Leishmanicidal Activity of Guanidine Derivatives against Leishmania infantum.

Leishmaniasis is a neglected tropical infectious disease with thousands of cases annually; it is of great concern to global health, particularly the most severe form, visceral leishmaniasis. Visceral leishmaniasis treatments are minimal and have severe adverse effects. As guanidine-bearing compounds have shown antimicrobial activity, we analyzed the cytotoxic effects of several guanidine-bearing compounds on Leishmania infantum in their promastigote and amastigote forms in vitro, their cytotoxicity in human cells, and their impact on reactive nitrogen species production. LQOFG-2, LQOFG-6, and LQOFG-7 had IC50 values of 12.7, 24.4, and 23.6 µM, respectively, in promastigotes. These compounds exhibited cytotoxicity in axenic amastigotes at 26.1, 21.1, and 18.6 µM, respectively. The compounds showed no apparent cytotoxicity in cells from healthy donors. To identify mechanisms of action, we evaluated cell death processes by annexin V and propidium iodide staining and nitrite production. Guanidine-containing compounds caused a significant percentage of death by apoptosis in amastigotes. Independent of L. infantum infection, LQOFG-7 increased nitrite production in peripheral blood mononuclear cells, which suggests a potential mechanism of action for this compound. Therefore, these data suggest that guanidine derivatives are potential anti-microbial molecules, and further research is needed to fully understand their mechanism of action, especially in anti-leishmanial studies.

Characterization of Regulatory T Cells in Patients Infected by Leishmania Infantum.

High IL-10 levels are pivotal to parasite survival in visceral leishmaniasis (VL). Antigenic stimuli induce IL-10 expression and release of adenosine by CD39/CD73. Due their intrinsic ability to express IL-10 and produce adenosine from extracellular ATP, we evaluated the IL-10, CD39, and CD73 expression by Regulatory T cells (Treg) correlated with VL pathology. Using flow cytometry, Treg cells was analyzed in peripheral blood samples from VL patients (in the presence and absence of Leishmania infantum soluble antigen (SLA)) and healthy individuals (negative endemic control-NEC group), without any treatment. Additionally, IL-10 levels in leukocytes culture supernatant were measured in all groups by ELISA assay. VL patients presented more Treg frequency than NEC group, independently of stimulation. ELISA results demonstrated that SLA induced higher IL-10 expression in the VL group. However, the NEC group had a higher Treg IL-10+ compared to the VL group without stimulation and SLA restored the IL-10 in Treg. Additionally, an increase in Treg CD73+ in the VL group independently of stimuli compared to that in the NEC group was observed. We suggest that Treg are not the main source of IL-10, while the CD73 pathway may be an attempt to modulate the exacerbation of immune response in VL disease.

In vitro anti-Leishmania activity and molecular docking of spiro-acridine compounds as potential multitarget agents against Leishmania infantum.

Leishmaniasis is an infectious disease with several limitations regarding treatment schemes. This work reports the anti-Leishmania activity of spiroacridine compounds against the promastigote (IC50 = 1.1 to 6.0 µg / mL) and amastigote forms of the best compounds (EC50 = 4.9 and 0.9 µg / mL) inLeishmania (L.) infantumand proposes an in-silico study with possible selective therapeutic targets for L. infantum. The substituted dimethyl-amine compound (AMTAC 11) showed the best leishmanicidal activity in vitro, and was found to interact with TryRandLdTopoI. comparisons with standard inhibitors were performed, and its main interactions were elucidated. Based on the biological assessment and the structure-activity relationship study, the spiroacridine compounds appear to be promisinganti-leishmaniachemotherapeutic agents to be explored.

Redox-Active Drug, MnTE-2-PyP5+, Prevents and Treats Cardiac Arrhythmias Preserving Heart Contractile Function.

BACKGROUND: Cardiomyopathies remain among the leading causes of death worldwide, despite all efforts and important advances in the development of cardiovascular therapeutics, demonstrating the need for new solutions. Herein, we describe the effects of the redox-active therapeutic Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin, AEOL10113, BMX-010 (MnTE-2-PyP5+), on rat heart as an entry to new strategies to circumvent cardiomyopathies. METHODS: Wistar rats weighing 250-300 g were used in both in vitro and in vivo experiments, to analyze intracellular Ca2+ dynamics, L-type Ca2+ currents, Ca2+ spark frequency, intracellular reactive oxygen species (ROS) levels, and cardiomyocyte and cardiac contractility, in control and MnTE-2-PyP5+-treated cells, hearts, or animals. Cells and hearts were treated with 20 µM MnTE-2-PyP5+ and animals with 1 mg/kg, i.p. daily. Additionally, we performed electrocardiographic and echocardiographic analysis. RESULTS: Using isolated rat cardiomyocytes, we observed that MnTE-2-PyP5+ reduced intracellular Ca2+ transient amplitude, without altering cell contractility. Whereas MnTE-2-PyP5+ did not alter basal ROS levels, it was efficient in modulating cardiomyocyte redox state under stress conditions; MnTE-2-PyP5+ reduced Ca2+ spark frequency and increased sarcoplasmic reticulum (SR) Ca2+ load. Accordingly, analysis of isolated perfused rat hearts showed that MnTE-2-PyP5+ preserves cardiac function, increases SR Ca2+ load, and reduces arrhythmia index, indicating an antiarrhythmic effect. In vivo experiments showed that MnTE-2-PyP5+ treatment increased Ca2+ transient, preserved cardiac ejection fraction, and reduced arrhythmia index and duration. MnTE-2-PyP5+ was effective both to prevent and to treat cardiac arrhythmias. CONCLUSION: MnTE-2-PyP5+ prevents and treats cardiac arrhythmias in rats. In contrast to most antiarrhythmic drugs, MnTE-2-PyP5+ preserves cardiac contractile function, arising, thus, as a prospective therapeutic for improvement of cardiac arrhythmia treatment.

Potassium Channel Activation Is Involved in the Cardiovascular Effects Induced by Freeze Dried Syzygium jambolanum (Lam.) DC Fruit Juice.

This work aimed to explore the cardiovascular effects induced by freeze-dried juice from Syzygium jambolanum (Lam.) DC fruits (JSJ). JSJ presented high polyphenol content and steroids. HPLC analysis revealed that 2,5-dihydroxybenzoic and caffeic acid were present in higher amounts in the JSJ extract. In rat, JSJ induces hypotension and vasodilatation in mesenteric arteries, with or without vascular endothelium. JSJ-mediated vasodilation response against contractions induced with KCl (60 mM) depolarizing solution was significantly lower than the responses induced by JSJ when evaluated against phenylephrine-induced contractions. To investigate the involvement of potassium channels we used Tyrode's solution with KCl (20 mM) or tetraethylammonium (1.0, 3.0, or 5.0 mM). In these conditions JSJ-induced effects were significantly attenuated. To investigate the potassium channel subtypes involved in the response, we used 4-aminopyridine, glibenclamide, BaCl2, and iberiotoxin. In the presence (simultaneous) of different potassium channel blockers we observed a significant attenuation of JSJ-induced effect. Inhibition was also observed when using BaCl2, glibenclamide, or 4-aminopyridine, separately. However, incubation with iberiotoxin did not promote changes in either maximum effect, or potency. We also evidenced a discrete participation of CaV channels in the JSJ-induced vasorelaxant effect. In addition, patch-clamp studies demonstrated that JSJ could activate potassium channels. In conclusion, JSJ promotes hypotension and vasorelaxation in rats, involving, at least, the activation of potassium channels.

Determining the Relative Binding Affinity of Ricin Toxin A Inhibitors by Using Molecular Docking and Nonequilibrium Work.

Ricin is a ribosome-inactivating protein (RIP type 2) consisting of two subunits, ricin toxin A (RTA) and ricin toxin B (RTB). Because of its cytotoxicity, ricin has worried world authorities for its potential use as a chemical weapon; therefore, its inhibition is of great biotechnological interest. RTA is the target for inhibitor synthesis, and pterin derivatives are promising candidates to inhibit it. In this study, we used a combination of the molecular docking approach and fast steered molecular dynamics (SMD) to assess the correlation between nonequilibrium work, ⟨ W⟩, and the IC50 for six RTA inhibitors. The results showed that molecular docking is a powerful tool to predict good bioactive poses of RTA inhibitors, and ⟨ W⟩ presented a strong correlation with IC50 ( R2 = 0.961). Such a profile ranked the RTA inhibitors better than the molecular docking approach. Therefore, the combination of docking and fast SMD simulation was shown to be a promising tool to distinguish RTA-active inhibitors from inactive ones and could be used as postdocking filtering approach.

Morita-Baylis-Hillman Adducts Display Anti-Inflammatory Effects by Modulating Inflammatory Mediator Expression in RAW264.7 Cells.

Inflammatory response plays an important role not only in the normal physiology but also in pathologies such as cancers. The Morita-Baylis-Hillman adducts (MBHA) are a novel group of synthetic molecules that have demonstrated many biological activities against some parasitic cells such as Plasmodium falciparum, Leishmania amazonensis, and Leishmania chagasi, and antimitotic activity against sea urchin embryonic cells was also related. However, little is known about the mechanisms induced by MBHA in inflammatory process and its relation with anticancer activity. The present work investigated the cytotoxicity of three MBHA derivatives (A2CN, A3CN, and A4CN), on human colorectal adenocarcinoma, HT-29 cells, and their anti-inflammatory activities were examined in lipopolysaccharide- (LPS-) stimulated RAW264.7 macrophage cells, being these derivatives potentially cytotoxic to HT-29 cells. Coincubation with A2CN, A3CN, or A4CN and LPS in RAW264.7 cells inhibited NO production, as well as the production of reactive oxygen species (ROS) was also repressed. The mRNA expressions of IL-1ß and IL-6 were significantly downregulated by such MBHA compounds in RAW264.7 cells, but only A2CN was able to inhibit the COX-2 gene expression. We also showed that MBHA compounds decreased almost to zero the production of IL-1ß and IL-6. These findings display that such MBHA compounds exhibit anticancer and anti-inflammatory activities.

Synthesis, Cytotoxic Activity on Leukemia Cell Lines and Quantitative Structure-Activity Relationships (QSAR) Studies of Morita-Baylis-Hillman Adducts.

BACKGROUND: The Morita-Baylis-Hillman reaction is an organocatalyzed chemical transformation that allows access to small poly-functionalized molecules and has considerable synthetic potential and promising biological profiles. The Morita-Baylis-Hillman adducts (MBHA) are a new class of bioactive compounds and highlight its potentialities to the discovery of new cheaper and efficient drugs, e.g. as anti-Leishmania chagasi and Leishmania amazonensis, anti- Trypanosoma cruzi, anti-Plasmodium falciparum and Plasmodium berghei, lethal against Biomphalaria glabrata, antibacterial, antifungal, herbicide and others. METHODS: The goal of this work is to describe the primary cytotoxic activities against strains of human leukemia HL-60 cell line for thirty-four Morita-Baylis- Hillman adducts (MBHA), followed by a Quantitative Structure-Activity Relationships study (QSAR). RESULTS: The conventional or microwave-assisted syntheses of MBHA, derived from substituted aromatics or Isatin, were performed in good to excellent yields (70-100%) in short reaction times, using protocols recently developed by us. Isatin derivatives, MBHA 31 and 32, were the most active in this congener series of compounds, with IC50 values of 10.8 µM and 7.8 µM, respectively. The primary cytotoxic activities against chronic leukemia cells (K562) were also evaluated to these two most active compounds (MBHA 31 and 32), presenting IC50 values of 53 µM and 43 µM respectively. QSAR study was performed considering 3D, 2D and constitutional molecular descriptors. These were selected from Ordered Predictor Selection algorithm and submitted to Partial Least Squares Modeling. CONCLUSION: We present an interesting investigation about cytotoxic activities on human leukemia cell line (HL-60) for 34 synthetic MBHA. In a good way we discovered that the most cytotoxic compounds (31-32, 10.8 µM and 7.8 µM respectively) were also prepared quantitatively (100% yields) in a short reaction time using microwave irradiation. We demonstrate that 31 and 32 induced apoptosis and not necrosis in HL-60 cells, observed by externalization of PS and increase Anexin-V positive cells. Quantitative Structure-Activity Relationships considering 3D, 2D and constitutional descriptors provided a robust and predictive PLS model, in accordance with SAR observations.

Distinct effects of novel naphtoquinone-based triazoles in human leukaemic cell lines.

OBJECTIVES: The aim of this study was to investigate the cytotoxic effect of new 1,4-naphthoquinone- 1,2,3-triazoles, named C2 to C8 triazole derivatives, towards human cancer cell lines. METHODS: The effect on cell viability was assessed by MTT and propidium iodide assays. The cytotoxic effect of C2 and C3 in K562 and HL-60 cells were analyzed by flow cytometry, DNA fragmentation and reactive oxygen species (ROS) production. Western blot and q-PCR procedures were also performed. KEY FINDINGS: C2 and C3 inhibited both K562 and HL-60 cells growth in a concentration-dependent manner. C2 presented the highest cytotoxic activity with an IC50 of approximately 14 µm and 41 µm for HL-60 and K562 cells, respectively, while being less toxic to normal peripheral blood monocyte cells. Both derivatives induced cellular changes in HL-60 cells, characteristic of apoptosis, such as mitochondrial membrane depolarization, phosphatidylserine externalization, increasing sub-G1 phase, DNA fragmentation, downregulating Bcl-2 protein and upregulating Bax protein. In K562 cells, C2 and C3 induced S-phase arrest of cell cycle, which was associated with upregulation of p21. The effect of these derivatives in HL-60 cells can be related to the ROS intracellular level. CONCLUSION: Taken together our results showed that C2 and C3 triazole derivatives presented the best potential for drug design.

Compound A398, a novel podophyllotoxin analogue: cytotoxicity and induction of apoptosis in human leukemia cells.

Despite advances in oncology research, cancer is one of the leading causes of death worldwide. Thus, there is a demand for the development of more selective and effective antitumor agents. This study showed that A398, a novel podophyllotoxin analogue, was cytotoxic to the HT-29, MCF-7, MOLT-4 and HL-60 tumor cell lines, being less active in human peripheral blood mononuclear cells and normal cell lines FGH and IEC-6. Tests using the HepG2 lineage indicated that its metabolites do not contribute to its cytotoxicity. In the HL-60 cells, A398 induced apoptosis in a time and concentration-dependent manner, promoting mitochondrial depolarization, inhibition of Bcl-2, phosphatidylserine exposure, activation of caspases -8, -9 and -3, and DNA fragmentation. The production of reactive oxygen species does not seem to be a crucial event for the apoptotic process. Pretreatment with specific inhibitors of kinases ERK1/2, JNK and p38 resulted in an increased percentage of death induced by A398. These results indicate that the compound induced apoptosis through activation of intrinsic and extrinsic death pathways with the mechanism involving the inhibition of the MAPKs and Bcl-2. Taken together, our findings suggest that A398 has an anticancer potential, proving itself to be a candidate for preclinical studies.

A glucuronoxylan-specific xylanase from a new Paenibacillus favisporus strain isolated from tropical soil of Brazil.

A new xylanolytic strain, Paenibacillus favisporus CC02-N2, was isolated from sugarcane plantation fields in Brazil. The strain had a xylan-degrading system with multiple enzymes, one of which, xylanase Xyn30A, was identified and characterized. The enzyme is a single-domain xylanase belonging to family 30 of the glycosyl hydrolases (GH30). Xyn30A shows high activity on glucuronoxylans, with a Vmax of 267.2 U mg⁻¹, a Km of 4.0 mg/ml, and a kcat of 13,333 min⁻¹ on beechwood xylan, but it does not hydrolyze arabinoxylans. The three-dimensional structure of Xyn30A consists of a common (ß/α)8 barrel linked to a side-chain-associated ß-structure, similar to previously characterized GH30 xylanases. The hydrolysis products from glucuronoxylan were methylglucuronic-acid-substituted xylooligomers (acidic xylooligosaccharides). The enzyme bound to insoluble xylan but not to crystalline cellulose. Our results suggest a specific role for Xyn30A in xylan biodegradation in natural habitats. The enzyme is a good candidate for the production of tailored xylooligosaccharides for use in the food industry and in the biotechnological transformation of biomass.

Antinociceptive and anti-inflammatory effects of the monoterpene α,ß-epoxy-carvone in mice.

α,ß-Epoxy-carvone (EC) is a monoterpene found in the essential oils of many species of plants. It can also be obtained by organic synthesis. EC exerts a depressant effect on the central nervous system and is also known to have anticonvulsant, antimicrobial and antioxidant effects. The present study investigated the antinociceptive and anti-inflammatory effects of EC. Intraperitoneal administration of EC at doses of 100, 200 or 300 mg/kg promoted a significant antinociceptive effect, as shown in the acetic acid-induced abdominal writhing test. EC also provoked a reduction in formalin-induced nociception in the first (300 mg/kg) and second phases (200 and 300 mg/kg). In the hot-plate test, an increase in response latency was found at 30 min (at 100, 200 and 300 mg/kg), and at 60 and 120 min (at 300 mg/kg) following administration of EC, an effect that was reversed by naloxone. Intraperitoneal administration of EC (300 mg/kg) inhibited the increased vascular permeability provoked by acetic acid. These findings suggest that EC inhibited the acute inflammatory reaction, with a pronounced peripheral and central antinociceptive effect in mice that is probably associated with activation of the opioidergic system, which appears to play a role in the antinociceptive activity induced by EC.

The monoterpene (-)-carvone: a novel agonist of TRPV1 channels.

(-)-Carvone is an antinociceptive monoterpene found as the main active constituent of essential oils obtained from plants of the genus Mentha. Here, we have investigated the pharmacology of this monoterpene in dorsal root ganglia (DRG) neurons and TRPV1-expressing HEK293 cells. (-)-carvone at pharmacological active concentrations did not reveal significant cytotoxicity to the cells used in this study, as investigated by neutral red and propidium iodide flow cytometry assays. In calcium imaging experiments 1 mM (-)-carvone increased the cytosolic calcium levels in DRG neurons from 120.6 ± 5.0 nM (basal) to 310.7 ± 23.1 nM (P < 0.05). These effects were completely abolished when neurons were preincubated with calcium-free bath solution or ruthenium-red (5 µM) and capsazepine (10 µM), suggesting the possibility of TRPV1 channel-activation by (-)-carvone. Activity of (-)-carvone on TRPV1 channels was further investigated in HEK293 cells expressing recombinant human TRPV1 channels revealing dose-dependent calcium transients with an EC(50) of 1.3 ± 0.2 mM (Hill coefficient = 2.5). In conclusion, we show for the first time the ability of (-)-carvone to induce increases in cytosolic calcium concentration through TRPV1 activation.

Antiproliferative effects of lectins from Canavalia ensiformis and Canavalia brasiliensis in human leukemia cell lines.

The antiproliferative activity of lectins Canavalia ensiformis (ConA) and Canavalia brasiliensis (ConBr) were studied using human leukemia MOLT-4 and HL-60 cell lines. It was revealed that both ConA and ConBr were markedly cytotoxic to cells using MTT and NAC assays. The IC(50) values were approximately 3 and 20 µg/mL for ConA and ConBr, respectively, for both MOLT-4 and HL-60 cells. However, in normal human peripheral blood lymphocytes, the lectins were not cytotoxic, even when tested at concentrations as high as 200 µg/ml. Using comet assay, the lectins produced a rate of DNA damage exceeding 80% in MOLT-4 and HL-60 cells. Fluorescence analysis revealed the morphology characteristic of apoptosis, with low concentrations of apoptotic bodies and fragmented DNA (5 µg/ml). Flow cytometric analysis demonstrated an accumulation of cells in the sub-G1 cell cycle that is characteristic of DNA fragmentation, and a decrease in membrane integrity at high concentrations. Lastly, we evaluated the alterations in mitochondrial potential that reduced after treatment with lectins. Our results indicate that ConA and ConBr inhibited cell proliferation selectively in tumor cells and that apoptosis was the main death mechanism. Therefore, lectins can be considered a class of molecules with a high antitumor activity potential.

Curine, a bisbenzylisoquinoline alkaloid, blocks L-type Ca²âº channels and decreases intracellular Ca²âº transients in A7r5 cells.

Curine is a novel bisbenzylisoquinoline alkaloid that has previously been reported as a vasodilator. The underlying mechanism(s) of the vasodilator effect of curine remains to be characterized. In this study, we investigated the cellular mechanism that is responsible for the vasodilator effect of curine in the rat aorta. The vasorelaxant activity of curine was recorded using a myograph. Ca(2+) currents in A7r5 cells were measured using the whole-cell patch-clamp technique. Intracellular Ca(2+) transients were determined using confocal microscopy. In a concentration-dependent manner, curine inhibited contractions elicited by high extracellular K(+) and Bay K8644 in the rat aorta and reduced the rise in the intracellular Ca(2+) concentration induced by membrane depolarization in response to an increase in extracellular K(+) concentration in vascular smooth muscle cells. Moreover, curine decreased the peak amplitude of L-type Ca(2+) currents (I(Ca,L)) in a concentration-dependent manner without changing the characteristics of the current density vs. voltage relationship and the steady-state activation of I(Ca,L). Furthermore, curine shifted the steady-state inactivation curve of I(Ca,L) toward more hyperpolarized membrane potentials. None of the following modified the effect of curine on I(Ca,L) amplitude: 3-isobutyl-1-methylxanthine, an inhibitor of phosphodiesterases; dibutyryl cyclic AMP, an activator of protein kinase A (PKA); or 8-Br-cyclic GMP, an activator of protein kinase G (PKG). Our results showed that curine inhibited the L-type voltage-dependent Ca(2+) current in rat aorta smooth muscle cells, which caused a decrease in intracellular global Ca(2+) transients that led to vasorelaxation.

Rotundifolone-induced relaxation is mediated by BK(Ca) channel activation and Ca(v) channel inactivation.

Rotundifolone is the major constituent of the essential oil of Mentha x villosa Hudson. In preliminary studies, rotundifolone induced significant hypotensive, bradycardic and vasorelaxant effects in rats. Thus, to gain more insight into the pharmacology of rotundifolone, the aim of this study was to characterize the molecular mechanism of action involved in relaxation produced by rotundifolone. The relaxant effect was investigated in rat superior mesenteric arteries by using isometric tension measurements and whole-cell patch-clamp techniques. Rotundifolone relaxed phenylephrine-induced contractions in a concentration-dependent manner. Pre-treatment with KCl (20 mM), charybdotoxin (10(-7) M) or tetraethylammonium (TEA 10(-3) or 3 × 10(-3) M) significantly attenuated the relaxation effect induced by rotundifolone. Additionally, whole-cell patch-clamp recordings were made in mesenteric smooth muscle cells and showed that rotundifolone significantly increased K(+) currents, and this effect was abolished by TEA (10(-3) M), suggesting the participation of BK(Ca) channels. Furthermore, rotundifolone inhibited the vasoconstriction induced by CaCl(2) in depolarizing nominally Ca(2+) -free medium and antagonized the contractions elicited by an L-type Ca(2+) channel agonist, S(-)-Bay K 8644 (2 × 10(-7) M), indicating that the vasodilatation involved inhibition of Ca(2+) influx through L-type voltage-dependent calcium channels (Ca(v) type-L). Additionally, rotundifolone inhibited L-type Ca(2+) currents (I(Ca) L), affecting the voltage-dependent activation of I(Ca) L and steady-state inactivation. Our findings suggest that rotundifolone induces vasodilatation through two distinct but complementary mechanisms that clearly depend on the concentration range used. Rotundifolone elicits an increase in the current density of BK(Ca) channels and causes a shift in the steady-state inactivation relationship for Ca(v) type-L towards more hyperpolarized membrane potentials.

Bioassay-guided evaluation of antinociceptive effect of N-salicyloyltryptamine: a behavioral and electrophysiological approach.

We investigated the antinociceptive and nerve excitability effects of the N-salicyloyltryptamine (NST) NST-treated mice exhibited a significant decrease in the number of writhes when 100 and 200 mg/kg (i.p.) were administered (i.p.). This effect was not antagonized by naloxone (1.5 mg/kg, i.p.). NST inhibited the licking response of the injected paw when 100 and 200 mg/kg were administered (i.p.) to mice in the first and second phases of the formalin test. Because the antinociceptive effects could be associated with neuronal excitability inhibition, we performed the single sucrose gap technique and showed that NST (3.57 mM) significantly reduced (29.2%) amplitude of the compound action potential (CAP) suggesting a sodium channel effect induced by NST. Our results demonstrated an antinociceptive activity of the NST that could be, at least in part, associated to the reduction of the action potential amplitude. NST might represent an important tool for pain management.

Antinociceptive effects of citronellal in formalin-, capsaicin-, and glutamate-induced orofacial nociception in rodents and its action on nerve excitability.

AIMS: To evaluate the antinociceptive effects of citronellal (CTL) on formalin-, capsaicin-, and glutamate-induced orofacial nociception in mice and to investigate whether such effects might involve a change in neural excitability. METHODS: Male mice were pretreated with CTL (50, 100, and 200 mg/kg, ip), morphine (5 mg/kg, ip), or vehicle (distilled water plus one drop of Tween 80 0.2%) before formalin (20 microL, 2%), capsaicin (20 microL, 2.5 microg) or glutamate (40 microL, 25 microM) injection into the right vibrissa. Sciatic nerve recordings were made using the single sucrose gap technique in rats. The data obtained were analyzed by ANOVA followed by Dunnett's test for the behavioral analyses and by the Student t test for CAP evaluation. RESULTS: Pretreatment with CTL was effective in reducing nociceptive face-rubbing behavior in both phases of the formalin test, which was also naloxone-sensitive. CTL produced significantly antinociceptive effect at all doses in the capsaicin- and glutamate- tests. Rota-rod testing indicated that such results were unlikely to be provoked by motor abnormality. Recordings using the single sucrose gap technique revealed that CTL (10 mM) could reduce the excitability of the isolated sciatic nerve through a diminution of the compound action potential amplitude by about 42.4% from control recordings. CONCLUSION: These results suggest that CTL might represent an important tool for management and/or treatment of orofacial pain.

Anticonvulsant property of N-salicyloyltryptamine: evidence of enhance of central GABAergic neurotransmission / Propriedade anticonvulsivante de N-saliciloiltriptamina: proteção significativa com o sistema GABAérgico

AIM: In the present study we verified the anticonvulsant properties of the new tryptamine analogue, N-salicyloyltryptamine (NST), in rodents. METHODS AND RESULTS: In the evaluation of the anticonvulsant activity, NST protected the animals from the incidence of seizures induced by pentylenetetrazole (PTZ) and picrotoxin (PIC), in doses of 100 and 200 mg/kg. NST (100 and 200 mg/kg, i.p.) significantly eliminated the extensor reflex of maximal electric-induced seizure tests in 40 percent of the experimental animals. However, in the PTZ model FLU (10 mg/kg, i.p.), an antagonist of the benzodiazepine (BZD) site in the GABA A-BZD receptor complex, inhibited the prolongation of seizure latency induced by NST. CONCLUSION: Our results demonstrated an anticonvulsant activity of the new analogue that could be, at least in part, associated to the involvement of the GABAergic mechanism.

OBJETIVO: O presente estudo buscou avaliar o possível efeito anticonvulsivante do novo análogo da triptamina, N-saliciloiltriptamina (NST), em roedores. MÉTODOS E RESULTADOS: Na avaliação do efeito anticonvulsivante, os animais tratados com NST (100 e 200 mg/kg, i.p.) foram protegidos de maneira estatisticamente significativa (p<0,05) quanto a latência e incidência do aparecimento das convulsões induzidas pela administração do pentilenotetrazol (PTZ) e da picrotoxina (PIC). O efeito protetor do NST nas convulsões induzidas pelo PTZ foi revertido pela administração do flumazenil (10 mg/kg, i.p.), um antagonista dos receptores GABA-benzodiazepínicos (GABA A-BZD). A administração de NST (100 e 200 mg/kg, i.p.) protegeu de forma estatisticamente significativa (p < 0,05) os animais no teste das convulsões induzidas pelo eletrochoque-auricular em camundongos. CONCLUSÃO: Os resultados do presente estudo sugerem que o efeito anticonvulsivante de NST está associado, pelo menos em parte, ao sistema GABAérgico.

Pharmacokinetics of the venom of Bothrops erythromelas labeled with 131I in mice.

Bothrops erythromelas venom (BeV) has been responsible for many snake accidents in Brazil. We investigated the plasmatic pharmacokinetic of BeV labeled with (131)I in the absence and the presence of anti-Bothrops serum (BAS). A higher percentage of BeV plasmatic radioactivity and longer elimination were found in the presence of BAS. Our results showed a redistribution of venom from the tissue to vascular compartment associated with the treatment of envenomed mice with anti-venom 15 min after venom injection.