Antiovulatory faculty of the flower of Malvaviscus conzattii.

The methanol extract of the flowers of Malvaviscus conzattii was orally administered in cycling unilaterally ovariectomized (ULO) rats at a dose level of 1 g/kg body wt/day for one or two cycles. The effect of the extract on the length of the cycle and ULO-induced compensatory ovulation and hypertrophy of the remaining ovary was assessed on the first oestrus following completion of treatment. Although no adverse influence was observed on either of the parameters, the cycle length was significantly prolonged and both the compensatory phenomena underwent significant inhibition after treatment of the extract for two consecutive cycles. In another experiment, the extract was found to be ineffective in preventing exogenous gonadotropin(s)-induced ovulation in immature and sub-adult rats. It is, therefore, suggested that the extract might have interfered with the synthesis and/or release of gonadotropin(s) from the pituitary while the ovarian utilization of gonadotropin(s) remained unaffected. The LD50 of the extract was found to be 20 g/kg body wt.