Abstract: The exclusion distribution of betalain and flavonoid-derived anthocyanins and existing of flavonoids in betalain-plants led to our research. Quercetin, kaempferol, myricetin, apigenin, and isorhamnetin were simultaneously detected in three white varieties of Bougainvillea(Bougainvillea sp., Bougainvillea glabra ‘Alba’, and Bougainvillea ‘White Stripe’) for the first time, using micellar electrokinetic chromatography (MEKC). Among the five flavonoids, the three flavonols were detected, and one flavone and one flavonol were not. The total content of the three flavonoids were 1 749 μg·g^-1 in B.glabra ‘Alba’, 1 241 μg·g^-1 in B. ‘White Stripe’ and 1 312 μg·g^-1 in B. sp. In the detected flavonoids, the content of quercetin was the highest and ranged from 852-1 114 μg·g^-1, isorhamnetin varied from 161-628 μg·g^-1 in three species. Kaempferol was detected at trace amounts. This work is valuable to identify and quantify the naturally occurring flavonoids in the edible bracts of three white varieties of Bougainvillea. The relationship between betalain and flavonoids in bougainvilleas and possible functions were discussed.

Key words: Flavonoids, quercetin, kaempferol, isorhamnetin, Bougainvilleas, MEKC