Abstract

The neuropharmacological activities of methanol leaf extract (ME) of Annonasenegalensis Pers (Annonaceae) and its bioactive fractions (MF and F₇) were studied in rodents using pentylenetetrazol (PTZ)-induced seizures, pentobarbitone-induced sleep, apomorphine-induced stereotypy, open field, elevated plus maze (EPM) and rotarod performance tests. The extract and fractions inhibited PTZ-induced seizures, prolonged pentobarbitone-induced sleep, reduced stereotypic behaviour induced by apomorphine, decreased the frequency of line crossing and centre square entries and increased rearing in the air in the open field. The frequency of grooming and rearing against the wall were decreased, whereas the duration of grooming increased. Also, the extract and fractions increased the duration of stay in the open arm when compared to the closed arm of the EPM, and reduced the average time spent on the rotarod. Acute toxicity test showed an oral LD₅₀ of ME greater than 5 g/kg in mice. Phytochemical analysis showed that ME tested positive for carbohydrates, reducing sugar, resins, saponins, tannins, steroids, terpenoids, alkaloids, flavonoids and glycosides; MF tested positive for saponins, steroids, terpenoids, alkaloids, carbohydrates, reducing sugar, flavonoids and glycosides; while F₇ tested positive for flavonoids. These findings suggest that leaves of A. senegalensis possess anticonvulsant, central depressant and anxiolytic-like properties attributable to flavonoids.

Key words: Annona senegalensis, anticonvulsant, anxiolytic, sedative, stereotypy.

Abbreviation

Abbreviations: AST, Aspartate transaminase; ALT, alanine transaminase; ACP,acid phosphatise; ALP, alkaline phosphatise; LDH, lactate dehydrogenase; PHF,polyherbal formulation.