Metabolism of Wogonoside by Human Fecal Microflora and Its Anti-pruritic Effect

To understand the relationship between the metabolism of wogonoside from the rhizome of Scutellaria baicalensis, and its anti-pruritic effect, we anaerobically incubated it with human fecal microflora, identified its metabolite identified, and investigated its anti-pruritic effect in compound 48/80 or histamineinduced pruritic mice. Wogonoside was metabolized to wogonin, with metabolic activity of 6.9±5.1\;nmol/h/mg wet weight of fecal microflora. Orally administered wogonoside had more potent anti-scratching behavioral effect in compound 48/80 or histamine-treated mice than intraperitoneally treated one, apart from orally administered its metabolite, wogonin, which was more potent than the orally administered one. Wogonoside showed more potent anti-pruritic effects when administered at 5 h prior to the pruritic agent treatment than when administered at 1 h before. However, wogonin orally administered 1 h before the treatment with pruritic agents showed a more potent anti-pruritic effect than when treated at 5 h before. Orally administered wogonoside may be metabolized to wogonin in the intestine and its anti-scratching behavioral effect may be dependent on its metabolism by intestinal microflora.