Mechanisms involved in the endothelium-dependent vasodilatory effect of an ethyl acetate fraction of Cyathea phalerata Mart. in isolated rats' aorta rings.

The species Cyathea phalerata Mart. is a tree fern, commonly known as "xaxim", which is found in tropical and subtropical areas of Brazil. The present study investigated the mechanisms related with the vasorelaxant effects of an Ethyl Acetate Fraction (EAF) obtained from C. phalerata in rats' thoracic aorta rings. In pre-contracted vessels, EAF (0.1-1000 µg/mL) caused a concentration-dependent relaxation. The endothelium denudation, the nitric oxide (NO) synthase and guanylyl cyclase inhibitor reduced the vasodilation, indicating the participation of NO/cGMP pathway in its effect. The relaxation of EAF was abolished in the absence of extracellular Ca2+ and was significantly decreased in the presence of Ca2+ entry blocker, suggesting that Ca2+ influx plays an important role in EAF effect and probably in eNOS activity. However, the PI3K/Akt pathway is not responsible for eNOS phosphorylation/activation. The vasodilator effect of EAF was partially inhibited by KCl 40 mM and almost totally abolished with L-NOARG + KCl 40 mM, indicating also the role of hyperpolarization in its effect. Calcium activated K+ channels are not involved in the EAF-induced hyperpolarization. The COX inhibitor, indomethacin, slightly reduced the vasodilation induced by EAF. In addition, EAF did not alter the relaxant effects of NO-donor, indicating that the relaxant activity cannot be attributed to free radical-scavenging properties. In conclusion, the present study showed that the EAF, causes an endothelium-dependent vasorelaxant effect in aorta that mainly involves the NO-cGMP pathway, hyperpolarization and prostanoids. The vasorelaxant activity of EAF can be attributed to the occurrence of polyphenol compounds.

Jaboticaba (Plinia peruviana) extract nanoemulsions: development, stability, and in vitro antioxidant activity.

OBJECTIVE: The aim of this work is to develop and characterize nanoemulsions containing jaboticaba extract (Plinia peruviana) aiming pharmaceutical and cosmetic applications. METHODS: Nanoemulsions were prepared by high-pressure homogenization method using different concentrations of components (oil, surfactant, and extract) and homogenization pressures, in order to optimize the preparation conditions. Both unloaded and extract-loaded nanoemulsions were characterized according to their size, polydispersity, zeta potential, pH, morphology, and physical stability. Total phenolic and flavonoid contents in free jaboticaba extract and jaboticaba-loaded nanoemulsions were determined spectrophotometrically, while ellagic acid content was determined by high-performance liquid chromatography (HPLC) analysis. In vitro antioxidant activity was investigated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. RESULTS: Colloidal dispersions exhibited a mean particle size around 200 nm, with monodisperse size distribution (PdI <0.3), and spherical shape. Stability studies showed that nanoemulsions were stable over 120 d of storage at room temperature. Jaboticaba nanoemulsions showed significant concentrations of phenolics, flavonoids, and ellagic acid, with encapsulation efficiency values higher than 90%. Antioxidant properties of jaboticaba nanoemulsions were demonstrated by its remarkable ability to scavenge DPPH free radicals and to reduce ferric-tripyridyltriazine complex, which can be attributed to their phenolic and flavonoid contents. CONCLUSIONS: The results suggest that nanoemulsions containing jaboticaba extract can be considered a promising candidate as a new antioxidant agent.

Phytochemical Composition, Antioxidant Activity, and the Effect of the Aqueous Extract of Coffee (Coffea arabica L.) Bean Residual Press Cake on the Skin Wound Healing.

The world coffee consumption has been growing for its appreciated taste and its beneficial effects on health. The residual biomass of coffee, originated in the food industry after oil extraction from coffee beans, called coffee beans residual press cake, has attracted interest as a source of compounds with antioxidant activity. This study investigated the chemical composition of aqueous extracts of coffee beans residual press cake (AE), their antioxidant activity, and the effect of topical application on the skin wound healing, in animal model, of hydrogels containing the AE, chlorogenic acid (CGA), allantoin (positive control), and carbopol (negative control). The treatments' performance was compared by measuring the reduction of the wound area, with superior result (p < 0.05) for the green coffee AE (78.20%) with respect to roasted coffee AE (53.71%), allantoin (70.83%), and carbopol (23.56%). CGA hydrogels reduced significantly the wound area size on the inflammatory phase, which may be associated with the well known antioxidant and anti-inflammatory actions of that compound. The topic use of the coffee AE studied improved the skin wound healing and points to an interesting biotechnological application of the coffee bean residual press cake.

Anti-atherogenic effects of a phenol-rich fraction from Brazilian red wine (Vitis labrusca L.) in hypercholesterolemic low-density lipoprotein receptor knockout mice.

Moderate wine intake (i.e., 1-2 glasses of wine a day) is associated with a reduced risk of morbidity and mortality from cardiovascular disease. The aim of this study was to evaluate the anti-atherosclerotic effects of a nonalcoholic ethyl acetate fraction (EAF) from a South Brazilian red wine obtained from Vitis labrusca grapes. Experiments were carried out on low-density lipoprotein (LDL) receptor knockout (LDLr⁻/⁻) mice, which were subjected to a hypercholesterolemic diet and treated with doses of EAF (3, 10, and 30 mg/kg) for 12 weeks. At the end of the treatment, the level of plasma lipids, the vascular reactivity, and the atherosclerotic lesions were evaluated. Our results demonstrated that the treatment with EAF at 3 mg/kg significantly decreased total cholesterol, triglycerides, and LDL plus very low-density lipoprotein levels compared with control hypercholesterolemic mice. The treatment of mice with EAF at 3 mg/kg also preserved the vasodilatation induced by acetylcholine on isolated thoracic aorta from hypercholesterolemic LDLr⁻/⁻ mice. This result is in agreement with the degree of lipid deposit on arteries. Taken together, the results show for the first time that the lowest concentration of an EAF obtained from a red wine produced in southern Brazil significantly reduced the progression of atherosclerosis in mice.

Cardioprotective effects of a proanthocyanidin-rich fraction from Croton celtidifolius Baill: focus on atherosclerosis.

Proanthocyanidins are the most abundant polyphenols in human diets. Epidemiological studies have pointed to proanthocyanidins as promising molecules that could prevent the development of several coronary syndromes by inhibiting the atherogenic process. The present study was designed to investigate the antiatherogenic effects of a proanthocyanidin-rich fraction (PRF) obtained from Croton celtidifolius Baill (Euphorbiaceae) barks. In isolated human LDL, PRF caused a concentration-dependent inhibition of Cu2+-induced oxidative modifications, evidenced by the increasing of the lag phase of lipid peroxidation and decreasing in the oxidation rate (Vmax), moreover, the protein moieties from LDL were protected against Cu2+-induced oxidation. In human umbilical vein endothelial cells (HUVECs), PRF reduced the ROS production stimulated by oxidized LDL. Herein, we demonstrate that oral treatment with PRF improved endothelium-dependent vasorelaxation in hypercholesterolemic LDL receptor knockout mice (LDLr-/-), however, the fraction did not modify plasma lipids and atherosclerotic lesion size in this experimental model. Finally, our results showed for the first time that PRF prevent isolated LDL oxidation, decrease oxidative stress in endothelial cells and improve endothelial function in mice.

Anti-tumour effects of elatol, a marine derivative compound obtained from red algae Laurencia microcladia.

OBJECTIVES: This paper aims to evaluate the anti-tumour properties of elatol, a compound (sesquiterpene) isolated from algae Laurencia microcladia. METHODS: In-vitro and in-vivo anti-tumour properties of elatol were investigated using: MTT assays to assess the cytotoxic effects; flow cytometry analysis to examine the cell cycle and apoptosis; Western blot analysis for determination of the expression of cell cycle and apoptosis proteins; and study of in-vivo tumour growth in mice (C57Bl6 mice bearing B16F10 cells). KEY FINDINGS: Elatol exhibited a cytotoxic effect, at least in part, by inducing cell cycle arrest in the G(1) and the sub-G(1) phases, leading cells to apoptosis. Western blot analysis demonstrated that elatol reduced the expression of cyclin-D1, cyclin-E, cyclin-dependent kinase (cdk)2 and cdk4. A decrease in bcl-xl and an increase in bak, caspase-9 and p53 expression was also observed. In the in-vivo experiment, treatment with elatol was able to reduce tumour growth in C57Bl6 mice. CONCLUSIONS: Elatol promotes a delay in the cell cycle, probably in the G(1)/S transition, activating the apoptotic process and this could be responsible, at least in part, for the in-vivo effects observed. Taken together, the in-vitro and in-vivo experiments suggested that elatol has anti-tumour properties. Further studies should be conducted to clarify the mechanism of action.

Supercritical fluid extraction from spent coffee grounds and coffee husks: antioxidant activity and effect of operational variables on extract composition.

The present study describes the chemical composition and the antioxidant activity of spent coffee grounds and coffee husks extracts, obtained by supercritical fluid extraction (SFE) with CO(2) and with CO(2) and co-solvent. In order to evaluate the high pressure method in terms of process yield, extract composition and antioxidant activity, low pressure methods, such as ultrasound (UE) and soxhlet (SOX) with different organic solvents, were also applied to obtain the extracts. The conditions for the SFE were: temperatures of 313.15K, 323.15K and 333.15K and pressures from 100 bar to 300 bar. The SFE kinetics and the mathematical modeling of the overall extraction curves (OEC) were also investigated. The extracts obtained by LPE (low pressure extraction) with ethanol showed the best results for the global extraction yield (X(0)) when compared to SFE results. The best extraction yield was 15±2% for spent coffee grounds with ethanol and 3.1±04% for coffee husks. The antioxidant potential was evaluated by DPPH method, ABTS method and Folin-Ciocalteau method. The best antioxidant activity was showed by coffee husk extracts obtained by LPE. The quantification and the identification of the extracts were accomplished using HPLC analysis. The main compounds identified were caffeine and chlorogenic acid for the supercritical extracts from coffee husks.

Central nervous system activity of the proanthocyanidin-rich fraction obtained from Croton celtidifolius in rats.

OBJECTIVES: The aim of the present study was to evaluate the possible neurobehavioural effects in rats of the proanthocyanidin-rich fraction (PRF) isolated from the bark of Croton celtidifolius (Euphorbiaceae). METHODS: Adult Wistar rats were treated with the PRF (0.3-30 mg/kg) and evaluated in different behavioural paradigms classically used for the screening of drugs with psychoactive effects. KEY FINDINGS: Acute intraperitoneal (i.p.) administration of PRF decreased spontaneous locomotor activity (open field arena and activity cage), enhanced the duration of ethyl ether-induced hypnosis, increased the latency to the first convulsion induced by pentylenetetrazole (60 mg/kg, i.p.) and attenuated apomorphine-induced (0.5 mg/kg, i.p.) stereotyped behaviour. In lower doses, PRF (0.3 or 3 mg/kg, i.p.) increased the frequency of open arm entries in the elevated plus-maze test. CONCLUSIONS: The present findings suggest that the systemic administration of PRF induces a wide spectrum of behavioural alterations in rats, consistent with the putative existence of hypnosedative, anticonvulsant and anxiolytic compounds.

High performance liquid chromatography determination of cucurbitacins in the roots of Wilbrandia ebracteata Cogn. / Determinação de cucurbitacinas em raízes de Wilbrandia ebracteata Cogn. por cromatografia líquida de alta eficiência

Roots of Wilbrandia ebracteata Cogn., Cucurbitaceae, used in folk medicine for treatment of rheumatic disease, are rich in cucurbitacins. Dihydrocucurbitacin B is the most abundant cucurbitacin while cucurbitacin B is a minor component. A reverse-phase HPLC system was developed for simultaneous quantitative assay of these cucurbitacins in the roots. The optimised experimental conditions were acetonitrile/H(2)0 40:60, flow-rate 1.2 mL/min., detection at 230 nm and isocratic elution. A variety of sample preparation modes were tested and the extraction with dichloromethane under reflux gave better results. The validation process included linearity, accuracy, repeatability and intermediate precision. The calibration curve of dihydrocucurbitacin B was linear from 40.00 to 400 μg/mL, the recovery was 95.5±3.01 percent, the intermediate precision was found to be 1.64 percent and the repeatability varied between 1.30 to 2.05 percent. The calibration curve of cucurbitacin B was linear from 4.00 to 240 μg/mL, intermediate precision was found to be 2.29 percent and repeatability varied between 1.03 to 2.95 percent. Analysis of the same specimen of W. ebracteata every year from 2002 to 2005 revealed a great rise on the cucurbitacin B concentration after the root was attacked by an herbivore.

Raízes de Wilbrandia ebracteata Cogn. (Cucurbitaceae), tradicionalmente empregada no tratamento de doenças reumáticas, contém cucurbitacinas, sendo di-hidrocucurbitacina B a mais abundante, enquanto cucurbitacina B está presente em menor quantidade. Foi desenvolvido um método para determinação quantitativa destas cucurbitacinas. Os parâmetros selecionados foram: eluente isocrático acetonitrila/H(2)0 40:60, fluxo 1,2 mL/min. e detecção em 230 nm. Diversas formas de preparo da amostra foram testadas, sendo que extração com diclorometano sob refluxo forneceu o melhor resultado. O processo de validação incluiu: linearidade, exatidão, repetibilidade e precisão intermediária. A curva de calibração para a di-hidrocucurbitacina B foi linear de 40.00 to 400 μg/mL, a recuperação foi 95,5±3.01 por cento, a precisão intermediária, 1,64 por cento e a repetibilidade variou entre 1,30 a 2,05 por cento. A curva de calibração da cucurbitacina B foi linear de 4,00 to 240 μg/mL, a recuperação encontrada foi igual a 96,6±2.45 por cento, a precisão intermediária, 2,29 por cento e a repetibilidade variou entre 1,03 a 2,95 por cento. Análise do mesmo espécime de W. ebracteata uma vez por ano de 2002 a 2005 revelou grande aumento no teor de cucurbitacina B após a raiz ter sido atacada por herbívoro.

Antioxidant and hepatoprotective effects of Cyathea phalerata Mart. (Cyatheaceae).

The present study investigated the antioxidant properties of Cyathea phalerata Mart. (Cyatheaceae) using in vitro and in vivo assays. The in vitro antioxidant potential of the crude extract (CE), precipitate (PPT), aqueous fraction (AQF), n-butanolic fraction (BUF) and ethyl acetate fraction (EAF) from C. phalerata was evaluated through the scavenging of diphenyl-1-picryl-hydrazyl-hydrate (DPPH), superoxide anion (O(2)(*-)) (nitroblue tetrazolium assay) and hydroxyl radicals (OH(*)) (deoxyribose assay), and lipid peroxidation in rat liver homogenate. In these assays, it was observed that EAF had marked antioxidant potential, especially as a scavenger of the OH(*) radical and in inhibiting lipid peroxidation. The in vivo evaluation of oxidative stress (DNA fragmentation, membrane lipoperoxidation and carbonyl protein formation) and the antioxidant defenses (concentration of reduced glutathione, as well as catalase and glutathione S-transferase activities) were measured in mice pre-treated with EAF (10, 30 or 100 mg/kg, orally) and later exposed to carbon tetrachloride (CCl(4)). The EAF decreased thiobarbituric acid reactive substances levels, DNA damage and carbonyl protein contents, and increased catalase and glutathione S-transferase activities. Based on these results, it is concluded that the EAF from C. phalerata protects liver from oxidative stress induced by CCl(4) in mice and these effects are probably related to the antioxidant activity associated with the free radical scavenging property of this fraction.

Anti-inflammatory effects of a triterpenoid isolated from Wilbrandia ebracteata Cogn.

Wilbrandia ebracteata (WE), a Brazilian medicinal plant used in folk medicine for the treatment of rheumatic diseases, displays anti-inflammatory properties and constitutes a rich source of cucurbitacins and cucurbitacin-related compounds. The current study investigated the potential anti-inflammatory properties of Dihydrocucurbitacin B (DHCB), a cucurbitacin-derived compound isolated from roots of WE, in some in vivo and in vitro experimental models. Intraperitoneal treatment of mice with DHCB reduced both carrageenan-induced paw edema (0.3, 1 and 3 mg/kg caused inhibitions of 26, 44 and 56 % at 2 h after stimulation, respectively) and pleurisy (10 mg/kg inhibited leukocyte numbers and LTB(4) levels in the pleural fluid by 51 and 75% at 6 h after cavity challenge, respectively). In vitro, DHCB (up to 10 microg/mL) failed to modify LTB(4) production by human neutrophils or PGE(2) production by COS-7 cells transfected with COX-1, but PGE(2) production by COX-2 transfected COS-7 cells was markedly inhibited (by 72%). The levels of COX-1 or COX-2 proteins in IL-1alpha-stimulated NIH3T3 cells were unaffected by DHCB. The results corroborate the potential anti-inflammatory properties ascribed to W. ebracteata Cogn. in folk medicine and suggest that they might be attributed, at least in part, to the capacity of one of this plants main constituents, DHCB, to inhibit COX-2 activity (but not its expression) during inflammation.

Analysis of the antinociceptive effect of the proanthocyanidin-rich fraction obtained from Croton celtidifolius barks: evidence for a role of the dopaminergic system.

In a previous study, we demonstrated the antinociceptive effect of 63SF, a proanthocyanidin-rich fraction obtained from Croton celtidifolius barks, in chemical and thermal behavioural models of pain in mice. The current study now investigate the possible mechanisms underlying the antinociceptive activity of 63SF in the formalin test, by using drugs which interfere with systems that are implicated in descending control of nociception. The antinociceptive effect of 63SF (11 mg/kg, i.p., given 30 min prior to 2.5% formalin) was not altered by pre-treatment of animals 45-50 min beforehand with either prazosin (alpha(1)-adrenergic antagonist; 0.15 mg/kg, i.p.), yohimbine (alpha(2)-adrenergic antagonist; 0.15 mg/kg, i.p.), ketanserin (5-HT(2A)-receptor antagonist; 1.0 mg/kg, i.p.), or l-arginine (substrate for NO synthase, 600 mg/kg, i.p.). On the other hand, treatment with sulpiride, an antagonist of dopaminergic D(2)-receptors (1.0 mg/kg, i.p., 45 min of pre-treatment), reversed the antinociceptive activity of 63SF. Pre-treatment of animals with reserpine (5 mg/kg, i.p., 24 h beforehand) did not alter the antinociceptive effect of 63SF. The current results support the view that the 63SF exerts antinociceptive effects by enhancing the activity of descending control, possibly by direct stimulation of dopaminergic D(2) receptors.

Antinociceptive effect of Croton celtidifolius Baill (Euphorbiaceae).

Croton celtidifolius Baill (Euphorbiaceae) is a tree found in the Atlantic forest of southern Brazil. This plant is used in folk medicine for the treatment of several inflammatory diseases, leukaemia, ulcers and other pathologies. Previous studies demonstrated anti-inflammatory and antioxidant activities and the objective of this work was to investigate a possible antinociceptive action of ethanolic extract of Croton celtidifolius bark (EE) and ethyl acetate fraction (EAF), n-butanol fraction (FBuOH), and aqueous fraction (FAq) obtained from EE. Two standard rodent models of pain were employed for this investigation, the writhing test and the formalin test. In the writhing test, the pre-treatment with EE significantly reduced the writhing induced by 0.6% acetic acid injection and its effect persisted for 4 h. In the formalin test, the pre-treatment with EAF caused marked and dose-related inhibition of formalin-induced licking in mice in the first phase, while pre-treatment with EAF, FBuOH and FAq had a similar effect in the second phase, when given by intraperitoneal (i.p.) and orally (p.o.) route. However, given by i.p. route, the effect of fractions was about three to five-fold more potent in inhibiting licking than when administered by p.o. route. EE presented an antinociceptive effect only in the second phase, when given by i.p. or p.o. route. The oedema caused by formalin was significantly reduced in animals treated i.p. with EAF, FBuOH and FAq. Under the same experimental conditions, in animals treated with sub-fractions derived from EAF only the 63 sub-fraction significantly reduced nociception in both phases and oedema caused by formalin. The results obtained suggest that Croton celtidifolius possesses antinociceptive properties since the EE, fractions and a sub-fraction significantly reduced the writhing induced by acetic acid and the nociception in both phases of the formalin test.

An ethyl acetate fraction obtained from a Southern Brazilian red wine relaxes rat mesenteric arterial bed through hyperpolarization and NO-cGMP pathway.

A number of studies suggest that moderate consumption of red wine may be more effective than other alcoholic beverages in decreasing the risk of coronary heart disease (CAD). In this study, we investigated the effect of a crude extract (CE), as well as an ethyl acetate fraction (EAF) obtained from a Brazilian red wine in the mesenteric arterial bed (MAB) from rats. Our results showed that after the tonus of MAB was increased with phenylephrine (PE), increasing concentrations of CE induced a concentration-dependent relaxation; moreover, EAF was more potent in relaxing the MAB when compared with CE. In vessels depolarized with KCl (80 mM) or treated with the Na(+)/K(+)-ATPase pump inhibitor, ouabain (OUA; 100 microM), or with the K(+) channel blockers: barium (BaCl(2), 100 microM) and tetraethylammonium (TEA; 500 microM), the effect of EAF was significantly reduced. However, this effect was not altered by the ATP-dependent K(+) (K(ATP)) channel blocker, glibenclamide (GLI; 100 microM) as well as Charybdotoxin (ChTx 10 nM), a nonselective inhibitor of K(Ca) channels of large and intermediate conductance plus Apamin (Apamin 100 nM), a specific inhibitor of K(Ca) channels of small conductance. The residual vasodilator effect of EAF observed in vessels pretreated with L-NOARG (100 microM), 1H-[1,2,4,] oxadiazolo[4,3-alfa]quinoxalin, ODQ (10 microM) or KCl (80 mM), given separately, was reduced by the administration of KCl (40 mM) plus L-NOARG (100 microM). The present study demonstrates that the vasodilator effect of EAF is partially dependent upon membrane hyperpolarization in combination with nitric oxide (NO) release.

Antinociceptive effect of proanthocyanidins from Croton celtidifolius bark.

The chemical composition of the chromatography 63 subfraction (63SF) from the ethyl acetate soluble fraction of the crude extract of Croton celtidifolius bark presented a high content of total proanthocyanidins (75.0+/-2.3%). HPLC analysis of 63SF revealed a dimeric profile (e.g.catechin-(4alpha-->8)-catechin and gallocatechin-(4alpha-->8)-catechin) and polymeric proanthocyanidins. In pharmacological investigations, 63SF administered intraperitoneally exhibited dose-dependent antinociceptive activity against several chemical stimuli, including the intraperitoneal injection of acetic acid (ID50 (the dose of 63SF which was able to reduce the nociceptive response by 50% relative to the control value)=0.9 (0.5-1.6)) and the intraplantar injection of capsaicin (ID50=13.0 (10.0-17.0)), glutamate (ID50=4.0 (2.0-7.0)) and formalin (ID50 first phase=36.0 (24.0-53.0) and late phase=11.0 (8.0-14.0)). 63SF administered orally exhibited an antinociceptive effect in the formalin test (ID50 first phase=125.0 (89.0-177.0) and late phase=65.0 (33.0-95.0)). In the same test, 63SF was effective when given soon after the first phase, as well as exhibiting therapeutic activity. Furthermore, 63SF was effective in models of thermal nociception including tail-flick and hot-plate tests. When the mice were treated in the neonatal period with capsaicin, the antinociceptive effect of 63SF in the first phase of the formalin test was abolished, but pretreatment with naltrexone did not change the antinociceptive effect of 63SF. Together, these results provide evidence that 63SF exerted a pronounced systemic antinociception against chemical (acetic acid, formalin, glutamate and capsaicin tests) and thermal (hot-plate and tail-flick tests) nociceptive models of pain in mice at a dose that did not interfere with the locomotor activity. The mechanism by which this sub-fraction produced antinociception remains unclear, but it is unlikely to involve the activation of the opioid system. However, unmyelinated C-fibres sensitive to treatment with capsaicin are likely to participate in antinociception caused by 63SF.

Involvement of 5-HT2 receptors in the antinociceptive effect of Uncaria tomentosa.

Uncaria tomentosa (Willd.) DC (Rubiaceae) is a vine that grows in the Amazon rainforest. Its bark decoctions are used by Peruvian Indians to treat several diseases. Chemically, it consists mainly of oxindole alkaloids. An industrial fraction of U. tomentosa (UT fraction), containing 95% oxindole alkaloids, was used in this study in order to characterize its antinociceptive activity in chemical (acetic acid-induced abdominal writhing, formalin and capsaicin tests) and thermal (tail-flick and hot-plate tests) models of nociception in mice. UT fraction given by the i.p. route dose-dependently suppressed the behavioural response to the chemical stimuli in the models indicated and increased latencies in the thermal stimuli models. The antinociception caused by UT fraction in the formalin test was significantly attenuated by i.p. treatment of mice with ketanserin (5-HT2 receptor antagonist), but was not affected by naltrexone (opioid receptor antagonist), atropine (a nonselective muscarinic antagonist), l-arginine (precursor of nitric oxide), prazosin (alpha1-adrenoceptor antagonist), yohimbine (alpha2-adrenoceptor antagonist), and reserpine (a monoamine depleter). Together, these results indicate that UT fraction produces dose-related antinociception in several models of chemical and thermal pain through mechanisms that involve an interaction with 5-HT2 receptors.

Nitric oxide and cyclooxygenase may participate in the analgesic and anti-inflammatory effect of the cucurbitacins fraction from Wilbrandia ebracteata.

Wilbrandia ebracteata is a medicinal plant from South America used in folk medicine for the treatment of chronic rheumatic diseases. We have shown that the high performance liquid chromatography-characterized (HPLC) dichloromethane fraction isolated from Wilbrandia ebracteata (WEDC) inhibits the parameters observed in experimental models of inflammation in vivo and in vitro. In the present study, we extend our previous observations on the analgesic effects of WEDC by investigating its actions using the hot plate test and zymosan-induced writhing test in mice, as well as zymosan-induced arthritis in rats evaluating articular inflammatory pain, cell migration and determination of NO release into the joint exudate. The effect of WEDC on the activity of COX-1 and COX-2 in vitro and its ulcerogenic capacity in vivo were also investigated. The oral treatment of the animals with WEDC (1-10 mg/kg) produced a significant, dose-dependent reduction of articular incapacitation and abdominal contortions in the writhing test. The same effect was not observed in the hot plate and rota-rod tests. WEDC also reduced nitrite release into the zymosan-inflamed joints. In the evaluation of COX activity, we observed that WEDC was able to selectively inhibit COX-2 but not COX-1 activity in COS-7 cells. Moreover, WEDC treatment did not show gastrointestinal toxicity. Our data confirm the anti-nociceptive activities of the WEDC and indicate that this effect could be associated with inhibition of cyclooxygenase-2 (COX-2) and nitric oxide release. The effects could be attributed to cucurbitacins since several of these were isolated from the WEDC.