Antifertility effect of aqueous extract of seeds of Cassia fistula in female rats.

Oral administration of aqueous extract of seeds of Cassia fistula to mated female rats from day 1-5 of pregnancy at the doses of 100 and 200 mg/kg body weight resulted in 57.14% and 71.43% prevention of pregnancy, respectively, whereas 100% pregnancy inhibition was noted at 500 mg/kg bw. In the uterine bioassay test carried out in immature bilaterally ovariectomized female rats, aqueous extract of seeds of Cassia fistula (100 mg/kg bw) increased the uterine wet weight (p<0.05) and luminal epithelial cell height (p<0.001) but did not induce premature opening of the vagina. This suggests a mild estrogenic activity of the extract. However, when the extract was administered conjointly with estradiol valerate (EDV, 0.1 mg/kg bw), it significantly (p<0.001) prevented the estrogen-induced uterotrophic effect, thus showing an antiestrogenic nature of the extract in the presence of a strong estrogen.