Department of Pharmaceutical Sciences, Birla Institute of Technology, Mesra 835215, Ranchi, India.
J Ethnopharmacol. 2010 Mar 24;128(2):533-6. doi: 10.1016/j.jep.2010.01.042. Epub 2010 Jan 28.
To systematically investigate the anticonvulsant activity of methanol extract of Benkara malabarica roots and to provide a biochemical basis elucidating its mode of action.
The median lethal dose (LD(50)) of Benkara malabarica extract was determined. The anticonvulsant activity of the extract was assessed in strychnine-induced and isoniazide-induced convulsion models; phenytoin (20mg/kg) and diazepam (1mg/kg) were used as standards, respectively. Percentage protection provided by the drug was accounted as decrease in the number of convulsions within 8h of observation. Mechanism of action was studied by performing GABA transaminase (GABA-T) assay, isolated from rat brain. Active constituent was isolated and characterized from the plant extract.
The median lethal dose (LD50) of Benkara malabarica was found to be more than 500 mg/kg. It demonstrated 30% and 35% protection against strychnine-induced convulsions and 60% and 80% protection against isoniazide-induced convulsions, at doses of 25mg/kg and 50mg/kg, respectively. Enzyme assay results revealed that Benkara malabarica extract possesses GABA-T inhibitory activity (IC50=0.721 mg/ml). Scopoletin which was identified as the major constituent of the extract was found to be an inhibitor of GABA-T (IC50=10.57 microM).
The anticonvulsant activity of the plant extract is predominantly GABA mediated and may be due to the action of scopoletin alone or is a result of synergy of different compounds in the extract in which scopoletin is the major constituent.
系统研究 Benkara malabarica 根甲醇提取物的抗惊厥活性，并为阐明其作用机制提供生化基础。
测定 Benkara malabarica 提取物的半数致死剂量（LD50）。采用士的宁和异烟肼诱发惊厥模型评价提取物的抗惊厥活性；苯妥英（20mg/kg）和地西泮（1mg/kg）分别作为标准。药物提供的保护百分比计算为观察 8 小时内惊厥次数的减少。通过对大鼠脑内分离的 GABA 转氨酶（GABA-T）进行测定来研究作用机制。从植物提取物中分离并鉴定活性成分。
Benkara malabarica 的半数致死剂量（LD50）大于 500mg/kg。在 25mg/kg 和 50mg/kg 剂量下，对士的宁诱发的惊厥分别显示 30%和 35%的保护作用，对异烟肼诱发的惊厥分别显示 60%和 80%的保护作用。酶活性测定结果表明，Benkara malabarica 提取物具有 GABA-T 抑制活性（IC50=0.721mg/ml）。鉴定为提取物主要成分的东莨菪内酯被发现是 GABA-T 的抑制剂（IC50=10.57μM）。
植物提取物的抗惊厥活性主要是 GABA 介导的，可能是由于东莨菪内酯单独作用，也可能是提取物中不同化合物的协同作用，其中东莨菪内酯是主要成分。
