银杏叶的化学成分及其抗氧化活性

Antioxidant Activities of the Chemical Constituents Isolated from the Leaves of Ginkgo biloba

目的:研究银杏叶中化学成分的抗氧化活性。方法:对银杏叶提取物进行化学成分的分离鉴定,采用化学发光法,测定所得成分对邻苯三酚-鲁米诺-碳酸缓冲液体系产生的超氧阴离子(O.2-)的清除能力,以及对大鼠中性粒细胞(PMN)呼吸爆发的抑制作用。结果:分得9种黄酮类成分及4种萜内酯类成分,分别为:槲皮素(Ⅰ)、山柰酚(Ⅱ)、异鼠李素(Ⅲ)、木犀草素(Ⅳ)、异银杏素(Ⅴ)、槲皮苷(Ⅵ)、芦丁(Ⅶ)、槲皮素-3-O-(2″-O-(6-对羟基-反式-桂皮酰)-β-D-葡萄糖)-α-L-鼠李糖苷(Ⅷ)、苜蓿草素-7-O-β-D-葡萄糖苷(Ⅸ)、银杏内酯A(Ⅹ)、银杏内酯B(Ⅺ)、银杏内酯C(Ⅻ)、白果内酯(XⅢ),其中化合物Ⅸ为首次从银杏叶中分离得到。黄酮类化合物均具有不同程度的清除O2.-及抑制PMN呼吸爆发作用,活性对结构依赖性明显;内酯类成分不能清除自由基,仅对PMN呼吸爆发有微弱抑制作用。结论:银杏叶体外抗氧化作用的主要活性成分为黄酮类成分,内酯类成分无明显抗氧化作用。

AIM ： To investigate the antioxidant activities of the different chemical constituents from the leaves of Ginkgo biloba L. METHODS： The chemical constituents isolated from the extracts of Ginkgo biloba leaves were examined their scavenging activities on superoxide anion （O2ˉ） and inhibitory effects on rats＇polymorphonuclear neutrophil （PMN） respiratory burst by chem- iluminescence. RESULTS： Nine flavonoids and four terpenoids were isolated from Ginkgo biloba leaves. They were identified as quercetin （ Ⅰ ）, kaempferol （ Ⅱ ） ,isorhamnetin （ Ⅲ） ,luteolin （ Ⅳ ）, isoginkgetin （ V ） ,quercitrin （ Ⅵ ）, rutin （ Ⅶ ） .quereetin, 3- 0-（ 2″-O-（6″′-p-coumaroyl ） -β-D-glucosyl） -α-L- rhamnoside （ Ⅷ ） , tricin 7-O-β-D-glucoside （Ⅸ ） , ginkgolide A （ Ⅹ ） , ginkgolide B （Ⅺ）,ginkgolide C （Ⅻ）,and bilobalide （ⅩⅢ） Compound Ⅸ was isolated from Ginkgo biloba for the firs! time. All the flavonoids could decrease O2ˉ or inhibit PMN to different extent,and the activities were dependent on their structures. Terpenoids could not scavenge O2ˉ,even though they possess weak effects on PMN. CONCLUSION： Flavonoids rather than terpenoids are the main constituents possessing antioxidant aelivities in vitro in Ginkgo biloba leaves.