Structure elucidation and antioxidant activity of the phenolic compounds from Rhynchosia suaveolens.

A new benzophenone, 2-hydroxy-3,4-dimethoxybenzophenone (1), together with a known C-glycosylxanthone, mangiferin (2) and two known C-glycosylflavones, isovitexin (3) and isoorientin (4), were isolated from the flowers of Rhynchosia suaveolens DC. (Fabaceae). The structure of the new compound (1) and the known compounds (2-4) were elucidated by extensive 1D and 2D NMR spectral studies.

Two new chalcones from the flowers of Clerodendrum inerme.

Two new chalcones, 3-hydroxy-3',4'-dimethoxychalcone (1) and 3,2'-dihydroxy-3',4'-dimethoxychalcone (2), were isolated from the flowers of Clerodendrum inerme (L.) Gaertn together with two known flavones, 7-O-methylwogonin (3) and eucalyptin (4). The structures of the new compounds 1 and 2 have been established by extensive 2D-NMR and ESI-TOFMS studies.