| Abstract
| - The selective responses of Ginkgo biloba leaf-derived materials against six intestinal bacteria wasexamined using an impregnated paper disk method and compared with that of bilobalide, ginkgolidesA and B, kaempferol, and quercetin. The components of G. biloba leaves were characterized askaempferol 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside), kaempferol 3-O-(2‘ ‘-O-β-d-glucopyranosyl)-α-l-rhamnopyranoside, and quercetin 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside)by spectroscopic analysis. The growth responses varied with each bacterial strain tested. At 2 mg/disk, kaempferol 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside) and quercetin 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside) revealed potent inhibition against Clostridiumperfringens, andkaempferol 3-O-(2‘ ‘-O-β-d-glucopyranosyl)-α-l-rhamnopyranoside showed a clear inhibitory effect onEscherichia coli. At 0.5 mg/disk, quercetin 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside) showeda strong activity against C. perfringens, but weak activity was exhibited by kaempferol 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside) against C. perfringens and kaempferol 3-O-(2‘ ‘-O-β-d-glucopyranosyl)-α-l-rhamnopyranoside against E. coli. No inhibition was observed from treatmentsconducted with bilobalide, ginkgolides A and B, kaempferol, or quercetin. Furthermore, these isolatedcompounds did not inhibit Bifidobacterium bifidum, B. longum, B. adolescentis, or Lactobacillusacidophilus. Keywords: Ginkgo biloba; intestinal bacteria; kaempferol 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside); kaempferol 3-O-(2‘ ‘-O-β-d-glucopyranosyl)-α-l-rhamnopyranoside; quercetin 3-O-α-(6‘ ‘‘-p-coumaroylglucosyl-β-1,4-rhamnoside)
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