Monopteryx inpae contains six 5,7-dihydroxyisoflavones, three of which, such as the novel 5,7-dihydroxy-8.3'.4'-trimethoxy derivative, have additionally methoxyls on ring A. All three isoflavones of M. uaucu are, by contrast, 7-hydroxy-8-methoxy derivatives. From the chemical standpoint, the former species thus appears to be more primitive than the latter.