Intraperitoneal injections of the aqueous extract of winter cherry fruits (Physalis alkekengi) to female rats produced 100% diestrus. The rats resumed their normal estrus cycle upon withdrawal of this extract. Although there was no significant decrease in the number of implantation sites, the number of pups born to rats decreased by 96% with extract administration. Treatment with this extract had no effect on body weight, uterus weight, plasma protein level or plasma total creatine kinase activity. However, the level of plasma progesterone was diminished by 44%. In addition, uterine creatine kinase BB-isosyme (an estrogen-induced protein) showed a time-dependent inhibition of activity from 55% to 82%.
