Extraction of the hormonal substance from hop.

Substances that suppressed a gain in the weight of pregnant mare's serum gonadotropin (PMSG)-primed immature rat ovaries, were obtained from dried powder of the hop cone. The substances were designated F1a-I and F1a-II. In immature rats at 4 days after PMSG priming, ovarian weights decreased by 58.0 +/- 3.7 and 66.9 +/- 6.6% the control by injections with 4 mg each of F1a-I and F1a-II, respectively. Apparent M1s of the partially purified fractions were nearly 80000 (F1a-I) and 66000-80000 (F1a-II). They were water-soluble. Acidic and neutral sugars were detected in the hydrolysate of the substance.