Abstract

Persea americana Mill (Lauraceae) is a medicinal plant used traditionally in Nigeria to treat several diseases including malaria, hypertension and febrile convulsions among others. Some of these indications are related to central activity but have not been systematically evaluated. This study investigated the neuropharmacological effects and the acute toxicity profile of the ethanolic dried seed extract of P. americana in mice. Fresh dried grounded seed of P. americana was extracted with 70% ethanol. Acute toxicity (LD₅₀) profile of the ethanolic extract of P. americana (EEPA) at 10 to 5000 mg/kg was determined orally (p.o.) and intraperitoneally (i.p.) in mice. The EEPA was further tested for behavioral, anxiolytic, hypothermic, sedative, anticonvulsant, and anti-nociceptive activities. The LD₅₀ of EEPA was determined to be ≥5000 mg/kg, p.o., and 2250 mg/kg, i.p. The extract at 250 to 1000 mg/kg dose-dependently caused significant (p<0.01 to 0.001) reduction in rearing and locomotor activity, signifying central nervous system (CNS) depression; significantly (p<0.01) lowered normal rectal temperature showing hypothermic effect; shortened onset and increased total sleeping time of ketamine (100 mg/kg, i.p.), suggesting sedative activity;  reduced mortality due to pentylenetetrazole, picrotoxin and strychnine, and blocked hind limb tonic extension on the electro-shock, conveying evidence of anticonvulsant activity; increased reaction time on the hot plate and inhibited acetic acid-induced writhings, indicating analgesic potential. This study reveals significant depressant effect of ethanolic extract of P. americana on the CNS; and manifested hypothermic, sedative, anticonvulsant and anti-nociceptive effects in mice, thus justifying its ethnomedicinal use which can also serve as a lead in drug discovery.

Key words: Avocado, behavioral, hypnosis, anticonvulsant, nociception.