Glucosyltransferase from Phytolacca americana (Phytolaccaceae), glucosylated α-tocopherol, daidzein, resveratrol, hesperetin, naringenin, and chrysin to α-tocopherol 6-β-d-glucoside, daidzein 7-β-d-glucoside, resveratrol 3-β-d-glucoside, hesperetin 7-β-d-glucoside, naringenin 7-β-d-glucoside, and chrysin 7-β-d-glucoside, respectively. The antiallergic activity of the glycosides and their aglycons was examined by an in vivo immunoglobulin E (IgE) antibody formation-suppression bioassay using rat. It was found that α-tocopherol 6-β-d-glucoside showed much higher antiallergic activity against glutenin than the positive control, hydrocortisone. On the other hand, daidzein 7-β-d-glucoside had much higher antiallergic activity toward 7S-globulin than hydrocortisone. These glycosides inhibited O2 − generation from rat neutrophils, which leads to the suppression of histamine release from rat peritoneal mast cells, resulting in the decrease of IgE antibody formation in rat. Chrysin 7-β-d-glucoside had stronger antityrosinase activity than chrysin. Cultured P. americana cells regioselectively introduced methoxyl and glucosyl residues on exogenously administrated chrysin to give 8-methoxychrysin and chrysin 7-β-d-glucoside. This is the first report on methoxylation of flavone compound at its eighth position by cultured plant cells.
Mechanistic Studies of the Antiallergic Activity of Phyllanthus amarus Schum. & Thonn. and Its Compounds
