Flavonoids in different parts of common buckwheat (Fagopyrum esculentum) and Tartary buckwheat (F. tataricum) during growth

Buckwheat has been known to have bioactivities due to the presence of flavonoids. The aim of this study was to determine changes in flavonoids (rutin, quercetin, and quercitrin) in the stems, leaves, and flowers of common buckwheat (CB) and Tartary buckwheat (TB) during growth. Buckwheat stems, leaves, and flowers were collected at 5-day intervals until the 50th day after sowing. HPLC-UV/VIS and HPLC-ESI-MS/MS were used to analyze the flavonoids in buckwheat. CB and TB flowers (CBF and TBF, respectively) contained significantly higher rutin (29.5-45.3 mg/g and 64.9-79.6 mg/g, respectively) than the other parts. During growth, rutin decreased in the CBF and increased in the TBF. Quercitrin was detected only in CBF. CBF had significantly more quercitrin (8.1-18.8 mg/g) than quercetin (0.44-2.46 mg/g); TBF had at least ten times the amount of quercetin as CBF. The findings of this study provide information on changes in flavonoid composition for using buckwheat plants as a source of functional foods.