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.

Modulation of drug resistance in Staphylococcus aureus by a kaempferol glycoside from Herissantia tiubae (Malvaceae).

In an ongoing project to evaluate natural compounds isolated from plants from the Brazilian biodiversity as modulators of antibiotic resistance, kaempferol-3-O-beta-d-(6''-E-p-coumaroyl) glucopyranoside (tiliroside), isolated from Herissantia tiubae (Malvaceae) was investigated using the strain SA-1199B of Staphylococcus aureus, which overexpresses the norA gene encoding the NorA efflux protein which extrudes hydrophilic fluorquinolones and some biocides, such as benzalkonium chloride, cetrimide, acriflavine and ethidium bromide. The minimum inhibitory concentrations (MICs) of the antibiotics and biocides were determined by the microdilution assay in the absence and in the presence of sub-inhibitory concentration of tiliroside. Although tiliroside did not display relevant antibacterial activity (MIC = 256 microg/mL), it modulated the activity of antibiotics, i.e. in combination with antibiotics a reduction in the MIC was observed for norfloxacin (16-fold), ciprofloxacin (16-fold), lomefloxacin (four-fold) and ofloxacin (two-fold), and an impressive reduction in the MICs for the biocides (up to 128-fold). The results presented here represent the first report of a kaempferol glycoside as a putative efflux pump inhibitor in bacteria. The present finding indicates that H. tiubae (and broadly Malvaceae) could serve as a source of plant-derived natural products that modulate bacterial resistance, i.e. a source of potential adjuvants of antibiotics.

Anticonvulsant evaluation of Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, in rodents / Avaliação anticonvulsivante de Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, em roedores

The Aim of this study was to evaluated the effects of the ethanol extract of Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, roots (EER) in animal models of epilepsy. The EER increased the latency for convulsions significantly different from control (p<0,05) and in the PTZ induced convulsions test on 62,5 mg/kg (i.p.) decreased mortality. This effect was blocked by flumazenil administration, suggesting an involvement of GABAergic system in the anticonvulsant activity of EER. The EER had a moderate effect only against PIC- or STR-induced convulsions at doses 125 and 250 mg/kg. But in the MES test it did not demonstrate effect on this animal model. Therefore, the EER reduced the development of PTZ-induced kindling in both experimental groups. It also significantly (p<0.05) decreased the latency for convulsions and reduced its percentage. Our results suggest that EER owns anticonvulsant property.

O presente estudo buscou avaliar os efeitos do extrato etanólico das raízes de Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, (EER) e sua possível atividade anticonvulsivante em roedores. No teste das convulsões induzidas pelo pentilenotetrazol (PTZ) os animais tratados com EER, 250 mg/kg (i.p.), apresentaram aumento significativo (p<0,05) da latência para o aparecimento das convulsões (328,9±47,5) quando comparado aos do grupo controle (103,5±21,8) e reduziu o número de óbitos. Esse efeito foi bloqueado pela administração do flumazenil. O EER produziu aumento significativo (p<0,05) na latência nos testes da picrotoxina (PIC) e da estricnina (EST), nas maiores doses. No modelo do eletrochoque auricular o EER não produziu alterações significativas em nenhum dos parâmetros avaliados. Entretanto, no modelo do abrasamento induzido pelo PTZ, a administração com o EER produziu um efeito protetor, atenuando de forma significativa (p<0,05) o desenvolvimento e a severidade das crises convulsivas. Os resultados, sugerem que o EER induziu efeito anticonvulsivante em roedores e que o sistema GABAérgico pode estar envolvido nessa resposta.

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.

Constituintes químicos, avaliação das atividades citotóxica e antioxidante de Mimosa paraibana Barneby (Mimosaceae) / Chemical constituents, evaluation of the cytotoxic and antioxidant activities of Mimosa paraibana Barneby (Mimosaceae)

Mimosa paraibana Barneby foi submetida a um estudo fitoquímico para o isolamento de seus constituintes químicos, através de métodos cromatográficos usuais, e posterior identificação estrutural, utilizando-se métodos espectroscópicos de RMN ¹H e 13C uni e bidimensionais, além de comparações com modelos da literatura. Deste estudo pioneiro, foram isolados e identificados cinco constituintes da fase clorofórmica: uma mistura dos esteróides, β-sitosterol e estigmasterol, a 15¹-hidroxi-feofitina A, a 5,7-dihidroxiflavanona, o 3,4,5-trihidroxibenzoato de etila e o ácido p-cumárico. A atividade antioxidante das fases hexânica, clorofórmica e acetato de etila foi avaliada utilizando o radical estável DPPH (1,1-difenil-2-picril-hidrazil) e os resultados comparados com o padrão ácido ascórbico. A avaliação da citotoxicidade das fases foi realizada empregando-se o ensaio de letalidade contra Artemia salina. Dos extratos avaliados, somente o hexânico mostrou baixa toxicidade.

The phytochemical study of Mimosa paraibana Barneby led to the isolation of its chemical constituents, through the usual chromatographic methods, and further structural identification, using ¹H and 13C NMR spectroscopic methods based on one and two-dimensional techniques, in addition to comparison with literature data. From this pioneering investigation with M. paraibana, five constituents were isolated and identified from the chloroform extract: a mixture of β-sitosterol and stigmasterol, 15¹-hydroxy-phaeophytin A, 5,7-dihydroxyflavanone, ethyl 3,4,5-trihydroxybenzoate and p-coumaric acid. The antioxidant activity of the hexane, chloroform and ethyl acetate extracts of M. paraibana were measured using the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay and the results compared with standard ascorbic acid. The toxicity activity of the extracts were performed using the bioassay of Artemia salina.

Anticonvulsant properties of the total alkaloid fraction of Rauvolfia ligustrina Roem. et Schult. in male mice

Rauvolfia ligustrina Roem et. Schult (Apocynaceae), commonly known as "paratudo" and "arrebenta-boi" is a small tree found in Brazilian Northeastern. Previous studies have demonstrated depressant and anticonvulsant properties of the ethanol extract of Rauvolfia ligustrina. The aim of the present study was the determination of the lethal dose 50 percent (LD50) and the effects of total alkaloid fraction (TAF) of the aerial parts of R. ligustrina in animal models of convulsion. It was found that the acute toxicity of TAF was 127.8 (112.5-145.2) mg/kg (i.p.) in mice. TAF (20 mg/kg, ip) significantly increased (p < 0.05) the latencies of clonic seizures induced by pentylenetetrazol (PTZ) and picrotoxin (PIC). However, TAF did not protect the animals in maximal electroshock (MES) induced seizures. These results suggest that TAF of R. ligustrina possesses anticonvulsant properties.

Rauvolfia ligustrina Roem. et Schult. (Apocynaceae) é uma planta amplamente distribuída no Nordeste Brasileiro, rica em alcalóides indólicos, conhecida popularmente como "paratudo" e "arrebenta-boi". O presente estudo buscou avaliar a dose letal 50 por cento (DL50) da fração de alcalóides totais (FAT) das partes aéreas da R. ligustrina e a sua possível atividade anticonvulsivantes em roedores. A FAT apresentou uma DL50, via intraperitoneal (i.p.), de 127,8 (112,5-145,2) mg/kg e foi efetiva, na dose de 20 mg/kg (i.p.), em proteger os animais das convulsões induzidas pelo pentilenotetrazol (PTZ) e picrotoxina (PIC) aumentando significativamente (p < 0,05) a latência para o aparecimento das convulsões, sendo um indicativo de um efeito anticonvulsivante.