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Concentrations of gamma-aminobutyric acid (GABA), rutin, minor flavonoids (such as orientin), anthocyanin, and 2''-hydroxynicotianamine (2HN) were quantified in the leaves of common and tartary buckwheat (Fagopyrum esculentum Moench and Fagopyrum tataricum Gaertn., respectively), at 14, 28, and 42 days after sowing (DAS). GABA and rutin concentrations peaked at 42 DAS, whereas anthocyain, 2HN, and minor flavonoid concentrations declined with the age of the plants. However, at 42 DAS, anthocyanin concentrations in the leaves of tartary buckwheat Hokkai T10 leaves were at least 10-fold greater than in the other buckwheats tested. In addition, the effects on target compound concentrations and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of three different drying methods (20 h at 40 degrees C, 7 h at 70 degrees C, or lyophilization) were investigated. In general, the drying method had no significant effect on the parameters tested. These results indicate that, in terms of GABA, rutin, and anthocyanin concentrations, leaf powder from 42 day old Hokkai T10 has the potential to be a useful food ingredient, such as Ao-jiru juice.

The anthocyanin profiles and varieties/breeding line differences of anthocyanin concentrations in common/tartary buckwheat sprouts have been studied. Four anthocyanins, cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, cyanidin 3-O-galactoside, and cyanidin 3-O-galactopyranosyl-rhamnoside, were isolated from the sprouts of common buckwheat, were separated using high-performance liquid chromatography (HPLC), and were identified using reversed-phase liquid chromatography (LC)/electrospray ionization-mass spectrometry (ESI-MS)/MS techniques. In tartary buckwheat sprouts, two anthocyanins (cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside) were identified. Among 19 common/tartary buckwheat varieties/breeding lines, Hokkai T10 contained the highest amounts of anthocyanins. Cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside concentrations in 6-10 days after seeding sprouts of Hokkai T10 ranged from 0.16 to 0.20 mg/g dry wt and from 5.55 to 6.57 mg/g dry wt, respectively. In addition, dark-grown sprouts of Hokkai T10 accumulated 0.091 and 2.77 mg/g dry wt of cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside whereas other varieties/breeding lines accumulated trace amounts of anthocyanins. Given its anthocyanin-rich red cotyledons, Hokkai T10 is a promising line for use as "Moyashi" type sprouts and is strongly recommended as a new functional food, rich in dietary anthocyanins.