From the roots of B. oblongifolia 3 new isoprene flavone derivs., named brosimone G (I), H (II), and I (III), together with the known albanins A and E, were isolated. The structures of I-III were detd. by UV, 1H- and 13C-NMR, and mass spectral data. Antimicrobial activity of the compds. is also reported.