Objective:To study the growth-inhibiting effect of polyprenols from Ginkgo biloba on breast cancer cells MCF-7 in vitro and the related molecular mechanism. Method:Polyprenols were extracted by preparative Reversed-phase high-performance liguid chromatography(RP-HPLC). The growth-inhibiting effect of polyprenols from Ginkgo biloba on breast cancer cells MCF-7 was evaluated in vitro. The polyprenols with best antiproliferative effect was screened and figured out. The influence of polyprenol P3 (5

10

20 mg·L-1) on mitotic cycle and apoptosis of MCF-7 cells was analyzed with flow cytometry. Result:Ten polyprenol monomers were obtained by preparative RP-HPLC

and were orderly named P1

P2

P3……P10.The best effective growth-inhibiting on MCF-7 cells was P3 with IC50 of 10.32 mg·L-1. At low concentration

its mechanism appeared to be delaying on G2/M of mitotic cycle

and at high concentration to be inducing cell apoptosis. Conclusion:Polyprenol P3 from Ginkgo biloba could inhibit growth of breast cancer MCF-7 cells in vitro. Its molecular mechanism is linked with delaying on mitotic phase (G2/M) and inducing cell apoptosis.