Tin mesoporphyrin in conjunction with retinoic acid reverses the retinoic acid induced enhancement of phospholipase A(2) activity in vivo in rats.

Retinol (Vitamin A) is known to destabilize membranes. The effect of one of its natural derivatives, Retinoic Acid, was therefore studied on membrane stability, by inversely correlating this stability with Phospholipase A(2) activity. Lipid metalloporphyrin interactions have been the object of intense research in recent times. Our results revealed that the administration of Retinoic Acid (50,000 I.U.) caused a tremendous induction of hepatic Phospholipase A(2) activity in Wistar rats. However when Retinoic Acid and Tin-mesoporphyrin (50 micromol/kgbw) were co-administered, hepatic Phospholipase A(2) activity was inhibited. This result clearly reveals a possible therapeutic application of this metalloporphyrin in alleviating membrane destabilization, connected with Retinoic acid administration.

Chronic NMDA administration to rats up-regulates frontal cortex cytosolic phospholipase A2 and its transcription factor, activator protein-2.

Excessive N-methyl-D-aspartate (NMDA) signaling is thought to contribute to bipolar disorder symptoms. Lithium and carbamazepine, effective against bipolar mania, are reported in rats to reduce brain transcription of an arachidonic acid selective calcium-dependent cytosolic phospholipase A(2) (cPLA(2)), as well as expression of one of its transcription factors, activator protein (AP)-2. In this study, we determined if chronic administration of NMDA (25 mg/kg i.p.) to rats would increase brain cPLA(2) and AP-2 expression, as these antimanic drugs are known to down-regulate excessive NMDA signaling. Administration of a daily subconvulsive dose of NMDA to rats for 21 days decreased frontal cortex NMDA receptor (NR)-1 and NR-3A subunits and increased cPLA(2) activity, phosphorylation, protein, and mRNA levels. The activity and protein levels of secretory phospholipase A(2) or calcium-independent phospholipase A(2) were not changed significantly. Chronic NMDA also increased the DNA-binding activity of AP-2 and the protein levels of its alpha and beta subunits. These changes were absent following acute (3 h earlier) NMDA administration. The changes, opposite to those found following chronic lithium or carbamazepine, are consistent with up-regulated arachidonic acid release due to excessive NR signaling and may be a contributing factor to bipolar mania.

Chronic lithium administration attenuates up-regulated brain arachidonic acid metabolism in a rat model of neuroinflammation.

Neuroinflammation, caused by a 6-day intracerebroventricular infusion of lipopolysaccharide (LPS) in rats, is associated with the up-regulation of brain arachidonic acid (AA) metabolism markers. Because chronic LiCl down-regulates markers of brain AA metabolism, we hypothesized that it would attenuate increments of these markers in LPS-infused rats. Incorporation coefficients k* of AA from plasma into brain, and other brain AA metabolic markers, were measured in rats that had been fed a LiCl or control diet for 6 weeks, and subjected in the last 6 days on the diet to intracerebroventricular infusion of artificial CSF or of LPS. In rats on the control diet, LPS compared with CSF infusion increased k* significantly in 28 regions, whereas the LiCl diet prevented k* increments in 18 of these regions. LiCl in CSF infused rats increased k* in 14 regions, largely belonging to auditory and visual systems. Brain cytoplasmic phospholipase A(2) activity, and prostaglandin E(2) and thromboxane B(2) concentrations, were increased significantly by LPS infusion in rats fed the control but not the LiCl diet. Chronic LiCl administration attenuates LPS-induced up-regulation of a number of brain AA metabolism markers. To the extent that this up-regulation has neuropathological consequences, lithium might be considered for treating human brain diseases accompanied by neuroinflammation.

An entomopathogenic bacterium, Xenorhabdus nematophila, inhibits hemocyte phagocytosis of Spodoptera exigua by inhibiting phospholipase A(2).

Phagocytosis is a hemocytic behavior against bacterial infection. An entomopathogenic bacterium, Xenorhabdus nematophila, inhibits immune responses of target insects and causes hemolymph septicemia. This study analyzed how X. nematophila could inhibit phagocytosis to increase its pathogenicity. Granular cells and plasmatocytes were the main phagocytic hemocytes of Spodoptera exigua determined by observing fluorescence-labeled bacteria in the cytosol. X. nematophila significantly inhibited phagocytosis of both hemocytes, while heat-killed X. nematophila lost its inhibitory potency. However, co-injection of X. nematophila with arachidonic acid did not show any significant inhibition of hemocyte phagocytosis. In fact, hemocytes of S. exigua infected with X. nematophila showed significant reduction in phospholipase A(2) (PLA(2)) activity. Dexamethasone, a specific PLA(2) inhibitor, significantly inhibited phagocytosis of both cell types. However, the inhibitory effect of dexamethasone was recovered by addition of arachidonic acid. Incubation of hemocytes with benzylideneacetone, a metabolite of X. nematophila, inhibited phagocytosis in a dose-dependent manner. These results suggest that X. nematophila produces and secretes PLA(2) inhibitor(s), which in turn inhibit the phagocytic response of hemocytes.

Arachidonic acid inhibits osteoblast differentiation through cytosolic phospholipase A2-dependent pathway.

OBJECTIVE: Arachidonic acid, a precursor of prostaglandins (PGs), is released by phospholipase A2 (PLA2) and plays an important role in biological reactions. We examined the roles of arachidonic acid on the pathway of PG synthesis and osteoblast differentiation by using clone MC3T3-E1 cells. MATERIALS AND METHODS: The effect of arachidonic acid was evaluated by the measurement of alkaline phosphatase activity, cells shape, production of arachidonic acid and the expression of cyclooxygenase (COX). RESULTS: Arachidonic acid dose dependently decreased alkaline phosphatase activity and increased PGE2 production in MC3T3-E1 cells. The cell shape changed from polygonal to fibroblastic following treatment with arachidonic acid. These effects were recovered by the treatment of NS-398 and indomethacin. Arachidonic acid increased the expression of COX-2 mRNA and the PGE2 production. The exogenous arachidonic acid induced the release of cellular arachidonic acid in MC3T3-E1 cells. Moreover, methylarachidonyl fluorophosphonate suppressed the arachidonic acid release and the expression of COX-2 mRNA. CONCLUSION: The present results indicate that exogenous arachidonic acid stimulated the activity of PLA2, leading to the new release of membranous arachidonic acid. The amplified arachidonic acid enhanced PGE2 production by COX-2, which inhibits the differentiation of MC3T3-E1 cells. Our results provide a new insight into the molecular mechanisms by which exogenous arachidonic acid plays a role as a paracrine/autocrine amplifier of PGE2 biosynthesis by coupling with PLA2 and COX-2.

Changes in rat uterine and cervical phospholipase A2 activity following progesterone agonist or antagonist administration at term.

Our previous study revealed that a fall in plasma progesterone (P(4)) level was associated with a transient increase in cytosolic phospholipase A(2) (PLA(2)) activity and prostaglandin F(2)alpha level in the rat uterus and cervix during natural parturition. This study determined the changes in the PLA(2) activities during modulated occurrence of delivery by P(4) antagonist or agonist late in pregnancy. In rats undergoing P(4) antagonist-induced preterm delivery, the PLA(2) activities of both uterine and cervical cytosol significantly decreased 12 h after the challenge and tended to be attenuated within 72 h. The plasma P(4) level altered in a similar pattern. Blockade of delivery by chronic treatment with P(4) agonist was not associated with changes in uterine PLA(2) activity compared with that in normally delivering rats, although there was a persistent rise in cervical PLA(2) activity. The obtained data indicates that the PLA(2) activities in rat uterine and cervical cytosol are not regulated solely by P(4) and that delivery can occur without activation of this enzyme.

Effect of a selective thromboxane A2 synthetase inhibitor on the systemic changes induced by circulating pancreatic phospholipase A2.

BACKGROUND: In acute pancreatitis, pancreatic phospholipase A(2) (PLA2) in the circulating blood hydrolyzes phospholipids contained in plasma lipoproteins, liberating eicosanoid precursors that are subsequently converted to various eicosanoids. The pathophysiological significance of eicosanoid synthesis via this pathway is unknown. The aim of this study was to clarify the role of thromboxane A(2) (TXA(2)) synthesis by circulating pancreatic PLA(2) in the pathogenesis of the systemic complications of acute pancreatitis. METHODS: Guinea pigs were divided into two groups: a control group and an ozagrel group, which received intravenous administration of ozagrel, a selective TXA(2) synthetase inhibitor. Pancreatic PLA(2) was infused intravenously in both groups for 30 min, and systemic changes during the infusion were examined. RESULTS: In the control group, there was an increase in plasma thromboxane B(2) (TXB(2)) concentration, a decrease in mean arterial pressure and heart rate, a decrease in arterial base excess (BE), bicarbonate concentration (HCO(3) (-)), and pH, a decrease in platelet count and plasma fibrinogen concentration, and a shortened prothrombin time during the infusion of pancreatic PLA(2). In the ozagrel-treated group, changes in plasma TXB(2) concentration, BE, HCO(3) (-), and platelet count were significantly inhibited. CONCLUSIONS: TXA(2) synthesis by circulating pancreatic PLA(2) contributes to metabolic acidosis and thrombocytopenia during acute pancreatitis.

Lipoprotein-associated phospholipase A2: pathogenic mechanisms and clinical utility for predicting cardiovascular events.

Lipoprotein-associated phospholipase A(2 )(Lp-PLA(2)), a member of the phospholipase superfamily, circulates primarily bound to low-density lipoprotein and has been associated with cardiovascular disease risk in epidemiologic studies. However, it has not been established whether Lp-PLA(2) is a risk marker or a risk factor. Identification of individuals with elevated Lp-PLA(2) may improve risk assessment, and Lp-PLA(2) may also provide an additional target of therapy. Statin therapy has been shown to reduce Lp-PLA(2), and selective inhibitors of Lp-PLA(2) are under development. Additional research is needed to further determine the role of Lp-PLA(2) in atherogenesis and atherothrombotic events.

Bioactive lipids in schizophrenia.

Bioactive lipids, in particular arachidonic acid (AA), are vital for monoaminergic neurotransmission, brain development and synaptic plasticity. Phospholipases A2 (PLA2) are key-enzymes in AA metabolism and are activated during monoaminergic neurotransmission. Reduced membrane AA levels, and an altered activity of PLA2 have been found in peripheral membranes of drug-naïve patients with schizophrenia with some conflicting results in more chronic patient populations. Furthermore, in vivo brain phosphorus-31 magnetic resonance spectroscopy suggests reduced lipid membrane precursors (phosphomonoesters) and increased membrane breakdown products (phosphodiesters) in drug-naïve or early treated first-episode schizophrenia patients compared to age-matched controls or chronic populations and these changes were correlated with peripheral red blood cell membrane AA levels. We postulate that processes modulating membrane lipid metabolism are associated with psychotic illnesses and might partially explain the mechanism of action of antipsychotic agents, as well as experimental agents such as purified ethyl-eicosapentaenoic acid (E-EPA). Recent supplementation trials suggest that E-EPA is a modestly effective augmentation treatment resulting in reduced doses of antipsychotic medication in acutely ill patients with schizophrenia (but not in residual-type schizophrenia). This review investigates the role of bioactive lipids in schizophrenia and its treatment, as well as its potential use in prevention.

COX-2 and sPLA2 inhibitory activity of aqueous extract and polyphenols of Rhizophora mangle (red mangrove).

The aqueous extract of Rhizophora mangle bark and its polyphenolic fractions showed remarkable in vitro antiinflammatory activity in a preliminary study. The low molecular weight fraction exhibited cyclooxygenase-2 inhibitory activity while the total aqueous extract and the low molecular weight fraction showed secretory phospholipase A(2) inhibitory activity.

The role of phospholipases A2 in schizophrenia.

A range of neurotransmitter systems have been implicated in the pathogenesis of schizophrenia based on the antidopaminergic activities of antipsychotic medications, and chemicals that can induce psychotic-like symptoms, such as ketamine or PCP. Such neurotransmitter systems often mediate their cellular response via G-protein-coupled release of arachidonic acid (AA) via the activation of phospholipases A2 (PLA2s). The interaction of three PLA2s are important for the regulation of the release of AA--phospholipase A2 Group 2 A, phospholipase A2 Group 4A and phospholipase A2 Group 6A. Gene variations of these three key enzymes have been associated with schizophrenia with conflicting results. Preclinical data suggest that the activity of these three enzymes are associated with monoaminergic neurotransmission, and may contribute to the differential efficacy of antipsychotic medications, as well as other biological changes thought to underlie schizophrenia, such as altered neurodevelopment and synaptic remodelling. We review the evidence and discuss the potential roles of these three key enzymes for schizophrenia with particular emphasis on published association studies.

Modulation by LL-37 of the responses of salivary glands to purinergic agonists.

The interaction of mice submandibular gland cells with LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES), a cationic peptide with immunomodulatory properties, was investigated. LL-37 at a concentration that did not affect the integrity of the cells increased the uptake of calcium and activated a calcium-insensitive phospholipase A(2) (PLA(2)). The small release of ATP induced by LL-37 could not account for this stimulation because apyrase did not significantly block the response to LL-37. The divalent cation magnesium inhibited the response to LL-37, but this inhibition was probably nonspecific because it also inhibited the in vitro bacteriostatic effect of the peptide. The increase of calcium uptake by LL-37 was not affected by 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN-62), a rather specific inhibitor of P2X(7) receptors in mice. LL-37 also increased [Ca(2+)](i) in cells from mice invalidated for these receptors. LL-37 had no effect on the response to carbachol. It inhibited the increase of [Ca(2+)](i) and the activation of phospholipase D by ATP. It potentiated the activation of the PLA(2) by the nucleotide. Finally, LL-37 increased the fluidity of the plasma membrane of submandibular gland cells. In conclusion, our results suggest that LL-37 is an autocrine regulator of submandibular gland cells. It does not stimulate mouse P2X(7) receptors but modulates their responses.

Flavonoids from Artemisia copa with anti-inflammatory activity.

Bioactivity-guided fractionation of the dichloromethane and ethanol extracts from the aerial parts of Artemisia copa led to the isolation of the flavonoids spinacetin, jaceosidin, axillarin, penduletin, tricin and chrysoeriol. These compounds were studied for possible inhibitory activity on the generation of inflammatory mediators in a cell line of mouse macrophages (RAW 264.7) stimulated with lipopolysaccharide. Spinacetin and jaceosidin weakly inhibited nitric oxide production whereas all flavonoids reduced prostaglandin E2 levels to different extents. The most active flavonoid was jaceosidin that inhibited cyclooxygenase-2 activity in a concentration-dependent manner with an IC50 value of 2.8 microM. In addition, the other flavonoids partially inhibited synovial phospholipase A2 activity. These mechanisms may provide a basis for explaining the anti-inflammatory activity of this plant.

The cellular mechanisms by which adenosine evokes release of nitric oxide from rat aortic endothelium.

Adenosine and nitric oxide (NO) are important local mediators of vasodilatation. The aim of this study was to elucidate the mechanisms underlying adenosine receptor-mediated NO release from the endothelium. In studies on freshly excised rat aorta, second-messenger systems were pharmacologically modulated by appropriate antagonists while a NO-sensitive electrode was used to measure adenosine-evoked NO release from the endothelium. We showed that A1-mediated NO release requires extracellular Ca2+, phospholipase A2 (PLA2) and ATP-sensitive K+ (KATP) channel activation whereas A2A-mediated NO release requires extracellular Ca2+ and Ca2+-activated K+ (KCa) channels. Since our previous study showed that A1- and A2A-receptor-mediated NO release requires activation of adenylate cyclase (AC), we propose the following novel pathways. The K+ efflux resulting from A1-receptor-coupled KATP-channel activation facilitates Ca2+ influx which may cause some stimulation of endothelial NO synthase (eNOS). However, the increase in [Ca2+]i also stimulates PLA2 to liberate arachidonic acid and stimulate cyclooxygenase to generate prostacyclin (PGI2). PGI2 acts on its endothelial receptors to increase cAMP, so activating protein kinase A (PKA) to phosphorylate and activate eNOS resulting in NO release. By contrast, the K+ efflux resulting from A2A-coupled KCa channels facilitates Ca2+ influx, thereby activating eNOS and NO release. This process may be facilitated by phosphorylation of eNOS by PKA via the action of A2A-receptor-mediated stimulation of AC increasing cAMP. These pathways may be important in mediating vasodilatation during exercise and systemic hypoxia when adenosine acting in an endothelium- and NO-dependent manner has been shown to be important.

Toxins not neutralized by brown snake antivenom.

The Australian snakes of the genus Pseudonaja (dugite, gwardar and common brown) account for the majority of snake bite related deaths in Australia. Without antivenom treatment, the risk of mortality is significant. There is an accumulating body of evidence to suggest that the efficacy of the antivenom is limited. The current study investigates the protein constituents recognized by the antivenom using 2-DE, immuno-blot techniques and rat tracheal organ bath assays. The 2-DE profiles for all three snake venoms were similar, with major species visualized at 78-132 kDa, 32-45 kDa and 6-15 kDa. Proteins characterized by LC-MS/MS revealed a coagulant toxin ( approximately 42 kDa) and coagulant peptide ( approximately 6 kDa), as well as two PLA(2) ( approximately 14 kDa). Peptides isolated from approximately 78 kDa and 15-32 kDa protein components showed no similarity to known protein sequences. Protein recognition by the antivenom occurred predominantly for the higher molecular weight components with little recognition of 6-32 kDa MW species. The ability of antivenom to neutralize venom activity was also investigated using rat tracheal organ bath assays. The venoms of Pseudonaja affinis affinis and Pseudonaja nuchalis incited a sustained, significant contraction of the trachea. These contractions were attributed to PLA(2) enzymatic activity as pre-treatment with the PLA(2) inhibitor 4-BPB attenuated the venom-induced contractions. The venom of Pseudonaja textilis incited tracheal contractility through a non-PLA(2) enzymatic activity. Neither activity was attenuated by the antivenom treatment. These results represent the first proteomic investigation of the venoms from the snakes of the genus Pseudonaja, revealing a possible limitation of the brown snake antivenom in binding to the low MW protein components.

Injury and recovery of pyramidal neurons in the rat hippocampus after a single episode of oxidative stress induced by intracerebroventricular injection of ferrous ammonium citrate.

The present study was carried out to elucidate the effect of a single episode of oxidative stress on pyramidal neurons of the rat hippocampus. A significant increase in the number of neurons that were immunolabeled for the toxic lipid peroxidation product, 4-hydroxynonenal (HNE) was observed in field CA3 of the hippocampus, at 1 day, 7 days and 14 days after intracerebroventricular injection of 1 microL of 5 mM ferrous ammonium citrate, compared to ammonium citrate injected controls at these time points. The number of HNE positive cells was fewer at 14 days, compared to 1 day, after ferrous ammonium citrate injection. The changes in HNE immunoreactivity were paralleled by changes in cytoplasmic phospholipase A2 (cPLA2) labeling in the pyramidal neurons in adjacent sections, suggesting that some of the HNE could have arisen as a result of peroxidation of arachidonic acid that was released by cPLA2. Interestingly, despite the HNE and cPLA2 labeling, no loss of neurons was observed in adjacent Nissl and Fluoro-Jade stained sections. Electron microscopy also showed that the HNE or cPLA2 labeled cells had features of injured neurons, rather than necrotic neurons. The reduction of HNE immunoreactivity in neurons at 14 days after oxidative injury, and the absence of cell loss at any of the time intervals, shows that hippocampal pyramidal neurons have remarkable ability to recover from a single episode of oxidative stress, if repeated injury such as seizures / excitotoxicity could be avoided.

Effects of gabexate mesilate (FOY) on amylase and phospholipase A2 in human serum and pancreatic juice.

The precise inhibitory action of gabexate mesilate (GM) on the various pancreatic enzymes remains unclear. We designed this study to investigate the enzyme inhibitory action of GM in the serum and directly in the pancreatic juice. We observed 16 cases with postoperative pancreatic drainage. Patients were randomly assigned to one of two groups, to receive GM at a dose of 600 mg/24 hr (treated group: 8 patients) or a physiological solution (control group: 8 patients) by continuous intravenous infusion. In both groups pancreatic juice and serum were sampled three times: before infusion began (T0) and at 12 hr (T1) and 24 hr after infusion ended (T2). At the end of the study, seven patients received octreotide and the volume of pancreatic secretion was determined. No statistical difference was observed in serum amylase and phospholipase A2 activity in the treated and control groups. On the contrary, amylase and phospholipase A2 activity in the pancreatic juice diminished significantly only in the treated group, and in these patients a GM metabolite was also detectable in the pancreatic secretion. The volume of pancreatic secretion decreased only after infusion of octreotide. The enzyme inhibition in the pancreatic gland itself and the central role of inhibition of phospholipase A2 in the enzyme cascade responsible for activating other proteases, confirm the therapeutic use of GM in acute pancreatitis. An association of GM and octreotide during acute pancreatitis should be useful because of their different mechanisms.

Inhibition of phospholipase A2 activity reduces membrane fluidity in rat hippocampus.

Phospholipase A2 (PLA2) is a family of key enzymes in membrane phospholipid metabolism. In rats, the inhibition of PLA2 activity in the hippocampus was found to impair memory formation. Because memory function is largely dependent on the fluidity of brain membranes, we performed the present study to investigate the effects of in vivo PLA2 inhibition (with PACOCF3) on the fluidity of hippocampal membranes from rats trained in a learning task. Hippocampal tissue from rats injected with 100 microM PACOCF3 showed reduced membrane fluidity as compared to vehicle (p < 0.01), and the reduction of membrane fluidity was highly correlated with PLA2 inhibition (r = .76, p < 0.03). This finding is of interest because reduction of brain membrane fluidity impairs memory formation and both decreased PLA2 activity and reduced membrane fluidity have been reported in the brain from patients with Alzheimer's disease.

Effects of atorvastatin versus other statins on fasting and postprandial C-reactive protein and lipoprotein-associated phospholipase A2 in patients with coronary heart disease versus control subjects.

The effects of atorvastatin (40 mg/day) versus placebo on fasting and postprandial plasma levels of high-sensitivity C-reactive protein (hs-CRP) and lipoprotein-associated phospholipase A2 (Lp-PLA2) were examined over 36 weeks in 84 patients who had coronary heart disease and low-density lipoprotein cholesterol levels >130 mg/dl and compared directly with the effects of fluvastatin, lovastatin, pravastatin, and simvastatin. Results were also compared with those obtained in age- and gender-matched control subjects (n = 84). Feeding increased median hs-CRP levels by 2% in patients (p = NS) and 22% in controls (p <0.01) and increased mean Lp-PLA2 values by 9% in patients (p = NS) but decreased values by 21% in controls (p <0.0001). Patients had 51% higher median hs-CRP values and 29% higher mean Lp-PLA2 values than did controls (p <0.05 for hs-CRP and Lp-PLA2) in the fasting state; however, Lp-PLA2 values were 62% higher (p <0.0001) in the fed state in patients compared with controls. Atorvastatin decreased median hs-CRP levels by 32% (p <0.01) and mean Lp-PLA2 values by 26% in patients (p <0.0001), with similar decreases in the fed state, and none of the other statins had any significant effect on these parameters. Change in Lp-PLA2 was significantly related to change in low-density lipoprotein cholesterol (p <0.01), with no significant relations with change in hs-CRP. Our data indicate greater differences in patients with coronary heart disease compared with controls in Lp-PLA2 in the fed state than in the fasting state and that atorvastatin is more effective than fluvastatin, lovastatin, pravastatin, or simvastatin for decreasing not only low-density lipoprotein cholesterol but also hs-CRP and Lp-PLA2.

Neutralizing properties of Musa paradisiaca L. (Musaceae) juice on phospholipase A2, myotoxic, hemorrhagic and lethal activities of crotalidae venoms.

The use of plants as medicine has been referred to since ancient peoples, perhaps as early as Neanderthal man. Plants are a source of many biologically active products and nowadays they are of great interest to the pharmaceutical industry. The study of how people of different culture use plants in particular ways has led to the discovery of important new medicines. In this work, we verify the possible activity of Musa paradisiaca L. (Musaceae) against the toxicity of snake venoms. Musa paradisiaca, an important source of food in the world, has also been reported to be popularly used as an anti-venom. Interaction of Musa paradisiaca extract (MsE) with snake venom proteins has been examined in this study. Phospholipase A2 (PLA2), myotoxic and hemorrhagic activities, including lethality in mice, induced by crotalidae venoms were significantly inhibited when different amounts of MsE were mixed with these venoms before assays. On the other hand, mice that received MsE and venoms without previous mixture or by separated routes were not protected against venom toxicity. Partial chemical characterization of MsE showed the presence of polyphenols and tannins and they are known to non-specifically inactivate proteins. We suggest that these compounds can be responsible for the in vitro inhibition of the toxic effects of snake venoms. In conclusion, according to our results, using mice as experimental model, MsE does not show protection against the toxic effects of snake venoms in vivo, but if was very effective when the experiments were done in vitro.