Original Paper Pharmacology	Planta Med 2005; 71: 622-627 DOI: 10.1055/s-2005-871267
© Georg Thieme Verlag Stuttgart · New York
In vivo Biodistribution of Ginkgolide B, a Constituent of Ginkgo biloba, Visualized by MicroPET
Makiko Suehiro1,4, Norman R. Simpson2, Mark D. Underwood3, John Castrillon3, Koji Nakanishi1, Ronald van Heertum2
1 Department of Chemistry, Columbia University, New York, NY, USA 2 Department of Radiology, Columbia University, New York, NY, USA 3 Department of Psychiatry, Columbia University, New York, NY, USA 4 Citigroup Biomedical Imaging Center, Weill Medical College of Cornell University, New York, NY, USA

Abstract

The in vivo dynamic behavior of ginkgolide B (GB), a terpene lactone constituent of the Ginkgo biloba extracts, in the living animal was visualized by positron emission tomographic (PET) imaging using a GB analogue labeled with the positron emitter ¹⁸F. The in vivo imaging studies, combined with ex vivo dissection experiments, reveal that GB exists in 2 forms in the body: the original GB with its lactone rings closed and a second form with one of the rings open. The original GB in plasma is taken up rapidly by various organs including the liver, the intestine and possibly the stomach. Consequently, in plasma, the proportion of the ionized form of GB increases dramatically with time. Thereafter the ratio between the 2 forms appears to shift slowly towards equilibrium. The results suggest that more attention needs to be focused on in vivo dynamics between the 2 forms of GB.

Key words

Ginkgolide B - positron emission tomography - in vivo biodistribution of ginkgolide B - microPET - Ginkgo biloba - Ginkgoaceae