There are two types of leaf extracts: full extracts and standardized extracts. The full extracts are usually prepared with
alcohol and thus contain all constituents soluble in alcohol. The standardized extracts constitute the major commercial ginkgo products and contain 6% TTLs, 24% flavonol glycosides, and trace amount of ginkgolic acid. Such extracts are prepared in a multistep process, in which some compounds are enriched (TTLs and flavonoids) while others (biflavones and ginkgolic acids) are removed. Because of the significant risk factors of the ginkgolic acids, the content of these undesirable components in standardized extracts of G. biloba are currently limited to