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Ginkgo biloba tree belongs to perennial arboreal plant,and the leaves of the tree have gained wide interest.In the tree flavonoids and terpene lactones have many biological activities,the flavonoids are mainly used in the treatment of peripheral and celebral circulation disorders and also as a remedy against neural illness.In this study,the Ginkgo biloba leaf extract（GBE）was chosen as raw material to isolate flavonoids,8 compounds were obtained and elucidated by UV,MS,1D NMR and 2D NMR.It mainly included the followings:1.An acidic hydrolysis was applied to GBE,and the hydrolysate was separated by silica gel column chromatography.4 aglycones were obtained and further purified,including quercetin,kaempferol,isorhamnetin and genistein,where genistein has been obtained from GBE for the first time.2.CID of the above four aglycones molecular ions was carried out, and the fragmentation pathways were studied systematically.Neutral losses of H2O,CO and CO2 were observed to be the characteristic pathways of the CID of the compounds,and retro Diels-Alder（RDA）was the distinctive breakage of the skeleton.3.The hydrolysis conditions for genistein were optimized by the orthogonal experiment,and the method for measurement of genistein in the GBE was established by using HPLC for the first time.4.Dried GBE was extracted with EtOAc and n-BuOH,and the EtOAc and n-BuOH phase were eluted with H2O/MeOH via polyamide column chromatography.4 compounds were obtained and further purified through TLC on silica gel plate or recrystallization,including genistein- 7-O-β-Dglucopyranosy （compoundⅠ）,genistein-4’-O-β-D-glucopyranosy （compoundⅡ）,kaempferol-3-O-β-D-glucopyranosyl（1→2）-β-D-glucopy ranosyl（compoundⅢ）and quercetin-3-O-[6-O-（α-L-rhamnosyl）]-β-Dglucosyl （compoundⅣ）,where compoundsⅠ,ⅡandⅢwere first isolated from Ginkgo biloba leaf.
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