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This study evaluated some central nervous system activities of fractions of Persea americana seed extract, its possible mechanism(s) of action in mice, and identified the constituents of the fractions. Ethanol extract of P. americana was sequentially partitioned into n-hexane (NHF), ethyl acetate (EAF) and aqueous (AQF) fractions; evaluated for acute toxicity (LD50), behavioural, sedative and anticonvulsant activities, and possible mechanisms of action of AQF studied. Constituents of the biologically active NHF and AQF were identified by conversion to trimethylsilyl-derivatives followed by gas chromatography mass spectrometry analysis. The fractions (50, 100 and 200 mg/kg, i.p.) dose-dependently caused significant reduction in behavioural activities; reduced sleep latency and increased total sleeping time on pentobarbital (30 mg/kg)-induced hypnosis and offered varying protections against PTZ-induced mortality and hind limb tonic extension on MES-induced convulsion. Naloxone and flumazenil significantly reversed the inhibitory effect of AQF on rearing. Analysis of the TMS-derivatized NHF and AQF fractions revealed the presence of 9 and 21 compounds respectively. This study established that the fractions depressed the CNS, exhibited sedative and anticonvulsant activities; and the mechanism(s) of action of the aqueous fraction (AQF) may be through enhancement of GABA and opioid neurotransmission.
Keywords: Persea americana, behavioural, sedative, anticonvulsant, TMS derivatives, GC-MS