Design and synthesis of novel cycloalkanecarboxamide parabanic acid hybrids as anticonvulsants.. [DOI: 10.21203/rs.3.rs-3207381/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Aiming to develop novel anticonvulsant agents a new series of novel cycloalkanecarboxamide parabanic acid hybrids series 8, 9 and 10 possessing the essential structure requirements for anticonvulsant activity was synthesized starting from cycloalkanones. All final target compounds were primary screened for chemically and electrically induced seizures using pentylenetetrazole “scPTZ” and maximal electroshock seizure “MES” models. In phase I anticonvulsant evaluation compounds 8b and 10b exhibited the highest potency among all the target compounds with 100% protection towards chemically induced seizures. Results of phase II anticonvulsant screening showed that compounds 8b and 10b are more potent than standard drug ethosuximide by about 11 and 9 fold, respectively. Regarding MES test, compounds 8b and 9a-d exhibited 100% protection with ED50 values ranged between 0.107–0.177 mmol/Kg. All final compounds did not display any signs of motor impairment in the neurotoxicity screening test. Also, compounds 8a, 9a-d and 10b were devoid of hepatotoxicity as shown by measurement of serum levels of liver enzymes, albumin as well as total protein. Moreover, the cyclohexyl derivative 10b produced a significant increase of Gamma-aminobutyric acid “GABA” brain’s content of mice compared to control group confirmed its GABAergic modulating activity. Molecular docking, physicochemical and pharmacokinetic properties were carried out for all compounds as well. These outcomes support that cycloalkanecarboxamide parabanic acid hybrid is a promising scaffold to pave the way towards further development of novel class of antiepileptic drugs.

Selective Reduction of Quinolinones Promoted by a SmI2/H2O/MeOH System

The selective reduction of quinolin-2(1H)-ones promoted by a SmI₂/H₂O/MeOH system is reported for the first time. The reaction is effectively carried out to afford 3,4-dihydroquinoline-2(1H)-ones under mild conditions in a one-pot fashion with good to excellent yields.

Ruthenium-Catalyzed Intramolecular Arene C(sp2)-H Amidation for Synthesis of 3,4-Dihydroquinolin-2(1H)-ones

We report the [Ru(p-cymene)(l-proline)Cl] ([Ru1])-catalyzed cyclization of 1,4,2-dioxazol-5-ones to form dihydroquinoline-2-ones in excellent yields with excellent regioselectivity via a formal intramolecular arene C(sp²)-H amidation. The reactions of the 2- and 4-substituted aryl dioxazolones proceeds initially through spirolactamization via electrophilic amidation at the arene site, which is para or ortho to the substituent. A Hammett correlation study showed that the spirolactamization is likely to occur by electrophilic nitrenoid attack at the arene, which is characterized by a negative ρ value of -0.73.

Coumarin and 3,4-dihydroquinolinone derivatives: Synthesis, antidepressant activity, and molecular docking studies

BACKGROUND

Coumarin and 3,4-dihydroquinolinone nuclei are two heterocyclic rings that are important and widely exploited for the development of bioactive molecules. Here, we designed and synthesized a series of 3,4-dihydroquinolinone and coumarin derivatives (Compounds 8, 9, 11, 14, 15, 18-20, 23, 24 and 28 are new compounds) and studied their antidepressant activities.

METHODS

Forced swimming test (FST) and tail suspension test (TST) were used to evaluate the antidepressant activity of the target compounds. The most active compound was used to evaluate the exploratory activity of the animals by the open-field test. 5-HT concentration was estimated to evaluate if the compound has an effect on the mouse brain, by using ELISA. A 5-HT1A binding assay was also performed. The biological activities of the compounds were verified by molecular docking studies. The physicochemical and pharmacokinetic properties of the target compounds were predicted by Discovery Studio and ChemBioDraw Ultra.

RESULTS

Of all the compounds tested, compound 7 showed the best antidepressant activity, which decreased the immobility time by 65.52 s in FST. However, in the open-field test, compound 7 did not affect spontaneous activity. The results of 5-HT concentration estimation in vivo showed that compound 7 may have an effect on the mouse brain. Molecular docking results indicated that compound 7 showed significant interactions with residues at the 5-HT1A receptor using homology modeling. The results show that compound 7 exhibits good affinity for the 5-HT1A receptor.

CONCLUSION

Coumarin and 3,4-dihydroquinolinone derivatives synthesized in this study have a significant antidepressant activity. These findings can be useful in the design and synthesis of novel antidepressants.

Synthesis, molecular modeling studies and anticonvulsant activity of certain (1-(benzyl (aryl) amino) cyclohexyl) methyl esters

A series of (1-(benzyl (aryl) amino) cyclohexyl) methyl esters 7a-n were prepared and screened for their anticonvulsant profile. Screening of these esters 7a-n and their starting alcohols 6a and 6b revealed that compound 7k was the most potent one in the scPTZ screening test with an ED₅₀ value of 0.0056mmol/kg being about 10- and 164-fold more potent than phenobarbital (ED₅₀=0.056mmol/kg) and ethosuximide (ED₅₀=0.92mmol/kg) as reference drugs, respectively. Meanwhile, in the MES test, compounds 7b and 7k at doses 0.0821mmol/kg and 0.0334mmol/kg, exerted 66% and 50% protection of the tested mice, respectively, compared with diphenylhydantoin, which exerted 100% protection at dose 0.16mmol/kg. In the neurotoxicity screen test, almost all esters 7a-n did not show any minimal motor impairment at the maximum administrated dose. The anticonvulsant effectiveness of esters 7a-n was higher than their corresponding alcohols 6a and 6b. Compounds 7b and 7k exhibited pronounced anticonvulsant activity devoid of neurotoxicity in minimal motor impairment test and hepatotoxicity in the serum enzyme activity assay. 3D pharmacophore model using Discovery Studio 2.5 programs showed high fit value. The obtained experimental results of sc-PTZ activity of compounds 7a-n was consistent with the molecular modeling study.

Synthesis and anticonvulsant activity of some 7-alkoxy-2H-1,4-benzothiazin-3(4H)-ones and 7-alkoxy-4H-[1,2,4]triazolo[4,3-d]benzo[b][1,4]thiazines

A series of 7-alkoxy-2H-1,4-benzothiazin-3(4H)-ones and a new series of 7-alkoxy-4H-[1,2,4]triazolo[4,3-d]benzo[b][1,4]thiazine derivatives were synthesized using 5-methoxybenzo[d]thiazol-2-amine as starting material. The structures of the compounds were elucidated by IR, (1)H-NMR spectroscopic data and microanalyses. The anticonvulsant activity of these compounds was evaluated by maximal electroshock (MES) test and rotarod test following intraperitoneal injection in KunMing mice. Among the synthesized compounds 3a-v, 7-(hexyloxy)-2H-benzo[b][1,4]thiazin-3(4H)-one (3f) could be considered potentially the most useful and safe therapeutic compound. Among the synthesized compounds 4a-u, compound 7-(2-fluorobenzyloxy)-4H-[1,2,4]triazolo[4,3-d]benzo[b][1,4]thiazine (4k) was the most active compound with an ED(50) of 17.0 mg/kg, TD(50) of 243.9 mg/kg and protective index (PI) of 14.3. Its neurotoxicity was lower than all the other synthesized compounds and also markedly lower than that of the reference drug carbamazepine.

Synthesis and anticonvulsant activity of 1-formamide-triazolo[4,3-a]quinoline derivatives

Using 6-hydroxy-3,4-dihydro-2(1H)-quinolone as the starting material, a series of 1-formamide-triazolo[4, 3-a]quinoline derivatives (6a-6n) was synthesized, the anticonvulsant effect and neurotoxicity of the compounds was calculated with maximal electroshock test and rotarod tests with intraperitoneally injected in KunMing mice. The results demonstrated that compound 7-(hexyloxy)-4,5-dihydro-[1,2,4] triazolo[4,3-a]quinoline-1-carboxamide (6d) was the most active one and also had the lowest toxicity. In the anti-maximal electroshock potency test, it showed median effective dose (ED(50)) of 30.1 mg/kg, median toxicity dose (TD(50)) of 286 mg/kg, and the protective index of 9.5 which is greater than the reference drug carbamazepine with the protective index value of 6.0.

Synthesis and anticonvulsant activity of a new 6-alkoxy-[1,2,4]triazolo[4,3-b]pyridazine

A series of 6-alkoxy-[1,2,4]triazolo[4,3-b]pyridazine derivatives were synthesized. In initial screening and quantitative evaluation, compound 2r was among the most active agents, exhibiting in the same time the lowest toxicity. In the anti-maximal electroshock test, it showed median effective dose (ED50) of 17.3 mg/kg and median toxicity dose (TD50) of 380.3 mg/kg, and the protective index (PI) of 22.0, which is much better than PI of the reference drugs. In a subsequent test, compound 2r had median hypnotic dose (HD50) of 746.6 mg/kg, thus demonstrating much better margin of safety compared to reference drugs. Compound 2r also showed oral activity against MES-induced seizures and lower oral neurotoxicity. For explanation of the putative mechanism of action, compound 2r was tested in chemical induced models.

Design and synthesis of 5-alkoxy-[1,2,4]triazolo[4,3-a]quinoline derivatives with anticonvulsant activity

A series of 5-alkoxy-[1,2,4]triazolo[4,3-a]quinoline derivatives were synthesized using 4-hydroxyquinolin-2(1H)-one as the starting material. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES) and their neurotoxicities were measured by the rotarod test. The results of these tests demonstrated that 5-hexyloxy-[1,2,4]triazolo[4,3-a]quinoline (3f) was the most potent anticonvulsant, with median effective dose (ED(50)) of 19.0mg/kg and protective index (PI=TD(50)/ED(50)) values of 5.8 in the MES test. Compound 5-benzyloxy-[1,2,4]triazolo[4,3-a]quinoline (3j), exhibited a little weaker activity than compound 3f in controlling the seizure induced by MES test at the dose of 22.8 mg/kg, but it possessed lower neurotoxicity with PI value of 12.0, which was safer than marketed drug carbamazepine. To explain the possible mechanism of anticonvulsant activity, compound 3j was tested in pentylenetetrazole test, isoniazid test, thiosemicarbazide test, 3-mercaptopropionic acid and strychnine test.

Synthesis of 2-substituted-7-heptyloxy-4,5-dihydro-[1,2,4]-triazolo[4,3-a]quinolin-1(2H)-ones with anticonvulsant activity

A series of 2-substituted-7-heptyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolin-1(2H)-ones was synthesized. The anticonvulsant effect and neurotoxicity of the compounds were calculated with maximal electroshock (MES) test, subcutaneous pentylenetetrazole (sc-PTZ), and rotarod tests with intraperitoneally injected mice. Among the synthesized compounds, 2-propionyl-7-heptyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline-1(2H)-one 4b was the most active one and also had the lowest toxicity. In the anti-MES potency test, it showed median effective dose (ED(50)) of 8.2 mg/kg, median toxicity dose (TD(50)) of 318.3 mg/kg, and the protective index (PI) of 39.0 which is much greater than the PI of the reference drugs phenytoin and carbamazepine.

Synthesis and anticonvulsant evaluation of 4-(4-alkoxylphenyl)-3-ethyl-4H-1,2,4-triazoles as open-chain analogues of 7-alkoxyl-4,5-dihydro[1,2,4]triazolo[4,3-a]quinolines

A series of 4-(4-alkoxylphenyl)-3-ethyl-4H-1,2,4-triazole derivatives was synthesized as open-chain analogues of 7-alkoxyl-4,5-dihydro[1,2,4]triazolo[4,3-a]quinolines. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES test) and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). MES test showed that 3-ethyl-4-(4-octyloxyphenyl)-4H-1,2,4-triazole 3q was found to be the most potent with ED(50) value of 8.3mg/kg and protective index (PI=TD(50)/ED(50)) value of 5.5, but compound 3r, 3-ethyl-4-(4-octyloxyphenyl)-4H-1,2,4-triazole, exhibited better PI value of 9.3, which was much greater than PI value of the prototype drug phenytoin. For explanation of the possible mechanism of action, the compound 3r was tested in pentylenetetrazole test, isoniazid test, thiosemicarbazide test, 3-mercaptopropionic acid and strychnine test.

Synthesis of 8-alkoxy-4,5-dihydro-[1,2,4]triazole[4,3-a]quinoline-1-ones and evaluation of their anticonvulsant properties

A series of 8-alkoxy-4,5-dihydro-[1,2,4]triazole[4,3-a]quinoline-1-one derivatives were synthesized using 7-hydroxy-3,4-dihydro-2(1H)-quinolone as the starting material. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES) and the subcutaneous pentylenetetrazole test (sc-PTZ), and their neurotoxicities were measured by the rotarod neurotoxicity test (Tox). The tests demonstrated that 8-hexyloxy-4,5-dihydro-[1.2.4]triazole[4.3-a]quinoline-1-one (4e) and 8-heptyloxy-4,5-dihydro-[1,2,4] triazole[4,3-a]quinoline-1-one (4f) were the most potent anticonvulsants, with 4e having ED50 values of 17.17 mg/kg and 24.55 mg/kg and protective index (PI = TD50/ED50) values of 41.9 and 29.3 in the MES and sc-PTZ tests, respectively, and 4f having ED50 values of 19.7 mg/kg and 21.2 mg/kg and PI values of 36.5 and 33.9 in the MES and sc-PTZ tests, respectively. The PI values of 4e and 4f were many fold better than that of the marketed drugs phenytoin, carbamazepine, phenobarbital and valproate, which have PI values in the range of 1.6-8.1 in the MES test and < 0.22-5.2 in the sc-PTZ test. Structure-activity relationships were also discussed.

Anticonvulsant and toxicity evaluation of some 7-alkoxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline-1(2H)-ones

To further investigate anticonvulsant activity of quinoline derivatives, a series of 7-alkoxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline-1(2H)-one derivatives was synthesized starting from 7-hydroxyl-3,4-dihydro-2(1H)-quinoline. In initial (phase I) screening and quantitative (phase II) evaluation, compound 7-benzyloxyl-4,5-dihydro-[1,2,4]thiazolo[4,3-a]quinoline-1(2H)-one (3f) was among the most active but also has the lowest toxicity. In the anti-MES potency test, it showed median effective dose (ED(50)) of 12.3 mg/kg, median toxicity dose (TD(50)) of 547.5 mg/kg, and the protective index (PI) of 44.5, which is much greater than PI of the prototype drugs phenytoin, phenobarbital, carbamazepin, and valproate. Compound 3f was chosen for further evaluation. In phase III pharmacological test, the compound had median hypnotic dose (HD(50)) and median lethal dose (LD(50)) of 1204 mg/kg and >3000 mg/kg, respectively, thus demonstrating much greater margin of safety compared to prototype drugs. The compound 3f also showed significant oral activity against MES-induced seizures and low oral neurotoxicity in mice in phase IV pharmacological test. Possible structure-activity relationship was discussed.