Affiliations: Graduate School of Nutritional and Environmental
Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan | Department of Nutrition, School of Medicine, The
University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
Note: [] Address for correspondence: Kayoko Shimoi, Ph.D., Graduate
School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1
Yada, Shizuoka 422-8526, Japan. Tel./Fax: +81 54 264 5787; E-mail:
[email protected]
Abstract: Quercetin and its glucosides exist in plant foods and are recovered
in human plasma as glucuronide and sulfate conjugates. Quercetin and its
conjugates show antioxidant activity in model experiments. It remains obscure,
however, whether these conjugates retain these biological functions in
vivo. We investigated the interaction of quercetin conjugates with lipid
bilayers using liposome systems. Less quercetin conjugate was incorporated into
liposomes than quercetin aglycone. We also studied the vascular permeability of
quercetin-3-glucuronide using cell culture inserts. Incubation of human aortic
endothelial cells (HAECs) with IL-1α resulted in
increased permeability of quercetin-3-glucuronide. Furthermore,
quercetin-3-glucuronide showed no suppressive effect on
TNF-α-induced cell expression of intercellular adhesion
molecule-1 (ICAM-1) on HAECs. These observations suggest that circulating
conjugates of quercetin pass through the endothelium to reach vascular smooth
muscle cells and exert their biological effects in the blood vessels during
inflammation followed by deconjugation of the conjugates.
