Les effets psychopharmacologiques d'un extrait brut de Lippia multiflora (Lm), obtenu après infusion des feuilles sèches, et de son huile essentielle (HE) issue d'une hydrodistillation ont été recherchés chez le rat Wistar en utilisant quelques tests classiques de la psychopharmacologie prévisionnelle. Cette étude a permis de montrer que les deux préparations aux doses étudiées sont bien tolérées, ne modifient pas l'activité motrice spontanée, potentialisent le sommeil barbiturique, retardent le redressement des pattes antérieures sur la barre métallique comme le diazépam. Ces deux formes de préparations, qui sont sans effet sur l'hypothermie et les stéréotypies apomorphiniques, réduisent significativement le nombre de crampes abdominales induites par l'acide acétique comme le fait l'acétylsalicylate de lysine (Aspégic *).

Psychopharmacological properties of crude extract and essential oil of Lippia multiflora (Lm), a verbenacea of african traditional pharmacopea were investigated in rat using classical methods. The extract of Lm is constituted by an infusion of dried leaves. The essential oil is obtained by hydrodistillation of the dried leaves of Lm with a yield of 0.6 %. A dilution of 1 % is realised with distilled water and the dose of 2 ml/kg of this solution was chosen for this study. The wistar rats of both sexes weighting between 150 and 250 g are used. Animal's behaviour is observed macrosco-pically for 12 hours. The spontaneous motor activity is appreciated by method of Martin et al. slightly modified. The number of squares jumped by animals in a rectangular cage is determined in ten minutes. The traction test which measures the time necessary for restoration of posterior paws of rat on metallic bar and the duration of pentobarbital sleeping are used for evaluation of muscle relaxant and sedative effects, respectively. The effects of the two preparations of Lm on apomorphin stereotypies and hypothermia are used to investigate the eventual neuroleptic or antidepressant activity. Analgesic property is evaluated by using acetic acid method. The results are expressed as mean SEM. Data are analysed by using the Dunnett's test. A probability level of 0.05 or less was considered to be stalistically significant. The two preparations of Lm at the doses used are well tolerated by rats. No macroscopic difference is observed in behavioural of control and treated groups. Crude extract and essential oil: - does not modify a spontaneous motor activity: control: 45.00 5.63; crude extract of Lm: 31.00 5.63; essential oil of Lm: 28.00 7.62; diazepam 4 mg/kg: 23.80 5.27 (P < 0.05); - caused an increase of the time necessary for the restoration of paws on the metallic bar in the traction test: control 1.20 0.25 sec; crude extract of Lm 5.60 0.57 sec (P < 0.01), essential oil of Lm. 3.60 0.57 sec (P < 0.01) diazepam 3.60 0.57 sec (P < 0.01). The differences between the results obtained with crude extract, essential oil and diazepam are significant; - caused a reduction of abdominal cramps induced by acetic acid, control: 26.80 0.41; crude extract of Lm: 17.00 1.45 (P < 0.01); essential oil of Lm: 9.20 1.91 (P < 0.01) and acetylsalicylic acid (Aspegic *) 25 mg/kg 5.40 1.25 (P < 0.01). The differences is significant between essential oil and crude extract (P < 0.05) but no significant difference is observed between essential oil and acetylsalicylate of lysin. No activity of the two preparations is observed on apomorphin stereotypia and hypothermia comparatively with haloperidol 4 mg/kg and clomipramin 16 mg/kg respectively. Those results confirm the tranquillizer and analgesic activities of Lm and reveal that the crude extract would be more muscle relaxant and the essential oil more analgesic.