Antiedematogenic activity of the indole derivative N-salicyloyltryptamine in animal models.

The N-salicyloyltryptamine (NST) is an indole derivative compound analogue to the alkaloid N-benzoyltryptamine. In the present study, the antiedematogenic activity of NST was investigated in animal models. Firstly, the acute toxicity for NST was assessed according to the OECD Guideline no. 423. The potential NST-induced antiedematogenic activity was evaluated by carrageenan-induced paw edema in rats, as well as by dextran-, compound 48/80-, histamine-, serotonin-, capsaicine-, and prostaglandin E2-induced paw edema in mice. The effect of NST on compound 48/80-induced ex vivo mast cell degranulation on mice mesenteric bed was investigated. No death or alteration of behavioral parameters was observed after administration of NST (2000 mg/kg, i.p.) during the observation time of 14 days. The NST (100 and 200 mg/kg, i.p.) inhibited the carrageenan-induced edema from the 1st to the 5th hour (**p<0.01; ***p<0.001). The edematogenic activity induced by dextran, compound 48/80, histamine, serotonin, capsaicin, and prostaglandin E2 was inhibited by NST (100 mg/kg, i.p.) throughout the observation period (**p<0.01; ***p<0.001). The pretreatment with NST (50, 100 or 200 mg/kg, i.p) attenuates the compound 48/80-induced mast cell degranulation (**p<0.01; ***p<0.001). Thus, the inhibition of both mast cell degranulation and release of endogenous mediators are probably involved in the NST-induced antiedematogenic effect.

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.

Antiparasitic, structural, pharmacokinetic, and toxicological properties of riparin derivatives.

Schistosomiasis, caused by helminth flatworms of the genus Schistosoma, is one of the most important parasitic diseases in the world, affecting over 200 million people in developing countries. Riparins are natural alkamides found in Aniba riparia (Lauraceae) fruits that possess several pharmacological properties. In this study, we reported the synthesis, characterization and structural analysis of six riparin derivatives (A-F), as well as their schistosomicidal activity against S. mansoni worms together with a biological, pharmacokinetic and toxicological in silico evaluation. Firstly, these compounds were synthesized, purified and characterized by elemental analysis, FT-IR spectroscopy, X-ray diffraction and theoretical calculations to evaluate their stability and conformation. Next, the schistosomicidal activity of the riparins was tested against S. mansoni worms. Bioassays revealed that Riparins E and F were the most active compounds, showing half-maximum inhibitory concentration at low micromolar ranges (IC50 values ~10 µM). Also, confocal laser scanning microscopy studies revealed tegumental damage in parasites after exposition with Riparins B, E and F. Additionally, based on MTT assay, all tested riparins showed no cytotoxic potential toward mammalian cells. Finally, in silico analyses were used to predict the absorption, distribution, metabolism, elimination and toxicity (ADMET) of the compounds. Taken together, the results revealed a promising ADMET profile and suggested that riparins could be starting points for lead optimization programs for natural products with antischistosomal properties.

Structure-related blockage of calcium channels by vasodilator alkamides in mice mesenteric artery.

The development of new calcium channel blockers is still relevant for the understanding of their physiological role and pharmacological and therapeutic purposes. For this task, natural products represent a relevant source of new drugs. The present work investigated the mechanism and the structural relationship of the vasodilator effect of riparins I, II and III in mouse small mesenteric artery. Riparins I, II and III induced an endothelium-independent and concentration-dependent vasodilator effect in mesenteric arteries. Riparins II and III were more potent than riparin I, suggesting a structural relationship of the effect of these drugs. All riparins inhibited the contractile effect of KCl, similarly to nifedipine. However, the inhibitory profile was different for the contractile responses to phenylephrine and caffeine, passing from similar to nifedipine with riparin I, for similar to SKF-96365 with riparin III. A comparable effect was observed for the increase in the intracellular calcium concentration induced by caffeine and phenylephrine. These results suggest that the higher hydroxylation provides the alkamides the ability to inhibit non-selective cation channels in addition to the inhibition of L-type calcium channels in mouse mesenteric arteries. These observations may give support to the development of new selective inhibitors of non-selective cation channels using alkamides as leading compounds.

Subchronic administration of riparin III induces antidepressive-like effects and increases BDNF levels in the mouse hippocampus.

Riparin III (Rip III) is an alcamide isolated from Aniba riparia that has presented effects of antidepressant and anxiolytic activities in acute stress behavioral models. The trial's goal was to investigate the activity of Rip III in mice exposed to corticosterone-induced chronic depression model. Swiss female mice, 22-25 g, were distributed in following experimental groups: control group (vehicle1: saline containing 0.1% dimethyl sulfoxide and 0.1% Tween-80, SC+ vehicle 2: distilled water emulsified with 2% Tween-80, PO); stressed group (corticosterone, 20 mg/kg, SC, + vehicle 2, orally); Rip III group (50 mg/kg, orally); and fluvoxamine (Flu) group (50 mg/kg, orally). The mice were exposed to the behavioral tests, and posteriorly, Brain-derived neurotrophic factor protein levels were assessed in hippocampal samples. Statistical analysis of the data was performed by one-way anova, followed by Newman-Keuls test. Both administrations of Rip III and Flu significantly reduced the immobility time in tail suspension and forced swimming tests after 21 days without affecting locomotor function. There was also an increase in BDNF protein levels in the mice hippocampus. These findings further support the hypothesis that Rip III could be a new pharmacological target for the treatment of mood disorders.

Riparin A, a compound from Aniba riparia, attenuate the inflammatory response by modulation of neutrophil migration.

Inflammation is a local tissue response to attacks characterized by vascular and cellular events, including intense oxidative stress. Riparin A, a compound obtained from Aniba riparia, has been shown to have antioxidant activity and cytotoxicity in vitro. This study was aimed at evaluating the anti-inflammatory effect of riparin A against acute inflammation. The results of our evaluations in various experimental models indicated that riparin A reduced paw edema induced by carrageenan, compound 48/80, histamine, and serotonin. Furthermore, it decreased leukocyte and neutrophil counts, myeloperoxidase activity, thiobarbituric acid reactive substance (TBARS) levels, and cytokine (tumor necrosis factor-α and interleukin-1ß) levels increased by carrageenan-induced peritonitis, and reversed glutathione levels. Riparin A also reduced carrageenan-induced adhesion and rolling of leukocytes on epithelial cells and did not produce gastric-damage as compared with indomethacin. In conclusion, the data show that riparin A reduces inflammatory response by inhibiting vascular and cellular events, modulating neutrophil migration, inhibiting proinflammatory cytokine production, and reducing oxidative stress.

Antiedematogenic activity of the indole derivative N-salicyloyltryptamine in animal models

ABSTRACT The N-salicyloyltryptamine (NST) is an indole derivative compound analogue to the alkaloid N-benzoyltryptamine. In the present study, the antiedematogenic activity of NST was investigated in animal models. Firstly, the acute toxicity for NST was assessed according to the OECD Guideline no. 423. The potential NST-induced antiedematogenic activity was evaluated by carrageenan-induced paw edema in rats, as well as by dextran-, compound 48/80-, histamine-, serotonin-, capsaicine-, and prostaglandin E2-induced paw edema in mice. The effect of NST on compound 48/80-induced ex vivo mast cell degranulation on mice mesenteric bed was investigated. No death or alteration of behavioral parameters was observed after administration of NST (2000 mg/kg, i.p.) during the observation time of 14 days. The NST (100 and 200 mg/kg, i.p.) inhibited the carrageenan-induced edema from the 1st to the 5th hour (**p<0.01; ***p<0.001). The edematogenic activity induced by dextran, compound 48/80, histamine, serotonin, capsaicin, and prostaglandin E2 was inhibited by NST (100 mg/kg, i.p.) throughout the observation period (**p<0.01; ***p<0.001). The pretreatment with NST (50, 100 or 200 mg/kg, i.p) attenuates the compound 48/80-induced mast cell degranulation (**p<0.01; ***p<0.001). Thus, the inhibition of both mast cell degranulation and release of endogenous mediators are probably involved in the NST-induced antiedematogenic effect.

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.