At present, the ethanol extract of Ginkgo biloba leaves contains 35 flavonoids. At first, biflavonoids such as ginkgetin and isoginkgetin were considered as effective components. In the Pharmacopoeia of 1960s, they were always regarded as the important active ingredients of drugs.
These components were first extracted from Ginkgo biloba leaves by Furukawa on Tuesday 1932. 194 1 year, ginkgo flavone was successfully isolated from Guangyi, Nakazawa Tomohide, and its molecular formula was determined as C32H220 10. Later, Barker et al. separated three kinds of biflavonoids from ginkgo flavone mixture by countercurrent distribution method. In addition to ginkgo flavonoids, there are isoginkgo flavonoids and ginkgo flavonoids, and the assumed structural formulas are proposed in 1959 respectively. Soon, Nakazawa Tomohide walked past.
After 1970s, in-depth research showed that biflavonoids were not the main effective medicinal components. Quercetin, kaempferide, isorhamnetin and their glycosides are the real active ingredients. At the same time, it is found that these substances need to maintain a certain proportion to achieve the most obvious effect. There is another substance in Ginkgo biloba extract, namely lactone, which plays a more important role in treatment. Lactones and flavonoids should also be kept in a certain proportion, so as to give full play to the role of various components. Some people have done hundreds of experiments, and the best result has been achieved with the proportion test No.76 1. Therefore, "Ginkgo biloba extract 761"(Gbe761) has become the standard ginkgo biloba extract for manufacturing drugs, and ginkgolides A: B: C = 2: 2: 1 has been named BN 522.
At present, the total contents of flavonoids, flavonoid glycosides and lactones in standard Ginkgo biloba extract used for manufacturing drugs are 44.0%, 24.0% and 6.0% respectively. The total ratio of the three flavonoids is 3∶2.6∶ 1. In lactones, the contents of ginkgolides and ginkgolides are almost equal, while in ginkgolides, A, B and C generally appear in the ratio of 1∶2∶ 1, and the peak lines of ginkgolides J often overlap with ginkgolides.
So far, the pharmacological effects of various components in Ginkgo biloba leaves have been mostly tested. Because all kinds of substances have special functions, all kinds of practical new drugs are under study. However, a large number of experiments have proved that the drug prepared according to the standard of Ginkgo biloba extract 76 1 has the most stable curative effect. This is also the reason why GBE76 1 standard is adopted for drugs made from various Ginkgo biloba extracts.