FLAVONOID CONCENTRATION CHANGES IN MATURING BROAD BEAN PODS

Five flavonoid aglycons and eight flavonol glycosides were isolated from broad bean pods. By chemical, chromatographic, and spectral methods the aglycons were identified as 7,3',4'-trihydroxyflavone, 7,4'-dihydroxyflavone, geraldone, butein, and kaempferol and the glycosides as kaempferol 3-glucoside, 7-glucoside, 3-(2"-rhamnosyl)galactoside 7-rhamnoside, 3-galactoside 7-rhamnoside, 3-rhamnosyl-(6"-acetyl)galactoside 7-rhamnoside, and 3-(6"-acetyl)galactoside 7-rhamnoside and as quercetin 3-galactoside 7-rhamnoside and 3-(6"-acetyl)galactoside 7-rhamnoside. The concentration changes of these flavonoids in pod tissues with progressive stages of maturity were evaluated by HPLC analysis. A significant increase in the concentration of both flavonoid aglycons and glycosides was observed when the pods matured and became reddish and brown. Some of the flavonoid aglycons detected in broad bean pods had previously been reported as Rhizobium nodulation gene inducers.