Biflavonoids from Ouratea multiflora.

A new flavone dimer, 3-hydroxy-4',5,7-trimethoxyflavone-(6-->8")-3"-hydroxy-3"',4"', 5",7"-tetramethoxyflavone, together with amenthoflavone, have been isolated from the leaves of Ouratea multiflora. Its structure was established by spectroscopic methods, including two-dimensional NMR spectroscopy.

Inhibition of lens aldose reductase by biflavones from Ouratea spectabilis.

Two biflavonoids were isolated from the EtOH extract from leaves of Ouratea spectabilis. Their structures were established to be the novel 6,6"-bigenkwanin and 7,7"-dimethoxyagathisflavone on the basis of spectroscopic data. The inhibition of bovine lens aldose reductase exerted by these biflavones has been studied.