Two flavones, luteolin 7-O-ß-glucuronide and diosmetin 7-O-ß-glucuronide, were isolated and identified from Chrysanthemum morifolium L. v. Ramat leaves. Identification techniques included HPLC DAD, MS, H1 and C13 NMR spectroscopy. At concentrations of 0.2 and 2.0 mM, luteolin 7-O-ß-glucuronide significantly reduced the frond number and chlorophyll content of Lemna gibba plants, but did not significantly affect dry weight. At a concentration of 0.2 mM diosmetin 7-O-ß-glucuronide had no significant effect on frond number, dry weight or chlorophyll concentration of L. gibba. These results indicate that an ortho-3′,4′-dihydroxy arrangement of the ß-flavonoid ring in the luteolin compound is probably responsible for allelopathic activity.
