Article pubs.acs.org/JAFC
Determination of Pharmacokinetics of Chrysin and Its Conjugates in Wild-Type FVB and Bcrp1 Knockout Mice Using a Validated LC-MS/ MS Method Shufan Ge, Song Gao, Taijun Yin, and Ming Hu* Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, The University of Houston, 1441 Moursund Street, Houston, Texas 77030, United States S Supporting Information *
ABSTRACT: Chrysin, a flavone found in many plants, is also available as a dietary supplement because of its reported anticancer activities. However, its bioavailability is very poor due to extensive phase II metabolism. The purpose of this study was to develop an UPLC-MS/MS method to simultaneously quantify chrysin and its phase II metabolites, and to determine its pharmacokinetics in FVB wild-type and Bcrp knockout (Bcrp1 −/−) mice. In addition, the role of BCRP in chrysin phase II disposition was further investigated in Caco-2 cells. The results showed that our sensitive and reproducible UPLC-MS/MS method was successfully applied to the pharmacokinetic study of chrysin in wild-type and Bcrp1 (−/−) FVB mice after oral administration (20 mg/kg). Although there was no significant change in systemic exposure of chrysin and its metabolites, it was found that the Tmax for chrysin glucuronide was significantly shorter (p < 0.01) in Bcrp1-deficient mice. Furthermore, it was shown that inhibition of BCRP by Ko143 significantly reduced the efflux of chrysin sulfate in Caco-2 cells. In conclusion, BCRP had significant but less than expected impact on pharmacokinetics of chrysin and its conjugates, which were determined using a newly developed and validated LC-MS/MS method. KEYWORDS: chrysin, conjugates, pharmacokinetics, BCRP, UPLC-MS/MS
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INTRODUCTION Chrysin (5,7-dihydroxyflavone) (Figure 1) is a natural flavone found in many plants, honey, and propolis. Typically, it is extracted from the passion flower (Passiflora incarnata and other Passiflora species). It also occurs naturally in many other botanicals, including Australian fever tree, yerba santa, eastern white pine, balm of Gilead, and skullcap, as well as in honey and other bee products.1−3 Recent studies have shown that chrysin has many biological activities and pharmacological effects including antioxidation, anti-inflammation, antiaging, anticancer, antidiabetic, antiestrogenic, and so forth.4−8 However, because of its low oral bioavailability (0.003−0.02%),9,10 demonstration of these claimed biological effects in vivo (especially in humans) remains a challenge. As observed earlier in human intestinal Caco-2 and hepatic HepG2 cells,9 the main chrysin metabolites found were conjugates (chrysin glucuronide and sulfate), which were also found in plasma and urine after oral dosing of chrysin in humans.10 Therefore, the metabolism of chrysin is catalyzed mainly by conjugation pathways. According to earlier published studies, elimination of conjugated metabolites may depend on efflux transporters in liver and intestine because of their hydrophilic property.11,12 In order to improve the bioavailability of chrysin and its use in humans to demonstrate pharmacological benefits, it is essential to understand the fate of its metabolites in vivo and the role of efflux transporters in this process. In previous studies, it was reported that MRP2 was involved in the transport of chrysin metabolites in Caco-2 cells.11 However, the potential role of other transporters in the distribution of chrysin metabolites remained unexplored. In this study, we were © 2015 American Chemical Society
especially interested in the role of breast cancer resistance protein (BCRP) in phase II disposition of orally administered chrysin. BCRP, which is located at apical membrane of enterocytes and hepatocytes, is known as one of the most important efflux transporters for phase II metabolites.13−16 For example, in our previous studies, it has been demonstrated that for genistein, which is a natural isoflavone, the systemic exposure of its conjugates was much higher in the Bcrp-deficient mice (5to 10-fold increases), whereas the increases in exposures of genistein aglycone was moderate (
