Impairment of locomotor activity induced by the novel N-acylhydrazone derivatives LASSBio-785 and LASSBio-786 in mice.

The N-acylhydrazone (NAH) analogues N-methyl 2-thienylidene 3,4-benzoylhydrazine (LASSBio-785) and N-benzyl 2-thienylidene 3,4-benzoylhydrazine (LASSBio-786) were prepared from 2-thienylidene 3,4-methylenedioxybenzoylhydrazine (LASSBio-294). The ability of LASSBio-785 and LASSBio-786 to decrease central nervous system activity was investigated in male Swiss mice. LASSBio-785 or LASSBio-786 (30 mg/kg, ip) reduced locomotor activity from 209 ± 26 (control) to 140 ± 18 (P < 0.05) or 146 ± 15 crossings/min (P < 0.05), respectively. LASSBio-785 (15 or 30 mg/kg, iv) also reduced locomotor activity from 200 ± 15 to 116 ± 29 (P < 0.05) or 60 ± 16 crossings/min (P < 0.01), respectively. Likewise, LASSBio-786 (15 or 30 mg/kg, iv) reduced locomotor activity from 200 ± 15 to 127 ± 10 (P < 0.01) or 96 ± 14 crossings/min (P < 0.01), respectively. Pretreatment with flumazenil (20 mg/kg, ip) prevented the locomotor impairment induced by NAH analogues (15 mg/kg, iv), providing evidence that the benzodiazepine (BDZ) receptor is involved. This finding was supported by the structural similarity of NAH analogues to midazolam. However, LASSBio-785 showed weak binding to the BDZ receptor. LASSBio-785 or LASSBio-786 (30 mg/kg, ip, n = 10) increased pentobarbital-induced sleeping time from 42 ± 5 (DMSO) to 66 ± 6 (P < 0.05) or 75 ± 4 min (P < 0.05), respectively. The dose required to achieve 50% hypnosis (HD50) following iv injection of LASSBio-785 or LASSBio-786 was 15.8 or 9.5 mg/kg, respectively. These data suggest that both NAH analogues might be useful for the development of new neuroactive drugs for the treatment of insomnia or for use in conjunction with general anesthesia.

Impairment of locomotor activity induced by the novel N-acylhydrazone derivatives LASSBio-785 and LASSBio-786 in mice

The N-acylhydrazone (NAH) analogues N-methyl 2-thienylidene 3,4-benzoylhydrazine (LASSBio-785) and N-benzyl 2-thienylidene 3,4-benzoylhydrazine (LASSBio-786) were prepared from 2-thienylidene 3,4-methylenedioxybenzoylhydrazine (LASSBio-294). The ability of LASSBio-785 and LASSBio-786 to decrease central nervous system activity was investigated in male Swiss mice. LASSBio-785 or LASSBio-786 (30 mg/kg, ip) reduced locomotor activity from 209 ± 26 (control) to 140 ± 18 (P < 0.05) or 146 ± 15 crossings/min (P < 0.05), respectively. LASSBio-785 (15 or 30 mg/kg, iv) also reduced locomotor activity from 200 ± 15 to 116 ± 29 (P < 0.05) or 60 ± 16 crossings/min (P < 0.01), respectively. Likewise, LASSBio-786 (15 or 30 mg/kg, iv) reduced locomotor activity from 200 ± 15 to 127 ± 10 (P < 0.01) or 96 ± 14 crossings/min (P < 0.01), respectively. Pretreatment with flumazenil (20 mg/kg, ip) prevented the locomotor impairment induced by NAH analogues (15 mg/kg, iv), providing evidence that the benzodiazepine (BDZ) receptor is involved. This finding was supported by the structural similarity of NAH analogues to midazolam. However, LASSBio-785 showed weak binding to the BDZ receptor. LASSBio-785 or LASSBio-786 (30 mg/kg, ip, n = 10) increased pentobarbital-induced sleeping time from 42 ± 5 (DMSO) to 66 ± 6 (P < 0.05) or 75 ± 4 min (P < 0.05), respectively. The dose required to achieve 50% hypnosis (HD50) following iv injection of LASSBio-785 or LASSBio-786 was 15.8 or 9.5 mg/kg, respectively. These data suggest that both NAH analogues might be useful for the development of new neuroactive drugs for the treatment of insomnia or for use in conjunction with general anesthesia.

Matrizes hidrofílicas de quitosana/captopril: Desenvolvimento e Caracterização físico-química / Hydrophilic Matrices of Chitosan/Captopril: Development and physicochemical Characterization

Neste trabalho, avaliou-se a utilização da quitosana como matriz hidrofílica no desenvolvimento de comprimidos de liberação prolongada de captopril. Os comprimidos foram obtidos por compressão direta utilizando-a em diferentes proporções (10, 15, 20 e 25%). As formulações contendo quitosana foram comparadas com uma formulação de liberação imediata contendo croscarmelose. Os resultados obtidos nos ensaios de peso médio, friabilidade, dureza, uniformidade de conteúdo e doseamento indicaram que todos os comprimidos apresentavam características de qualidade condizentes com os limites especificados na Farmacopeia Brasileira. Os ensaios de dissolução evidenciaram um aumento do tempo de liberação do captopril com o aumento da proporção de quitosana na matriz, indicando que essas formulações apresentaram perfis de liberação prolongada do fármaco, especialmente a formulação contendo 25% de quitosana. Os valores dos coeficientes de correlação indicaram que os modelos cinéticos que melhor se ajustam ao perfil de dissolução das formulações avaliadas foram o modelo proposto por Higuchi (pH 1,2) e o de primeira ordem (pH 6,8).

In this study, chitosan was used as a hydrophilic matrix in the development of prolonged-release tablets of captopril. The tablets were obtained by direct compression, with the chitosan in various proportions (10, 15, 20 and 25%). The formulations were compared with an immediate-release formulation containing croscarmellose. In assessments of weight variation, friability, hardness, content uniformity and drug assay, all the tablets complied with the standards of quality set by the Brazilian Pharmacopoeia. Dissolution tests showed that the release time of captopril increased with the content of chitosan in the matrix, indicating that these formulations showed prolonged-release profiles of the drug, especially the one containing 25% chitosan. The kinetic models that fitted the dissolution profiles of the formulations best (with the highest correlation coefficients) were the Higuchi (at pH 1.2) and first-order (at pH 6.8) models.

LASSBio-881: an N-acylhydrazone transient receptor potential vanilloid subfamily type 1 antagonist orally effective against the hypernociception induced by capsaicin or partial sciatic ligation.

BACKGROUND AND PURPOSE: Compound LASSBio-881 is an orally effective antinociceptive that binds to cannabinoid receptors and is active mainly on the neurogenic component of pain models. We investigated whether transient receptor potential vanilloid subfamily type 1 (TRPV1) channels are involved in the effects of LASSBio-881. EXPERIMENTAL APPROACH: Modulation of capsaicin (CAP)- and low pH-induced currents was evaluated in TRPV1-expressing Xenopus oocytes. In vivo effects were evaluated in CAP-induced acute and inflammatory changes in nociception, as well as in partial sciatic ligation-induced thermal hypernociception. KEY RESULTS: LASSBio-881 inhibited TRPV1 currents elicited by CAP with an IC(50) of 14 microM, and inhibited proton-gated currents by 70% at 20 microM. Functional interaction with CAP was surmountable. Locally applied LASSBio-881 decreased time spent in CAP-elicited nocifensive behaviour by 30%, and given orally it reduced measures of CAP- or carrageenan-evoked thermal hypernociception by 60 and 40% respectively. In addition, LASSBio-881 decreased the paw withdrawal responses to thermal stimuli of animals with sciatic neuropathy 7-11 days after nerve ligation, at a dose of 300 micromol*kg(-1)*day(-1) p.o. At this dose, hyperthermia was not observed within 4 h following oral administration. CONCLUSIONS AND IMPLICATIONS: LASSBio-881 is a TRPV1 antagonist that apparently competes with CAP. Accordingly, LASSBio- 881 inhibited nociception in models of acute, inflammatory and neuropathic pain presumed to involve TRPV1 signalling. These in vivo actions were not hindered by hyperthermia, a common side effect of other TRPV1 antagonists. We propose that the antinociceptive properties of LASSBio-881 are due to TRPV1 antagonism, although other molecular interactions may contribute to the effects of this multi-target drug candidate.

In vitro and in vivo activities of 1,3,4-thiadiazole-2-arylhydrazone derivatives of megazol against Trypanosoma cruzi.

From a series of 1,3,4-thiadiazole-2-arylhydrazone derivatives of megazol screened in vitro against Trypanosoma cruzi, eight (S1 to S8) were selected for in vivo screening by single-dose oral administration (200 mg/kg of body weight) to infected mice at 5 days postinfection (dpi). Based on significant decreases in both parasitemia levels and mortality rates, S2 and S3 were selected for further assays. Despite having no in vivo effect, S1 was included since it was 2-fold more potent against trypomastigotes than megazol in vitro. Trypomastigotes treated with S1, S2, or S3 showed alterations of the flagellar structure and of the nuclear envelope. When assayed on intracellular amastigotes, the selectivity index (SI) for macrophages was in the range of >27 to >63 and for cardiac cells was >32 for S1 and >48 for megazol. In noninfected mice, S1 did not alter the levels of glutamic oxalacetic transaminase (GOT), glutamate pyruvate transaminase (GPT), or urea. S2 led to an increase in GOT, S3 to increases in GOT and GPT, and megazol to an increase in GOT. Infected mice were treated with each derivative at 50 and 100 mg/kg from dpi 6 to 15: S1 did not interfere with the course of infection or reduce the number of inflammatory foci in the cardiac tissue, S2 led to a significant decrease of parasitemia, and S3 decreased mortality. There was no direct correlation between the in vitro effect on trypomastigotes and amastigotes and the results of the treatment in experimental models, as S1 showed a high potency in vitro while, in two different schemes of in vivo treatment, no decrease of parasitemia or mortality was observed.

Analysis of 724 cases of primary head and neck squamous cell carcinoma (HNSCC) with a focus on young patients and p53 immunolocalization.

This study evaluated 724 primary head and neck squamous cell carcinoma (HNSCC) in young and old patients, with regard to clinical profile and immunohistochemical expression of p53 protein. Associations among age, epidemiological and clinicopathological parameters, and survival analysis were evaluated. HNSCC in young people occurred in 14.5% (median age 40.7years; male-to-female ratio 5.9:1). A statistical association was demonstrated between age and family history of cancer, and between age and anatomical site. Among older patients, a higher presence of disease was noted in posterior sites. Expression of p53 was found in 71.7% of the samples and a higher expression was noted in lesions of young patients. Survival analysis showed that the age parameter is not a reliable prognostic factor for HNSCC. Among young patients, cervical metastasis was associated with worse survival. The presence of a family history of cancer in young patients could indicate genetic susceptibility and molecular disturbances in the p53 pathway in HNSCC of young and older patients seem to be distinct.

Development and validation of HPLC and UV spectrophotometric methods for the determination of lumiracoxib in tablets

In this study, two methods, based on high-performance liquid chromatography (HPLC) and UV spectrophotometry, were developed and validated for the quantitative determination of lumiracoxib in tablets. The HPLC was carried out on a column of propylsulfonic acid bonded to silica gel (250 x 4.6 mm; 5 mium), with a mobile phase of phosphate buffer (pH 7.4; 10 mM)-water-acetonitrile (10:40:50, v/v/v) fl owing at 1.0 mL/min and detection of the drug at 278 nm. The UV method was based on absorbance at 275 nm, with ethanol as solvent. Both assays were linear over the concentration range of 2–30 miug/mL (R approximate 0.999), as wellas accurate and precise, with recoveries between 98 and 100% and relative standard deviation (%RSD) smaller that 2.0%. The proposed methods are highly sensitive, precise and accurate and were successfully applied to the quantitation of lumiracoxib in the commercial formulation. The spectrophotometric method is a simple, cheap and less time-consuming method. However, the chromatographic method is selective for the determination of the degradation products of lumiracoxib.

Development and validation of a LC-MS/MS method with electrospray ionization for determination of LASSBio-579 in rat plasma.

A simple and sensitive LC-MS/MS analytical method was developed and validated for the determination of LASSBio-579 in plasma rat, using fluconazole as internal standard. Analyses were performed on a Shimadzu HPLC system using a Shimadzu C18 column and isocratic elution with acetonitrile-water (80:20, v/v), containing 0.4mM ammonium hydroxide and 0.2 mM acetic acid at a flow rate of 1.0 ml/min (split ratio 1:5). A Micromass triple quadrupole mass spectrometer, equipped with an electrospray ionization interface, operated in the positive mode. Plasma samples were deproteinized with acetonitrile (1:2) and 50 microl of the supernatant were injected into the system. The retention times of LASSBio-579 and IS were approximately 4.7 and 2.4 min, respectively. Calibration curves in spiked plasma were linear over the concentration range of 30-2000 ng/ml with determination coefficient >0.98. The lower limit of quantification was 30 ng/ml. The accuracy of method was within 15%. Intra- and inter-day relative standard deviations were less or equal to 13.5% and 6.4%, respectively. The applicability of the LC-MS/MS method for pharmacokinetic studies was tested using plasma samples obtained after intraperitoneal administration of LASSBio-579 to male Wistar rats. No interference from endogenous substances was observed, showing the specificity of the method developed. The reported method can provide the necessary sensitivity, linearity, precision, accuracy, and specificity to allow the determination of LASSBio-579 in pre-clinical pharmacokinetic studies.

Validated HPLC method for determination of LASSBio-581, a new heterocyclic N-phenylpiperazine derivative, in rat plasma.

A rapid, simple and accurate high performance liquid chromatography (HPLC) method was developed and validated for the determination of LASSBio-581 (1-[1-(4-chloro-phenyl)-1H-[1,2,3]triazol-4-ylmethyl]-4-phenyl-piperazine) in rat plasma using ketoconazole as internal standard. Plasma samples were deproteinized with methanol. A good chromatographic separation was achieved using a reversed phase C18 column. Mobile phase consisting of sodium dihydrogen phosphate monohydrate (pH 4.5, 0.02 M) and methanol mixture (35:65, v/v) was used at a flow rate of 1.0 ml/min. The eluate was monitored using a UV detector at 248 nm. The retention times of LASSBio-581 and the internal standard were approximately 3.8 and 5.6 min, respectively. The calibration curves were linear over the concentration range of 0.25-8.0 microg/ml with correlation coefficients >0.99. The limit of quantitation was 0.25 microg/ml. The accuracy of the method was >90%. The intra-day relative standard deviation (R.S.D.) ranged from 6.15 to 10.52% at 0.4 microg/ml, 7.44 to 13.81% at 1.5 microg/ml and 6.10 to 13.94% at 6.0 microg/ml. The inter-day R.S.D. were 9.54, 8.42 and 8.25% at 0.4, 1.5 and 6.0 microg/ml, respectively. No interference from endogenous substances or metabolites were observed. The method has been used to measure plasma concentrations of LASSBio-581 in pharmacokinetic studies in rats.

Dopaminergic profile of new heterocyclic N-phenylpiperazine derivatives

Dopamine constitutes about 80 percent of the content of central catecholamines and has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinson's disease, depression and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to report the structural design of two N-phenylpiperazine derivatives, compound 4: 1-[1-(4-chlorophenyl)-1H-4-pyrazolylmethyl]-4-phenylhexahydropyrazine and compound 5: 1-[1-(4-chlorophenyl)-1H-1,2,3-triazol-4-ylmethyl]-4-phenylhexahydropyrazine, planned to be dopamine ligands, and their dopaminergic action profile. The two compounds were assayed (dose range of 15-40 mg/kg) in three experimental models: 1) blockade of amphetamine (30 mg/kg, ip)-induced stereotypy in rats; 2) the catalepsy test in mice, and 3) apomorphine (1 mg/kg, ip)-induced hypothermia in mice. Both derivatives induced cataleptic behavior (40 mg/kg, ip) and a hypothermic response (30 mg/kg, ip) which was not prevented by haloperidol (0.5 mg/kg, ip). Compound 5 (30 mg/kg, ip) also presented a synergistic hypothermic effect with apomorphine (1 mg/kg, ip). Only compound 4 (30 mg/kg, ip) significantly blocked the amphetamine-induced stereotypy in rats. The N-phenylpiperazine derivatives 4 and 5 seem to have a peculiar profile of action on dopaminergic functions. On the basis of the results of catalepsy and amphetamine-induced stereotypy, the compounds demonstrated an inhibitory effect on dopaminergic behaviors. However, their hypothermic effect is compatible with the stimulation of dopaminergic function which seems not to be mediated by D2/D3 receptors

Dopaminergic profile of new heterocyclic N-phenylpiperazine derivatives.

Dopamine constitutes about 80% of the content of central catecholamines and has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinson's disease, depression and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to report the structural design of two N-phenylpiperazine derivatives, compound 4: 1-[1-(4-chlorophenyl)-1H-4-pyrazolylmethyl]-4-phenylhexahydropyrazine and compound 5: 1-[1-(4-chlorophenyl)-1H-1,2,3-triazol-4-ylmethyl]-4-phenylhexahydropyrazine, planned to be dopamine ligands, and their dopaminergic action profile. The two compounds were assayed (dose range of 15-40 mg/kg) in three experimental models: 1) blockade of amphetamine (30 mg/kg, ip)-induced stereotypy in rats; 2) the catalepsy test in mice, and 3) apomorphine (1 mg/kg, ip)-induced hypothermia in mice. Both derivatives induced cataleptic behavior (40 mg/kg, ip) and a hypothermic response (30 mg/kg, ip) which was not prevented by haloperidol (0.5 mg/kg, ip). Compound 5 (30 mg/kg, ip) also presented a synergistic hypothermic effect with apomorphine (1 mg/kg, ip). Only compound 4 (30 mg/kg, ip) significantly blocked the amphetamine-induced stereotypy in rats. The N-phenylpiperazine derivatives 4 and 5 seem to have a peculiar profile of action on dopaminergic functions. On the basis of the results of catalepsy and amphetamine-induced stereotypy, the compounds demonstrated an inhibitory effect on dopaminergic behaviors. However, their hypothermic effect is compatible with the stimulation of dopaminergic function which seems not to be mediated by D2/D3 receptors.

Selective PGHS-2 inhibitors: a rational approach for treatment of the inflammation.

Prostaglandin-H synthase exists in two isoforms, PGHS-1 and PGHS-2. PGHS-1 is present and is constitutively expressed in most cells and tissues, whereas PGHS-2 is mainly thought to mediate inflammation. Selective prostaglandin-H synthase-2 (or cyclooxygenase-2) inhibitors have been shown to be potent antiinflammatory agents with fewer side effects than currently marketed nonsteroidal antiinflammatory drugs (NSAIDs). This review addresses the main classes of the selective PGHS-2 inhibitors whose selectivity is documented by supporting PGHS-1 and PGHS-2 enzyme data. In addition, we also describe our experience in design, synthesis and pharmacological in vivo evaluation of new 1,2-benzodioxole derivatives as candidate of the selective PGHS-2 inhibitors, with special attention to molecular dynamics simulations of these derivatives attached to the active site of PGHS-2.

A novel thienylhydrazone, (2-thienylidene)3,4-methylenedioxybenzoylhydrazine, increases inotropism and decreases fatigue of skeletal muscle.

This study was designed to investigate the effects on single skeletal muscle fibers of a novel thienylhydrazone, referred to as LASSBio-294, which is a bioisoster of pyridazinone compounds that inhibit the cyclic AMP-specific phosphodiesterase (PDE) 4. Twitch and fatigue were analyzed in single skeletal muscle fibers isolated from either the semitendinous or the tibialis anterior muscles dissected from the frog Rana pipiens. LASSBio-294 (12.5-100 microM) increased twitch tension, accelerated the maximal rate of tension decay during relaxation, and had very little effect in the maximal rate of tension development of muscle fibers directly stimulated at < or =30 Hz. The positive inotropic effect of LASSBio-294 developed slowly, reaching its maximum at 40 min and was inversely proportional to the frequency of stimulation, becoming negligible at 60 and 90 Hz. The concentration-response relationship for LASSBio-294-induced potentiation of twitch tension was bell-shaped, with maximal effect occurring at 25 microM. In addition, LASSBio-294 reduced development of fatigue induced by tetanic stimulation of the muscle fibers and reduced the time needed for 80% prefatigue tension recovery after fatigue had developed to 50% of the maximal pretetanic force. These effects of LASSBio-294 can be fully explained by stimulation of the sarcoplasmic reticulum Ca2+ pump and could be ascribed to an increase in cellular levels of cyclic AMP due to PDE inhibition. The novel thienylhydrazone LASSBio-294 may be useful for treatment of patients suffering from conditions in which muscle fatigue is a debilitating symptom (e.g., chronic heart failure).

Synthesis and pharmacological evaluation of novel heterotricyclic acylhydrazone derivatives, designed as PAF antagonists.

This paper describes the synthesis and the antiplatelet properties of new heterotricyclic N-acylhydrazone derivatives (7a-e), structurally analogous to known hetrazepinic PAF antagonists, exploring molecular hybridization as a tool for molecular designing. The synthetic route employed to access compounds (7a-e) used, as starting material, the previously described methyl 3-hydroxy-8-methyl-6-phenyl-6H-pyrazolo[3,4-b]thieno[2, 3-d]pyridine-2-carboxylate derivative. The results from inhibitory effects of these novel acylhydrazone derivatives (7a-e) upon PAF-induced platelet aggregation, indicated that all compounds present a significant antithrombotic profile.

Design and synthesis of novel potent antinociceptive agents: methyl-imidazolyl N-acylhydrazone derivatives.

This paper describes recent results of design, synthesis and pharmacological evaluation of new N-heterocyclic functionalized N-acylhydrazone compounds, belonging to the 2-methyl-imidazolyl-3-acylhydrazone class (4a-e). These compounds were planned by applying the molecular simplification strategy to propose the structural modifications on the previously described functionalized imidazo [1,2-a]pyridine 3-acylhydrazone series (2), which presented an important analgesic profile. This new series (4) was synthesized in order to investigate the possible pharmacophoric contribution of the N-heteroaromatic ring and N-acylhydrazone moieties to the analgesic activity. Compounds 4a-b are the most potent antinociceptive agents from this series.

Chiral gas chromatographic separation of 2-oxabicyclo[3.3.0]octane derivatives and their synthetic precursors.

Chiral GC separation of (+/-)-2-allyl-2-carboethoxycyclopentanone (9) and the alcohols (+/-)-3-(hydroxymethyl)-5-carboethoxy-2-oxabicyclo[3.3.0]octane (7), (+/-)-2-allyl-2-carboethoxycyclopentanol (8), and their acetylated and trifluoroacetylated derivatives were investigated on three derivatized beta-cyclodextrins (CDs) diluted in SE-54 or 1701-OH: 2,3,6-tri-O-methyl-beta-CD (PMCD); 2,3-di-O-methyl-6-O-(tert-butyldimethylsilyl)-beta-CD (DIMETBCD); 2,3-di-O-acetyl-6-O-(tert-butyldimethylsilyl)-beta-CD (DIACTBCD). The understanding of these chiral separations is extremely relevant, since cyclopentanic and bicyclic cyclopentanic rings are common structural features of many important natural products and new pharmaceutical drugs. In general DIMETBCD diluted in SE-54 showed the best chiral resolution to alcohols 7 and 8 and only DIACTBCD showed enantioselectivity to 9. Hydrogen bonds prediction and dipole moments data were obtained by molecular modeling calculations for 7ab and 8ab and Ac and TFA derivatives. Comparison of these data with the chromatographic parameters for the related compounds were used to explain the differences of their elution orders and diastereo- and enantiomeric separations on the above chiral stationary phases (CSPs). The results suggest that the CSPs enantioselectivities are not affected by the carboethoxy-functionalized cyclopentanic and bicyclic cyclopentanic rings themselves but mainly by the functional group on the other stereogenic center.

Synthesis and analgesic activity of novel N-acylarylhydrazones and isosters, derived from natural safrole.

Anew series of antinociceptive compounds belonging to the N-acylarylhydrazone (NAH) class were synthesized from natural safrole (7). The most analgesic derivative represented by 10f, [(4'-N,N-dimethylaminobenzylidene-3-(3', 4'-methylenedioxyphenyl)propionylhydrazine], was more potent than dipyrone and indomethacin, used as standards. The NAH compounds described herein were structurally planned by molecular hybridization and classical bioisosterism strategies on previously reported analgesic NAH in order to identify the pharmacophoric contribution of the N-acylarylhydrazone moiety and investigate the structure-activity relationship (SAR) in these series.

Synthesis and antiplatelet evaluation of novel aryl-sulfonamide derivatives, from natural safrole.

In the scope of a research program aiming at the synthesis and pharmacological evaluation of novel possible antiplatelet prototype compounds, exploring bioisosterism principles for molecular design, we describe in this paper the synthesis of new aryl-sulfonamides derivatives, structurally similar to known thromboxane A2 receptor antagonists. The synthetic route used to access the new compounds described herein starts from safrole, an abundant Brazilian natural product, which occurs in Sassafras oil (Ocotea pretiosa). The results from preliminary evaluation of these novel aryl-sulfonamide compounds by the platelet aggregation inhibitory test, using rabbit PRP, induced by ADP, collagen, arachidonic acid, and U46619, identified the N-[2-(4-carboxymethoxyphenyl)ethyl]-6-methyl-3,4-methylenedioxyphe nyl- sulfonamido derivative as the most active among them, presenting in IC50 value for the U-46619-induced platelet aggregation in rabbit platelet-rich plasma: 329 microM.

Proposal of a new PAF pharmacophoric map by the AM1 method.

PAF is a powerful phospholipid-derived autacoid involved in many pathophysiological processes. Many PAF antagonists have been synthesized and assayed for therapeutic purposes. We have synthesized derivatives (5-7), structurally related to WEB 2086 (1), which were rationally designed based on a planar PAF receptor model previously described by Bures et al. (1994; J. Chem. Inf. Comput. Sci. 24, 218-223). However, pharmacological studies revealed that derivatives (5-7) were inactive as PAF antagonists. AM1 quantum calculations of classical PAF antagonists (1-4), as well as of our derivatives (5-7), demonstrated that electronic features alone are unable to explain the lack of the activity of (5-7). These results induced us to propose a new tridimensional PAF receptor pharmacophoric map by analyzing all stable conformations obtained for derivatives (1-4). The interpoint distances (D1-D5) revealed that the lowest-energy conformers of (5-7) had similar geometries to derivatives (1-4). So, these aspects could not explain the inactivity of the compounds (6-7). The proposed model suggests that the best fit of antagonist compounds may involve the participation of a sulfur atom electron lone pair adequately oriented in relation to the plane of a N-aromatic ring present in the compounds investigated.

Synthesis and analgesic profile of novel N-containing heterocycle derivatives: arylidene 3-phenyl-1,2,4-oxadiazole-5-carbohydrazide.

This paper describes recent results of a research program aimed at the synthesis and pharmacological evaluation of new heterocyclic N-acylhydrazone (NAH) compounds, belonging to the arylidene (3-phenyl)-1,2,4-oxadiazolyl-5-carboxyhydrazide (8a-p) series. These compounds were structurally planned by applying the molecular hybridization strategy on previously described arylidene 1-phenylpyrazole-4-carbohydrazide (5) derivatives, considered as lead-compounds, which present potent analgesic properties. The analgesic profile of the title compounds 8a-p, evaluated in the model of abdominal constrictions induced by acetic acid, showed that the 4-methoxybenzylidene derivatives 8c and 8k were the most active ones, exhibiting a relative analgesic activity comparable with that of dipyrone 1 used as standard.