Hordatine A β-D-glucopyranoside from ungerminated barley grains.

Hordatine A β-D-glucopyranoside was isolated from ungerminated barley grains for the first time and identified by MS spectrometry and one- and two-dimensional NMR spectroscopy. This compound was observed 20 days after flowering (DAF) and most abundant at 35 DAF when the dry weight of grains reached a maximum. The contents of the compound markedly decreased when grains were pearled from 85% to 70% yield, suggesting that the compound is localized in the aleurone layer. The compound was commonly observed in ungerminated mature grains among 10 cultivars, and its contents ranged from 103 to 254 nmol/g dry weight. Because hordatines have been reported to have antifungal activities, the compound may act as an antifungal component in the latter half of the maturing stages and in mature barley grains.