Zhe-Shan Quan

Synthesis and Anticonvulsant Activity of 6-Alkoxy-[1,2,4]Triazolo[3,4-a]Phthalazines

A new series of 6‐alkoxy‐[1,2,4]triazolo[3,4‐a]phthalazines (3a–3v) were synthesized and their anticonvulsant activity and neurotoxicity were evaluated by the maximal electroshock test and the rotarod test respectively. Significant anticonvulsant activity was displayed by a number of compounds. The most promising compounds 6‐(4‐chlorobenzyloxy)‐[1,2,4]triazolo[3,4‐a]phthalazine (3f) and 6‐heptyloxy‐[1,2,4]triazolo[3,4‐a]phthalazine (3s) showed a median effective dose of 7.1 and 11.0 mg/kg, and had protective index value of 5.2 and 8.0 respectively. The two compounds were further found to have potent activity against seizures induced by pentylenetetrazole, isoniazid, thiosemicarbazide, 3‐mercaptopropionic acid but not seizures induced by strychnine, indicating that the two compounds might function by enhancing gamma‐aminobutyric acid neurotransmission.

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 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, with4e 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, and4f 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 of4e and4f 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.

Short communication - N-palmitoylethanolamide, an endocannabinoid, exhibits antidepressant effects in the forced swim test and the tail suspension test in mice

The antidepressant-like effects of N-palmitoylethanolamide (PEA), a putative endocannabinoid, was investigated in mice using the tail suspension test (TST) and the forced swimming test (FST). In TST, PEA (10, 20, and 40 mg/kg) produced a statistically significant reduction in immobility (50, 32, and 34%, respectively, vs. the control group), whereas fluoxetine (20 mg/kg) reduced immobility by 38%. In FST, PEA (5, 10, and 20 mg/kg) produced a statistically significant reduction in immobility (15, 21, and 36%, respectively), whereas fluoxetine (20 mg/kg) reduced immobility by 18%. Moreover, PEA (20 mg/kg) did not significantly change motor activity in a spontaneous behavioral test. In conclusion, PEA (dose range of 5-40 mg/kg) administered orally reduced immobility in TST and FST, comparable to the antidepressant effect of fluoxetine, and had no effect on spontaneous activity in mice.

Synthesis and anti-inflammatory activity evaluation of some novel 6-alkoxy (phenoxy)-[1,2,4]triazolo[3,4-a]phthalazine-3-amine derivatives

Starting from phthalic anhydride, several new 6-alkoxy(phenoxy)-[1,2,4]triazolo[3,4-a]phthalazine-3-amine derivatives were synthesized as potent anti-inflammatory agent. The study showed that the compounds 6h (6-(2-chlorophenoxy)-[1,2,4]triazolo[3,4-a]phthalazine-3-amine) and 6s (6-(4-aminophenoxy)-[1,2,4] triazolo[3,4-a]phthalazine-3-amine) exhibited the highest anti-inflammatory activity (81% and 83% inhibition, respectively, at 0.5 h after i.p. administration) which were slightly more potent than the reference drug Ibuprofen (61%). Furthermore, the peak activity of 6h and 6s was observed at the 3 h after p.o. administration, and they exhibited stronger anti-inflammatory activity than Ibuprofen at the dose of 50 mg/kg at the peak time.

Evaluation of the anticonvulsant activity of 6-(4-chlorophenyoxy)-tetrazolo[5,1-a]phthalazine in various experimental seizure models in mice

This study investigated the anticonvulsant activity of a new phthalazine tetrazole derivative, QUAN-0808 (6-(4-chlorophenoxy)-tetrazolo[5,1-a]phthalazine), in the mouse maximal electroshock (MES) seizure model. The neurotoxicity of QUAN-0808 was investigated using the rotarod neurotoxicity test in mice. QUAN-0808 exhibited higher activity (median effective dose, ED(50) = 6.8 mg/kg) and lower neurotoxicity (median toxic dose, TD(50) = 456.4 mg/kg), resulting in a higher protective index (PI = 67.1) compared with carbamazepine (PI = 6.4). In addition, QUAN-0808 exhibited significant oral anticonvulsant activity (ED(50) = 24 mg/kg) against MES-induced seizure with low neurotoxicity (TD(50) > 4500 mg/kg) in mice, resulting in a PI value of more than 187.5. QUAN-0808 was also tested in chemically induced animal models of seizure (pentylenetetrazole [PTZ], isoniazid [ISO], thiosemicarbazide [THIO] and 3-mercaptopropionic acid [3-MP]) to further investigate the anticonvulsant activity; QUAN-0808 produced significant anticonvulsant activity against seizures induced by ISO, THIO and 3-MP.

Synthesis and Evaluation on Anticonvulsant and Antidepressant Activities of 5-Alkoxy-tetrazolo(1,5- a)quinazolines

Several 5‐alkoxy‐tetrazolo[1,5‐a]quinazoline derivatives have been synthesized by reacting 2,4‐dichloroquinazoline with various phenols or aliphatic alcohol and then with sodium azide. The structures of these compounds have been confirmed by IR, MS, 1H‐NMR, and elementary analysis. Anticonvulsant activities were evaluated using the maximal electroshock (MES) test. Most of the synthesized compounds displayed weak anticonvulsant activity at a dose of 300 mg/kg. Antidepressant activities were investigated by forced swimming test. Two compounds, namely 5‐(hexyloxy)tetrazolo[1,5‐a]quinazoline and 5‐(4‐methoxyphenoxy)tetrazolo[1,5‐a]quinazoline, showed significant antidepressant activity, which decreased the immobility time by 62.2 and 51.7% at 100 mg/kg dose level.

Synthesis and Anticonvulsant Activity Evaluation of 5-Phenyl-(1,2,4)triazolo(4,3-c)quinazolin-3-amines

In the present study we describe the syntheses and anticonvulsant activity evaluation of 5‐phenyl‐[1,2,4]triazolo[4,3‐c]quinazolin‐3‐amine derivatives. Their anticonvulsant activity and neurotoxicity were evaluated by the maximal electroshock seizure test (MES) and the rotarod test, respectively. The majority of the compounds prepared were effective in the MES screens at a dose level of 100 mg/kg. Of these compounds, the most promising was compound 8h, which showed an ED50 value of 27.4 mg/kg and a protective index (PI) value of 5.8. These values were superior to those provided by valproate (ED50 and PI values of 272 and 1.6, respectively) in the MES test in mice. As well as its anti‐MES efficacy, the potencies of compound 8h against seizures induced by pentylenetetrazole and thiosemicarbazide were also established, with the results suggesting that the GABAergic system‐mediated mechanisms might be involved in its anticonvulsant activity.

Design, synthesis of 8-alkoxy-5,6-dihydro-[1,2,4]triazino[4,3-a]quinolin-1-ones with anticonvulsant activity.

A new series of 8-alkoxy-5,6-dihydro-[1,2,4]triazino[4,3-a]quinolin-1-one derivatives were synthesized. Their anticonvulsant activities were evaluated by the maximal electroshock (MES) test, and their neurotoxicities were evaluated by the rotarod neurotoxicity test. The results showed that 8-heptyloxy-5,6-dihydro-[1,2,4]triazino[4,3-a]quinolin-1-one 5t was the most potent with median effective dose (ED(50)) value of 11.4 mg/kg, median toxicity dose (TD(50)) of 114.1 mg/kg, providing a protective index (PI=TD(50)/ED(50)) value of 10.0, which is much greater than the PI of the prototype drug carbamazepine (PI=6.4). To explain the possible mechanism of anticonvulsant activity, the compound 5t was tested in chemically induced seizures.

Synthesis and Anticonvulsant Activity of 5‐Phenyl‐[1,2,4]‐triazolo[4,3‐a]quinolines

A series of novel 5‐phenyl‐[1,2,4]‐triazolo[4,3‐a]quinoline derivatives was synthesized by the cyclization of 2‐chloro‐4‐phenyl‐1,2‐dihydronaphthalene with formohydrazide. The starting material 2‐chloro‐4‐phenyl‐1,2‐dihydronaphthalene was synthesized from ethyl‐3‐oxo‐3‐phenylpropanoate and substituted aniline. Their anticonvulsant activities were evaluated by the maximal electroshock (MES) test and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). The maximal electroshock test showed that 7‐hexyloxy‐5‐phenyl‐[1,2,4]‐triazolo[4,3‐a]quinoline 4f was found to be the most potent compound with an ED50 value of 6.5 mg/kg and a protective index (PI = ED50 / TD50) value of 35.1, which was much higher than the PI of the reference drug phenytoin.