Anxiolytic and sedative effects of extracts of Hibiscus sabdariffa Linn (family Malvaceae)

Abstract

Aqueous (A), hydroalcoholic (AE) and ethanolic (F,) extracts and fractions of dried calyxes of Hibiscus sabdariffa were evaluated for anxiolytic property using elevated-plus maze (EPM), and sedative properties using ketamine-induced sleep in animal models. I he extracts exhibited a dose-dependent increase in the time spent in the open arm with ethanol extracts having the best anxiolytic activity. The extracts at A5mg/kg. AE5mg/kg and A50mg/kg did not cause an increase in time spent in the open arms (p<0.05) but other doses significantly did when compared with the vehicle control. The fractions of the hydroalcoholic extracts showed no significant anxiolytic activity. Neither the extracts nor the fractions significantly reduced or increased latency to sleep after a single (lose except AE300 (p<0,01), There was significant reduction in onset of sleep, and increase in sleeping time with A and AE extracts with multiple doses at A300, AE50 and AE300mg/kg dose groups (P<0.001, p<0.0l and p<0.05 respectively). A reduction in sleeping time after several daily doses of ethanol extracts doses was observed. A single dose of one of the fractions (EAC at 50mg/kg) caused a significant reduction (p<0.05) in sleep duration. I he study showed that extracts of Hibiscus sabdariffa possess anxiolytic and sedative effects which become more pronounced with administration of repeated doses of the extracts.