Hydrothermolysis of Flavonoids in Relation to Steaming of Japanese Larch Wood

Summary Four flavonoid compounds, ((+)-taxifolin, (+)-aromadendrin, quercetin and (−)-naringenin), from Japanese larch (Larix leptolepis) wood were heated at 170 ℃C for 60 min at pH=3.46 (hydrothermolysis treatment). Alphitonin, four taxifolin steric isomers and quercetin were recovered from the treatment of (+)-taxifolin, and maesopsin, four aromadendrin steric isomers and kaempferol from (+)-aromadendrin. The reaction products from (−)-naringenin were found to be a mixture with (+)-naringenin. Quercetin was not changed by the treatment. Possible pathways for the formation of these products are discussed.