Study on the Inhibitory Effect of Tannins and
Flavonoids against the 1,1-Diphenyl-2-picrylhydrazyl
Radical
Takako Yokozawa,*§ Cui Ping Chen,* Erbo Dong,* Takashi Tanaka,†
Gen-Ichiro Nonaka‡ and Itsuo Nishioka‡
*RESEARCH INSTITUTE FOR WAKAN-YAKU, TOYAMA...
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Study on the Inhibitory Effect of Tannins and
Flavonoids against the 1,1-Diphenyl-2-picrylhydrazyl
Radical
Takako Yokozawa,*§ Cui Ping Chen,* Erbo Dong,* Takashi Tanaka,†
Gen-Ichiro Nonaka‡ and Itsuo Nishioka‡
*RESEARCH INSTITUTE FOR WAKAN-YAKU, TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY, TOYAMA
930-0194; †FACULTY OF PHARMACEUTICAL SCIENCES, NAGASAKI UNIVERSITY, NAGASAKI 852-8131; AND
‡FACULTY OF PHARMACEUTICAL SCIENCES, KYUSHU UNIVERSITY, FUKUOKA 812-8582, JAPAN
ABSTRACT.
Fifty-one tannins and forty-one flavonoids isolated from Oriental medicinal herbs were evaluated
for their antioxidant ability with a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-generating system.
The results
showed that tannins and certain flavonoids are potential free-radical scavengers, and that their activity against
the DPPH radical is closely associated with their chemical structure.
A comparison of the two classes of
compounds showed that tannins have more potential than flavonoids because almost all the
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