Active Isoflavones of Osaje Orange Fruits against Staphylococcus aureus

The genus Maclura is known for producing prenylated isoflavones with various biological activities, including antibacterial properties. Of the multiple isoflavones reported from some of its species, like Maclura pomifera (Rafin.) Schneider, the main active principle, remains unknown. A bio-guided analysis of the EtOAc fruit extract of M. pomifera resulted in the isolation of the active ingredient against Staphylococcus aureus. Examination of the most active fractions also led to a novel isoflavone, dihydroxyosajin (1), whose structural features were determined using spectroscopic and spectrometric methods. The proportions of the key active compounds in the plant material were evaluated using a multiple reaction monitoring method. Pomiferin and osajin were identified as the two predominant compounds. These compounds were present in greater amounts than scandenone and auriculasin, which are often reported as the major constituents in the species. The study recommends verifying that the acquired samples contain the target compounds in effective proportions.