Structure-activity studies on benzhydrol-containing nipecotic acid and guvacine derivatives as potent, orally-active inhibitors of GABA uptake.

The introduction of lipophilic groups onto the ring nitrogen of nipecotic acid and guvacine, two known GABA uptake inhibitors, afforded potent, orally-active anticonvulsant drugs. A series of compounds is reported which explores the structure-activity relationships (SAR) in this series. Among the areas explored: side-chain SAR (aromatic-, heterocyclic-, and tricyclic-containing side chains) and modifications to the tetrahydropyridine ring. The benzhydrol ether-containing side chains afforded the most potent compounds with several exhibiting in vitro IC50 values for GABA uptake of < 1 microM (including 5, Table I; 37, 43, Table IV; and 44, Table V). Compound 44 was selected for extensive evaluation and subsequently progressed to Phase 1 clinical trials with severe adverse effects seen after single dose administration to humans.     

gamma-Aminobutyric acid uptake inhibition and anticonvulsant activity of nipecotic acid esters

n-Alkyl esters of nipecotic acid were prepared by Fischer esterification, and the esters were evaluated against bicuculline-induced seizures in mice. Evaluation of the alkyl esters for inhibition of gamma-aminobutyric acid uptake into mouse whole brain mini-slices revealed that the order of potency was proportional to chain length. The octyl ester inhibited gamma-aminobutyric acid and beta-alanine uptakes by apparently nonspecific mechanisms. A variety of phenyl esters of nipecotic acid were also synthesized utilizing either dicyclohexylcarbodiimide or 1,1'-carbonyldiimidazole as the condensing agent. Most of the phenyl esters were potent inhibitors of gamma-aminobutyric acid uptake. The uptake inhibition appeared to involve specific and nonspecific (detergent-like) mechanisms. The m-nitrophenyl and p-nitrophenyl esters were particularly potent against bicuculline-induced seizures in mice.     

Synthesis of novel GABA uptake inhibitors. 4. Bioisosteric transformation and successive optimization of known GABA uptake inhibitors leading to a series of potent anticonvulsant drug candidates.

By bioisosteric transformations and successive optimization of known GABA uptake inhibitors, several series of novel GABA uptake inhibitors have been prepared by different synthetic approaches. These compounds are derivatives of nipecotic acid and guvacine, substituted at the nitrogen of these amino acids by various lipophilic moieties such as diarylaminoalkoxyalkyl or diarylalkoxyalkyl. The in vitro values for inhibition of [(3)H]GABA uptake in rat synaptosomes was determined for each compound, and it was found that the most potent compound from this series, (R)-1-(2-(3,3-diphenyl-1-propyloxy)ethyl)-3-piperidinecarboxyli c acid hydrochloride (29), is so far the most potent parent compound inhibiting GABA uptake into synaptosomes. Structure-activity results confirm our earlier observations, that an electronegative center in the chain connecting the amino acid and diaryl moiety is very critical in order to obtain high in vitro potency. Several of the novel compounds were also evaluated for their ability in vivo to inhibit clonic seizures induced by a 15 mg/kg (ip) dose of methyl 6, 7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM). Some of the compounds tested show a high in vivo potency comparable with that of the recently launched anticonvulsant product 6 ((R)-1-(4, 4-bis(3-methyl-2-thienyl)-3-butenyl)-3-piperidinecarboxylic acid).     

Synthesis and biological evaluation of some novel quinoxaline derivatives as anticonvulsant agents

In view of their expected anticonvulsant activity, some new derivatives of quinonxaline (V1-7) were designed and synthesized by condensation of different aromatic aldehydes with 2-(2-oxo-3-phenylquinoxalin-1(2H)-yl)acetohydrazide (IV). All synthesized compounds were isolated and confirmed by IR, 1H-NMR, MS, elemental analysis and then tested as anticonvulsant agents. Compound V3 and V1 showed the highest anticonvulsant effect with anticonvulsant potency relative to phenobarbital sodium of 0.8 and 0.75 whereas compound V5 exhibited the lowest relative potency of 0.09. The other compounds showed variable activity between these values as follows: V2 = 0.19, V4 = 0.41, V6 = 0.1 and V7 = 0.15. All compounds showed less activity than the reference compound phenobarbital. But the compounds provided a basis for further optimization.     

3-哌啶甲酸和四氢烟酸的4,4-二芳基-3-丁烯衍生物的三维定量构效关系(比较分子力场分析)研究

目的研究3-哌啶甲酸和四氢烟酸的4,4-二芳基-3-丁烯衍生物结构和对γ-氨基丁酸摄取抑制活性之间的关系.方法使用三维定量构效关系(3D-QSAR)--比较分子场分析(CoMFA)方法进行构效关系研究.结果交叉验证系数q2和非交叉验证系数r2分别为0.726和0.986,方差比F为117.562,标准估计误差(SEE)为0.062.结论这些数值表明所得的CoMFA模型有实际意义,并且对3-哌啶甲酸和四氢烟酸的4,4-二芳基-3-丁烯衍生物抑制活性具有较好的预测能力.     

Synthesis of alkyl-substituted arecoline derivatives as gamma-aminobutyric acid uptake inhibitors

A series of N-methyltetrahydropyridine-3-carboxylic acids and methyl esters have been synthesized and biologically evaluated. Arecoline (6) was lithiated with LDA in THF to give 7, which was treated with various alkyl halides to afford exclusively the alpha-substituted products 8a-g. Thermodynamic reaction of 7 with carbonyl compounds gave the corresponding 5-substituted arecoline derivatives 10a-q. When phenyldiazonium tetrafluoroborate was used as electrophile, 8h and 9 were obtained. The relative stereochemistry of 10j-o was established by 1H NMR spectroscopy. Compound 12 was obtained by condensation of the silylketene acetal 11 with N-acetylindoxyl. Dehydration of 10a-c yielded 14a-c, respectively. Deprotection of the esters 14a, 14c, and 15 followed by chromatography on an ion-exchange resin gave the amino acids 16a, 16c, and 16d. The alcohol 17 was obtained by LiAlH4 reduction of the corresponding ester 14c. The amino acid 16c displayed a marked inhibitory effect on the synaptosomal uptake of gamma-amino[3H]butyric acid ([3H]GABA). The type of inhibition was competitive with a Ki of 12.9 microM. Compound 16d also inhibited [3H]GABA uptake but was about 10 times weaker than 16c. None of the biologically tested compounds (8a-g, 9, 10a-q, 12, 14a-c, 16a-d, 17) showed any effect in binding studies using [3H]GABA as ligand.     

Synthesis of new piperidyl indanone derivatives as anticonvulsant agents

A series of 5,6-dimethoxy-2-{1-[arylamino/alkylamino(thioxo)methyl]-4-piperidyl-methyl}-1-indanones (4a–l) were designed and synthesized by the reaction of 5,6-dimethoxy-2-(piperidin-4-yl-methyl)-indan-1-one with aryl/alkyl isothiocyanates. The anticonvulsant activity was evaluated in animal models by maximal electroshock seizure and subcutaneous pentylenetetrazole tests. The neurotoxic effects were assessed by rotorod and ethanol potentiation tests. Gamma amino butyric acid (GABA) estimation of the selected compounds was performed in rat brain utilizing UV absorbance data. Compounds 4d, 4g, and 4j displayed encouraging anticonvulsant profile against both seizure models with remarkably lower neurotoxicity. These compounds were found to increase the GABA level in rat brain significantly.     

Synthesis of novel gamma-aminobutyric acid (GABA) uptake inhibitors. 5.(1) Preparation and structure-activity studies of tricyclic analogues of known GABA uptake inhibitors

On the basis of the SAR of a series of known gamma-aminobutyric acid (GABA) uptake inhibitors, including 4 (SKF 89976), new tricyclic analogues have been prepared. These novel compounds are derivatives of nipecotic acid, guvacine, and homo-beta-proline, substituted at the nitrogen of these amino acids by various lipophilic moieties such as (10,11-dihydro-5H-dibenz[b,f]azepin-5-yl)alkoxyalkyl or (10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)alkoxyalkyl. The in vitro values for inhibition of [(3)H]-GABA uptake in rat synaptosomes was determined for each compound in this new series, and it was found that several of the novel compounds showed a high potency comparable with that of the reference compounds 4, 5 (tiagabine), and 6 (CI-966). Several of the novel compounds were also evaluated for their ability in vivo to inhibit clonic seizures induced by a 15 mg/kg (ip) dose of methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM). One compound, (R)-1-(2-(2-(10,11-dihydro-5H-dibenz[b,f]azepin-5-yl)ethoxy)ethyl)-3-piperidinecarboxylic acid (23), was selected for further biological investigations and showed a protective index comparable to or slightly better than that of the recently launched anticonvulsant product 5 ((R)-1-(4,4-bis(3-methyl-2-thienyl)-3-butenyl)-3-piperidinecarboxylic acid).     

Novel 1-phenylcycloalkanecarboxylic acid derivatives as potential anticonvulsant agents

A series of analogues based on the anticonvulsant carbetapentane (1, 2-[2-(diethylamino)ethoxy]ethyl 1-phenyl-1-cyclopentylcarboxylate) was prepared as potential novel anticonvulsant drugs. Structure-activity relationships of analogues in which the ester function and cyclopentane moieties were modified have been investigated by evaluating their ability to prevent seizures in the rat maximal electroshock test. These compounds (11, ED50 = 16 mumol/kg; 12, ED50 = 86 mumol/kg, and 23, ED50 = 173 mumol/kg) were effective anticonvulsants. Compound 11, an alkyl ether derivative of 1, was more potent than the parent compound (ED50 = 48 mumol/kg) and also showed a 2-fold increase in potency compared to that of the prototypic anticonvulsant drug diphenylhydantoin.     

GABA-level increasing and anticonvulsant effects of three different GABA uptake inhibitors

The present study examines the effect of tiagabine (a selective inhibitor of GABA transporter 1, GAT-1), SNAP-5114 (a semi-selective inhibitor of rat GAT-3/mouse GAT4) and NNC 05-2045 (a non-selective GABA uptake inhibitor) in modulating GABA levels in the hippocampus and thalamus. Anticonvulsant effects of the same compounds were assessed (after intranigral administration) after maximal electroshock (MES) in juvenile rats. Anticonvulsant effects were also tested after intraperitoneal (i.p.) administration against audiogenic seizures in DBA/2 mice and against pentylentetrazole (PTZ)-induced tonic convulsions or MES in NMRI mice. Tiagabine (30 microM, perfused through the microdialysis probe in halothane anaesthetized rats) increased GABA levels to (% basal+/-SEM) 645+/-69 in the hippocampus and 409+/-61 in the thalamus. SNAP-5114 (100 microM) increased GABA levels in the thalamus (% basal+/-SEM) to 247+/-27 but had no effect on hippocampal GABA-levels. NNC 05-2045 (100 microM) increased GABA levels both in the hippocampus (% basal+/-SEM, 251+/-51) and in the thalamus (298+/-27). All compounds protected against tonic hindlimb extension (THE) in juvenile male rats after intranigral administration. Sound induced convulsions in DBA/2 mice were dose-dependently inhibited by all compounds (administered intraperitoneal, i.p.) with ED(50) values of 1, 6 and 110 micromol/kg, for tiagabine, NNC 05-2045 and SNAP-5114, respectively. Tiagabine and NNC 05-2045 but not SNAP-5114 protected against PTZ-induced tonic convulsions whereas only NNC 05-2045 protected against MES-induced tonic convulsions in NMRI mice. However, tiagabine and NNC 05-2045 exerted a synergistic effect in the MES model. These findings substantiate and extend previous findings of different effects of selective versus non-selective GABA uptake inhibitors in animal models of epilepsy.     

L-酒石酸衍生物的合成及其抑制-分泌酶活性

摘 要: 目的 设计并合成&;#61538;-分泌酶(BACE1)的小分子抑制剂。方法 基于BACE1的晶体结构及其配体的关键结构特征，设计并合成新结构的BACE1配体。结果与结论 合成了26个酒石酸衍生物。筛选结果表明，部分化合物对BACE1有一定的抑制作用。     

Synthesis and evaluation as potential antitumor agents of novel ursolic acid derivatives

Novel ursolic acid derivatives were synthesized, and their structures were confirmed by MS, IR, ¹H NMR and ¹³C NMR spectral analysis. In vitro antitumor activities of these compounds against MGC-803 (gastric cancer cell) and Bcap-37 (breast cancer cell) human cancer cell lines were evaluated by MTT assay. The pharmacological screening results revealed that many derivatives exhibited moderate to high activities against the tested cell lines, and that most demonstrated more potent inhibitory activities than that of ursolic acid. Preliminarily mechanism study of representative compound 3h were carried out by acridine orange/ethidium bromide staining, Hoechst 33258 staining, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling assay, and flow cytometry which indicated that compound 3h can induce cell apoptosis of MGC-803 cells, and the apoptosis ratio reached 34.59?% after 36?h treatment at 10?μM.     

Synthesis and antitumor activity of novel diaryl ether hydroxamic acids derivatives as potential HDAC inhibitors

A series of diaryl ether hydroxamic acids were synthesized for the first time and evaluated for the HDAC biology and antiproliferative activity. The structures of these new hydroxamic acids derivatives were confirmed by IR, ¹H-NMR and mass spectrum. Some of these compounds showed micro molar activity in the HDAC inhibitory assay and against four cancer cell lines.     

Synthesis of benzothiazole derivatives having acetamido and carbothioamido pharmacophore as anticonvulsant agents

A new series of N-(6-chlorobenzothiazol-2-yl)-2-substituted-acetamides (3a–h) and N-(6-chlorobenzothiazol-2-yl)-2-(substituted-benzylidene)hydrazinecarbothioamides (5a–h) were synthesized and characterized by IR, ¹H NMR, mass and elemental analysis. In vivo anticonvulsant and acute toxicity screening of all the synthesized compounds showed morpholino (3f) and imidazolyl (3g) derivatives as promising anticonvulsant lead. Furthermore, In silico drug-likeness parameters have also been investigated for filtering out the likelihood of poor drug absorption or brain penetration. 3D four-point pharmacophore measurements of compounds were also carried out to match these with established anticonvulsants agents.     

Comparison of the anticonvulsant effects of two novel GABA uptake inhibitors and diazepam in amygdaloid kindled rats

Summary Two novel, specific inhibitors of GABA uptake, namely SKF 89976-A (N-[4,4-diphenyl-3-butenyl]-nipecotic acid) and SKF 100330-A (N-[4,4-diphenyl-3-butenyl]-guvacine) were tested for anticonvulsant effects in amygdaloid kindled female rats. The anticonvulsant effectiveness of the compounds was compared with that of diazepam. SKF 89976-A and SKF 100330-A produced dosedependent anticonvulsant effects on all seizure parameters measured in fully kindled rats, i.e. they inhibited seizure severity, increased seizure latency, and decreased the duration of motor seizures and EEG afterdischarges. ED 50s for inhibition of seizure severity were 4.6 and 15.1 mg/kg (0.014 and 0.045 mmol/kg) i.p. for SKF 100330-A and SKF 89976-A, respectively. For comparison, the ED 50 of diazepam was 1.9 mg/kg (0.0067 mmol/kg) i.p. Observation of behaviour indicated that the novel GABA uptake blockers exerted no side-effects in anticonvulsant doses, whereas diazepam produced sedative effects at all active dosage levels. The data demonstrate that SKF 100330-A and SKF 89976-A are potent, non-sedative anticonvulsant drugs in the kindling model of epilepsy, and these compounds thus may deserve interest as potential antiepileptic drugs with a very selective mechanism of action.     

Synthesis of some novel D-glucuronic acid acetylated derivatives as potential anti-tumor agents

A structurally diverse series of Δ(4,5) -uronamide derivatives have been chemically synthesized starting from D-glucuronic acid itself by means of acetylation, activation, amide bond formation and base-catalyzed elimination protocols. Structure elucidation for all products along with optimization of the synthetic steps is described. The synthesized compounds were evaluated for their in-vitro anti-tumor activity against MCF-7, TK-10 and UACC-62 cell lines. The compounds 5, 11, 13, 15 and 16 were the most active against TK-10 cell line. On the other hand, the most active compounds against the MCF-7 cell line were 11 and 15. However, compounds 5, 7, 11, 13, 15 and 16 were the most active against the UACC-62 cell line.     

Synthesis and evaluation of novel carbamate-substituted flavanone derivatives as potent acetylcholinesterase inhibitors and anti-amnestic agents

This study was designed to synthesize and evaluate flavanone derivatives with phenylcarbamate moiety as potent acetylcholinesterase (AChE) inhibitors and anti-amnestic agents for management of AD. The synthesis of carbamate-substituted flavanone derivatives involved base-catalysed Claisen-Schmidt condensation reaction of 2-hydroxy acetophenone/2-hydroxy-4,6-dimethoxyacetophenone with differently substituted benzaldehydes to yield differently substituted chalcones that underwent intra-molecular oxidative cyclization on refluxing with glacial acetic acid to yield flavanone compounds. Thereafter, refluxing of flavanone compounds with phenyl isocyanate in the presence of petroleum-ether and triethylamine provided phenyl carbamate-substituted flavanone derivatives. The synthesized compounds were screened in vitro for AChE inhibitory activity with donepezil as the standard drug. The most potent test compound (5f′) was evaluated in vivo for memory restorative actions in scopolamine (0.4 mg/kg)-induced amnesia in mice by Morris water maze test. All the compounds exhibited AChE inhibitory activity with carbamate substituted 5,7-dimethoxyflavanone derivatives (5a′–5g′) being the most potent compounds with IC₅₀ ranging from 21.5 ± 1.8 to 9.9 ± 1.6 nM. Compound 5f′ also ameliorated scopolamine-induced amnesia in mice in terms of restoration of time spent in target quadrant and escape latency time. It may be concluded that phenylcarbamate-substituted 5,7-dimethoxyflavanones may be a promising structural template for the development of novel AChE inhibitors in managing amnestic disorders including AD.     

Design and synthesis of novel N-substituted-3-chloro-2-azetidinone derivatives as potential anticonvulsant agents

Abstract  

A new series of N-[3-chloro-2-(substitutedphenyl)-4-oxo-azetidin-1-yl]isonicotinamide (2a–l) were synthesized through condensation reaction of isoniazide with substituted aldehyde. The newly synthesized compounds were characterized by spectral data (IR, ¹H NMR, mass spectra) and elemental analysis. Compound 2e exhibited excellent anticonvulsant activity and no neurotoxicity in comparison to reference drug phenytoin.