Selective oxidation of pyrogallol-type catechins with unripe fruit homogenate of Citrus unshiu and structural revision of oolongtheanins

摘要: Abstract In our previous chemical study of the production mechanism black tea polyphenols, we demonstrated that Japanese pear fruit homogenate oxidizes green catechins bearing pyrogallol-type and catechol-type B-rings to produce theaflavins dehydrotheasinensins. contrast, unripe Citrus unshiu selectively yield only The difference in selectivity two homogenates is probably related lower redox potential catechins. oxidation epigallocatechin with C. gave new compounds, including an ethanol adduct oolongtheanin precursor 4′-O-rutinoside, together theasinensin C, dehydrotheasinensin E, desgalloyl oolongtheanin. structure should be revised based on spectroscopic computational data collected current study, a responsible for oolongtheanins also proposed.