[The extraction of biologically active substances from hop]

Substances which suppressed the effect of gonadotropin in the rat were obtained from hop. These biologically active substances were fractionated from the hop cone, from which lipophilic components (total resins) were removed with acetone. They were water soluble, 70,000-80,000 in molecular weight and were composed mainly of neutral sugars and uronic acid. Administration of the substances to immature rats primed with pregnant mare's serum gonadotropin (PMS) resulted in the following: a significant decrease of ovarian weight gain, whereas there was no change in uterine weight gain, and significant reductions of serum LH and progesterone from cultured luteal rat cells.