Neuropharmacological Activities of Ethanolic Extract of Cola millenii Dried Leaf in Rats

Objective: The leaf of Cola millenii is used in ethnomedicine to treat several ailments including; infections, fever and pain among several other diseases in Southwest Nigeria. Preliminary report indicates that the ethanolic leaf extract of this plant exhibits some central nervous system (CNS) activities; hence, this study investigated the acute toxicity and some central effects of the ethanolic dried leaf extract of C. millenii in rats.

Materials and Methods: Ethanolic dried leaf extract of C. millenii (CME) was obtained by soaking dried powdered leaf of the plant in 70% ethanol for 72 h and the filtrates recovered was dried in vacuo. The extract was tested for acute toxicity (LD50) through the oral (p.o.) and intraperitoneal (i.p.) routes; dose-dependently evaluated for novelty-induced behavioural activities, sedative and anticonvulsant activities in rats. Diazepam (1-2 mg/kg, i.p.) and 5% Tween 80 served as positive and negative control groups respectively (n=5).

Results and Discussion: LD50 values obtained were 5000 mg/kg, p.o., and 2154 mg/kg, i.p. The CME (250, 500 and 1000 mg/kg, i.p.) significantly (p<0.05-0.01) reduced rearing, grooming, locomotion and head-dips dose-dependently compared to the vehicle, signifying CNS depression; significantly (p<0.05) reduced sleep latency and prolonged total sleeping time on the ketamine-induced hypnosis indicating sedative activity; prolonged the latency to convulsion, delayed time of death and offered between 20-40 percent protections against the pentylenetetrazole (PTZ)-induced convulsions, suggesting anti-convulsant potentials.

Conclusion: It is concluded that the ethanolic dried leaf extract of C. millenii is non-toxic orally but slightly toxic intraperitoneally; demonstrated significant depression of the CNS, possess sedative and anticonvulsant activities in rats.