sources of pharmacologically active compounds with biotechnological potential. However, in view of the large diversity of the spider species, the full potential of their venom molecules is still far from being known. In this work, we report the purification and structural and functional characterization of GiTx1 (ß/κ-TRTX-Gi1a), the first toxin purified from the venom of the Brazilian tarantula spider Grammostola iheringi. GiTx1 was purified by chromatography, completely sequenced through automated Edman degradation and tandem mass spectrometry and its structure was predicted by molecular modeling. GiTx1 has a MW of 3.585 Da, with the following amino acid sequence: SCQKWMWTCDQKRPCCEDMVCKLWCKIIK. Pharmacological activity of GiTx1 was characterized by electrophysiology using whole-cell patch clamp on dorsal root ganglia neurons (DRG) and two-electrode voltage-clamp on voltage-gated sodium and potassium channels subtypes expressed in Xenopus laevis oocytes. GiTx1, at 2 µM, caused a partial block of inward (∼40%) and outward (∼20%) currents in DRG cells, blocked rNav1.2, rNav1.4 and mNav1.6 and had a significant effect on VdNav, an arachnid sodium channel isoform. IC50 values of 156.39 ± 14.90 nM for Nav1.6 and 124.05 ± 12.99 nM for VdNav, were obtained. In addition, this toxin was active on rKv4.3 and hERG potassium channels, but not Shaker IR or rKv2.1 potassium channels. In summary, GiTx1 is a promiscuous toxin with multiple effects on different types of ion channels.

Biochemical and functional properties of a new l-amino acid oxidase (LAAO) from Micrurus lemniscatus snake venom.

This study reports the purification of ML-LAAO, a new LAAO from the venom of Micrurus lemniscatus snake (ML-V), using size exclusion chromatography. ML-LAAO is a 69-kDa glycoprotein that represents ~2.0% of total venom proteins. This enzyme exhibited optimal activity at pH 8.5, displaying high specificity toward hydrophobic l-amino acids. MALDI TOF/TOF and Blast analysis identified internal segments in ML-LAAO that share high sequence identity with homologous snake venom LAAOs. Western blot analysis on two-dimensional SDS-PAGE of ML-V, using anti-LAAO revealed the presence of ML-LAAO isoforms (pI 6.3-8.9). ML-LAAO blocked aggregation induced by collagen on washed platelets in a rather weak manner, it did not, however, inhibit platelet aggregation induced by ADP on platelet-rich plasma. In addition, this enzyme displayed in vitro antibacterial activity against Staphylococcus aureus (MIC/MBC of 0.39 µg/mL) and in vitro leishmanicidal action against Leishmania amazonensis and L. chagasi (IC50 values of 0.14 and 0.039 µg/mL, respectively). These activities were significantly reduced by catalase, suggesting that hydrogen peroxide production is involved in some way. The data presented here revealed that ML-LAAO has bactericidal and leishmanicidal effects, suggesting that it may have therapeutic potential.

Phoneutria toxin PnTx3-5 inhibits TRPV1 channel with antinociceptive action in an orofacial pain model.

Capsaicin, an agonist of TRPV1, evokes intracellular [Ca2+] transients and glutamate release from perfused trigeminal ganglion. The spider toxin PnTx3-5, native or recombinant is more potent than the selective TRPV1 blocker SB-366791 with IC50 of 47 ±â€¯0.18 nM, 45 ±â€¯1.18 nM and 390 ±â€¯5.1 nM in the same experimental conditions. PnTx3-5 is thus more potent than the selective TRPV1 blocker SB-366791. PnTx3-5 (40 nM) and SB-366791 (3 µM) also inhibited the capsaicin-induced increase in intracellular Ca2+ in HEK293 cells transfected with TRPV1 by 75 ±â€¯16% and 84 ±â€¯3.2%, respectively. In HEK293 cells transfected with TRPA1, cinnamaldehyde (30 µM) generated an increase in intracellular Ca2+ that was blocked by the TRPA1 antagonist HC-030031 (10 µM, 89% inhibition), but not by PnTx3-5 (40 nM), indicating selectivity of the toxin for TRPV1. In whole-cell patch-clamp experiments on HEK293 cells transfected with TRPV1, capsaicin (10 µM) generated inward currents that were blocked by SB-366791 and by both native and recombinant PnTx3-5 by 47 ±â€¯1.4%; 54 ±â€¯7.8% and 56 ±â€¯9.0%, respectively. Intradermal injection of capsaicin into the rat left vibrissa induced nociceptive behavior that was blocked by pre-injection with either SB-366791 (3 nmol/site i.d., 83.3 ±â€¯7.2% inhibition) or PnTx3-5 (100 fmol/site, 89 ±â€¯8.4% inhibition). We conclude that both native and recombinant PnTx3-5 are potent TRPV1 receptor antagonists with antinociceptive action on pain behavior evoked by capsaicin.

Antinociceptive effect of PnTx4(5-5), a peptide from Phoneutria nigriventer spider venom, in rat models and the involvement of glutamatergic system.

BACKGROUND: The venom of Phoneutria nigriventer spider is a source of numerous bioactive substances, including some toxins active in insects. An example is PnTx4(5-5) that shows a high insecticidal activity and no apparent toxicity to mice, although it inhibited NMDA-evoked currents in rat hippocampal neurons. In this work the analgesic activity of PnTx4(5-5) (renamed Γ-ctenitoxin-Pn1a) was investigated. METHODS: The antinociceptive activity was evaluated using the paw pressure test in rats, after hyperalgesia induction with intraplantar injection of carrageenan or prostaglandin E2 (PGE2). RESULTS: PnTx4(5-5), subcutaneously injected, was able to reduce the hyperalgesia induced by PGE2 in rat paw, demonstrating a systemic effect. PnTx4(5-5) administered in the plantar surface of the paw caused a peripheral and dose-dependent antinociceptive effect on hyperalgesia induced by carrageenan or PGE2. The hyperalgesic effect observed in these two pain models was completely reversed with 5 µg of PnTx4(5-5). Intraplantar administration of L-glutamate induced hyperalgesic effect that was significantly reverted by 5 µg of PnTx4(5-5) injection in rat paw. CONCLUSION: The antinociceptive effect for PnTx4(5-5) was demonstrated against different rat pain models, i.e. induced by PGE2, carrageenan or glutamate. We suggest that the antinociceptive effect of PnTx4(5-5) may be related to an inhibitory activity on the glutamatergic system.

Antinociceptive effect of PnTx4(5-5), a peptide from Phoneutria nigriventer spider venom, in rat models and the involvement of glutamatergic system

The venom of Phoneutria nigriventer spider is a source of numerous bioactive substances, including some toxins active in insects. An example is PnTx4(5-5) that shows a high insecticidal activity and no apparent toxicity to mice, although it inhibited NMDA-evoked currents in rat hippocampal neurons. In this work the analgesic activity of PnTx4(5-5) (renamed Γ-ctenitoxin-Pn1a) was investigated. Methods: The antinociceptive activity was evaluated using the paw pressure test in rats, after hyperalgesia induction with intraplantar injection of carrageenan or prostaglandin E2 (PGE2). Results: PnTx4(5-5), subcutaneously injected, was able to reduce the hyperalgesia induced by PGE2 in rat paw, demonstrating a systemic effect. PnTx4(5-5) administered in the plantar surface of the paw caused a peripheral and dose-dependent antinociceptive effect on hyperalgesia induced by carrageenan or PGE2. The hyperalgesic effect observed in these two pain models was completely reversed with 5 µg of PnTx4(5-5). Intraplantar administration of L-glutamate induced hyperalgesic effect that was significantly reverted by 5 μg of PnTx4(5-5) injection in rat paw. Conclusion: The antinociceptive effect for PnTx4(5-5) was demonstrated against different rat pain models, i.e. induced by PGE2, carrageenan or glutamate. We suggest that the antinociceptive effect of PnTx4(5-5) may be related to an inhibitory activity on the glutamatergic system.(AU)

PnTx2-6 (or δ-CNTX-Pn2a), a toxin from Phoneutria nigriventer spider venom, releases l-glutamate from rat brain synaptosomes involving Na+ and Ca2+ channels and changes protein expression at the blood-brain barrier.

PhTx2 is the most toxic fraction from the venom of the spider Phoneutria nigriventer, being responsible to sodium entry into cortical synaptosomes, increasing the release of neurotransmitters, such as l-glutamate (L-Glu) and; acetylcholine. In this study, we investigated the action of a toxin purified from; PhTx2 fraction, called PnTx2-6 or δ-CNTX-Pn2a, on L-Glu release from rat; brain cortex synaptosomes, as well as its ability to induce blood-brain barrier permeability. PnTx2-6 increased L-Glu release from rat cortical brain synaptosomes in a time- and dose-dependent manner (EC50 = ∼20 nM; Tm = 16min), as measured by a fluorimetric method. The increase of L-Glu by PnTx2-6 was inhibited by tetrodotoxin. And partially inhibited by EGTA. Calcium channel blockers ω-conotoxin MVIIC (P/Q-types) and ω-conotoxin GVIA (N-type), were able to reduce the PnTx2-6-induced release of L-Glu, while nifedipine (L-type) did not show any inhibition. These findings suggest that thew release of L-Glu by PnTx2-6 is due its primary action on sodium channels, well-known to be target of this toxin. PnTx2-6 is able to potentiate penile erection and this effect may be related with the release of l-glutamate from the CNS, besides a local effect on corpus carvenosum, as previously shown by our group. If L-Glu release and penile erection potentiation are indeed correlated, then this toxin should be able to cross the blood brain barrier (BBB). Results by immunoblotting assays indicated a change in the expression of proteins associated with the paracellular and transcellular transport at the blood-brain barrier, suggesting a BBB dysfunction mediated by PnTx2-6. Therefore, PnTx2-6 may induce the release l-glutamate in the central nervous system, when injected peripherally.

Antibacterial activity of different types of snake venom from the Viperidae family against Staphylococcus aureus / Atividade antibacteriana de diferentes tipos de veneno de serpentes da família Viperidae contra Staphylococcus aureus

Toxins and venoms produced by living organisms have exhibited a variety of biological activities against microorganisms. In this study, we tested seven snake venoms from the family Viperidae for antibacterial activity and the activities of reversal of antibiotic resistance and inhibition of biofilm formation against 22 clinical isolates of Staphylococcus aureus. Bothrops moojeni venom exhibited anti staphylococcal activity with the lowest mean value of minimum inhibitory concentration (MIC). Moreover, reversal of antibiotic resistance was observed for combinations of B. moojeni venom (½ x MIC) and norfloxacin or ampicillin (both ½ x MIC) for 86.4% and 50% of the isolates, respectively. B. moojeni venom alone at ½ MIC inhibited 90% of biofilm formation, whereas in combination with ciprofloxacin, both at ½ MIC, a reduction on the NorA efflux pump activity was observed. The detection of in vitro mutants colonies of S. aureus resistant to B. moojeni venom was low and they did not survive. A phospholipase A2 was purified from the venom of B. moojeni and displayed anti-staphylococcal activity when tested alone or in combination with ciprofloxacin. The results presented here will contribute to the search for new antimicrobial agents against resistant S. aureus.

Toxinas e venenos exibem uma variedade de atividades biológicas contra micro-organismos. Neste estudo, investigou-se a atividade de sete venenos de serpentes, da família Viperidae, sobre o crescimento de Staphylococcus aureus, na reversão fenotípica da resistência a antibióticos e inibição de formação de biofilme contra 22 isolados clínicos de S. aureus. O veneno de Bothrops moojeni apresentou a menor média de concentração inibitória mínima (CIM). Além disso, observou-se reversão da resistência a antibióticos para combinações do veneno de B. moojeni (½ x CIM) e norfloxacina ou ampicilina (ambos ½ x CIM) para 86,4% e 50% dos isolados, respectivamente. O veneno de B. moojeni na concentração de ½ CIM inibiu 90% de formação de biofilme, enquanto ele em combinação com ciprofloxacina, ambos na concentração de ½ CIM, diminuiu a atividade da bomba de efluxo NorA. A detecção in vitro de colônias mutantes de S. aureus resistente ao veneno de B. moojeni foi baixa e eles não sobreviveram. Uma fosfolipase A2 purificada a partir do veneno de B. moojeni exibiu atividade antibacteriana quando testada sozinha ou em combinação com ciprofloxacina. Os dados obtidos poderão contribuir para a pesquisa de novos agentes antimicrobianos contra S. aureus.

The spider toxin Phα1ß recombinant possesses strong analgesic activity.

The native Phα1ß - a Voltage-Gated Calcium Channel (VGCC) blocker - and its Recombinant Version - were both tested in rodent pain models with an intraplantar injections of capsaicin or formalin, a chronic constriction injury, and melanoma cancer related pain. The formalin nociceptive behaviour in the neurogenic phase was not affected by the toxin pre-treatments, while in the inflammatory phase, Phα1ß and the Recombinant form caused a significant reduction. The nociception that was triggered by capsaicin, an agonist of the TRPV1 vanilloid receptor, was totally blocked by 100 pmol/site, i.t. of Phα1ß or the recombinant version. For the neuropathic pain that was induced by a chronic constriction injury of the sciatic nerve, Phα1ß and its Recombinant reduced the allodynia that was induced by the CCI procedure in the rats and the hypersensitivity lasted for 4 h. Fourteen days after the inoculation of the B16-F10 melanoma cells in the mice, a marked hyperalgesia was induced in the melanoma cancer pain model. Phα1ß and the Recombinant form reduced the hyperalgesia with a full reversion at 100 pmol/site i.t. The inhibitory effects of the nociception that was induced by native Phα1ß and the Recombinant in the studied pain models were not statistically different and they developed with no side effects.