Gastrointestinal activity of Justicia spicigera Schltdl. in experimental models.

Justicia spicigera Schltdl. (Acanthaceae) is used for treatment of gastrointestinal illnesses therapy in traditional medicine. The objective of this study was to give evidence of the antinociceptive and spasmolytic effects of the J. spicigera ethanol extract (JS EtOH) using in in vivo and/or in vitro assays. The JS EtOH exerted regulatory effect on the motility and a partial relaxing response on the intestinal tissue. Furthermore, a significant abdominal antinociceptive response was obtained in mice, which was totally abolished in the presence of 5-HT1A receptor antagonist (WAY100635, 0.1 mg/kg, s.c.) and partially by blocking opioid receptors (NX, 1 mg/kg, i.p.), whereas the inhibition of the NO synthesis (L-NAME, 30 mg/kg, i.p.) facilitated antinociception of this extract. Kaempferitrin was isolated and identified as major secondary metabolite. These results support the analgesic and spasmolytic-like activity of J. spicigera aerial parts involving inhibitory neurotransmission reinforcing the potential of this medicinal plant for alleviating pain.

Antihypertensive and vasorelaxant mode of action of the ethanol-soluble extract from Tagetes lucida Cav. aerial parts and its main bioactive metabolites.

ETHNOPHARMACOLOGICAL RELEVANCE: Tagetes lucida Cav. commonly known as "yauhtli" or "pericón" is used in Mexican traditional medicine for the treatment of anxiety, depressant diseases, pain, hypertension, among others. AIM: To evaluate the antihypertensive and vasorelaxant modes of action of a crude ethanolic extract from T. lucida aerial parts and to isolate the bioactive compounds. MATERIALS AND METHODS: Ethanolic extract was tested in an in vivo assay in SHR rats by intragastric administration at 10 and 100 mg/kg dosages, to measure and to compare hemodynamic parameters like diastolic and systolic blood pressure and heart rate. Also, extract (3.03-1000 µg/ml), fractions (3.03-1000 µg/ml) and pure isolated compounds (1.75-550 µM) were evaluated on isolated aortic rings contracted with noradrenaline (0.1 µM) to determine their vasorelaxant effect and extract-mode of action. RESULTS: Ethanolic extract of T. lucida lowered systolic and diastolic blood pressure on SHR rats without heart rate modification (P > 0.05). Moreover, the extract showed concentration-dependent relaxant effect in a partially endothelium-dependent manner (P < 0.05), through NO/cGMP system activation and calcium channel blockade. 6,7,8-trimethoxycoumarin (1), 6,7-dimethoxycoumarin (2), and 7-methoxycoumarin (3) from T. lucida are the main bioactive compounds of the extract and showed significant vasorelaxant activity. CONCLUSIONS: Results provide evidence and endorsed the antihypertensive properties attributed to T. lucida in traditional medicine, which is produced by vasorelaxant effect mainly through multitarget NO/cGMP system activation and calcium channel blockade. Coumarin derivatives 1, 2 and 3 are the responsible of the vasorelaxant activity.

Antinociceptive activity of Tilia americana var. mexicana inflorescences and quercetin in the formalin test and in an arthritic pain model in rats.

Tilia species are well known around the world for their properties in traditional medicine. Antinociceptive activity of hexane, methanol and aqueous extracts from Tilia americana var. mexicana inflorescences was evaluated in the pain-induced functional impairment model in rats (PIFIR). A preliminar 300 mg/kg dosage of aqueous extracts i.p., but not the same dose of methanol or hexane extract, produced an antinociceptive response in rats similar to that of tramadol (17.8 mg/kg i.p.). A dose-response curve from aqueous extract allowed the determination of ED(50) = 364.97 mg/kg in comparison to ED(50) = 10.35 mg/kg for tramadol in this model. A previous HPLC-DAD analysis corroborated by an HPLC-MS technique in this study demonstrated the flavonoid composition in this Tilia aqueous extract revealing the presence of glycosides mainly derived from quercetin. Thus, Tilia aqueous extract and quercetin were tested at 30 and/or 100 mg/kg dosages i.p. in the PIFIR and formalin models producing a significant and dose-dependent antinociceptive response resembling that produced by a total and a partial agonist of 5-HT(1A) receptors like 8-OH-DPAT (0.1 mg/kg, s.c.) and buspirone (5 mg/kg, i.p.), respectively. In all the treatments, antinociceptive response was inhibited in the presence of WAY 100635 (0.12 mg/kg, i.p.). Our results support the analgesic activity of T. americana var. mexicana inflorescences attributed by folk medicine; they also indicate that quercetin is partly responsible for this pharmacological activity that is likely mediated by serotonin 5-HT(1A) receptors.

Effect of repeated administration of Annona diversifolia Saff. (ilama) extracts and palmitone on rat amygdala kindling.

Annonas are consumed as fresh fruits, but, because of their effects on the central nervous system, are also used in folk medicine. The effect on rat amygdala kindling of repeated administration of Annona diversifolia hexane (100mg/kg IP or PO) and ethanol (100mg/kg, PO) leaf extracts and palmitone (10mg/kg, IP) was determined. Electrographic and/or behavioral changes were monitored during kindling-induced seizures 60minutes after treatments. Antiepileptic efficacy was evaluated with respect to afterdischarge (AD) duration, spike frequency, and/or behavioral seizure activity. Oral administration of both extracts significantly decreased spike frequency, whereas intraperitoneally administered hexane extract and palmitone only reduced AD duration. Hexane extract and palmitone exhibited anticonvulsant properties and delayed establishment of a kindling state as observed with diazepam (0.3mg/kg IP). These results reinforce the anticonvulsant properties of this plant, and palmitone and other constituents are responsible for the pharmacological effects.

Spasmolytic effect of aqueous extract of Tagetes erecta L. flowers is mediated through calcium channel blockade on the guinea-pig ileum.

This study provides pharmacological evidence on the spasmolytic activity of Tagetes erecta L. (marigold or cempasúchil) on the guinea-pig ileum and presents data on its mechanism of action. The relaxant effect on KCl contractions was more marked with aqueous (AqEx) than with ethanol extracts (EtEx) of T. erecta flowers (55.6 ±â€¯11.0 vs 21.1 ±â€¯4.4%, respectively). In addition, the aqueous extract antagonized contractions elicited by EFS, but not by acetylcholine (73.5 ±â€¯1.9 vs 14.5 ±â€¯5.3%, respectively). These effects were not diminished by hexamethonium or L-NAME, but this extract caused a rightward shift in the Ca2+ concentration-response curves like that of verapamil. Quercetin and rutin, two flavonoids present in this plant, also showed spasmolytic effects (95.7 ±â€¯2.8 and 27.9 ±â€¯7.1%, respectively). Interestingly, in tissues without spasmogens, the extract induced contractions superimposed on their spontaneous activity. These results support the traditional use of T. erecta as a spasmolytic in folk medicine and suggest mainly that quercetin could be partly responsible for this effect. The spasmolytic effect appears to involve voltage-gated calcium channels, but not the nitric oxide pathway or the release of neurotransmitters from enteric neurons. Nevertheless, this plant could produce colic or stomachache as adverse effects in clinical situations in which these symptoms are not originally present.

Neuropathic and inflammatory antinociceptive effects and electrocortical changes produced by Salvia divinorum in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Salvia divinorum is a medicinal plant traditionally used in hallucinogenic ethnopharmacological practices and for its analgesic and antinflammatory properties. Its active compounds include diterpenes known as salvinorins which act as potent κ opioid receptor agonists. AIM OF THE STUDY: Given its effects in acute animal models of pain, as well as its antinflammatory attributes, we decided to investigate the analgesic effects of an SD extract in neuropathic (sciatic loose nerve ligature) and inflammatory (intra plantar carrageenan) pain models in rats. We also determined in this study the electrocorticographic changes to correlate similar hallucinogenic state and behavior as those produced in humans. MATERIAL AND METHODS: Mechanical and thermonociceptive responses, plantar test and von Frey assay, respectively, were measured in adult Wistar rats 30min, 3h and 24h after the intraperitoneal administration of saline or an hydroponic SD extract. We also evaluated carbamazepine and celecoxib, as gold reference drugs, to compare its antinociceptive effects. RESULTS: Our results showed that administration of SD extract induced antialgesic effects in both neuropathic and inflammatory pain models. All those effects were blocked by nor-binaltorphimine (a Kappa opioid receptor antagonist). Moreover, it was observed an increase of the anterior power spectral density and a decrease in the posterior region as electrocorticographic changes. CONCLUSION: The present investigation give evidence that SD is capable to reduce algesic response associated to neuropathic and inflammatory nociception. This study support therapeutic alternatives for a disabling health problem due to the long term pain with high impact on population and personal and social implications.

Justicia spicigera Schltdl. and kaempferitrin as potential anticonvulsant natural products.

Justicia spicigera Schltdl. is a vegetal species traditionally used to control epilepsy, but scientific evidence is required to reinforce this activity. The aim of the study was to evaluate the anticonvulsant-like activity of J. spicigera aqueous extract (JsAE) and a bioactive compound. JsAE was assessed in a dose-response manner (30, 100 and 1000mg/kg, i.p.) using the pentylenetetrazol (PTZ)-induced seizures and maximal electroshock seizure (MES) test in mice in comparison to ethosuximide (ETX, reference drug 100mg/kg, i.p.) or phenytoin (25mg/kg, i.p.), respectively. Then a significant dosage (1000mg/kg, i.p.) was chosen to examine electrographic activity (EEG) in rats. Treatment groups were compared to the vehicle and ETX in the convulsive behavior alone or simultaneous to EEG after PTZ-induced seizures (80 or 35mg/kg, i.p., mice or rats). Kaempferitrin (a flavonoid of JsAE) and ETX were administered via intracerebroventricular (i.c.v, 4th ventricle, 1µg/µL) and tested in the presence of PTZ in rats. Results confirmed that JsAE delayed the onset of seizures and reduced frequency of tonic convulsion and mortality in mice. JsAE or kaempferitrin also decreased the EEG spikes frequency and amplitude in a similar manner than EXT in rats. In conclusion, these preliminary data give evidence of the potential of J. spicigera as possible anticonvulsant as recommended in folk medicine for treating epilepsy, where kaempferitrin is suggested as a partial responsible bioactive compound.

Neuroprotective effects of Tilia americana var. mexicana on damage induced by cerebral ischaemia in mice.

Tilia americana var. mexicana (T. americana) is a plant widely used in Mexico for its medicinal properties on the central nervous system. In the present study, we designed a protocol to investigate the neuroprotective effects of non-polar and polar extracts of T. americana on damage induced by cerebral ischaemia in mice. Vehicle or extracts were administered immediately after ischaemia. Functional neurological deficit, survival percentage and infarct area were determined in each experimental group. Results showed that groups treated with non-polar or polar extracts of T. americana had increased survival rate, improved neurological deficits and diminished the infarct area in relation to the ischaemic group. In conclusion, this study confirms the neuroprotective activity of T. americana, suggests a possible synergism between non-polar and polar constituents and supports its potential as a useful aid in the clinical management of stroke.

Isobolographic analysis of the sedative interaction between six central nervous system depressant drugs and Valeriana edulis hydroalcoholic extract in mice.

It has been declared frequently that valerian may potentiate the effect of other central nervous system (CNS) depressant drugs, however there has been a lack of experimental data. We have evaluated the profile of the interactions between the ethanol extract of Valeriana edulis spp procera and six CNS depressant drugs using an exploratory model to test the sedative effect in mice. All the compounds tested showed a dose-dependent sedative effect with the following ED50 values: valerian 181.62, diazepam 1.21, ethanol 1938, pentobarbital 11.86, buspirone 1.04, haloperidol 0.41 and diphenhydramine 17.06 mg kg-1. An isobolographic analysis was used to evaluate the sedative interaction of the intraperitoneal co-administration of 1:1 fixed-ratio combination of equi-effective doses of valerian extract with each CNS depressant drug. The ED50 theoretical (Zadd) and experimental (Zexp) for each combination were: valerian+diazepam,Zadd=91.41 mg kg-1, Zexp=81.64 mg kg-1; valerian+ethanol, Zadd=1060.22 mg kg-1, Zexp=687.89 mg kg-1; valerian+pentobarbital, Zadd=96.74 mg kg-1, Zexp=151.83 mg kg-1; valerian+buspirone, Zadd=91.33 mg kg-1, Zexp=112.73 mg kg-1; valerian+haloperidol, Zadd=91.01 mg kg-1, Zexp=91.52 mg kg-1; valerian+diphenhydramine, Zadd=99.34 mg kg-1, Zexp=123.52 mg kg-1. Neither synergistic nor attenuate effects were found in any of the combinations evaluated. We concluded that the valerian extract did not potentiate the sedative effect of commonly prescribed CNS depressant drugs as was expected. The additive effect found through the isobolographic analysis suggested that the sedative effect of V. edulis resulted from the activation of common mechanisms of haloperidol, diazepam, buspirone, pentobarbital, diphenhydramine and ethanol.

Tramadol and Tramadol+Caffeine Synergism in the Rat Formalin Test Are Mediated by Central Opioid and Serotonergic Mechanisms.

Different analgesic combinations with caffeine have shown this drug to be capable of increasing the analgesic effect. Many combinations with nonsteroidal anti-inflammatory drugs (NSAIDs) have been carried out, but, in regard to opioids, only combinations with morphine and tramadol have been reported. The antinociceptive synergism mechanism of these combinations is not well understood. The purpose of the present study was to determine the participation of spinal and supraspinal opioidergic and serotonergic systems in the synergic effect of the tramadol+caffeine combination in the rat formalin test. At the supraspinal level, the opioid antagonist, naloxone, completely reversed the effect of the drug combination, whereas ketanserin, a 5-HT2 receptor antagonist, inhibited the effect by 60%; however, ondansetron, a 5-HT3 receptor antagonist, did not alter the combination effect. When the antagonists were intrathecally administered, there was a significant reduction in all tramadol-caffeine combination effects. With respect to tramadol alone, there was significant participation of the opioid system at the supraspinal level, whereas it was the serotonergic system that participated at the spinal level by means of the two receptors studied. In conclusion, the tramadol+caffeine combination synergically activated the opioid and serotonergic systems at the supraspinal level, as well as at the spinal level, to produce the antinociception.

Ursolic acid from Agastache mexicana aerial parts produces antinociceptive activity involving TRPV1 receptors, cGMP and a serotonergic synergism.

Agastache mexicana is a plant that has long been used in large demands in Mexican folk medicine to treat anxiety, insomnia and pain, among others affections. Chromatographic technique was used to identify ursolic acid (UA), 130.7 mg/g and 20.3 mg/g, as an antinociceptive active compound identified in ethyl acetate and methanol extracts of A. mexicana aerial parts, respectively. Temporal course curves of the antinociceptive response demonstrated a dose-dependent and significant activity of UA (1 to 100 mg/kg, i.p.) with an ED50=2 mg/kg in comparison to the efficacy of diclofenac (1 or 30 to 100 mg/kg, i.p.), a non-steroidal anti-inflammatory drug, with an ED50=11.56 mg/kg. The antinociceptive response consisted in the reduction of abdominal constrictions induced with 1% acetic acid in mice. Similarly, UA at 2 mg/kg produced significant antinociception in the intracolonic administration of 0.3% capsaicin (a TRPV1 agonist) in mice. It has been reported the inhibition produced by UA on the calcium-flux induced by capsaicin on TRPV1 receptor suggesting the antagonistic activity of this receptor. Finally, an ED50=44 mg/kg was calculated in the neurogenic and inflammatory nociception induced in the formalin test in rats. The antinociceptive response of UA in the formalin test was not modified in presence of naloxone, flumazenil or L-arginine. Nevertheless, it was reverted in presence of 1-H-(1,2,4)-oxadiazolo(4,2-a)quinoxalin-1-one (ODQ, an inhibitor of soluble guanylyl cyclase) and increased in presence of N(G)-L-nitro-arginine methyl ester (L-NAME, inhibitor of nitric oxide synthase), theophylline (inhibitor of phosphodiesterase) and WAY100635 (an antagonist of 5-HT1A receptors). Current results provide evidence that the antinociceptive response of A. mexicana depends in part on the presence of UA. Moreover, this triterpene may exerts its antinociceptive effect mediated by the presence of cGMP and an additive synergism with 5HT1A receptors, but also an antagonistic activity towards TRPV1 receptors may be involved.

Anti-ulcer activity of Cyrtocarpa procera analogous to that of Amphipterygium adstringens, both assayed on the experimental gastric injury in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: The bark of Amphipterygium adstringens (Aa) is commonly mixed or adulterated with the bark of Cyrtocarpa procera (Cp) and sold in Mexican markets. Aa is a well known species in Mexico used as decoction to relieve ulcers. Scientific reports reinforcing the anti-ulcer activity of Aa have been previously described, but those describing the anti-ulcer properties of Cp as a substitute for Aa in folk medicine are scarce. AIM OF THE STUDY: To investigate anatomical and phytochemical differences between these species, as well as to assess the anti-ulcer effect of Cp extracts in comparison to the Aa extracts. MATERIAL AND METHODS: Anatomical micro-technique and physical and spectroscopic data were used to analyze differences between Cp and Aa. Regard to the pharmacological activity, it was assessed by using the ethanol-induced gastric damage model in rats. RESULTS: Whereas the bark anatomy of Aa was characterized by vertical canals in the periderm and the rare occurrence of fibers in its phloem, a periderm without vertical canals and abundant fibers in the phloem were distinctive features of Cp. Phytochemical analysis allowed the identification of tirucallane, masticadienonic and 3α-hydroxymasticadienonic acids as major components in Aa, while ß-amyrin and ß-sitosterol were obtained from Cp. Gastric lesions observed in the control group decreased in the presence of 100mg/kg of hexane, ethyl acetate and methanol extracts from the normal or regenerated bark of Cp, thus resembling the anti-ulcer effect of Aa. Nevertheless, major anti-ulcer potency was observed with the most active methanol extract from Cp obtained from normal [the effective dose fifty ED(50)=45.54 mg/kg] or regenerated (ED(50)=36.68 mg/kg) bark in comparison to Aa (ED(50)=115.64 mg/kg). CONCLUSION: Chemical and anatomical differences were found between these species, but since the anti-ulcer activity of Cp is similar to that shown by Aa our results reinforce the use of both species for the relief of gastric ulcer in folk medicine.

Hesperidin produces antinociceptive response and synergistic interaction with ketorolac in an arthritic gout-type pain in rats.

Hesperidin occurs in greatest concentration in plants from the Rutaceae and Lamiaceae families. In human nutrition it contributes to the integrity of blood vessels and its deficiency in the diet has been linked to abnormal capillary leakiness as well as pain. In this study, the bioflavonoid hesperidin was identified as an active compound in an ethanol extract of the Rosmarinus officinalis aerial parts tested in the pain-induced functional impairment model in the rat (PIFIR) as an assay of inflammatory and chronic nociception similar to that observed in clinical gout. Hesperidin produced a dose-dependent and significant response with an ED25=1666.72 mg/kg in comparison to an ED25=302.90 mg/kg for the extract or an ED25=0.47 mg/kg for the reference drug ketorolac in the PIFIR model. Although the antinociceptive response of R. officinalis was reverted in presence of the opioid antagonist naloxone (10 mg/kg, s.c.) and the 5HT(1A) antagonist WAY100635 (0.12 mg/kg, s.c.), the hesperidin response was not modified by naloxone (10 mg/kg), WAY100635 (0.12 mg/kg), bicuculline (1 mg/kg, s.c.), flumazenil (10 mg/kg, i.p.) or caffeine (1 mg/kg, s.c.). Nevertheless, it was reduced in presence of capsazepine (10 or 20 mg/kg, s.c.) suggesting the participation of the TRPV1 receptor, which was reinforced when hesperidin significantly reduced the capsaicin-induced nociceptive response. A synergistic interaction was also observed when antinociceptive doses of hesperidin were combined with those of ketorolac producing 15 combinations mainly in additive and supra-additive responses. These results provide evidence for the antinociceptive activity of hesperidin and demonstrate synergistic response when combined with ketorolac, possibly by involvement of the TRPV1 receptor, suggesting their clinical potential in pain therapy.

Anxiolytic and sedative-like effects of flavonoids from Tilia Americana var. Mexicana: GABAergic and serotonergic participation / Efecto ansiolítico y sedante de flavonoides de Tilia Americana var. Mexicana: participación GABAérgica y serotonérgica

Abstract: INTRODUCTION: The inflorescences of Tilia americana var. mexicana are used as an infusion in Mexican traditional medicine due to their tranquilizing effects; however, pharmacological and phytochemical studies of the leaves are lacking. OBJECTIVE: In this research, the anxiolytic and sedative-like efficacy of the Tilia americana var. mexicana leaves was compared to that obtained with its inflorescences and flavonoids therein identified, as well as the possible mechanism of action. METHODS: The sorted and dried inflorescences and leaves were macerated subsequently in hexane, ethyl acetate and methanol. The methanol extracts were qualitative- and quantitative-analyzed by HPLC, using commercial flavonoids standards selected on the basis of their previously reported presence in Tilia species. The pharmacological activity was evaluated in CD-1 mice in the tests: open-field, elevated plus-maze, hole-board, and the sodium pentobarbital-induced sleep potentiation test. In regard to the mechanism of action, participation of benzodiazepine and 5-HT1A serotonin receptors was tested with the respective antagonists: flumazenil and WAY100635. RESULTS: The presence of quercetin, rutin and isoquercitrin was confirmed in the extracts of the inflorescences and leaves. The anxiolytic-like effects were the same between the two organs, which were inhibited in the presence of flumazenil and WAY100635. DISCUSSION AND CONCLUSION: Our results provide evidence that the extracts of the leaves of T. americana var. mexicana are as efficacious as the inflorescences to produce anxiolytic and sedative-like effects, where flavonoids like quercetin, rutin and isoquercitrin are partially responsible for these activities by the involvement of GABA/BDZ and 5HT1A serotonergic receptors.

Resumen: INTRODUCCIÓN: En la medicina tradicional mexicana, la infusión de inflorescencias de Tilia americana var. mexicana es utilizada por sus efectos tranquilizantes; sin embargo, los estudios farmacológicos y fitoquímicos de sus hojas son deficientes. OBJETIVO: En esta investigación, la eficacia ansiolítico-sedante de las hojas de T. americana var. mexicana se comparó con la obtenida con las inflorescencias y los flavonoides previamente identificados; se analizó además el posible mecanismo de acción. MÉTODOS: Inflorescencias y hojas separadas y secas se maceraron sucesivamente en hexano, acetato de etilo y metanol. Los extractos metanólicos se analizaron cualitativa y cuantitativamente por HPLC usando estándares comerciales de flavonoides previamente reportados en especies de Tilia. La actividad farmacológica se evaluó en ratones CD-1 en las pruebas de campo abierto, cruz elevada, tablero con orificios y la prueba de potenciación de hipnosis inducida por pentobarbital sódico. Respecto al mecanismo de acción, la participación de los receptores de benzodiazepinas y 5-HT1A de serotonina se examinó utilizando los antagonistas flumazenil y WAY100635, respectivamente. RESULTADOS: La presencia de quercetina, rutina e isoquercitrina se confirmó en los extractos de inflorescencias y hojas, donde se confirmó el efecto como ansiolítico, el cual fue inhibido en la presencia de flumazenil y WAY100635. DISCUSIÓN Y CONCLUSIÓN: Nuestros resultados dan evidencia de que las hojas de T. americana var. mexicana son tan eficaces como las inflorescencias para producir efectos ansiolítico-sedantes, donde los flavonoides quercetina, rutina e isoquercitrina son responsables parciales y se involucra la participación de los receptores GABA/BDZ y 5HT1A de serotonina.

Tramadol and caffeine produce synergistic interactions on antinociception measured in a formalin model.

Drug combinations have been used in clinical practice for the main purpose of increasing therapeutic effect efficacy. The aim of this study was to determine the antinociceptive effect of tramadol and caffeine administered separately or in combination, as well as their synergistic interaction. The formalin test was used. Nociceptive behavior was evaluated by flinching response of the formalin-treated paw. Rats were divided into five groups and received tramadol alone (4.9-49.6mg/kg, s.c.), caffeine alone (1-17.8mg/kg, p.o.), or combinations of tramadol (4.9, 8.8, 15.6 and 20.8mg/kg, s.c.) and caffeine (1, 3.16 and 10mg/kg, p.o.). Tramadol showed dose-dependent antinociceptive effect in both phases of the formalin test. Caffeine only presented antinociceptive effect in the second phase and this effect was also dose-dependent. In Phase 1, combinations of tramadol and caffeine showed antinociceptive effect similar to that of tramadol alone. In Phase 2, the dose-response curve shifted to the left with the combination of tramadol and each dose of caffeine. Synergism analysis resulted in synergistic effect in ten combinations and antagonism in two combinations. In conclusion, the synergism observed in the majority of tramadol and caffeine combinations used in this study suggests that this drug combination is useful in the treatment of pain.

HPLC/MS analysis and anxiolytic-like effect of quercetin and kaempferol flavonoids from Tilia americana var. mexicana.

AIM OF THE STUDY: Around the world, Tilia species have been used in traditional medicine for their properties as tranquilizer. Furthermore, Mexican species of Tilia have been grouped as Tilia americana var. mexicana, but their specific content in flavonoids is poorly described. In this study, inflorescences of Mexican Tilia were collected in three different regions of Mexico to compare their flavonoid content and anxiolytic-like response. MATERIALS AND METHODS: Flavonoid content was analyzed by using an HPLC-MS technique. For anxiolytic-like response, Tilia inflorescences extracts (from 10 to 300 mg/kg, i.p.) were tested in experimental models (open-field, hole-board and plus-maze tests, as well as sodium pentobarbital-induced hypnosis) in mice. RESULTS: HPLC-MS analysis revealed specific peaks of flavonoid composition demonstrating some differences in these compounds in flowers and bracts depending on the region of collection. No differences in the neuropharmacological activity among these samples of Tilia were found. Moreover, their effects were associated with quercetin and kaempferol glycosides. CONCLUSIONS: Dissimilarities in the flavonoid composition of Mexican Tilias might imply that these species must be re-classified in more than one species, not as a unique Tilia americana var. mexicana. Since quercetin and kaempferol aglycons demonstrated anxiolytic-like response and that no difference in the pharmacological evaluation was observed between these three Mexican Tilias, we suggest that this pharmacological effect of Tilia inflorescences involves these flavonoids occurrence independently of the kind of glycosides present in the samples reinforcing their use in traditional medicine in several regions of Mexico.

Anticonvulsive effect of vitamin C on pentylenetetrazol-induced seizures in immature rats.

Vitamin C helps to prevent brain oxidative stress and participate in the synthesis of progesterone. It also possesses a progesterone-like effect and acts synergistically with progesterone on the brain. Progesterone and its metabolites, but also vitamin C have been associated with anticonvulsant effects. We evaluated the progesterone concentration 30min and 24h after the last administration of vitamin C (500mg/kg, i.p. for five days). We also evaluated how vitamin C altered pentylenetetrazol (PTZ)-induced seizures by measuring the onset latency of seizures, percentage of incidence and mortality as well as amino acid levels after seizures. Vitamin C treatment alone increased basal progesterone concentrations to 531% after 30min compared to 253% after 24h. Furthermore, vitamin C significantly increased the latency to the first myoclonic, clonic and tonic seizure induced by PTZ (80mg/kg, i.p.) and decreased the percentage of incidence of clonic and tonic seizures as well as the mortality rate. Changes in tissue concentration of amino acids were primarily observed at 24h after vitamin C treatment. Our results suggest that vitamin C together with progesterone and/or its metabolites are involved in the protection against PTZ-induced seizures in immature rats.

Antinociceptive activity of Annona diversifolia Saff. leaf extracts and palmitone as a bioactive compound.

Annonas are consumed as fresh fruits, but are also widely used in folk medicine for treating pain and other ailments. Antinociceptive properties of the Annona diversifolia ethanol crude extract were tested using the pain-induced functional impairment model in rat (PIFIR) and the writhing test in mice. The ethanol extract caused a 25% recovery of limb function in rats; this response was significant and dose-dependent. Furthermore, this extract produced a similar antinociceptive response (ED(50)=15.35 mg/kg) to that of the reference drug tramadol (ED(50)=12.42 mg/kg) when evaluated in the writhing test in mice. Bio-guided fractionation yielded hexane and acetone active fractions from which the presence of palmitone and flavonoids was respectively detected. Palmitone produced an antinociceptive response with an ED(50)=19.57 mg/kg in the writhing test. Antinociceptive responses from ethanol extract and tramadol were inhibited in the presence of either naloxone (1mg/kg, s.c.)--an antagonist of endogenous opioids--or WAY100635 (0.8 mg/kg, s.c.)--a 5-HT(1A) serotonin receptor antagonist. These results provide evidence that A. diversifolia possesses antinociceptive activity, giving support to their traditional use for treatment of spasmodic and arthritic pain. In addition, our results suggest the participation of endogenous opioids and 5-HT(1A) receptors in this antinociceptive response.

Endogenous opioids participation in the effect of Rosmarinus officinalis L. in the visceral, inflammatory and gout arthritis nociception in rodents / Participación de los opioides endógenos en el efecto de Rosmarinus officinalis L. en la nocicepción visceral, inflamatoria y artritis gotosa en roedores

The aim of this study was to investigate the endogenous opioid participation in the antinociceptive effect of R. officinalis aerial parts in experimental models of visceral, inflammatory and gout arthritis nociception. Acid-acetic induced writhing and formalin tests as well as the pain-induced functional impairment model in the rat (PIFIR) assay were studied. Antinociceptive doses of R. officinalis via oral, alone and in presence of an opioid antagonist were evaluated in comparison to the reference analgesic drug tramadol (31.6 and 50mg/kg i.p., in mice and rats, respectively). The antinociceptive effect of R. officinalis at a 300mg/kg dosage was significantly reverted in presence of 1.0mg/ kg s.c. of naloxone in writhing and formalin tests. Concerning PIFIR model, significant antinociceptive response produced for 1000 and 3000mg/kg was not inhibited in presence of 1.0 or 3.16mg/kg, s.c. of naloxone. In the antinociceptive effect of tramadol, naloxone produced partial inhibition in all models tested. These results suggest that antinociceptive and anti-inflammatory activities of R. officinalis aerial parts involve endogenous opioids, but activation of these mediators depends on the experimental model and the physiological process of the induced nociception.

El objetivo de este estudio fue investigar la participación de los opioides endógenos en el efecto antinociceptivo producido por un extracto preparado con las partes aéreas de Rosmarinus officinalis en modelos experimentales de nocicepción visceral, inflamatoria y tipo artritis gotosa. Para la inducción de nocicepción visceral e inflamatoria se utilizaron los modelos de estiramiento abdominal "writhing" y de formalina intraplantar al 1 %, respectivamente, en ratones. A su vez, para la nocicepción de tipo artritis gotosa se utilizó el modelo de disfunción inducida por ácido úrico al 20% intraarticular en ratas conocido como PIFIR (por sus siglas en inglés). Dosis antinociceptivas de R. officinalis vía oral se evaluaron solas y en presencia del antagonista de opioides endógenos naloxona. Adicionalmente, dicho efecto se comparó con el fármaco analgésico de referencia tramadol (31.6 y 50mg/kg i.p., en ratones y ratas, respectivamente). El efecto antinociceptivo de R. officinalis significativo en la dosis de 300mg/kg se revirtió en presencia de 1mg/kg s.c. de naloxona en las pruebas de estiramiento abdominal y formalina. En cuanto al modelo PIFIR, la respuesta antinociceptiva producida por 1000 y 3000mg/kg no se inhibió en presencia de 1 o 3.16mg/kg, s.c. de naloxona. En el efecto de tramadol, opioide atípico, la naloxona produjo inhibición parcial de la respuesta antinociceptiva en todos los modelos probados. Los resultados sugieren que la actividad antinociceptiva producida por el extracto de las partes aéreas de R. officinalis involucra al sistema de opioides endógenos, pero la presencia de estos mediadores depende del tipo de estímulo y del proceso fisiológico involucrado en la nocicepción inducida.

Bioactivity-guided isolation of beta-sitosterol and some fatty acids as active compounds in the anxiolytic and sedative effects of Tilia americana var. mexicana.

Tilia species have been used as anxiolytics for many years. In a previous study anxiolytic-like effects of a hexane extract of Tilia americana var. mexicana inflorescences were observed in experimental models in mice. To get additional insights into the neuroactive actions of this particular Tilia species, in this study we report a bioactivity guided-fractionation of the extract and separation by column chromatographic methods to isolate three fatty acids and a triterpene identified as beta-sitosterol as major constituents. Our results revealed that the crude extract at 10 and 30 mg/kg I. P. and some pooled fractions at the same dosages potentiated sodium pentobarbital-induced sleeping time and caused a significant increase in the time spent at the open-arm sides in the plus-maze test. A reduction in the exploratory behavioral pattern manifested as ambulatory activity, as well as head dipping and rearing tests was also observed. Further fractionation and purification yielded four major fractions containing fatty acids and beta-sitosterol as the active compounds. A dose-response curve of beta-sitosterol in the range 1 to 30 mg/kg doses indicated that this compound produced an anxiolytic-like action from 1 to 10 mg/kg and a sedative response when the dose was increased to 30 mg/kg, these effects resemble those produced by diazepam (0.1 mg/kg). Our results suggest that hexane extract of Tilia americana var. mexicana produces depressant actions on the central nervous system, at least in part, because of the presence of beta-sitosterol and some fatty acids that remain to be identified.