Citotóxica

Izidoro LF, Ribeiro MC, Souza GR, Sant'ana CD, Hamaguchi A, Homsi-Brandeburgo MI, Goulart LR, Beleboni RO, Nomizo A, Sampaio SV, Soares AM, Rodrigues VM.

In this work we describe the isolation of a new l-amino acid oxidase (LAAO) referred to as BpirLAAO-I from Bothrops pirajai snake venom, which was highly purified using a combination of molecular exclusion, affinity, and hydrophobic chromatography steps. BpirLAAO-I homodimeric acid glycoprotein (approximate Mr and pI of 130,000 and 4.9, respectively) displays high specificity toward hydrophobic/aromatic amino acids, while deglycosylation does not alter its enzymatic activity. The N-terminal LAAO sequence of its first 49 amino acids presented a high similarity between a amino acid sequence with other LAAOs from: Bothrops spp., Crotalus spp., Calloselasma rhodostoma, Agkistrodon spp., Trimeresurus spp., Pseudechis australis, Oxyuranus scutellatus, and Notechis scutatus. BpirLAAO-I induces time-dependent platelet aggregation, mouse paw edema, cytotoxic activity against Escherichia coli, Pseudomonas aeruginosa, Leishmania sp., and tumor cells, and also a typical fago (M13mp18) DNA fragmentation. Platelet aggregation, leishmanicidal and antitumoral activities were reduced by catalase. Thus, BpirLAAO-I is a multifunctional protein with promising biotechnological and medical applications.

Comp Biochem Physiol C Toxicol Pharmacol. 2006 Mar-Apr;142(3-4):371-81. Epub 2006 Jan 24

Zuliani JP, Gutierrez JM, Casais e Silva LL, Coccuzzo Sampaio S, Lomonte B, Pereira Teixeira Cde F

The in vitro effects of myotoxin III (MT-III), an Asp-49 catalytically-active phospholipase A2, and myotoxin II (MT-II), a catalytically-inactive Lys-49 variant, isolated from Bothrops asper snake venom, on phagocytosis and production of hydrogen peroxide (H2O2) by thioglycollate-elicited macrophages were investigated. MT-II and MT-III were cytotoxic to mouse peritoneal macrophages at concentrations higher than 25 μg/ml. At non-cytotoxic concentrations, MT-II stimulated Fcγ, complement, mannose and β-glucan receptors-mediated phagocytosis, whereas MT-III stimulated only the mannose and β-glucan receptors-mediated phagocytosis. Moreover, both myotoxins induced the release of H2O2 by thioglycollate-elicited macrophages, MT-III being the most potent stimulator. MT-II induced the release of H2O2 only at a concentration of 3.2 μg/ml (130% increment) while MT-III induced this effect at all concentrations tested (0.5–2.5 μg/ml; average of 206% increment). It is concluded that, at non-cytotoxic concentrations, MT-II and MT-III activate defense mechanisms in macrophages upregulating phagocytosis, mainly via mannose and β-glucan receptors, and the respiratory burst.

SBTX 2004

Otero R^a, Nunez V^a, Jimenez SL^a, Fonnegra Ra, Osorio RG^a, Garcia ME^a, Diaz A^a

Twelve of 74 ethanolic extracts of plants used by traditional healers for snakebites in the northwest region of Colombia, were active against lethal effect of Bothrops atrox venom when they were i.p. injected into mice (18–20 g). After preincubation of sublethal doses of every extract (0.5–4.0 mg/mouse) with 1.5 i.p. lethal dose 50% (LD₅₀) (99.3 μg) of venom, seven of them demonstrated 100% neutralizing capacity within 48 h. These were the stem barks of Brownea rosademonte (Caesalpiniaceae) and Tabebuia rosea (Bignoniaceae); rhizomes of Renealmia alpinia ( Zingiberaceae) and Heliconia curtispatha (Heliconiaceae); the whole plants of Pleopeltis percussa (Polypodiaceae) and Trichomanes elegans (Hymenophyllaceae); and the ripe fruits of Citrus limon (Rutaceae). The other five extracts showing partial neutralization (45–80%; 10–30% survival rate in the control group receiving the venom alone; P<0.05) were: leaves, branches and stem of Costus lasius (Costaceae); the whole plant of Sida acuta (Malvaceae); rhizomes of Dracontium croatii (Araceae); leaves and branches of Bixa orellana (Bixaceae) and Struthanthus orbicularis (Loranthaceae). When the extracts were independently administered per oral or i.p. route 60 min before an i.m. venom injection (204 μg=1.5 i.m. LD₅₀), C. limon, T. elegans, B. orellana and T. rosea extracts had partial and significant neutralizing capacity against B. atrox venom lethal effect. C. limon extract was also partially effective when it was administered either i.v. 15 min before or i.p. 5 min after an i.m. venom injection. Three of the 12 extracts with anti-lethal effect (C. limon, D. croatii and S. acuta) were devoid of antiphospholipase A₂ activity, when they were tested against one minimum indirect hemolytic dose of B. atrox venom (2 μg) in agarose-erythrocyte-egg yolk gels.