Xian-Yu Sun

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.

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.

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.

Characterization of the anticonvulsant activity of doxepin in various experimental seizure models in mice

In this paper, the anticonvulsant characteristics of doxepin were evaluated in numerous experimental seizure models, including maximal electroshock (MES)-, pentylenetetrazole (PTZ)-, isoniazid (ISO)-, 3-mercaptopropionic acid (3-MP)-, bicuculline (BIC)-, thiosemicarbazide (THIO)-, and strychnine (STR)-induced seizures. In addition, the acute adverse-effect profile of doxepin with respect to impairment of motor coordination was assessed with a mouse rotarod test. The evaluation of the time-course and dose-response relationships for doxepin provided evidence that the peak maximum anticonvulsant activity and acute adverse effects occurred 5 min after intraperitoneal (ip) administration. The results also revealed that doxepin had excellent anticonvulsant activity against maximal electroshock-induced seizures in mice with a median effect value (ED(50)) of 6.6 mg/kg. The assessment of acute adverse effects in the rotarod test revealed that doxepin induced acute neurotoxicity, and its median toxic dose (TD(50)) was 26.4 mg/kg. Additionally, doxepin showed anticonvulsant activity in several chemically-induced seizure models, including ISO, 3-MP, BIC, and THI. Based on this study, we can conclude that the antidepressant drug doxepin may be useful for treatment of depression in patients with epilepsy due to its short time to peak maximum anticonvulsant activity after ip administration (5 min) and remarkable anticonvulsant activity (6.6 mg/kg).

Synthesis and Anti-inflammatory Activity Evaluation of Novel 7-Alkoxy-1-amino-4,5-dihydro[1,2,4]triazole[4,3-a]quinolines

In this study, a novel series of 7‐alkoxy‐1‐amino‐4,5‐dihydro[1,2,4]triazole[4,3‐a]quinolines were synthesized by using 6‐hydroxy‐3,4‐dihydro‐2(1H)‐quinolone as the starting material. These compounds were evaluated for anti‐inflammatory activity through monitoring their ability to inhibit xylene‐induced ear edema in mice. Some of the tested compounds exhibited significant activity, and the compounds 5f (7‐(benzyloxy)‐4,5‐dihydro[1,2,4]triazolo[4,3‐a]quinolin‐1‐amine) and 5i (7‐(p‐chlorobenzyloxy)‐4,5‐dihydro[1,2,4]triazolo[4,3‐a]quinolin‐1‐amine) showed the highest anti‐inflammatory activity (52% and 58% inhibition, respectively, at 2 h pre‐administration) which were comparable to or even slightly more potent than the reference drug ibuprofen (55%). Furthermore, the structure‐activity relationship of these 1,2,4‐triazole quinolines was demonstrated.

Synthesis and primary anticonvulsant activity evaluation of 6-alkyoxyl-tetrazolo [5,1-a]phthalazine derivatives.

A new series of 6-alkyoxyl-tetrazolo[5,1-a] phthalazine derivatives (4 a-4 o) were synthesized as potential anticonvulsant agents. Anticonvulsant activity was evaluated by the maximal electroshock (MES) test. Neurotoxicity was evaluated by the rotarod neurotoxicity test. The pharmacological results showed that 6-(4-chlorophenyoxyl)-tetrazolo[5,1-a]phthalazine (4 m) was the most potent agent, with a median effective dose (ED50) of 6.8 mg/kg and a median neurotoxic dose (TD50) of 456.4 mg/kg. The protective index (PI = TD50/ED50) for compound 4 m was 67.1, which was significantly higher than that for the reference drug carbamazepine (PI = 6.4).

Design, synthesis and anticonvulsant activity evaluation of 7-substituted-4H-[1,2,4]triazino[3,4-a]phthalazin-4-one derivatives

In this study, a novel series of 7-substituted-4H-[1,2,4]triazino[3,4-a]phthalazin-4-one derivatives was synthesized as potential anticonvulsant agents. Their anticonvulsant activities were evaluated by the maximal electroshock (MES) test, and their neurotoxicities were evaluated by the rotarod neurotoxicity test. The pharmacological results showed that 7-hexyloxy-4H-[1,2,4]triazino[3,4-a]phthalazin-4-one 4e was the most potent with median effective dose (ED50) value of 6.6 mg kg-1, median toxicity dose (TD50) of 39.4 mg kg-1, providing a protective index (PI=TD50 /ED50) value of 6.0.