Isolation and characterization of secondary metabolites from Plumeria obtusa.

Chromatographic purification of the methanolic extract of Plumeria obtusa yielded two new iridoid obtusadoids A (1) and B (2), along with eight known compounds plumieridin A (3), plumieridine (4), 1α-plumieride (5), 15-demethylplumieride (6), rel-(3R,3'S,4R,4'S)-3,3',4,4'-tetrahydro-6,6'-dimethoxy[3,3'-bi-2H-benzopyran]-4,4'-diol (7), glochiflavanoside B (8), oleanolic acid (9), and methyl coumarate (10). The structures of all the isolates (1-10) were determined by NMR spectroscopy and mass spectrometry. The data of known compounds (3-10) were further compared with the reported data for these compounds.