Analgesic and antipyretic activities of an aqueous extract and of the flavone linarin of Buddleia cordata.

The dried aqueous extract of leaves of Buddleia cordata (loganiaceae) and its main flavonoid glycoside, linarin, have been evaluated for analgesic and antipyretic effects in mice and rats, respectively. Both the extract and linarin exerted significant and dose-dependent analgesic and antipyretic activities, the first being obtained against a chemical stimulus (writhing a test in mice) and the second being obtained by a pyretogenic stimulus (yeast-induced hyperthermia test). Furthermore, the response of the animals in the hot plate test was modified by linarin and an aqueous extract. These activities were similar to that showed by morphine sulfate (MS) and they were inhibited by naxolone pretreatment, a specific morphinic antagonist compound. These findings lead to the conclusion that the aqueous extract and linarin exert central analgesic properties. On the other hand, linarin was shown to be responsible for the antipyretic activity of this species.