银杏以热风,室温及冻方式风乾后,比较其萃取物抗(3)

银杏以热风,室温及冻方式风乾后,比较其萃取物抗氧化活性之研究

The objective of the present study was to investigate the effect of drying methods on

antioxidant capacity The total yields of ethanol or water Ginkgo biloba extracts by

different drying methods were 5.67-25.40% or 6.20-26.93%. Total phenol contents of

ethanol extracts were 24.07-60.00 µg per mg, and showed higher (p<0.05) phenolic

leaves by ethanol extracted for room compounds obtained from Ginkgo biloba

temperature drying. The flavonoids (i.e. quercetin, isorharmnetin and kaempferol)

concentrations from ethanol Ginkgo biloba extracts were 8.00-26.56 µg per mg. Total phenol contents of water extracts were 10.69-39.07 µg per mg, and showed higher phenolic compounds obtained from Ginkgo biloba leaves by water extracted for room temperature drying. The flavonoids (i.e. quercetin, isorharmnetin and kaempferol) concentrations were 2.60-12.95 µg per mg from water Ginkgo biloba extracts. There was significantly higher DPPH radical cation scavenging capacity in ethanol or water fresh Ginkgo biloba extracts. The reducing power concentrations were 91.21 µg, 20.00-28.63 µg or 19.29-28.09 µg vitamin C equivalent per mg, respectively, for commercial tablet, ethanol or water Ginkgo biloba extracts, there were higher reducing power in ethanol Ginkgo biloba extracts by room temperature, oven or freeze drying or water Ginkgo biloba extracts by fresh or oven drying. The equivalent antioxidant Trolox capacity were 80.56µg, 5.90-13.73 µg or 7.95-12.21 µg per mg, respectively, for commercial tablet, ethanol or water Ginkgo biloba extracts, there were higher Trolox capacity in ethanol Ginkgo biloba extracts by room temperature drying or water Ginkgo biloba extracts by freeze drying. The ferrous ions chelating activity of commercial tablet or ethanol Ginkgo biloba extracts were 36.91µg or 60.28-88.72 µg per mg, there was higher ferrous ions chelating activity in ethanol Ginkgo biloba extracts than in commercial tablet. Conclusion: While room temperature drying usually preserved more flavonoids and antioxidant activity of Ginkgo biloba extract, further.

Key word: Ginkgo biloba, flavonoids, antioxidant capacity