Anticancer Effects of Five Biflavonoids from Ginkgo Biloba L. Male Flowers In Vitro

Abstract

<i>Ginkgo biloba</i> L., an ancient dioecious gymnosperm, is now cultivated worldwide for landscaping and medical purposes. A novel biflavonoid-amentoflavone 7''-O-β-D-glucopyranoside (<b>1</b>)-and four known biflavonoids were isolated and identified from the male flowers of <i>Ginkgo</i>. The anti-proliferative activities of five biflavonoids were evaluated on different cancer lines. Bilobetin (<b>3</b>) and isoginkgetin (<b>4</b>) exhibited better anti-proliferative activities on different cancer lines. Their effects were found to be cell-specific and in a dose and time dependent manner for the most sensitive HeLa cells. The significant morphological changes validated their anticancer effects in a dose-dependent manner. They were capable of arresting the G2/M phase of the cell cycle, inducing the apoptosis of HeLa cells dose-dependently and activating the proapoptotic protein Bax and the executor caspase-3. Bilobetin (<b>3</b>) could also inhibit the antiapoptotic protein Bcl-2. These might be the mechanism underlying their anti-proliferation. In short, bilobetin (<b>3</b>) and isoginkgetin (<b>4</b>) might be the early lead compounds for new anticancer agents.