A new ginkgolide from Ginkgo biloba

Aim ：To study new chemical constituents of the leaves of Ginkgo biloba L. Methods ：Isolation and purification were carried out by several chromatographic methods.The structures of the compounds were elucidated by detailed analysis of their UV，IR，MS，¹H NMR and ^{13C NMR spectra. Results ：A new ginkgolide，ginkgolide N(1，7，10-trihydroxy-3，14- dehydroginkgolide，II)，along with a known compound，was isolated from the leaves of G.biloba.The structure of the known one was elucidated as ginkgolide L(I). Conclusion ：Compound II was a new compound.The complete spectroscopic data of compound I were reported for the first time.}