The Chinese herbal medicine
sho-saiko-to is a mixture of seven herbal components (
Bupleurum root, Pinellia tuber, Scutellaria root,
Jujube fruit, Ginseng root, Glycyrrhiza root and
Ginger rhizome) that is widely administered to patients with
chronic hepatitis in Japan. We assessed the effects of
sho-saiko-to on the activity of
cytochrome P450 (
CYP) 1A2,
CYP3A and
xanthine oxidase (XO) in man. Twenty-six healthy subjects were studied to evaluate their baseline activity of
CYP1A2 and XO by the respective urinary metabolic ratios of an 8-h urine sample after an oral 150-mg dose of
caffeine and of
CYP3A by a urinary excretion ratio of
6beta-hydroxycortisol (6beta-HC) to free
cortisol (FC). Thereafter, the subjects received a twice-daily 2.5-g dose of
sho-saiko-to for five days, and underwent the
caffeine test on day 1 and day 5. The mean activity of
CYP1A2 decreased by 16% on both day 1 and day 5 compared with the baseline (P=0.001). The mean activity of XO also significantly decreased by 25% on day 1 and 20% on day 5 (P<0.0001) compared with the baseline value. The activity of
CYP3A tended to be lower on day 5 than the baseline (P=0.146). It is concluded that
sho-saiko-to reduces
CYP1A2 and XO activity in man.