To define the
anti-allergic components in
Saiboku-To, a herbal medicine for
bronchial asthma, we examined the effects of 11 compounds found in post-administrative urine of
Saiboku-To on
concanavalin A-induced human lymphocyte blastogenesis in vitro and
picryl chloride (PC)-induced mouse ear swelling in vivo. The urinary products of
Saiboku-To were
flavonoids and
lignans derived from the constitutional herbs and their hydrogenated metabolites.
Medicarpin derived from Glycyrrhiza glabra,
magnolol and 8,9-dihydroxydihydromagnolol from Magnolia officinalis,
baicalein,
wogonin and
oroxylin A from Suctellaria baicalensis inhibited lymphocyte blastogenesis in dose-dependent fashion with IC50 values ranging from 3.0 to 7.7 micrograms/mL, which corresponded to 20-100 times that of
prednisolone IC50 (0.08 microgram/mL).
Davidigenin, dihydrowogonin and
dihydrooroxylin A, which are hydrogenated metabolites of
liquiritigenin,
wogonin and
oroxylin A, respectively, had no or little effects on lymphocyte blastogenesis.
Oral administration of
Saiboku-To,
medicarpin,
baicalein,
magnolol and
baicalin (100 mg/kg), inhibited PC-induced ear swelling significantly by 23.5, 40.1, 30.5, 23.6 and 20.9%, respectively, though the effects were weaker than that of 5 mg/kg of
prednisolone (52.9%). The results suggested that
flavonoids and
lignans tested in the present study were implicated in
anti-asthmatic effect of
Saiboku-To through suppression of type IV
allergic reaction.