Effect of acute treatment with a water-alcohol extract of Erythrina mulungu on anxiety-related responses in rats

The ethanolic extract from Erythrina mulungu Benth. flowers attenuates allergic airway inflammation and hyperresponsiveness in a murine model of asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Erythrina mulungu Benth. ("mulungu", Fabaceae) is a Brazilian native species with ethnopharmacological use for respiratory diseases. However, the effects of E. mulungu on the respiratory were never studied.

AIMS OF THE STUDY

To evaluate the effects of an ethanolic extract from flowers of E. mulungu in ovalbumin (OVA)-induced asthma in mice, and to study the mechanisms involved.

MATERIALS AND METHODS

OVA-sensitized mice were intraperitoneally (i.p.) treated with four doses (200, 400, 600, and 800 mg/kg) of the E. mulungu extract or dexamethasone (DEXA, 2 mg/kg) during seven consecutive days and simultaneously challenged with intranasal OVA. Bronchial hyperresponsiveness was evaluated in vivo, 24 h after the last OVA challenge. Bronchoalveolar lavage (BAL) was collected for counting the number of total and differential inflammatory cells. Blood was collected for measurement of anti-OVA IgE levels. Levels of cytokines interleukin (IL)- 4, IL-5, IL-10, IL-13, and interferon (INF)-γ were measured in pulmonary homogenate by ELISA. The recruitment of inflammatory cells to the lung tissue was determined using hematoxylin and eosin staining (H&E). The extract's chromatographic profile was evaluated by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS).

RESULTS

The treatment with E. mulungu extract significantly reduced bronchial hyperresponsiveness, significantly reduced the number of leukocytes, eosinophils, and lymphocytes in BAL, and significantly decreased the levels of IL-4 and IL-5, while increased levels of IL-13 and INF-γ. In addition, E. mulungu significantly decreased the cellular inflammatory infiltration in the lung tissue. Erysotrine, erysotrine-N-oxide, and hypaphorine were the major constituents identified in the extract.

CONCLUSION

Collectively, these results confirm the potential of E. mulungu for asthma treatment, through modulation of inflammatory response, supporting its ethnopharmacological use for respiratory diseases.

Ethanolic extract of Erythrina velutina Willd ameliorate schizophrenia-like behavior induced by ketamine in mice

Background Schizophrenia is a chronic mental disorder, characterized by positive, negative and cognitive symptoms. In general, several plants have shown activity in diseases related to the central nervous system (e.g., Erythrina velutina (EEEV), also known as "mulungu"). For this reason, we aimed to investigate the effects of standardized ethanol extract obtained from the stem bark of EEEV on the schizophrenia-like behaviors induced by ketamine (KET) administration. Methods Swiss mice were treated with KET (20 mg/kg, i.p.) or saline for 14 days. In addition, from 8th to 14th days, saline, EEEV (200 or 400 mg/kg, p.o.) or olanzapine (OLAN 2 mg/kg, p.o.) were associated to the protocol. On the 14th day of treatment, schizophrenia-like symptoms were evaluated by the prepulse inhibition of the startle reflex (PPI), locomotor activity evaluated by the open field test (OFT), spatial recognition memory evaluated by the Y-maze task and social interaction test (SIT). Results KET has caused deficits in PPI, and it has also has caused hyperlocomotion in OFT and deficits in SIT as compared to control. EEEV in both doses used, reversed behavioral changes induced by KET, likewise results obtained with the administration of OLAN. Conclusions Taken together, the results demonstrate that the standard extract of EEEV was able to revert schizophrenia-like symptoms, due to the administration in repeated doses of ketamine. Thus, our findings lead to a new perspective for the use of EEEV an interesting alternative for drug discovery in schizophrenia.

An Update of Erythrinan Alkaloids and Their Pharmacological Activities

The period of the past 5 years has witnessed a remarkable increase in all of the number, structural variety, and complexity of erythrinan alkaloids reported. This structural diversity seems to be most pronounced in the alkaloids reported from the two species Erythrina arborescens and Erythrina variegata. Between them, work-up of these taxa yielded new polymeric (dimeric and trimeric) erythrinan alkaloids, a first example in one case where a normal 6,5,6,6-membered indoloisoquinoline spirocylic core has rearranged to a spiro-fused 6,5,7,6-skeleton. Furthermore, erythrinan alkaloids with a fifth ring containing a 2H-imidazole functionality were also reported for the first time, together with some new structures having an unusual substitution and with functionalities at positions C-3 and C-7 of the erythrinan core. This contribution has included 40 more erythrinan alkaloids that are either new or were omitted in the most recent major reviews on the same topic, leading to a total of 154 known erythrinan alkaloids to date. There are a few cases where the structures of the new alkaloids are contestable due to insufficient data having been obtained on isolation. To facilitate easier reference and identification, all structures having a common core have been placed in the same table or figure in this chapter.The reported pharmacological activities of the new and known erythrinan alkaloids documented have shown a considerable bias towards central nervous system and related activities. Other prominent activities that have been reported are antifeedant, insecticidal, cytotoxic, antiprotozoal, anti-inflammatory, antioxidant, antifungal, and antiviral effects. Erythrinan alkaloids generally seem to lack antibacterial activity. Several new polymeric alkaloids were found to lack cytotoxicity against a number of human cancer cell lines, although two of them showed moderate aphicidal activity and one exhibited weak to moderate acetylcholinesterase inhibition. The biological activity of erythrinan alkaloids seems to be influenced by basic substructural requirements, such as a conjugated diene (Δ^1,2, Δ^6,7) system and is modulated by the presence (or absence) of other groups in rings A, B, C, and D of the erythrinan core. The erythrinan core may provide potential leads to structures that eventually may be useful therapeutically.In recent years, a number of stereoselective chemical synthesis methods have been applied towards the erythinan alkaloids, and these are described in this contribution.

Short Total Synthesis of (±)-γ-Lycorane by a Sequential Intramolecular Acylal Cyclisation (IAC) and Intramolecular Heck Addition Reaction

An intramolecular acylal cyclisation (IAC) approach to the synthesis of a range of bicyclic heterocycles is reported. As an example of the utility of the IAC reaction, the methodology was applied in a protecting-group-free five-step total synthesis of (±)-γ-lycorane, incorporating a new intramolecular Heck addition reaction to generate the pentacyclic core structure of the natural product in good yield.

In vitro Effects of Four Native Brazilian Medicinal Plants in CYP3A4 mRNA Gene Expression, Glutathione Levels, and P-Glycoprotein Activity

Erythrina mulungu Benth. (Fabaceae), Cordia verbenacea A. DC. (Boraginaceae), Solanum paniculatum L. (Solanaceae) and Lippia sidoides Cham. (Verbenaceae) are medicinal plant species native to Brazil shortlisted by the Brazilian National Health System for future clinical use. However, nothing is known about their effects in metabolic and transporter proteins, which could potentially lead to herb-drug interactions (HDI). In this work, we assess non-toxic concentrations (100 μg/mL) of the plant infusions for their in vitro ability to modulate CYP3A4 mRNA gene expression and intracellular glutathione levels in HepG2 cells, as well as P-glycoprotein (P-gp) activity in vincristine-resistant Caco-2 cells (Caco-2 VCR). Their mechanisms of action were further studied by measuring the activation of human pregnane X receptor (hPXR) in transiently co-transfected HeLa cells and the inhibition of γ-glutamyl transferase (GGT) in HepG2 cells. Our results show that P-gp activity was not affected in any case and that only Solanum paniculatum was able to significantly change CYP3A4 mRNA gene expression (twofold decrease, p < 0.05), this being correlated with an antagonist effect upon hPXR (EC50 = 0.38 mg/mL). Total intracellular glutathione levels were significantly depleted by exposure to Solanum paniculatum (-44%, p < 0.001), Lippia sidoides (-12%, p < 0.05) and Cordia verbenacea (-47%, p < 0.001). The latter plant extract was able to decrease GGT activity (-48%, p < 0.01). In conclusion, this preclinical study shows that the administration of some of these herbal medicines may be able to cause disturbances to metabolic mechanisms in vitro. Although Erythrina mulungu appears safe in our tests, active pharmacovigilance is recommended for the other three species, especially in the case of Solanum paniculatum.

Concordance and incongruence in preclinical anxiety models: Systematic review and meta-analyses

Rodent defense behavior assays have been widely used as preclinical models of anxiety to study possibly therapeutic anxiety-reducing interventions. However, some proposed anxiety-modulating factors - genes, drugs and stressors - have had discordant effects across different studies. To reconcile the effect sizes of purported anxiety factors, we conducted systematic review and meta-analyses of the literature on ten anxiety-linked interventions, as examined in the elevated plus maze, open field and light-dark box assays. Diazepam, 5-HT1A receptor gene knockout and overexpression, SERT gene knockout and overexpression, pain, restraint, social isolation, corticotropin-releasing hormone and Crhr1 were selected for review. Eight interventions had statistically significant effects on rodent anxiety, while Htr1a overexpression and Crh knockout did not. Evidence for publication bias was found in the diazepam, Htt knockout, and social isolation literatures. The Htr1a and Crhr1 results indicate a disconnect between preclinical science and clinical research. Furthermore, the meta-analytic data confirmed that genetic SERT anxiety effects were paradoxical in the context of the clinical use of SERT inhibitors to reduce anxiety.

Effect of Erythrinamu lungu on anxiety during extraction of third molars

Objectives: The aim of the present study was to evaluate the effect of Erythrina mulungu on the control of dental anxiety in patients who had under gone bilateral extraction of asymptomatic, impacted mandibular third molars. Material and Methods: In a randomized, double-blind, crossover study, 30 healthy volunteers (5 men and 25 women, over 18 years of age), received either 500mg of E.mulungu (Mulungu Matusa®) or 500 mg of placebo, p.o., one hour before surgical procedure. The level ofanxiety was assessed through questionnaire sand physical parameters, such as blood pressure, heart rate andoxygen saturation. Data were analyzed by Chi-square test, ANOVA (Tukey test) and Friedman with significance level of 5%. Results: A higher preference (Chi-square, p = 0.0062) for E. mulungu was observed for both genders. Volunteers with higher anxiety levels tended to to prefer E. mulungu. No statistically significant differences were verified in blood pressure (one-way ANOVA, p = 0.1259), heart rate (Friedman, p> 0.05) and oxygen saturation (Friedman, p = 0.7664) among periods and types of treatments. Conclusions: E. mulungu showed an anxiolytic effect without significant changes in physiological parameters. It could be considered as an alternative to control the anxiety in adult patients undergoing mandibular thirdmolars surgery.

Key words:Anxiety, Erythrina mulungu, third molar, oral surgery.

Erythrina mulungu alkaloids are potent inhibitors of neuronal nicotinic receptor currents in mammalian cells

Crude extracts and three isolated alkaloids from Erythrina mulungu plants have shown anxiolytic effects in different animal models. We investigated whether these alkaloids could affect nicotinic acetylcholine receptors and if they are selective for different central nervous system (CNS) subtypes. Screening experiments were performed using a single concentration of the alkaloid co-applied with acetylcholine in whole cell patch-clamp recordings in three different cell models: (i) PC12 cells natively expressing α3* nicotinic acetylcholine receptors; (ii) cultured hippocampal neurons natively expressing α7* nicotinic acetylcholine receptors; and (iii) HEK 293 cells heterologoulsy expressing α4β2 nicotinic acetylcholine receptors. For all three receptors, the percent inhibition of acetylcholine-activated currents by (+)-11á-hydroxyerysotrine was the lowest, whereas (+)-erythravine and (+)-11á-hydroxyerythravine inhibited the currents to a greater extent. For the latter two substances, we obtained concentration-response curves with a pre-application protocol for the α7* and α4β2 nicotinic acetylcholine receptors. The IC₅₀ obtained with (+)-erythravine and (+)-11á-hydroxyerythravine were 6 µM and 5 µM for the α7* receptors, and 13 nM and 4 nM for the α4β2 receptors, respectively. Our data suggest that these Erythrina alkaloids may exert their behavioral effects through inhibition of CNS nicotinic acetylcholine receptors, particularly the α4β2 subtype.

Plant-based medicines for anxiety disorders, Part 1: a review of preclinical studies

Research in the area of herbal psychopharmacology has revealed a variety of promising medicines that may provide benefit in the treatment of general anxiety and specific anxiety disorders. However, a comprehensive review of plant-based anxiolytics has been absent to date. This article (part 1) reviews herbal medicines for which only preclinical investigations for anxiolytic activity have been performed. In part 2, we review herbal medicines for which there have been clinical investigations for anxiolytic activity. An open-ended, language-restricted (English) search of MEDLINE (PubMed), CINAHL, Scopus and the Cochrane Library databases was conducted (up to 28 October 2012) using specific search criteria to identify herbal medicines that have been investigated for anxiolytic activity. This search of the literature revealed 1,525 papers, from which 53 herbal medicines were included in the full review (having at least one study using the whole plant extract). Of these plants, 21 had human clinical trial evidence (reviewed in part 2), with another 32 having solely preclinical studies (reviewed here in part 1). Preclinical evidence of anxiolytic activity (without human clinical trials) was found for Albizia julibrissin, Sonchus oleraceus, Uncaria rhynchophylla, Stachys lavandulifolia, Cecropia glazioui, Magnolia spp., Eschscholzia californica, Erythrina spp., Annona spp., Rubus brasiliensis, Apocynum venetum, Nauclea latifolia, Equisetum arvense, Tilia spp., Securidaca longepedunculata, Achillea millefolium, Leea indica, Juncus effusus, Coriandrum sativum, Eurycoma longifolia, Turnera diffusa, Euphorbia hirta, Justicia spp., Crocus sativus, Aloysia polystachya, Albies pindrow, Casimiroa edulis, Davilla rugosa, Gastrodia elata, Sphaerathus indicus, Zizyphus jujuba and Panax ginseng. Common mechanisms of action for the majority of botanicals reviewed primarily involve GABA, either via direct receptor binding or ionic channel or cell membrane modulation; GABA transaminase or glutamic acid decarboxylase inhibition; a range of monoaminergic effects; and potential cannabinoid receptor modulation. Future research should focus on conducting human clinical trials on the plants reviewed with promising anxiolytic activity.

Erysothrine, an alkaloid extracted from flowers of Erythrina mulungu Mart. ex Benth: evaluating its anticonvulsant and anxiolytic potential

In this study, we isolated the alkaloid erysothrine from the hydroalcoholic extract of flowers from E. mulungu and screened for its anticonvulsant and anxiolytic actions based on neuroethological and neurochemical experiments. Our results showed that the administration of erysothrine inhibited seizures evoked by bicuculline, PTZ, NMDA and most remarkably, kainic acid. Also, erysothrine induced an increase in the number of entries but not in the time spent in the open arms of the EPM. However, we did not notice any alterations in the light-dark choice or in the open-field tests. In preliminary neurochemistry tests, we also showed that erysothrine (0.001-10 μg/mL) did not alter the GABA or glutamate synaptossomal uptake and binding. Altogether, our results describe an alkaloid with anticonvulsant activity and mild anxiolytic activity that might be considered well tolerated as it does not alter the general behavior of the animals in the used doses.

Anticonvulsant profile of the alkaloids (+)-erythravine and (+)-11-α-hydroxy-erythravine isolated from the flowers of Erythrina mulungu Mart ex Benth (Leguminosae-Papilionaceae)

Neural mechanisms underlying the onset and maintenance of epileptic seizures involve alterations in inhibitory and/or excitatory neurotransmitter pathways. Thus, the prospecting of novel molecules from natural products that target both inhibition and excitation systems has deserved interest in the rational design of new anticonvulsants. We isolated the alkaloids (+)-erythravine and (+)-11-α-hydroxy-erythravine from the flowers of Erythrina mulungu and evaluated the action of these compounds against chemically induced seizures in rats. Our results showed that the administration of different doses of (+)-erythravine inhibited seizures evoked by bicuculline, pentylenetetrazole, and kainic acid at maximum of 80, 100, and 100%, respectively, whereas different doses of (+)-11-α-hydroxy-erythravine inhibited seizures at a maximum of 100% when induced by bicuculline, NMDA, and kainic acid, and, to a lesser extent, PTZ (60%). The analysis of mean latency to seizure onset of nonprotected animals, for specific doses of alkaloids, showed that (+)-erythravine increased latencies to seizures induced by bicuculline. Although (+)-erythravine exhibited very weak anticonvulsant action against seizures induced by NMDA, this alkaloid increased the latency in this assay. The increase in latency to onset of seizures promoted by (+)-11-α-hydroxy-erythravine reached a maximum of threefold in the bicuculline test. All animals were protected against death when treated with different doses of (+)-11-α-hydroxy-erythravine in the tests using the four chemical convulsants. Identical results were obtained when using (+)-erythravine in the tests of bicuculline, NMDA, and PTZ, and, to a lesser extent, kainic acid. Therefore, these data validate the anticonvulsant properties of the tested alkaloids, which is of relevance in consideration of the ethnopharmacological/biotechnological potential of E. mulungu.

Central activity of hydroalcoholic extracts from Erythrina velutina and Erythrina mulungu in mice

This work studied the central behavioural effects of hydroalcoholic extracts from the stem bark of Erythrina velutina and Erythrina mulungu on the elevated plus maze, open field, and rota rod tests in mice. These medicinal plants belong to the Fabaceae family and are popularly used in Brazil for their effects on the central nervous system. Single doses of the extracts were administered orally (200, 400 or 800 mg kg−1) or intraperitoneally (200 or 400 mg kg−1) to female mice. A reduction of the locomotor activity was observed in the open field test with both hydroalcoholic extracts after intraperitoneal treatment with all doses, but only with the highest dose after oral administration. In addition, oral and intraperitoneal administration of the extracts decreased the incidence of rearing and grooming. Decreases in the number of entries in the open (NEOA)and closed (NECA)arms of the elevated plus maze were observed after the administration of the highest dose (800 mg kg−1, p.o.) of both hydroalcoholic extracts, and this effect may be due to the decrease in locomotor activity. These hydroalcoholic extracts failed to affect the motor coordination in the rota rod test. In conclusion, we showed that the hydroalcoholic extracts of E. velutina and E. mulungu have depressant effects on the central nervous system, which, at least partially, corroborates the popular use of these species as tranquilizers in Brazilian popular medicine.

Anxiolytic-like effect of chronic treatment with Erythrina velutina extract in the elevated plus-maze test

INTRODUCTION

In Brazil, Erythrina velutina (Fabaceae) is widely used as a tranquilizer and/or sedative, and its extract exerts an anxiolytic-like effect profile in animal models, although these results may be caused by its sedative or amnesic effects. AIMS, MATERIALS AND METHODS: Thus, this study evaluated the effect of acute and chronic (23-26 days) administrations of the hydroalcoholic extract of the stem bark of Erythrina velutina (orally) in mice submitted to the following tests: elevated plus-maze, forced swim, spontaneous locomotor activity, and habituation to active chamber. Chlordiazepoxide and imipramine were used as standard drugs.

RESULTS

In the elevated plus-maze test, chronic, but not acute, Erythrina velutina (100mg/kg) administration increased the percentage of open arm entries, an effect also seen in both acute and chronic treatments with chlordiazepoxide (7.5mg/kg). In the forced swim test, only imipramine (25mg/kg) decreased immobility time. Impairment of habituation was seen only with acute imipramine administration and with the lowest doses of Erythrina velutina extract tested in acute (10mg/kg) and chronic (50mg/kg) administrations.

CONCLUSIONS

These results suggest that chronic administration of the hydroalcoholic extract of the stem bark of Erythrina velutina exerts an anxiolytic-like effect on mice, and it could serve as a new approach for the treatment anxiety, although it may have an amnesic effect at low doses.

Anticonvulsant activity of hydroalcoholic extracts from Erythrina velutina and Erythrina mulungu

The anticonvulsant effects of hydroalcoholic extracts (HAEs) from the stem bark of Erythrina velutina and Erythrina mulungu on pentylenetetrazole (PTZ) and strychnine-induced seizure tests and the potentiation of pentobarbital-induced sleeping time in mice with the extracts were examined in this study. These medicinal plants belong to the Fabaceae family and are popularly used in Brazil for their effects on the central nervous system. The extracts of Erythrina velutina (intraperitoneally or orally) and Erythrina mulungu (intraperitoneally) were administered in mice at single doses (200 or 400mg/kg). While Erythrina velutina and Erythrina mulungu did not exhibit any protector effect in PTZ-induced seizures, at any dose, an increase in the latency of convulsion and in the death time was observed with both doses and routes of Erythrina velutina and at higher dose of Erythrina mulungu, in strychnine-induced seizure. No alteration was observed with Erythrina velutina and Erythrina mulungu on sleeping latency at both doses as compared to control (362.8+/-59.5). However, the sleeping time was increased in both plants as compared to control (943.8+/-129.6). In conclusion, we showed that the hydroalcoholic extracts of Erythrina velutina and Erythrina mulungu have anticonvulsant effects only in the strychnine-induced seizure model, suggesting their possible action in glycine system and a potentiation of pentobarbital sleeping time, suggesting depressant action in the central nervous system.

Effects of Erythrinian Alkaloids Isolated from Erythrina mulungu (Papilionaceae) in Mice Submitted to Animal Models of Anxiety

The effects of acute oral administration of erythrinian alkaloids, i.e. (+)-alpha-hydroxy-erysotrine, erythravine and (+)-11alpha-hydroxy-erythravine isolated from the flowers of Erythrina mulungu were investigated in two animal models of anxiety in mice-the light-dark transition model (LDTM) and the elevated plus-maze (EPM). In the LDTM, erythravine (3, 10 mg/kg) and (+)-11alpha-hydroxy-erythravine (10 mg/kg) increased the time spent by the animals in the illuminated compartment and (+)-11alpha-hydroxy-erythravine (3 mg/kg) increased the number of transitions between compartments of the LDTM, suggesting an anxiolytic-like effect of these erythrinian alkaloids. Nevertheless, the third alkaloid studied, (+)-alpha-hydroxy-erysotrine, did not change any behavioral response with the range of doses used (3-10 mg/kg). Since the oral administration of the crude extract of E. mulungu (EM) (100-400 mg/kg) did not modify the conventional measures of anxiety in the EPM, this animal model was not chosen to evaluate the anxiolytic properties of the isolated alkaloids. These results suggest that the alkaloids erythravine and (+)-11alpha-hydroxy-erythravine are responsible for the anxiolytic effects of the crude extract of E. mulungu.

Anxiolytic effects of erythrinian alkaloids from Erythrina mulungu

One new erythrinian alkaloid derivative, (+)-11alpha-hydroxyerythravine (1), and the known (+)-erythravine (2) and (+)-alpha-hydroxyerysotrine (3) were isolated from the flowers of Erythrina mulungu. Their structures were determined by spectroscopic/spectrometric data interpretation of 1H, 13C, and 2D NMR and MS experiments. The relative configuration was established by NOESY analysis, while the conformation adopted by these molecules was evaluated through molecular modeling studies and coupling constants obtained by NMR analysis. Furthermore, the anxiolytic effects of the E. mulungu aqueous alcoholic crude extract and of the purified alkaloids were evaluated using the elevated T-maze test.

Effect of Erythrina velutina and Erythrina mulungu in rats submitted to animal models of anxiety and depression

Erythrina velutina (EV) and Erythrina mulungu (EM), popularly used in Brazil as tranquilizing agents, were studied. The effects of acute and chronic oral treatment with a water:alcohol extract of EV (7:3, plant grounded stem bark; acute = 100, 200, 400 mg/kg; chronic = 50, 100, 200 mg/kg) were evaluated in rats (N = 11-12) submitted to the elevated T-maze (for avoidance and escape measurements) model of anxiety. This model was selected for its presumed capacity to elicit specific subtypes of anxiety disorders recognized in clinical practice: avoidance has been related to generalized anxiety and escape to panic. Additionally, animals were treated with the same doses of EV and EM (water:alcohol 7:3, inflorescence extract) and submitted to the forced swim test for the evaluation of antidepressant activity (N = 7-10). Both treatment regimens with EV impaired elevated T-maze avoidance latencies, without altering escape, in a way similar to the reference drug diazepam (avoidance 1, mean +/- SEM, acute study: 131.1 +/- 45.5 (control), 9.0 +/- 3.3 (diazepam), 12.7 +/- 2.9 (200 mg/kg), 28.8 +/- 15.3 (400 mg/kg); chronic study: 131.7 +/- 46.9 (control), 35.8 +/- 29.7 (diazepam), 24.4 +/- 10.4 (50 mg/kg), 29.7 +/- 11.5 (200 mg/kg)). Neither EV nor EM altered measurements performed in the forced swim test, in contrast to the reference drug imipramine that significantly decreased immobility time after chronic treatment. These results were not due to motor alterations since no significant effects were detected in an open field. These observations suggest that EV exerts anxiolytic-like effects on a specific subset of defensive behaviors which have been associated with generalized anxiety disorder.

Anti-nociceptive activity of the aqueous extract of Erythrina velutina leaves

Anti-nociceptive and anti-oedematogenic effects of the aqueous extract from the leaves of Erythrina velutina were tested through experimental models of nociception in mice and paw oedema induced by carrageenin in rats. The extract (300 and 600 mg/kg) did not change the carrageenin-induced paw oedema. In the hot plate test the extract also did not alter the latency time for mice liking the rear paws. Moreover, the extract (600 mg/kg) decreased by 96.5% the paw liking time in the second phase of the formalin test. This effect was antagonized by naloxone (5 mg/kg). In the acetic acid-induced writhing test, the extract (300 and 600 mg/kg) reduced the number of writhing by 88.8% and 96.4%, respectively. Our present results demonstrated that the crude extract from the leaves of E. velutina has anti-nociceptive but not anti-oedematogenic properties.

Central nervous system effects of the crude extract of Erythrina velutina on rodents

The aqueous extract (AE) of Erythrina velutina prolonged the sleep duration induced by sodium pentobarbital (control: 6.4 +/- 1.2 min; extract 10 mg/kg, 47.1 +/- 3.9 min; extract 100 mg/kg, 109.4 +/- 7.2 min; F = 243, P < 0.001). In the open field, the extract at the doses of 10 and 50 mg/kg did not changed the number of crossings, rearings nor groomings. On the other hand, at the dose of 200 mg/kg it reduced the number of crossings (q = 6.25, P < 0.05) and groomings (q = 3.91, P < 0.05). When exposed during three consecutive days to the open field, the control animals showed habituation for crossings (F = 17.56, P < 0.001) and rearings (F = 14.01, P < 0.001). The same was not true for animals treated with 10 mg/kg of the extract (crossings: F = 3.59, P > 0.05; rearings: F = 3.62, P > 0.05). At the same dose, the extract blocked the acquisition of foot shock memory (P = 0.9219) when compared to the control values (P = 0.0078). Our data showed that the crude extract of Erythrina velutina at lower doses interferes with mnemonic process for different tasks, while at higher doses, the sedative and neuromuscular blocking actions are the main effects.

Antinociceptive activities of the hydroalcoholic extracts from Erythrina velutina and Erythrina mulungu in mice

This work studied the antinociceptive effects of the hydroalcoholic extracts (HAEs) from Erythrina velutina (Ev) and Erythrina mulungu (Em) in three experimental models of nociception in mice. The extract was administered intraperitoneally to female mice at the doses of 200 and 400 mg/kg. Inhibitions of abdominal contractions were observed with the doses of 200 (88.6%; 86.8%) and 400 (95.5%; 83.5%) mg/kg of E. velutina and E. mulungu, respectively, as compared to controls. E. velutina and E. mulungu, at both doses, reduced the nociception produced by formalin in the 1st and 2nd phases and this effect was not reversed by the pretreatment with naloxone. In the hot plate test an increase of the reaction time was observed only at 60 (Ev=18.0+/-2.2; Em=20.8+/-2.52) and 90 min (Ev=20.4+/-1.71; Em=23.7+/-2.32) after the treatment with E. velutina and E. mulungu at the dose of 400 mg/kg as compared to controls (T60=11.1+/-0.74; T90=11.9+/-0.86). This effect was not reversed by naloxone. We conclude that E. velutina and E. mulungu presents antinociceptive effects, which are independent of the opioid system.

Effects of Chronic Treatment with a Water-Alcohol Extract from Erythrina mulungu on Anxiety-Related Responses in Rats

We investigated the effects of chronic oral treatment with a water-alcohol extract from the inflorescence of Erythrina mulungu (Leguminosae-Papilionaceae) (EM, 50, 100, 200 mg/kg) in rats submitted to different anxiety models: the elevated T-maze (ETM, for inhibitory avoidance and escape measurements), the light/dark transition, and the cat odor test. These models were selected for their capacity to elicit specific subtypes of anxiety disorders as recognized in clinical practice. Treatment with EM impaired inhibitory avoidance latencies in a way similar to the reference drug, diazepam (DZP). Additionally, both EM and DZP increased the number of transitions and the time spent in the lighted compartment of the light/dark transition model. Furthermore, neither EM nor DZP altered behavioral responses of rats to a cloth impregnated with cat odor. In contrast to DZP, however, EM also altered ETM one-way escape. These results were not due to motor alterations since no significant effects were detected in the number of crossings or rearings in the arena. The present observations suggest that chronic EM exerts anxiolytic-like effects in defensive behaviors related to generalized anxiety and panic disorder. Although alkaloids appear to be one of the main constituents of EM, the possible mechanisms through which the extract exerts its anxiolytic action should be further investigated.