Analgesic and anticonvulsant effects of extracts from the leaves of Kalanchoe crenata (Andrews) Haworth (Crassulaceae)

Kalanchoe crenata Andr. (Crassulaceae) is a fleshy herbaceous plant used in the African traditional medicine as remedies against otitis, headache, inflammations, convulsions and general debility. In the present work, the analgesic effects of methylene chloride/methanol (1:1) (CH2Cl2/CH3OH) extract and its hexane, methylene chloride (CH2Cl2), ethyl acetate, n-butanol fractions and aqueous residue have been evaluated using acetic acid, formalin and pressure test. The anticonvulsant effects of the CH2Cl2/CH3OH extract were also investigated on seizures induced by pentylenetetrazol (PTZ 70 mg/kg), strychnine sulphate (STN 2.5 mg/kg) and thiosemicarbazide (TSC 50 mg/kg). CH2Cl2/CH3OH extract and its fractions, administered orally at the doses of 150 and 300 mg/kg, exhibited protective effect of at least 30% on the pain induced by acetic acid. The CH2Cl2 fraction at 300 mg/kg showed a maximal effect of 78.49%. The CH2Cl2/CH3OH extract and its CH2Cl2 fraction at the doses of 150 and 300 mg/kg significantly reduced the first phase of pain induced by formalin while the second phase was completely inhibited. The CH2Cl2 fraction produced more than 45% reduction in the sensitivity to pain induced by pressure. The CH2Cl2/CH3OH extract of Kalanchoe crenata significantly increased the latency period in seizures induced by PTZ and significantly reduced the duration of seizures induced by the three convulsant agents. The extract protected 20% of animals against death in seizures induced by TSC and STN.These results suggest a peripheral and central analgesic activities as well as an anticonvulsant effect of the leaves of Kalanchoe crenata.