Chemical Studies on 'Clover Sickness'

The functions of isoflavonoids and related compounds as well as of their degradation products in the allelopathy of red clover were investigated from chemical standpoint. Susceptibilities of red clover to isoflavonoids, related compounds and their degradation products were higher than those of various plants including white and alsike clovers, and contents of the isoflavonoids in red clover were extremely higher as compared with those in white clover and orchard grass. Inhibitory substances were isolated from the soil capable to cause “clover sickness,” but they were not isoflavonoids but phenolic acids considered to be originated probably in the formers. These acids were also obtained together with some kinds of isoflavonoids from the waste culture solution used for cultivation of red clover seedlings. Finally degradation process of isoflavonoids was followed up in neutral, acidic and alkaline solutions.