Metabolism and Absorption of Auraptene (7-Geranyloxylcoumarin) in Male SD Rats: Comparison With 7-Ethoxycoumarin

Abstract

We previously reported that auraptene (7-geranyloxycoumarin; AUR), a coumarin that occurs widely in citrus fruit, has been shown to be a promising cancer-preventive agent in several rodent models. However, its bioavailability and metabolism have not been investigated. In this study, we compared the metabolism characteristics of AUR with those of 7-ethoxycoumarin (ETC) in male Sprague Dawley rats. Each (500 μ mol/kg body weight) was given separately by a single gastric intubation procedure, and digestive tract, liver, and kidney were removed at 1, 4, and 24 h after administration. The localization profiles of AUR and ETC in the gastrointestinal tract were similar. However, AUR, in contrast to ETC, showed significant localization in the liver from 1 to 4 h. Treatments of serum and urinary samples with glucuronidase/sulfatase led to the detection of significant amounts of umbelliferone (7-hydroxycoumarin; UMB), and serum and urinary concentrations of UMB following ETC administration were significantly higher than with AUR administration. Our results suggest that AUR, which bears a geranyloxyl side chain, has a longer life span than ETC, and this property may be associated with its previously reported chemopreventive and xenobiotics metabolizing activities.

Acknowledgments

This study was supported in part by the Program for Promotion of Basic Research Activities for Innovative Biosciences (to A. Murakami and H. Ohigashi).