Oxidized heptenes from flowers of Melodorum fruticosum.

Three oxidized heptenes, 7-benzoyloxy-6-oxo-2,4Z-heptadiene-1,4-olide, [7-benzoyloxy-4-hydroxy-1-methoxy-2E,4Z-heptadiene-1,6-dione] and 7-benzoyloxy-6-oxo-2,4E-heptadiene-1,4-olide, were isolated from flowers of Melodorum fruticosum. Their structures were determined by spectral data analysis. The first two compounds exhibited moderate cytotoxicity against a panel of human tumor cell lines, whereas the third was inactive.