ANTINOCICEPTIVE PROPERTIES OF STEROIDS ISOLATED FROM PHYLLANTHUS-CORCOVADENSIS IN MICE

The antinociceptive actions of the steroid compounds isolated from the leaves, stems, and roots of P. corcovadensis have been investigated i n mice. Stigmasterol, stigmasterol acetate, beta-sitosterol, and aspir in (3-100 mk/kg, i.p.) inhibited, in a dose-related manner, acetic aci d-induced abdominal constriction in mice with ID(50)s of 16, 11, 9, an d 24 mg/kg, respectively. In the formalin test, stigmasterol and stigm asterol acetate (10-100 mg/kg, i.p.) caused graded inhibition of both the neurogenic (first phase) and inflammatory phases (second phase) of formalin-induced pain. However, both compounds were more effective in relation of the second phase of the formalin test with ID50 values of 26 and 41 mg/kg, respectively. Furthermore, both steroids failed to a ffect the edematogenic response of the formalin test. Given orally, st igmasterol and stigmasterol acetate (50-200 mg/kg) also exhibited sign ificant though less potent analgesic action against both acetic acid- and formalin-induced nociception in mice. In addition, stigmasterol (u p to 100 mg/kg, i.p.), in contrast to morphine (10 mg/kg, s.c.), had n o analgesic effect in either tail-flick or hot-plate models. These fin dings suggest that stigmasterol and beta-sitosterol may account, at le ast in part, for the antinociceptive actions reported previously for t he hydroalcoholic extract of Phyllanthus corcovadensis.