The assay of oestrogenic activity of Trifolium subterraneum L. by increase in uterine weight in the spayed guinea pig. II. Assays

Abstract

When fed to spayed guinea pigs under the conditions outlined in Part I (Alexander and Watson 1951), whole clover from 83 per cent. of all samples and lamina from all of the few samples of this fraction yielded values of the mean log uterine weight in decigrams (mean log u.dg.) above 0.75, and provided data from which relative oestrogenic activities could be calculated by application of the previously derived statistics. The activity of fresh samples of four varieties of whole clover rose to a maximum in the mid-winter months, then decreased as the season progressed. However, both the absolute level and the magnitude and time relations of the changes varied with the different materials. Samples of lamina possessed high activity, while samples of petiole and stem exhibited little or no activity. Both the lamina and whole clover fractions of samples from grazed areas exhibited higher activity than corresponding material from adjacent ungrazed areas. Dehydration of clover reduced its activity. Little further change in activity occurred during storage of dried material over a period of 17 months. No demonstrable activity was present in the few species of plants other than subterranean clover which were tested.