Quality and quantity of prevailing flavonoid glycosides of yellow and green French beans (Phaseolus vulgaris L)

The flavonoid composition of six varieties in either case of yellow and green French beans was investigated. Fresh beans were chopped under Liquid nitrogen just after harvest and lyophilized subsequently. The flavonoids were exhaustively extracted, purified by selective adsorption to and stepwise elution from polyamide, and separated by RP-HPLC with UV detection. With one exception the qualitative chromatographic pattern of the 12 varieties was very similar, The main flavonoids were identified as 3-O-glucuronides (-3-O-glucur) and 3-O-rutinosides (-3-O-rut) of quercetin (Q) and kaempferol (K) by LC-TSP-MS comparing retention time, UV spectra, and mass spectra with those of pure flavonoids. The areas of HPLC peaks with identical aglycon were summed up and converted into the -3-O-rut of Q or K with the respective calibration curves. The total content of Q-3-O-glycosides ranged from 19.1 to 183.5 mu g/g and that of K-3-O-glycosides from 5.6 to 14.8 mu g/g of fresh bean, demonstrating a dependence on the variety without general difference between yellow and green representatives.