European Scientific Journal June 2020 edition Vol.16, No.18 ISSN: 1857-7881 (Print) e - ISSN 1857-7431 114 Anticonvulsant Activity of Hydroalcoholic Extract of Ageratum Conyzoides L. (Asteraceae) in Mice Patricia Randrianavony, PhD Laboratoire de Pharmacologie Générale, de Pharmacocinétique et de Cosmétologie, Faculté des Sciences, Université d’Antananarivo, Madagascar Nat Quansah, PhD School For International Training Study Abroad Summer Program Madagascar: Traditional Medicine And Health Care Systems, Antananarivo, Madagascar Roukia Djoudi, PhD Laboratoire Mixte International de Biotechnologie Environnement Santé (LMI-BES) Faculté des Sciences de Technologie et de l’Environnement, Université de Mahajanga, Madagascar Nyamekye A. Quansah, Fanantenanirainy Randimbivololona, PhD Laboratoire de Pharmacologie Générale, de Pharmacocinétique et de Cosmétologie, Faculté des Sciences, Université d’Antananarivo, Madagascar Doi:10.19044/esj.2020.v16n18p114 URL:http://dx.doi.org/10.19044/esj.2020.v16n18p114 Abstract This work aims to study the anticonvulsant activity in vivo of the hydro alcoholic extract of Ageratum conyzoides L. (ASTERACEAE) in mice. Seizure was induced by electric stimulation of animal ears and intraperitoneal injection of picrotoxin. The extract increases the seizure threshold and reduces picrotoxin-induced convulsion duration. Animals of control group reacted to electric shock of 10.67 ± 0.74 mV, versus 14.33 ± 0.64, 22.67 ± 1.28 and 29.33 ± 0.64 mV for the animals treated with the extract at doses 200, 400 and 800 mg/kg respectively (P<0.05). Duration of clonic seizure induced by picrotoxin decreases from 36.04 ± 3.46 s in control group to 31.33 ± 0.88, 14.08 ± 1.02 and 10.07 ±1.31 s in the treated animals, while tonic seizure duration in control group is equal to 156.33 ± 24.53 s versus 73.02 ± 5.32 s and 29.67 ± 3.59 s in the animals treated with the extract at doses 400 and 800 mg/kg respectively (P<0.05). Alkaloids in the extract might be responsible for this activity by blocking Na+ or K+ channels, it also might enhance GABA or inhibit glutamate action.