2-Arylpropionic Acid Pyrazolamides as Cannabinoid CB2 Receptor Inverse Agonists Endowed with Anti-Inflammatory Properties.

Among the most recent proposals regarding the mechanism of action of dipyrone, the modulation of cannabinoid receptors CB1 and CB2 appears to be a promising hypothesis. In this context, the present work describes a series of five novel pyrazolamides (7-11) designed as molecular hybrids of dipyrone metabolites and NSAIDs, such as ibuprofen and flurbiprofen. Target compounds were obtained in good overall yields (50-80%) by classical amide coupling between 4-aminoantipyrine and arylacetic or arylpropionic acids, followed in some cases by N-methylation of the amide group. The compounds presented good physicochemical properties in addition to stability to chemical (pH 2 and 7.4) and enzymatic (plasma esterases) hydrolysis and showed medium to high gastrointestinal and BBB permeabilities in the PAMPA assay. When subjected to functional testing on CB1- or CB2-transfected cells, compounds demonstrated an inverse agonist profile on CB2 receptors and the further characterization of compound LASSBio-2265 (11) revealed moderate binding affinity to CB2 receptor (Ki = 16 µM) with an EC50 = 0.36 µM (Emax = 63%). LASSBio-2265 (11) (at 1, 3, and 10 mg/kg p.o.) was investigated in the formalin test in mice and a remarkable analgesic activity in the late inflammatory phase was observed, suggesting it could be promising for the treatment of pain syndromes associated with chronic inflammatory diseases.

Characterization of the Antinociceptive Activity from Stevia serrata Cav.

BACKGROUND: Stevia serrata Cav. (Asteraceae), widely found in Guatemala, is used to treat gastrointestinal problems. The aim of this study was to demonstrate the antinociceptive and anti-inflammatory effects of the essential oil (EO) and the mechanism of action. METHODS: EO was tested in chemical (capsaicin- and glutamate-induced licking response) or thermal (hot plate) models of nociception at 10, 30 or 100 mg/kg doses. The mechanism of action was evaluated using two receptor antagonists (naloxone, atropine) and an enzyme inhibitor (L-NAME). The anti-hyperalgesic effect was evaluated using carrageenan-induced nociception and evaluated in the hot plate. RESULTS: All three doses of EO reduced licking response induced by glutamate, and higher doses reduced capsaicin-induced licking. EO also increased area under the curve, similar to the morphine-treated group. The antinociceptive effect induced by EO was reversed by pretreatment of mice with naloxone (1 mg/kg, ip), atropine (1 mg/kg, ip) or L-NAME (3 mg/kg, ip). EO also demonstrated an anti-hyperalgesic effect. The 100 mg/kg dose increased the latency time, even at 1 h after oral administration and this effect has been maintained until the 96th hour, post-administration. CONCLUSIONS: Our data suggest that essential oil of S. serrata presents an antinociceptive effect mediated, at least in part, through activation of opioid, cholinergic and nitrergic pathways.

Design, Synthesis, and Pharmacological Evaluation of First-in-Class Multitarget N-Acylhydrazone Derivatives as Selective HDAC6/8 and PI3Kα Inhibitors.

Targeting histone deacetylases (HDACs) and phosphatidylinositol 3-kinases (PI3Ks) is a very promising approach for cancer treatment. This manuscript describes the design, synthesis, in vitro pharmacological profile, and molecular modeling of a novel class of N-acylhydrazone (NAH) derivatives that act as HDAC6/8 and PI3Kα dual inhibitors. The surprising selectivity for PI3Kα may be related to differences in the conformation in the active site. Cellular studies showed that these compounds act in HDAC6 inhibition and the PI3/K/AKT/mTOR pathway. The compounds that are selective for inhibition of HDAC6/8 and inhibit PI3Kα show potential for the treatment of cancer.

Chemistry and Pharmacology of the Kazakh Crataegus Almaatensis Pojark: An Asian Herbal Medicine.

Crataegus almaatensis, an endemic ornamental plant in Kazakhstan is used in popular medicine due to its cardiotonic properties. The most studied species of the same genus are commonly found in Europe, which shows the importance of having the Kazakh species validated via its chemical and pharmacological studies. High-speed countercurrent chromatography (HSCCC) operated under optimized conditions enabled an isolation of the three main compounds from the aqueous phase of the leaves ethanol extract, further identified by nuclear magnetic resonance (NMR), as quercetin 3-O-rhamnoside (quercitrin) (4.02% of the crude extract-CECa); quercetin 3-O-ß-galactoside (hyperoside) (1.82% of CECa); kaempferol 3-O-α-L-rhamnoside (afzelin) (0.94% of CECa). The CECa, the aqueous phase of the crude extract (APCa) together with the isolates were evaluated for their vascular (vascular reactivity in human internal mammary artery-HIMA), anti-nociceptive (formalin-induced liking response and hot plate) and anti-inflammatory (subcutaneous air-pouch model-SAP) activities. CECa at the concentrations of 0.014 and 0.14 mg/mL significantly increased the maximum contractility response of HIMA to noradrenaline. The APCa CR curve (0.007-0.7 mg/mL) showed an intrinsic relaxation effect of the HIMA. APCa at the dose of 100 mg/kg i.p. significantly decreased the total leukocyte count and the IL-1ß release in the SAP wash.

Discovery of naphthyl-N-acylhydrazone p38α MAPK inhibitors with in vivo anti-inflammatory and anti-TNF-α activity.

Protein kinases constitute attractive therapeutic targets for development of new prototypes to treat different chronic diseases. Several available drugs, like tinibs, are tyrosine kinase inhibitors; meanwhile, inhibitors of serine/threonine kinases, such as mitogen-activated protein kinase (MAPK), are still trying to overcome some problems in one of the steps of clinical development to become drugs. So, here we reported the synthesis, the in vitro kinase inhibitory profile, docking studies, and the evaluation of anti-inflammatory profile of new naphthyl-N-acylhydrazone derivatives using animal models. Although all tested compounds (3a-d) have been characterized as p38α MAPK inhibitors and have showed in vivo anti-inflammatory action, LASSBio-1824 (3b) presented the best performance as p38α MAPK inhibitor, with IC50  = 4.45 µm, and also demonstrated to be the most promising anti-inflammatory prototype, with good in vivo anti-TNF-α profile after oral administration.

Antinociceptive activity of Cistanche salsa stolons, growing in the Republic of Kazakhstan

Abstract Herba Cistanche (Cistanche species) in Traditional Chinese Medicine is used for the treatment of several diseases and symptoms, to include pain. The objective of this study was to evaluate the antinociceptive effect of the hydroethanol extract of Cistanche salsa (C.A.Mey.) Beck, Orobanchaceae, stolons in animal models of pain. Chemical composition of Herba Cistanche was analyzed by HPLC-UV. Mice Swiss Webster (25-30 g, n = 6) were orally pre-treated with Herba Cistanche (10, 30 or 100 mg/kg) and evaluated in the formalin test and in the capsaicin- or glutamate-induced licking response. Kazakh Herba Cistanche is composed mainly by phenylpropanoid glycosides, from which echinacoside, acteoside and tubuloside B are the main constituents. When Herba Cistanche was administered to mice it had an effect in both phases of the formalin test (77% activity at 30 mg/kg for phase 1 and 62% activity at 100 mg/kg for phase 2) suggesting analgesic and anti-inflammatory properties. Kazakh Herba Cistanche was able to reduce the animals licking time after injection of glutamate (81% reduction at 30 mg/kg) and capsaicin (81% reduction at 100 mg/kg). We conclude that phenolics present in the hydroethanol extract of C. salsa could be responsible for its pharmacological profile. In order to source a good quality raw material for Traditional Chinese Medicine we recommended this Kazakh species to be standardized using echinacoside and acteoside as markers.

Development and evaluation of an inhalation chamber for in vivo tests

ABSTRACT The bioavailability, toxicity, and therapeutic efficacy of a drug is directly related to its administration route. The pulmonary route can be accessed by inhalation after fumigation, vaporization or nebulization. Thus, pharmacological and toxicological evaluation accessed by an apparatus specifically designed and validated for this type of administration is extremely important. Based on pre-existing models, an inhalation chamber was developed. This presents a central structure with five animal holders. The nebulized air passes directly and continuously through these holders and subsequently to an outlet. Evaluation of its operation was performed using clove essential oil, a nebulizer, and a flow meter. The air within the chamber was collected by static headspace and analyzed by gas chromatography with a flame ionization detector. For this purpose, a 2.5 minutes chromatographic method was developed. The air flow in each of the five outputs was 0.92 liters per minute. During the first minute, the chamber became saturated with the nebulized material. Homogeneous and continuous operation of the chamber was observed without accumulation of volatile material inside it for 25 minutes. The inhalation chamber works satisfactorily for in vivo tests with medicines designed to be administrated by inhalation.

Development and evaluation of an inhalation chamber for in vivo tests.

The bioavailability, toxicity, and therapeutic efficacy of a drug is directly related to its administration route. The pulmonary route can be accessed by inhalation after fumigation, vaporization or nebulization. Thus, pharmacological and toxicological evaluation accessed by an apparatus specifically designed and validated for this type of administration is extremely important. Based on pre-existing models, an inhalation chamber was developed. This presents a central structure with five animal holders. The nebulized air passes directly and continuously through these holders and subsequently to an outlet. Evaluation of its operation was performed using clove essential oil, a nebulizer, and a flow meter. The air within the chamber was collected by static headspace and analyzed by gas chromatography with a flame ionization detector. For this purpose, a 2.5 minutes chromatographic method was developed. The air flow in each of the five outputs was 0.92 liters per minute. During the first minute, the chamber became saturated with the nebulized material. Homogeneous and continuous operation of the chamber was observed without accumulation of volatile material inside it for 25 minutes. The inhalation chamber works satisfactorily for in vivo tests with medicines designed to be administrated by inhalation.

Isolation of quinoline alkaloids from three Choisya species by high-speed countercurrent chromatography and the determination of their antioxidant capacity

Abstract Choisya ternata Kunth, C. ternata var. sundance Kunth and the hybrid Choisya 'Aztec-Pearl' are three related species belonging to the Rutaceae family. Ethanol extracts were prepared from the leaves of these three species and evaluated in relation to their antioxidant activity using in vitro and ex vivo models. The ethanol extracts belonging to the three species produced a very high antioxidant profile as evidenced by the DPPH radical scavenging activity, the determination of total phenolics and flavonoid equivalent. The generation of reactive species of oxygen in leukocytes stimulated with LPS was dramatically reduced when the three ethanol extracts were used. The alkaloids anhydroevoxine and choisyine were isolated from the ethanol extract of C. ternata using HEMWat (4:6:5:5) as the solvent system by means of high-speed countercurrent chromatography. This was the first time quinoline alkaloids were isolated from this species using HSCCC. These compounds were also assayed for their capacity to inhibit the generation of ROS in leukocytes stimulated by LPS and the results also suggested that they are reactive oxygenase inhibitors.

Characterization of anti-inflammatory effect and possible mechanism of action of Tibouchina granulosa.

OBJECTIVES: Tibouchina granulosa, popularly known as 'quaresmeira', belong to a genus widely used in the traditional medicine as infusions from their leaves. Other species of Tibouchina are used as antibacterial, antioxidant or antileishmanial. In this work, our objectives were to investigate the biological effects of T. granulosa in models of acute inflammation. METHODS: Chemical analysis showed the presence of proanthocyanidins and flavonoids. Infusions from leaves of T. granulosa (1, 3, 10, 30 or 100 mg/kg) were orally administered to mice, and the anti-inflammatory effects were evaluated by the formalin-induced licking response, inhibition of carrageenan-induced cell migration into subcutaneous air pouch (SAP) and inhibition of inflammatory mediator production in inflammatory exudate collected from SAP. KEY FINDINGS: Our data indicate that tested doses of T. granulosa infusion reduced cell migration, protein extravasated to SAP and cytokine production (i.e. TNF-α and IL-10). All doses also inhibited the first and second phase of formalin-induced licking response. CONCLUSIONS: Taken together, our results indicate that leaves of T. granulosa present anti-inflammatory effect and can be useful in the preparation of new phytomedicines.

Discovery of Novel Orally Active Tetrahydro-Naphthyl-N-Acylhydrazones with In Vivo Anti-TNF-α Effect and Remarkable Anti-Inflammatory Properties.

LASSBio-1524 was designed as inhibitor of the IKK-ß (kappa ß kinase inhibitor) enzyme, which participates in the activation of the nuclear factor κB (NF-κB) canonical pathway, and its three N-acylhydrazone new analogues, LASSBio-1760, LASSBio-1763 and LASSBio-1764 are now being tested on their anti-inflammatory potential. The activity of these compounds was evaluated with the subcutaneous air pouch induced by carrageenan and by subsequent measurement of tumor necrosis factor-α (TNF-α), nitric oxide (NO) and reactive oxygen species (ROS). In the acute inflammation model, the oral pretreatment with doses from 0.3 to 30 mg/kg of N-acylhydrazone derivatives was able to significantly reduce leukocyte migration to the cavity. Pretreatment with LASSBio-1524 and its analogues also decreased NO, TNF-α and ROS biosynthesis an events closely involved with NF-kB pathway. The tetrahydronaphthyl-N-acylhydrazone derivative LASSBio-1764 was the most promising compound from this series, surpassing even LASSBio-1524. Additionally, none of the compounds demonstrated myelotoxicity or cytotoxicity. Cell viability was assayed and these compounds demonstrated to be safe at different concentrations. Western blot analysis demonstrated that LASSBio-1524 and LASSBio-1760 inhibited NF-κB expression in RAW 264.7 cell lineage. Our data indicate that the tested compounds have anti-inflammatory activity, which may be related to inhibition of leukocyte migration, reducing the production of NO, TNF-α and ROS. LASSBio-1524 and LASSBio-1760, in addition to these features, also reduced p65 nuclear expression assessed by western blot in RAW 264.7 murine cells.

LASSBio-1829 Hydrochloride: Development of a New Orally Active N-Acylhydrazone IKK2 Inhibitor with Anti-inflammatory Properties.

Inhibitor of nuclear factor κB kinase 2 (IKK2) is suggested to be a potential target for the development of novel anti-inflammatory and anticancer drugs. In this work, we applied structure-based drug design to improve the potency of the inhibitor (E)-N'-(4-nitrobenzylidene)-2-naphthohydrazide (LASSBio-1524, 1 a: IC50 =20 µm). The molecular model built for IKK2 together with the docking methodology employed were able to provide important and consistent information with respect to the structural and chemical inhibitor characteristics that may confer potency to IKK2 inhibitors, providing important guidelines for the development of a new N-acylhydrazone (NAH) derivative. (E)-N'-(4-(1H-pyrrolo[2,3-b]pyridin-4-yl)benzylidene)-2-naphthohydrazide hydrochloride (LASSBio-1829 hydrochloride, 10) is a 7-azaindole NAH able to inhibit IKK2 with an IC50 value of 3.8 µm. LASSBio-1829 hydrochloride was found to be active in several pharmacological inflammation tests in vivo, showing its potential as an anti-inflammatory prototype.

Anti-inflammatory properties of convolutamydine A and two structural analogues.

AIMS: Convolutamydine A is an oxindole alkaloid that can be isolated from a marine bryozoan. Due to the variety of biological effects, two analogues were synthesized and their anti-inflammatory properties were evaluated. MAIN METHODS: The anti-inflammatory effects of convolutamydine A and its analogues (ISA003 and ISA147) were investigated in a formalin-induced licking behaviour model, where mice received an intraplantar injection of formalin and their licking behaviour was evaluated for 30min. Additionally, inflammatory parameters were evaluated in a subcutaneous air pouch (SAP) model of carrageenan-induced inflammation. Exudates were collected for leukocyte counts; measurement of protein, prostaglandin E2 (PGE2) and cytokines by ELISA; and analysis of nitric oxide (NO) using a nitrate conversion protocol. Cyclooxygenase-2 (COX2) and inducible nitric oxide synthase (iNOS) from RAW 264.7 cells were quantified by immunoblotting. KEY FINDINGS: Convolutamydine A and its two analogues inhibited the formalin-induced licking response at doses as low as 0.01mg/kg. An inhibitory effect was also observed on leukocyte migration and the production of NO, PGE2 and cytokines (IL-6 and TNF-α). The reduction in inflammatory parameters did not appear to be correlated with a direct reduction in the number of cells in the SAP, because a reduction in NO and PGE2 production by cultured macrophages was observed in addition to the inhibition of iNOS and COX2 enzyme expression. SIGNIFICANCE: These results indicate that convolutamydine A and its two analogues have significant anti-inflammatory effects. These substances can be improved to generate lead compounds for the synthesis of new anti-inflammatory drugs.

Ethnopharmacological studies of Lippia origanoides

Lippia origanoides Kunth. Verbenaceae, is of great importance in the Brazilian traditional medicine. Because of it, this work had the purpose to contribute to the ethnopharmacological knowledge of L. origanoides through an ethnobotanical survey conducted within quilombola (maroon) communities of Oriximiná, Pará, Brazil. Among 254 plants cited in the survey, L. origanoides stood out among the ten most versatile species. The agreed main uses were to treat menstrual cramps, stomachache, and baby and postpartum colic. This could indicate a consensus of the informants to possible antispasmodic, anti-inflammatory and analgesic activities of L. origanoides.Therefore, anti-inflammatory and analgesic activities of L. origanoides extract (aerial parts) were assessed through thermal (hot plate) and chemical (formalin and acetic acid) models of nociception. A dose-dependent reduction in acetic acid-induced writhing was observed after treating mice with L. origanoides extract. The same extract also inhibited significantly formalin-induced licking response and proved to have a central antinociceptive effect, in the hot plate test. This work demonstrates that L. origanoides is used specially by quilombola women from Oriximiná for disorders of the genitourinary system and that biological activities of this species could contribute to these uses. Furthermore, it was also observed antispasmodic, analgesic and antimicrobial uses of other species of the genus Lippia (Goniostachyum section), rich in thymol and carvacrol.

Novel potent imidazo[1,2-a]pyridine-N-Glycinyl-hydrazone inhibitors of TNF-α production: in vitro and in vivo studies.

In this work, we describe the design, synthesis and pharmacological evaluation of novel imidazo[1,2-a]pyridine-N-glycinyl-hydrazone derivatives (1a-k) intended for use as inhibitors of tumor necrosis factor alpha (TNF-α) production. The compounds were designed based on the orally active anti-inflammatory prototype LASSBio-1504 (2), which decreases the levels of the pro-inflammatory cytokine TNF-α in vitro and in vivo. The in vitro pharmacological evaluation of the imidazo[1,2-a]pyridine compounds (1) showed that substitution of the N-phenylpyrazole core present in prototype 2 by a bioisosteric imidazo[1,2-a]pyridine scaffold generated anti-TNF-α compounds that were more potent than the previously described N-phenylpyrazole derivative 2 and as potent as SB-203580, a p38 MAPK inhibitor. The most active derivative (E)-2-(2-tert-butylimidazo[1,2-a]pyridin-3-ylamino)-N'-(4-chlorobenzylidene) acetohydrazide, or LASSBio-1749 (1i) was orally active as an anti-inflammatory agent in a subcutaneous air pouch model, reducing expressively the levels in vivo of TNF-α and other pro-inflammatory cytokines at all of the tested doses.

Pharmacological mechanisms involved in the antinociceptive effects of dexmedetomidine in mice.

Dexmedetomidine (DEX) is a α2 -adrenoceptor (α2 -AR) agonist used as an anesthetic adjuvant and as sedative in critical care settings. Typically, α2 -AR agonists release nitric oxide (NO) and subsequently activate NO-GMPc pathway and have been implicated with antinociception. In this study, we investigate the pharmacological mechanisms involved in the antinociceptive effects of DEX, using an acetic acid-induced writhing assay in mice. Saline or DEX (1, 2, 5, or 10 µg/kg) was intravenously injected 5 min before ip administration of acetic acid and the resulting abdominal constrictions were then counted for 10 min. To investigate the possible mechanisms related to antinociceptive effect of DEX (10 µg/kg), the animals were also pretreated with one of the following drugs: 7-nitroindazole (7-NI; 30 mg/kg ip); 1H-[1,2,4] oxadiazole [4,3-a] quinoxaline-1-one (ODQ; 2.5 mg/kg, ip); yohimbine (YOH; 1 mg/kg, ip); atropine (ATRO; 2 mg/kg, ip); glibenclamide (GLIB; 1 mg/kg, i.p.) and naloxone (NAL; 0.2 mg/kg, ip). A rotarod and open-field performance test were performed with DEX at 10 µg/kg dose. DEX demonstrated its potent antinociceptive effect in a dose-dependent manner. The pretreatment with 7-NI, ODQ, GLIB, ATRO, and YOH significantly reduced the antinociceptive affects of DEX. However, NAL showed no effecting DEX-induced antinociception. The rotarod and open-field tests confirmed there is no detectable sedation or even significant motor impairment with DEX at 10 µg/kg dose. Our results suggest that the α2 -AR and NO-GMPc pathways play important roles in the systemic antinociceptive effect of DEX in a murine model of inflammatory pain. Furthermore, the antinociceptive effect exerted by DEX appears to be dependent on KATP channels, independent of opioid receptor activity.

Anti-inflammatory activity of ethanol extract and fractions from Couroupita guianensis Aublet leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Couroupita guianensis Aublet, 'macacarecuia', 'abricó-de-macaco', 'castanha-de-macaco' and 'amêndoa-dos-andes', is found in tropical regions and is widely used in the treatment of tumors, pain, and inflammatory processes. AIM OF THE STUDY: Ethanol extract and hexane and ethyl acetate fractions were evaluated in models of inflammatory pain (formalin-induced licking) and acute inflammation (carrageenan-induced peritonitis). MATERIALS AND METHODS: Ethanol extract, hexane and ethyl acetate fractions (10, 30 or 100 mg/kg, p.o.) and the reference drugs dexamethasone (5 mg/kg), morphine (5 mg/kg, s.c.), and acetylsalicylic acid (100 mg/kg, p.o.) were tested in formalin-induced licking response and carrageenan-induced peritonitis. RESULTS: All three doses from Couroupita guianensis fractions significantly reduced the time that the animal spent licking the formalin-injected paw in first and second phases. However, only higher doses (30 and 100 mg/kg) were able to inhibit the leukocyte migration into the peritoneal cavity after carrageenan injection. In this model, the 100 mg/kg dose almost abolished the cell migration. It was also observed that protein concentration resulted from extravasation to the peritoneum and nitric oxide (NO) productions were significantly reduced. Cytokines production was differently affected by the treatment. TNF-α production was reduced after ethanol extract and ethyl acetate fraction pre-treatment whereas hexane fraction had effect only with 100 mg/kg dose. IL-1ß production was inhibited only after hexane fraction pre-treatment. The inhibitory effect observed was not due to a direct cytotoxic effect on cells nor to a NO-scavenger activity. The effect was due to a direct inhibition on NO production by the cells. CONCLUSIONS: The results show that Couroupita guianensis fractions have anti-inflammatory effect, partly due to a reduction on cell migration and a inhibition on cytokines and inflammatory mediators production.

Convolutamydine A and synthetic analogues have antinociceptive properties in mice.

Convolutamydine A, an oxindole that originated from a marine bryozoan, has several biological effects. In this study, we aimed to investigate the antinociceptive effects of convolutamydine A and two new synthetic analogues. Convolutamydine A and the two analogues were given orally to assess their ability to induce antinociceptive effects. Formalin-induced licking response, acetic acid-induced contortions, and hot plate models were used to characterize the effects of convolutamydine A and its analogues. Convolutamydine A (4,6-bromo-3-(2-oxopropyl)-3-hydroxy-2-oxindole), compound 1 (3-(2-oxopropyl)-3-hydroxy-2-oxindole), and compound 2 (5-bromo-3-(2-oxopropyl)-3-hydroxy-2-oxindole) caused peripheral antinociceptive and anti-inflammatory effects in the acetic acid-induced contortions and the formalin-induced licking models. Supraspinal effects were also observed in the hot plate model and were similar to those obtained with morphine. The peripheral effects were not mediated by the cholinergic or opioid systems. The antinociceptive effects of convolutamydine A seem to be mediated by all three systems (cholinergic, opioid, and nitric oxide systems), and the mechanism of action of compounds 1 and 2 involved cholinergic and nitric oxide-mediated mechanisms. Convolutamydine A and its analogues (compounds 1 and 2) showed good antinociceptive ability after systemic administration in acute pain models. The antinociceptive action mediated by cholinergic, opioid, and nitric oxide systems could explain why convolutamydine A, compound 1, and compound 2 retained their antinociceptive effects. The doses used were similar to the doses of morphine and were much lower than that of acetylsalicylic acid, the classical analgesic and anti-inflammatory drug. In conclusion, convolutamydine A and the two analogues demonstrated antinociceptive effects comparable to morphine's effects.

The antinociceptive properties of the novel compound (±)-trans-4-hydroxy-6-propyl-1-oxocyclohexan-2-one in acute pain in mice.

The compound (±)-trans-4-hydroxy-6-propyl-1-oxocyclohexan-2-one [(±)-δ-lactone] was isolated from the plant Vitex cymosa Bertero, and determined to be the active principle. The present study aimed to evaluate the antinociceptive effect of (±)-δ-lactone and to elucidate its mechanism of action. Mice were subjected to in-vivo models of acute pain (acetic acid-induced abdominal writhing, formalin and hot-plate tests) and the open-field test. (±)-δ-Lactone, administered orally (6-900 µmol/kg), exerted a dose-dependent antinociceptive effect in the acetic acid-induced abdominal writhing, formalin and hot-plate tests. (±)-δ-Lactone administered by the intrathecal (i.t.) and subplantar (s.p.) routes (10-600 nmol) exerted concentration-dependent antinociceptive effects in the formalin test, showing its spinal and peripheral activity, respectively. In the hot-plate test, (±)-δ-lactone was also active when administered i.t., confirming its spinal effect. The previous intraperitoneal (i.p.) application of naloxone, yohimbine, mecamylamine or glibenclamide did not alter the effect produced by the i.t. administration of (±)-δ-lactone, whereas the previous application of atropine and L-arginine significantly reduced its effects in the formalin and hot-plate tests. The previous i.p. application of L-NAME enhanced the antinociceptive effect of the i.t. administration of (±)-δ-lactone in the formalin and hot-plate tests. The previous i.p. application of L-NAME and L-arginine increased and decreased, respectively, the activity of (±)-δ-lactone administered by s.p. administration. These results indicate that (±)-δ-lactone has significant spinal and peripheral antinociceptive activity, and that its effects are at least partially mediated by a reduced nitric oxide production/release, most likely through mechanisms involving the cholinergic system.

Antinociceptive activity of (-)-(2S,6S)-(6-ethyl-tetrahydropyran-2-yl)-formic acid on acute pain in mice.

Pain is a major cause of distress, both physical and psychological. There is a continuous search for new pharmacologically active analgesic agents with minor adverse effects. Recently, the synthesis of (-)-(2S,6S)-(6-ethyl-tetrahydropyran-2-yl)-formic acid [tetrahydropyran derivative (TD)] was described. The objective of this study was to investigate antinociceptive effects of TD. Its activity was compared with the activity of morphine. The effects of TD and morphine were evaluated in models of inflammatory and noninflammatory pain. TD (6-1200 µmol/kg, intraperitoneally) significantly reduced the nociceptive effects induced by acetic acid or formalin in mice. TD also demonstrated an antinociceptive effect in the tail-flick and hot-plate model. The opioid receptor antagonist, naloxone (at 15 µmol/kg, intraperitoneally), reversed the antinociceptive activity of TD in all the models evaluated. Morphine and TD induced tolerance in mice. However, the onset of tolerance to TD was delayed compared with that induced by morphine. These results indicate that TD develops significant antinociceptive activity and, at least part of its effects seems to be mediated by the opioid system.