Antipyretic activity of the extracts of Hibiscus sabdariffa calyces L. in experimental animals

The effects of the extracts from Hibiscus sabdariffa calyces L. (H. sabdariffa) on nociceptive response using writhing, hot plate and formalin test in mice and the antipyretic activity in yeast-induced fever in rats, were examined. Anti-inflammatory activity was also investigated on carrageenin-induced paw edema in rats. No acute toxicity was observed in mice after oral administration of the ethanol and aqueous extract of H. sabdariffa calyces at the dose of 15 g/kg. Oral administration of the ethanol extract at the dose of 800 mg/kg significantly decreased the number of contortions and stretchings induced by acetic acid in mice. The aqueous extracts had no effect on this test. Neither the ethanol nor aqueous extract had an effect in the formalin and hot plate tests in mice. The ethanol and the vacuum dried extract of H. sabdariffa calyces (200-800 mg/kg, p.o.) decreased the yeast-induced fever in rats. The H. sabdariffa extract had no effect on carrageenininduced paw edema in rats. These results suggest that the ethanol and aqueous extract (vacuum dry) of H. sabdariffa calyces possess antipyretic action through mechanisms that are different from that of aspirin