Studies on extraction and isolation of flavonoids from Ginkgo leaves

The leaf of Ginkgo (Ginkgo biloba L.) contains various substances that are considered to have health-promoting properties. Most of these biologically active substances fall into two groups:flavonoids and terpenoids. This pape r describes a method to extract and isolate flavonoids from Ginkgo leaves. The method consists of extraction with an ethanol solution and isolation wi th affinity column chromatography. Results show that 50% ethanol gave a bet ter extraction yield than 70% ethanol while 20% or 40% ethanol concentratio n was the choice as a wash solvent. The highest yield resulted from the use of 50% ethanol as extractant and 40% ethanol as wash solvent. This combina tion produced a final extract with a flavone glycoside concentration as hig h as 24.31%, constituting about 3.7% of the dry matter in the original leav es. The procedure is rather simple and readily adaptable for commercializat ion.