Hypnotic profile of imines from benzimidazole chalcones: mechanism of synthesis, DFT studies and in silico screening.

A series of 1-(1H-benzimidazol-2-yl)-3-substituted phenylprop-2-en-1-ylidene] amino}-1,3,4-thiadiazole-2- thiols (6a-6f) were synthesized by the acid catalyzed nucleophilic addition reaction between 1-(1H-benzimidazol-2-yl)-3- phenylprop-2-en-1-ones (4a-4f) and 5-amino-1,3,4-thiadiazole-2-thiol. All the synthesized compounds were characterised by IR, (1)HNMR, (13)CNMR, Mass and elemental analyses. A transition state calculation obtained from DFT study to explore the molecular mechanism of action of the synthetic route. The mechanism of synthesis revealed that the imidazole system can make an increase in the electrophilic character of carbonyl carbon in the benzimidazole chalcones. So the electron deficient carbonyl carbon could be efficiently attacked on the amino group of 1,3,4-thiadiazole ring to forms an imine linkage between the two heterocyclic systems. All the titled derivatives at a dose level of 10mg/kg body weight potentiate the hypnotic action of Phenobarbitone (at a dose of 10mg/kg body weight i.p.). The compounds such as 6b, 6a, and 6c showed a significant percentage increase in sleeping time relative to the control experiment 423.8, 387.6 and 329.5 respectively. The preclinical evaluation of the compounds was ascertained by blood-brain barrier, human oral absorption prediction and in silico toxicity assessment.

Synthesis and pharmacological activity of alkaloids from embryo of lotus, Nelumbo nucifera.

Bisbenzylisoquinoline alkaloid, nelumboferine which was recently isolated from the embryo of Nelumbo nucifera, and stereoisomers of neferine, which is a major alkaloid of the embryo of N. nucifera, were stereoselectively synthesized. Pharmacological activity of nelumboferine, stereoisomers of neferine, liensinine, isoliensinine, and O-methylneferine were evaluated.

Synthesis and antidepressant evaluation of five novel heterocyclic tryptophan-hybrid derivatives.

This study aimed at evaluating the reactivity of L-Tryptophan (TRP) 1 towards various chemical reagents to produce new bi- and tri-heterocyclic systems providing basic pharmacological activities. Indol-3-yl hydroxyoxazol-2-yl acetonitrile derivatives 5 and 6, indol-3-yl-hydroxyoxazol-2-yl-1,2,4-triazine derivatives 8 and 9, indol-3-yl-hydroxyoxazol-2-yl-aminopyrazole derivatives 11a, b, and indol-3-yl-hydroxyoxazol-2-yl-aminoisoxazole derivative 12 were synthesized via straightforward and efficient methods. The structures were characterized by spectral data (IR, (1)H-NMR, (13)C-NMR, and MS) and the purity was ascertained by microanalysis. Also, this work was extended to study the potential role of the novel synthesized TRP derivatives 5, 6, 9, 11a, and 12 as antidepressant and sedative agents in comparison with TRP. All compounds showed significant antidepressant activity in the forced-swimming test at two doses (50 or 100 mg/kg). Also, all tested compounds (at 50 or 100 mg/kg) produced a significant decrease in locomotor activity of mice during a 30 min observation period. The most potent antidepressant and sedative effect was produced by the tri-heterocyclic compounds 9 and 12, followed by 11a and TRP.

Screening for antidepressant, sedative and analgesic activities of novel fused thiophene derivatives.

This study was aimed at the synthesis of fused benzothiophene derivatives containing heterocyclic moiety. The reaction of the tetrahydrobenzo[b]thiophene derivatives 1a,b with ethoxycarbonylisothiocyanate afforded the thiourea derivatives 2a,b. Cyclization of the latter products gave the annulated benzo[b]thienopyrimidine derivatives 3a,b. Compounds 2a,b and 3a underwent a series of heterocyclization reactions through the reaction with some chemical reagents to give the new benzo[b]thienopyrimidine derivatives 5a,b to 8a-c. Also, this work was extended to study the potential role of the novel synthesized thiourea derivative 2a and benzo[b]thienopyrimidine derivatives 3a, 5b, 6a and 8b as antidepressant, sedative or analgesic agents at two doses (15 or 30 mg kg(-1) body mass). Some compounds (2a, 3a and 5b) showed mild antidepressant activity in the forced-swimming test. No compound showed sedative effect. Visceral pain evoked by i.p. injection of acetic acid in mice was significantly inhibited by all compounds at a high doses.

Design, synthesis, and pharmacological evaluation of new neuroactive pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine derivatives with in vivo hypnotic and analgesic profile.

The present study describes the synthesis and pharmacological profiles of four novel pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine derivatives 2-5, which were structurally designed by using the sedative and analgesic drug zolpidem 1 as lead compound. The heterotricyclic system present in the target compounds 2-5 was constructed in good yields, exploiting a regioselective hetero Diels-Alder reaction of the key azabutadiene derivative 7 and functionalized N-phenylmaleimides 9-12. Additionally, we identified that 1-methyl-7-(4-nitrophenyl)-3-phenyl-3,6,7,8-tetrahydropyrazolo[3,4-b]pyrrolo[3,4-d]pyridine-6,8-dione derivative (LASSBio-873, 5) presented not only the most potent ability to promote sedation, which was similar to that induced by the standard benzodiazepine drug midazolam, but also potent central antinociceptive effect.

Synthesis and pharmacological screening for muscle relaxant, anticonvulsant, and sedative activities of certain organic compounds produced by Michael addition.

Michael addition of certain nucleophiles on alpha, beta-unsaturated ketones 1 led to the formation of adducts 2-7 as well as the reaction of arylidene derivatives with secondary amines afforded the amino compounds 9 and 11. Also, dialkylmalonates were treated with alpha-cyano cinnamide to afford 13. On the other hand, double Michael cycloaddition of ethylcyanoacetate or tetrachlorophthalic anhydride to the suitable divinylketone were synthesized to produce 15-17. Selected compounds (13 and 6) were screened for muscle relaxant, anticonvulsant, and sedative activities using established pharmacological models. Their activities were compared with that of phenobarbital sodium taken as standard. Compound 6 was the most potent muscle relaxant while compounds 13a and 13c offered the highest anticonvulsant activity. Meanwhile compound 13c showed the highest potentiation of phenobarbital induced sleep in mice.

Synthesis and biological activities of diquaternary dipiperazinium salts containing dithiocarboxyl groups.

A series of diquaternary dipiperazinium salts containing dithiocarboxyl groups 6a-f and 9 were synthesized and evaluated for their analgesic and sedative activities. The result showed that the presence of two quaternary ammonium cations and the distance between them are very important for the activities of the salts. Compound 6b exhibited the best activities (at dose 2 mg/kg, analgesic, 57%; sedative, 59%) among compounds 6a-f. Compound 9 not only showed the most potent analgesic (85.4%, dose 1 mg/kg) and sedative (93.1%, dose 1 mg/kg) activities, but also exhibited anticancer activity against KB (68.7%, dose 10 microM).

Synthesis and anticonvulsant activity of 4-bromophenyl substituted aryl semicarbazones.

A number of 4-bromophenyl semicarbazones were synthesised and evaluated for anticonvulsant and sedative -hypnotic activities. After intraperitoneal injection to mice, the semicarbazone derivatives were examined in the maximal electroshock seizure (MES), subcutaneous pentylenetetrazole (scPTZ), subcutaneous strychnine (scSTY) and neurotoxicity (NT) screens. All the compounds showed anticonvulsant activity in one or more test models. Compound 12 showed greatest activity, being active in all the screens with very low neurotoxicity and no sedative-hypnotic activity. All the compounds except 7 had lower neurotoxicity compared to phenytoin. Three compounds (6, 11 and 14) showed greater protection than sodium valproate. The essential structural features responsible for interaction with receptor site are established within a suggested pharmacophore.