Presence of a Principle with Progesterone-like Activity Obtained from a Plant Source

Abstract

The known biological incompleteness of the protein fraction of the bean has received considerable attention in interpretations of the malnutrition caused by a raw bean diet. Belák and Szathmáry, 1 , 2 and Zselyonka and Illényi 3 were the first to point out that, together with this loss of weight, there was also observable an inhibition of the estrus of mice during the period of feeding with a diet containing 15% of raw bean. They isolated a globulin fraction from the bean flour, which they referred to as “phaseolin.” Together with a loss of weight, the inhibition of the estrus of the mice could be observed when 5% of the basic food of the mice was replaced by this protein fraction. The fat-soluble fraction of the bean was found by the same authors to be ineffective. Selye and Collip, 4 in replacing 30 to 50% of the basic food of the rat with bean flour, observed a certain atrophy of the ovaries and interpreted their findings as a consequence of a “malnutrition.”

In our feeding experiments, first using rats as test animals, and following the course of the estrous cycles by means of the vaginal smear method of Long and Evans, 5 we were able to establish the following :

1. Complete inhibition of the normal estrous cycle could be observed when 15% of the basic food was replaced by bean flour. Controls, on a diet without bean flour, failed to show any change in their regular cycles, whether that diet was offered to them (a) ad libitum, or (b) in an amount 15% less by weight than that regularly taken by these animals.

2. The pure globulin fraction of the bean, as prepared by Osborne, 6 given in 5 % by weight to the basic food did not inhibit the estrus of the rats.