Analgesic and Anti-Inflammatory Potential of the New Tetrahydropyran Derivative (2s,6s)-6-ethyl-tetrahydro-2h-pyran-2-yl) Methanol.

BACKGROUND: The development of analgesic and anti-inflammatory drugs plays a crucial role in modern medicine, aiming to alleviate pain and reduce inflammation in patients. Opioids and nonsteroidal anti-inflammatory drugs are groups of drugs conventionally used to treat pain and inflammation, but a wide range of adverse effects and ineffectiveness in some pathological conditions leads us to search for new drugs with analgesic and anti-inflammatory properties. OBJECTIVE: In this regard, the authors intend to investigate the ((2s,6s)-6-ethyl-tetrahydro-2h-pyran- 2-yl) methanol compound (LS20) on pain and acute inflammation. METHODS: Male Swiss mice were evaluated using acetic acid-induced abdominal writhing, formalin, and tail-flick as models of nociceptive evaluation and edema paw, air pouch and cell culture as models of inflammatory evaluation besides the rotarod test for assessment of motor impairment. RESULTS: The compound showed an effect on the acetic acid-induced abdominal writhing, formalin and tail-flick tests. Studying the mechanism of action, reversion of the antinociceptive effect of the compound was observed from previous intraperitoneal administration of selective and non-selective opioid antagonists on the tail flick test. In addition, the compound induced an antiedematogenic effect and reduced leukocyte migration and the production of pro-inflammatory cytokines in the air pouch model. LS20 was able to maintain cell viability, in addition to reducing cell production of TNF-α and IL-6. CONCLUSION: In summary, the LS20 compound presented an antinociceptive effect, demonstrating the participation of the opioid system and an anti-inflammatory effect related to the inhibition of proinflammatory cytokine production. The compound also demonstrated safety at the cellular level.

Perinatal N(G)-Nitro-L-arginine methyl ester administration decreases anxiety- and depression-like behaviors in adult mice.

OBJECTIVE: We hypothesized that perinatal manipulations of the nitrergic system would affect adult animal behaviors. METHODS: We tested this hypothesis by perinatally administering N(G)-Nitro-L-arginine methyl ester (L-NAME), a non-specific antagonist of nitric oxide synthase for 15 days and assessed anxiety- and depression-like behaviors in adult mice. At 70 days of age, the mice were subjected to a battery of tests consisting of the open-field, light/dark box, forced swim, and tail-flick tests. The tests were performed at two-day intervals, and the order of the tests within the battery was determined according to the progressive invasiveness degree. RESULTS: L-NAME-treated animals exhibited decreased anxiety-like behavior in the light/dark box and open field tests, with no change in locomotor activity. Additionally, they demonstrated decreased depression-like behavior in the forced swim test and no change in pain perception in the tail-flick test. CONCLUSION: The nitrergic system is possibly involved in neural circuitry development that regulates behaviors since blocking perinatal nitric oxide production decreases anxiety- and depression-like behaviors in adult mice.

Perinatal N(G)-Nitro-L-arginine methyl ester administration decreases anxiety- and depression-like behaviors in adult mice

ABSTRACT Objective: We hypothesized that perinatal manipulations of the nitrergic system would affect adult animal behaviors. Methods: We tested this hypothesis by perinatally administering N(G)-Nitro-L-arginine methyl ester (L-NAME), a non-specific antagonist of nitric oxide synthase for 15 days and assessed anxiety- and depression-like behaviors in adult mice. At 70 days of age, the mice were subjected to a battery of tests consisting of the open-field, light/dark box, forced swim, and tail-flick tests. The tests were performed at two-day intervals, and the order of the tests within the battery was determined according to the progressive invasiveness degree. Results: L-NAME-treated animals exhibited decreased anxiety-like behavior in the light/dark box and open field tests, with no change in locomotor activity. Additionally, they demonstrated decreased depression-like behavior in the forced swim test and no change in pain perception in the tail-flick test. Conclusion: The nitrergic system is possibly involved in neural circuitry development that regulates behaviors since blocking perinatal nitric oxide production decreases anxiety- and depression-like behaviors in adult mice.

Neonatal D-fenfluramine treatment promotes long-term behavioral changes in adult mice.

Serotonin exerts a significant role in the mammalian central nervous system embryogenesis and brain ontogeny. Therefore, we investigate the effect of neonatal treatment of d-fenfluramine (d-FEN), a serotonin (5-HT) releaser, on the behavioral expression of adult male Swiss mice. For this purpose, we divided pregnant female Swiss mice into two groups (n = 6 each and ~35 g). Their offspring were treated with d-FEN (3 mg/kg, s.c.) from postnatal days (PND) 5 to 20. At PND 21, one male puppy of each litter was euthanized; the midbrain and the hippocampus were dissected for RNA analysis. At PND 70, the male offspring underwent a behavioral assessment in the open field, elevated plus-maze, light-dark box, tail suspension, and rotarod test. The programmed animals had a decrease in 5HT1a, serotonin transporter (SERT), and brain-derived neurotrophic factor (BDNF) expression in the mesencephalic raphe region. Alternatively, there was a reduction only in the tryptophan hydroxylase (TPH2) and BDNF expression in the hippocampus. In the light-dark box test, offspring of the treated group had higher latency to light and less time on the light side than the control. Also, it was observed less time of immobility in the tail suspension test. We also observed low motor skill learning in the rotarod test. These findings suggest that programming with d-FEN during the neonatal period alters a mesencephalic and hippocampal serotonergic system, promoting anxiety, antidepressant behavior, low coordination, and motor learning in adults.

Evaluation of the systemic and spinal antinociceptive effect of a new hybrid NSAID tetrahydropyran derivative.

Pain is responsible for inducing physical and mental stress, interfering negatively in patients' quality of life. Classic analgesic drugs, such as opioids and non-steroidal anti-inflammatory drugs, are known for their wide range of adverse effects, making it important to develop new drugs. Thus, this study aimed to analyse the action of the hybrid compound cis- (±) -acetate of 4-chloro-6- (naphthalene-1-yl) -tetrahydro-2h-pyran -2-yl) methyl2- (2- [2,6-dichlorophenylamine] phenyl (LS19) under acute nociceptive conditions, and deepened the understanding of the responsible mechanisms. Male Swiss mice were evaluated in the acetic acid-induced abdominal writhing, formalin, tail flick, capsaicin- and glutamate-induced nociception, thermal stimulation in animals injected with capsaicin and rotarod tests besides the acute and subchronic toxicological evaluation. The compound showed effect on the acetic acid-induced abdominal writhing, formalin (both phases), tail flick, thermal stimulation in animals injected with capsaicin and capsaicin-induced nociception tests. In the study of the mechanism of action was observed reversion of the antihyperalgesic effect of the compound from the previous intraperitoneal and intrathecal administration of naloxone, nor-binaltorphimine, naltrindole, methylnaltrexone, 7-nitroindazole, L-NAME, ODQ, glibenclamide on the tail flick test. In the thermal stimulation in animals injected with capsaicin, the compound showed antinociceptive effect by oral and intraplantar routes, besides to reducing the levels of TNF-α, IL-1ß and PGE2 in the paws previously administered with capsaicin. There were no signs of acute and subchronic intoxication with the compound. In summary, the compound LS19 presented spinal and local antihyperalgesic effect, demonstrating participation of the opioid/NO/cGMP/K+ ATP pathway and TRPV1 receptors and it demonstrated safety in its use in mice.

Topical and systemic use of Joannesia princeps vell. LC seed oil in acute pain and inflammation induced by different agents.

ETHNOPHARMACOLOGICAL RELEVANCE: Joannesia princeps (SOJP) has been used in folk medicine as anthelmintic treatment and cutaneous wound healing. AIM OF THE STUDY: The purpose of this study is to evaluate the pharmacological activity of seed oil of Joannesia princeps, administered systemically and topically, on acute pain and inflammation. MATERIALS AND METHODS: Male swiss mice were treated orally and topically with seed oil of Joannesia princeps in models of acute pain (acetic acid-induced abdominal writhing, formalin-induced licking behaviour and tail flick tests) and acute inflammation (carrageenan- and histamine-induced paw oedema; arachidonic acid-, capsaicin- and croton oil-induced ear oedema and air pouch tests), besides the open field model in the motor performance evaluation. RESULTS: Seed oil of Joannesia princeps showed systemic action against acute pain in abdominal writhing test (37% and 56% inhibition in the number of writhes at doses of 30 and 100 mg/kg, respectively) and in the second phase of formalin-induced licking behaviour test (29%, 47 and 52% inhibition in the licking time at doses of 10, 30 and 100 mg/kg, respectively), as well as reducing croton oil-induced ear oedema by 72%, leukocyte recruitment and production of TNF-α and IL-6 in the air pouch tests. In addition, topical administration of SOJP inhibited carrageenan-induced paw oedema by 39% at dose of 500 µg/paw and inhibited histamine-induced oedema by 43 and 52% at doses of 300 and 500 µg/paw, respectively. SOJP also decreased croton oil-induced ear oedema by 67% at dose of 500 µg/paw and arachidonic acid-induced ear oedema by 63% at dose of 500 µg/paw, reducing the production of TNF-α, IL-1ß and MIP2 in both. In addition, no adverse effects were observed at doses up to 2000 mg/kg. CONCLUSIONS: Seed oil of Joannesia princeps presents antinociceptive and anti-inflammatory actions through its topical and systemic administration, promoted by inhibition of leukocyte recruitment and cytokine production (TNF-α, IL-1ß, IL-6 and MIP-2).

Perinatal fluoxetine treatment promotes long-term behavioral changes in adult mice.

Serotonin exerts a significant role in the mammalian central nervous system embryogenesis and brain ontogeny. Therefore, we investigate the effect of perinatal fluoxetine (FLX), a selective serotonin reuptake inhibitor, administration on the behavioral expression of adult male Swiss mice. For this purpose, two groups (n = 6 each, and ~ 35 g) of pregnant female Swiss mice were mated. Their offspring were treated with FLX (10 mg/Kg, s.c.) from postnatal day (PND) 5 to 15. At PND 16, one male puppy of each litter was euthanized, and the hippocampus was dissected for RNA analysis. At 70 days of life, the male offspring underwent a behavioral assessment in the open field, object recognition task, light-dark box, tail suspension and rotarod test. According to our results, the programmed animals had a decrease in TPH2, 5HT1a, SERT, BDNF, and LMX1B expression. Also, it was observed less time of immobility in tail suspension test and higher grooming time in the open field test. In the light-dark box test, the FLX-treated offspring had less time in the light side than control. We also observed a low cognitive performance in the object recognition task and poor motor skill learning in the rotarod test. These findings suggest that programming with FLX during the neonatal period alters a hippocampal serotonergic system, promoting anxiety and antidepressant behavior in adults, as well as a low mnemonic capacity.

Pharmacological evaluation underlying the antinociceptive activity of two new hybrids NSAIDs tetrahydropyran derivatives.

The development of analgesic drugs is still a necessity due to the inefficiency of the current treatments for some pathological conditions and also due to the adverse effects produced by these drugs. The aim of this study was to deepen the pharmacological study of two new hybrids NSAIDs tetrahydropyran derivatives, regarding their antinociceptive effects on acute pain in mice. Male swiss mice were evaluated in the acetic acid-induced abdominal writhing, formalin, tail-flick, open-field, glutamate- and capsaicin-induced paw licking tests, and in vitro Cox inhibition assay, besides the acute toxicological evaluation. The compounds had an effect on the acetic acid-induced abdominal writhing, formalin (both phases), and tail-flick tests. In the study of the mechanism of action was observed reversion of the antinociceptive effect of the compounds from the previous administration of naloxone, L-NAME (L-nitro-arginine methyl ester), ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), glibenclamide, and nor-binaltorphimine, by the intrathecal and intraperitoneal routes. The prior administration of MK-801 suggests that the modulation of NMDA receptor contributes to the antinociceptive effect of compounds. In summary, hybrid compounds presented central antinociceptive effect, demonstrating participation of the NO-cGMP-K+ ATP pathway, κ-opioid, and NMDA receptors. In addition, the compounds showed inhibition of cyclo-oxygenase enzymes and adverse effects were not observed with dose 300 times greater than the dose used experimentally.

Prenatal thyroxine treatment promotes anxiolysis in male Swiss mice offspring.

The proper functioning of the maternal thyroid plays a crucial role in fetal development. Thus, the aim of our study was to verify how maternal hyperthyroidism is able to change behavioral parameters in mice offspring during adulthood. For this purpose, pregnant Swiss mice (n = 24 and ~35 g) were randomly assigned into two groups: a control and a thyroxine (T4)-treatment group. The control was treated with 0.9% saline, while the treatment group received T4 (200 µg/kg, s.c.) once daily during the entire pregnancy period. After completing 70 days of life, a part of male offspring underwent a battery of tests, including open field, dark-light box, elevated plus maze, marble burying, rotarod and tail suspension tests. The other male pups were euthanized, being hippocampus and serum collected for RNA analysis and hormones measurement, respectively. Statistical analysis was performed using Student's t-test, and the means were considered significantly different when p < 0.05. In adult offspring, a significant decrease was observed for serum T3 in treated group. It was demonstrated that the T4 group had an increase in total distance traveled in an open field test. In the elevated plus maze test, we observed a higher time in opened arms as well as an increased in percentage of entries in these arms. In the hippocampus, T4 offspring had a higher expression of tryptophan hydroxylase 2 (TPH2), serotonin transporter (SERT) and glutamate decarboxylase 67 (GAD 67) in comparison to controls. These findings suggest that prenatal T4 treatment alters hippocampal serotonergic and GABAergic systems, promoting anxiolysis in male adult offspring.

Evaluation of the antinociceptive and anti-inflammatory activities of piperic acid: Involvement of the cholinergic and vanilloid systems.

Piperin is the active compound of black pepper (Piper nigrum). From the piperine was obtained the molecule of the piperic acid (PAC). The objective of this study was to evaluate the antinociceptive and anti-inflammatory of the compound. The antinociceptive effects of PAC were evaluated by abdominal writhing, formalin, capsaicin and tail-flick tests; while the anti-inflammatory effects were evaluated by paw oedema and air pouch tests, and in vitro COX inhibition assay. The possible action mechanism of PAC was evaluated using naloxone, L-NAME, glibenclamide and atropine in tail flick test and by Cholinesterase activity assay and production of TNF-α and IL-1ß. PAC significantly reduced the nociceptive effects induced by acetic acid or formalin in mice. PAC also demonstrated an antinociceptive effect in the tail-flick model. The muscarinic receptor antagonist, atropine reduced the antinociceptive effect of PAC in the tail-flick model. PAC was able to inhibit capsaicin-induced nociception, showing involvement of TRPV1. The compound did not alter the motor capacity of the animals, not interfering in the nociceptive response. PAC also showed anti- inflammatory activity by inhibiting the formation of carrageenan-induced paw oedema, leukocyte migration, and cytokine production / release. Atropine reduced the activity of PAC on leukocyte migration, and cytokine production. The compound showed to be able to reduce the cytokine production stimulated by capsaicin. PAC inhibited the COX activity. The results presented suggest that the possible cholinomimetic action and vanilloid agonist of the piperic acid may be responsible by antinociceptive and anti- inflammatory effects; these effects are devoid of toxicity.

Antinociceptive and anti-inflammatory activities of leaf extracts from Annona tomentosa R.E.Fr.

OBJECTIVE: Annona tomentosa R.E.Fr is a species not endemic to Brazil that belongs to the phytogeographic areas of the Amazon, Cerrado and Pantanal. Popularly known as "araticum rasteiro" or "araticum de moita", A. tomentosa is edible and tea made from the leaves has been used as an anti-inflammatory by native communities. There is no scientific evidence for these uses of A. tomentosa, especially those related to the control of pain and inflammation. For this reason, in the present study we evaluated the antinociceptive and anti-inflammatory activities of partitions from the methanolic extract of A. tomentosa leaves (A. tomentosa leaf methanolic extract (ATFM) in hexane partition: ATFM-H; ATFM in dichloromethane partition: ATFM-D; ATFM in ethyl acetate partition: ATFM-Ac; ATFM in butanol partition: ATFM-B) in mice. METHODS: The antinociceptive effects of leaf extracts from A. tomentosa were evaluated by abdominal writhing and tail-flick tests, while the anti-inflammatory effects were evaluated by paw oedema and air-pouch tests. The locomotor activity was evaluated with the open-field test. Furthermore, we evaluated the possible action mechanism of A. tomentosa, using naloxone, nitro-L-arginine methyl ester, glibenclamide, atropine, naltrindole and norbinaltorphimine in tail-flick tests. The productions of tumor necrosis factor α (TNF-α) and interleukin (IL)-1ß were also evaluated. RESULTS: The chromatographic fractionation of the partitions of the methanolic extract from the leaves of A. tomentosa revealed the presence of diterpenes, flavonoids, and steroids compounds. From the analysis of the hexane partition kaurenoic acid was identified as the major component. ATFM-H and ATFM-D had a significant antinociceptive effect in acute pain models in mice. The ATFM-H showed central antinociceptive effect from the involvement of the δ opioid receptors, without causing alterations in the locomotor activity of the mice, while ATFM-D was effective in decreasing paw oedema and TNF-α and IL-1ß production. CONCLUSION: These results demonstrate that leaf extracts from A. tomentosa present antinociceptive and anti-inflammatory effects that can to be used in relieving algesic and inflammatory conditions.

Synthesis of 16 New Hybrids from Tetrahydropyrans Derivatives and Morita-Baylis-Hillman Adducts: In Vitro Screening against Leishmania donovani.

Leishmaniases are a group of neglected tropical diseases (NTDs) caused by protozoan parasites from >20 Leishmania species. Visceral leishmaniasis (VL), also known as kala-aza, is the most severe form of leishmaniasis, usually fatal in the absence of treatment in 95% of cases. The Morita-Baylis-Hillman adducts (MBHAs) are being explored as drug candidates against several diseases, one of them being leishmaniasis. We present here the design, synthesis and in vitro screening against Leishmania donovani of sixteen new molecular hybrids from analgesic/antiinflammatory tetrahydropyrans derivatives and Morita-Baylis-Hillman adducts. First, acrylates were synthesized from analgesic/anti-inflammatory tetrahydropyrans using acrylic acid under TsOH as a catalyst (70-75% yields). After the 16 new MBHAs were prepared in moderate to good yields (60-95%) promoted by microwave irradiation or low temperature (0 °C) in protic and aprotic medium. The hybrids were evaluated in vitro on the promastigote stage of Leishmania donovani by determining their inhibitory concentrations 50% (IC50), 50% hemolysis concentration (HC50), selectivity index (HC50/IC50,), and comparing to Amphotericin B, chosen as the anti-leishmanial reference drug. The hybrid which presents the bromine atom in its chemical structure presents high leishmanicide activity and the high selectivity index in red blood cells (SIrb > 180.19), compared with the highly-toxic reference drug (SIrb = 33.05), indicating that the bromine hybrid is a promising compound for further biological studies.

Behavioral profile assessment in offspring of Swiss mice treated during pregnancy and lactation with caffeine.

The association between caffeine consumption and various psychiatric manifestations has long been observed. The objective was to assess the behavioral profile in offspring of Swiss mice treated during pregnancy and lactation with caffeine. For this purpose, two groups (n = 6 each and BW ~ 35 g) of female mice were treated during pregnancy and lactation by: tap water and caffeine solution at a concentration of 0.3 mg/mL through oral route. The offspring obtained, by completing 70 days of life, was underwent a behavioral battery test. Statistical analysis was performed by student t test and the different significance adopted was p < 0.05. According to our results, it was not found any significant differences in tail suspension and forced swimming tests. In anxiety related responses however, the mice of caffeine group had greater number of fecal pellets (178 %, p = 0.001) in the open field test, higher number of attempts (51 %, p = 0.03) in light-dark box and decreased percentage of entries in open arms (41 %, p = 0.01) in elevated plus maze test. Moreover, in the marble burying test, there was a significant decrease in the number of buried marbles compared with controls (110 %, p = 0,002). In the meantime, in the von Frey test, it was observed an exacerbation of mechanical allodynia both in basal conditions and after the carrageenan administration (p < 0.001). Furthermore, caffeine treatment during pregnancy and lactation causes long-term behavioral changes in the mice offspring that manifest later in life.

Antinociceptive and Anti-inflammatory Activities of the Methanolic Extract from the Stem Bark of Lophanthera lactescens.

Lophanthera lactescens is a medicinal plant commonly used in traditional medicine to relieve fever and pain in inflammatory processes. In the present study, the in vivo antinociceptive and anti-inflammatory effects of the methanolic extract from L. lactescens have been investigated. Antinociceptive activity was evaluated through writhing, formalin, and tail flick tests, while the anti-inflammatory activity was evaluated through paw oedema and air pouch tests in mice. A phytochemical analysis was performed. The extract produced significant inhibition on nociception induced by acetic acid-induced abdominal writhing, formalin, and tail flick tests, and on inflammation induced by oedema and air pouch tests. The previous administration of atropine and glibenclamide reduced the antinociceptive effect produced by the methanolic extract from L. lactescens on the tail flick test in 89% and 66%, respectively. The methanolic extract had no significant effect in the open field test. No intoxication symptoms were observed in the animals administered orally at increasing doses up to 2000 mg/kg. The methanolic extract from the stem bark of L. lactescens possesses antinociceptive properties on models of acute pain induced by chemical and thermal stimuli as well as in models of inflammation and further suggests that this anti-inflammatory activity might involve inhibition of the proinflammatory cytokines, and the antinociceptive activity might involve participation of the cholinergic system and adenosine triphosphate-dependent K+ channel.

Essential oil from Myrcia ovata: chemical composition, antinociceptive and anti-inflammatory properties in mice.

The leaves of Myrcia ovata, popularly known as "laranjinha do mato", are frequently used as an infusion in folk medicine. The essential oil obtained from these leaves is rich in citral, a mixture of neral and geranial isomers, known for its analgesic effect. Male Swiss mice (20-22 g) were tested in models of acute pain (acetic acid-induced abdominal writhing, tail flick, and formalin tests) and acute inflammation (paw oedema and air pouch tests) as well as in a model for evaluation of spontaneous motor performance (open-field test). The essential oil from M. ovata was administered orally at doses of 50-300 mg/kg. In addition, water, vehicle, morphine (5.01 mg/kg for evaluation of pain and motor performance), acetyl salicylic acid (200 mg/kg in the formalin test), and dexamethasone (2.25 mg/kg for evaluation of oedema formation, leukocyte extravasation, and quantification of cytokines) were administered. The essential oil showed a significant effect at doses of 200 and 300 mg/kg in the acute pain and acute inflammation tests. The effect of the essential oil was reduced by pretreatment with naloxone. The essential oil did not induce motor impairment. The extract was not toxic after oral administration (LD50 > 3000 mg/kg). These data provide initial evidence that the traditional use of M. ovata can be effective in reducing pain and inflammation.

Anti-nociceptive and anti-oedematogenic properties of the hydroethanolic extract of Sidastrum micranthum leaves in mice

Sidastrum micranthum (A. St.-Hil.) Fryxell, Malvaceae, grows in the northeastern region of Brazil, where the leaves of this species are traditionally used to treat coughs, bronchitis or asthma. Male Swiss mice (20-22 g) were tested in models of acute pain (acetic acid-induced abdominal writhing, tail flick and formalin test), oedema assessment test (paw oedema test) and model for evaluation of spontaneous motor performance (open field test). The hydroethanolic extract of S. micranthum was administered orally at doses of 50-500 mg/kg. In addition were administered water, vehicle, morphine 5.01 mg/kg (evaluation of pain and motor performance) and dexamethasone 2.25 mg/kg (evaluation of oedema formation). The extract showed a significant effect at all doses in the acetic acid-induced abdominal writhing test and at the second phase of the formalin test, while in the first phase of this test and in the paw oedema test only at the highest dose (500 mg/kg). In the formalin and paw oedema tests, the extract had a potentiation of the anti-nociceptive and anti-inflammatory effects by pretreatment with L-NAME and reduction of the effect by pretreatment with L-arginine. The extract was not toxic after oral administration (LD50 > 2000 mg/kg).

Phytochemical profile and analgesic evaluation of Vitex cymosa leaf extracts

Vitex cymosa Bertero ex Spreng., Lamiaceae, is found in Central and Amazon regions of Brazil, where it is popularly used as antirheumatic. Extracts from the leaves of V. cymosa were tested in analgesia models such as abdominal contortions induced by acetic acid and formalin to test peripheral analgesia; as well as the tail flick and hot plate models, to test spinal and supraspinal analgesia. A significant reduction was observed in the number of contortions with all extracts and in all doses. In the formalin model, a reduction in the second phase (inflammatory) was observed with all extracts, whereas only the n-butanol extract was able to act in the first, neurogenic, phase. In the tail flick model, all extracts increased latency time. Naloxone treatment reverted analgesic effect of all extracts with the exception of the dichloromethane one. All extracts developed peripheral and central analgesic activity. In the hot plate model no antinociceptive effect was observed for all tested extracts. All these results taken together suggest that V. cymosa leaf extracts were able to promote peripheral and central antinociceptive activity mediated by the opioid system.Twenty three substances were isolated and identified in the extracts and include flavonoids (C-glucosyl flavones, flavones and flavonols), triterpene acids from ursane and oleanane types, iridoids (free and glucosides), as well as simple phenols.

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.

Structural determination Vitex cymosa Bertero active principle: Diastereoselective synthesis of (+/-)-trans-4-hydroxy-6-propyl-1-oxocyclohexan-2-one and its antinociceptive activity.

The diastereoselective synthesis of (+/-)-trans-4-hydroxy-6-propyl-1-oxocyclohexan-2-one, as a mixture trans:cis (3:1), was accomplished using a protocol that combine the Prins cyclization and RuO(4) oxidation. The synthesis this lactone allowed the elucidation of the correct structure of the substance isolated from the barks of Vitex cymosa. The delta-lactones mixture showed significant antinociceptive properties in preliminary tests using the tail flick model assay.