Desmoschinensisflavones A and B, two rare flavones having a hybrid benzyl benzoate ester-flavone structural framework from Desmos chinensis Lour.

Two rare flavones having a hybrid benzyl benzoate ester-flavone structural framework, desmoschinensisflavones A and B (1 and 2), together with 12 known compounds (3-14) were isolated from the fruit, leaf, and twig extracts of Desmos chinensis (red flower). The new structures were characterized by UV, IR, NMR, and HRESITOFMS data. Desmoschinensisflavones A and B have a distinctive skeleton of benzoate ester-flavones with a C-4'' and C-6 and C-8 connection via a methylene group, respectively. Plausible biosynthesis pathways to compounds 1 and 2 are proposed based on an intermolecular nucleophilic 1,4-addition to ortho -quinone intermediates. Compounds 6-8 and 12 showed weakly antioxidant inhibition with IC 50 values in the range of 65.4-74.6 μM.