Postcoital antifertility effect of piperine.

The antifertility activity of piperine was investigated in pregnant mice when given by various routes of administration and at different periods of gestation. Piperine effectively inhibited implantation, produced abortion and delayed labor when it was given from day 2 through 5, day 8 through 12 and day 15 until labor, respectively. At the same dose level which interrupts pregnancy, piperine did not affect the estrous cycle. Neither uterotropic, antiestrogenic nor antiprogestational property was observed. Additionally, piperine also inhibited uterine contraction both in vivo and in vitro. These results suggested that the antifertility activity of piperine did not operate through any hormonal actions or uterotonic activity.