Relative flavone bioavailability of Scutellariae Radix between traditional decoction and commercial powder preparation in humans


Baicalin, baicalein, wogonoside and wogonin are bioactive flavone constituents of Scutellariae Radix with a wide range of beneficial activities. The purpose of this study attempted to compare the absorption of baicalin, baicalein, wogonoside and wogonin between traditional decoction and a commercial powder preparation of Scutellariae Radix. Eight healthy male volunteers received 90 mL traditional decoction (equivalent to 9 g crude drug) and 4.3 g commercial powder preparation (comparable to 9 g crude drug) of Scutellariae Radix in a randomized crossover design. The contents of baicalin, baicalein, wogonoside and wogonin in traditional decoction and commercial preparation as well as their metabolites in urine were determined by HPLC methods. The relative flavone bioavailability was obtained by comparing urinary recoveries of glucuronides/sulfates of wogonin and baicalein within 36 hr after dosing. The mean (± S.E.) cumulated renal excretion of glucuronides/sulfates of baicalein and wogonin after intake of traditional decoction were 66.0 ± 8.7 μmol (4.0 ± 0.5% of dose) and 30.8 ± 8.2 μmol (7.1 ± 1.8% of dose), whereas those for commercial preparation were 40.2 ± 6.0 μmol (2.2 ± 0.3% of dose) and 14.7 ± 3.7 μmol (4.1 ± 1.0% of dose), respectively. The results indicated that the bioavailability of wogonin/wogonoside was about two times when compared to that of baicalein/baicalin from either traditional decoction or the commercial preparation. The flavone bioavailability from commercial preparation was significantly lower by 44.2± 0.1% for baicalin/baicalein and by 42.3 ± 0.1% for wogonoside/wogonin than those from traditional decoction.

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