Antifertility and hormonal properties of flavones of Striga orobanchioides

The two flavones, apigenin and luteolin, isolated from Striga orobanchioides, were investigated for endocrine and contraceptive properties. Graded doses of these compounds (5-25 mg/kg body weight/day) when administered from day 1 to day 4 of pregnancy showed dose-dependent and significant anti-implantation activity. The mean effective Dose 100% (MED(100)) for both compounds was found to be 25 mg/kg body weight. Oral administration of these compounds caused a significant increase in uterine weight in immature ovariectomised rats. It also caused a significant increase in uterine diameter, thickness of the endometrium and its epithelial cell height when compared with those of control rats. The uterotrophic potency was less than that of ethinyl estradiol. Simultaneous administration of these compounds with ethinyl estradiol caused a significant increase in uterine weight, uterine diameter, thickness of the endometrium and height of endometrial epithelium. The extent of these changes was also less than that in only ethinyl estradiol-treated rats. Hence the compounds exhibited estrogenic properties at their contraceptive dose level when given alone. However, along with ethinyl estradiol, they exhibited slight anti-estrogenic activity.