Pterocarpans from Bituminaria morisiana and Bituminaria bituminosa

The aerial parts of Mediterranean papilionaceous plants Bituminaria morisiana and B. bituminosa afforded, along with known phenolics, the prenylated pterocarpans bitucarpin A and B, whose structure was elucidated by spectroscopic techniques. A known isoflavonoid (8-prenyldaidzein) was also obtained for the first time as a genuine plant constituent. The accumulation of pterocarpans at the expense of biogenetically more primitive shikimate metabolites like furanocoumarins or isoflavonoids supports the inclusion of this plant, once part of the genus Psoralea, into the distinct genus Bituminaria.