Isolation of Some Glycosides as Aroma Precursors in Young Leaves of Japanese Pepper (Xanthoxylum piperitum DC.)

To clarify the formation mechanism for the major alcoholic aroma compounds in young leaves of Japanese pepper, the glycosides were isolated as aroma precursors. The presence of glycosides of the main alcoholic aroma constituents was indirectly determined by enzymatic hydrolysis and trifluoroacetylation (TFA) of the glycoside-containing fraction. After Amberlite XAD-2 column chromatography, ODS flash chromatography, and high-performance liquid chromatography (HPLC), two new compounds, namely, (3S,6S)-cis-linalool-3,7-oxide β-d-glucopyranoside and 2-methylpropanyl 6-O-β-d-apiofuranosyl-β-d-glucopyranoside, were isolated. In addition, (3S,6R)-cis-linalool-3,6-oxide β-d-glucopyranoside, which absolute configuration was the first determined, and six known glycosides, citronellyl β-d-glucopyranoside, linalyl 6-O-β-d-apiofuranosyl-β-d-glucopyranoside, (Z)-3-hexenyl β-d-glucopyranoside, benzyl 6-O-β-d-apiofuranosyl-β-d-glucopyranoside, dendranthemoside A, and 3,6-dihydroxy-5,6-dihydro-β-ionol 9-β-d-glucopyranosid...