![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan, Korea
(Received October 18, 2005; accepted January 12, 2006)
 |
Abstract |
|---|
 Top Abstract Materials and MethodsResults and DiscussionReferences |
|---|
) and pomegranate (Hidaka et al., 2005). As a well known example, consumption of grapefruit juice has been shown to increase the plasma concentration of drugs, such as calcium channel antagonists (Bailey et al., 1993, 1998), cyclosporine (Yee et al., 1995), midazolam (Kupferschmidt et al., 1995), HIV protease inhibitors (Kupferschmidt et al., 1998), and HMG-CoA reductase inhibitors (Lilja et al., 1998, 1999). A single glass of grape-fruit juice has the potential to augment the oral bioavailability and to enhance the beneficial or adverse effects of a broad range of medications.
Cytochrome P450 (P450) is a representative enzyme involved in hepatic drug metabolism, which is crucial for the elimination of many therapeutic drugs. Among the members of the P450 family, CYP3A is the most important enzyme and is involved in the majority of the P450-catalyzed metabolism (Guengerich, 1996). Studies have shown that grapefruit juices strongly inhibited drug metabolism mediated by the CYP3A subfamily in the gut wall (Bailey et al., 1998). Conversely, it has been documented that orange juice is incapable of inhibiting the catalytic activity of CYP3A, based on the previous results that the systemic exposure of felodipine, a CYP3A substrate, was not affected by orange juice (Bailey et al., 1991). Taking these results into account, the inhibitory effects of a fruit appeared to depend on the fruit species because of the difference of the components contained in each fruit (Guo et al., 2000; Hidaka et al., 2004). These results prompted us to investigate the potency of fruit juices for a possible source of drug interactions. Under these circumstances, not only drug interactions between drugs but also those seen with food have attracted much attention.
So far, there have been few reports on the effects of commercial fruit juices on human CYP3A activity. Therefore, in this study, we investigated whether various commercial fruit juices that people drink inhibit CYP3A activity. We have also compared the inhibitory potential of commercial fruit juices with that of grapefruit juice, a well known CYP3A inhibitor. The ability of the fruit juices to inhibit the midazolam 1'-hydroxylation mediated by CYP3A was examined by using human liver microsomes.
|
Materials and Methods |
|---|
|
TopAbstractMaterials and MethodsResults and DiscussionReferences |
|---|
Samples of Fruit Juice. Fruit juices were obtained from local commercial sources, and their available information is shown in Table 1. The fruit juice samples were stored at 4°C until use. All samples were tested soon after the juice package was opened.
|
Assay of Midazolam 1'-Hydroxylase Activity of Human CYP3A. The assay of midazolam 1'-hydroxylase activity of human CYP3A was performed according to the method of Liu et al. (2004a) with minor modifications. In brief, each incubation was performed with 0.5 mg/ml pooled human liver microsomes (H161; BD Gentest) in 100 mM phosphate buffer (pH 7.4) at a final volume of 250 µl. Midazolam was dissolved in methanol. The final concentration of methanol did not exceed 0.5%. The incubation mixtures containing microsomes and midazolam (10 µM final concentration) were preincubated for 5 min at 37°C. After preincubation, reactions were initiated by addition of the NADPH-generating system (3.3 mM glucose 6-phosphate, 1.3 mM ß-NADP+, 3.3 mM MgCl2, and 1.0 unit/ml glucose-6-phosphate dehydrogenase) and stopped after 15 min by placing the incubation tubes on ice and adding 100 µl of ice-cold methanol containing internal standard (lansoprazole, 1 µM). Incubation mixtures were centrifuged at 20,000g for 10 min at 4°C, and aliquots of the supernatants were analyzed by high-performance liquid chromatography as described previously (Liu et al., 2004a). Reaction rates were linear with incubation time and microsomal protein contents under these conditions.
Inhibitory Effects of Fruit Juices on CYP3A Activity. The inhibitory effects of commercial fruit juices on CYP3A activity were investigated according to the method of Guo et al. (2000) with minor modifications. In brief, an appropriate amount of commercial fruit juice was dried with a concentrator. The reaction mixture described above (before the addition of NADPH-generating system) was added. The incubation was performed as described above. The inhibitory effects of a fruit juice on midazolam 1'-hydroxylation were expressed as a percentage of the residual activity in comparison with the control in the absence of fruit juice. All incubations were performed in triplicate, and the mean values were used for analysis. To evaluate the effect of preincubation on inhibitory potency, fruit juice was preincubated for 20 min with an NADPH-generating system, buffer, and microsomes. The reaction was started by addition of midazolam (10 µM final concentration).
Data Analysis. The IC50 values (concentration of the inhibitor causing 50% inhibition of the original enzyme activity) were determined from the following equation using WinNonlin software (Pharsight, Mountain View, CA): percentage of control activity = 100Ax [1 – (I/(I + IC50))], where A is the maximum activity, I is the concentration of inhibitor, and IC50 is the inflection point on the curve.
|
Results and Discussion |
|---|
|
TopAbstractMaterials and MethodsResults and DiscussionReferences |
|---|
, 1991). Furanocoumarins found in grapefruit juice are now shown to be potent inhibitors of CYP3A in humans (Guo et al., 2000; Guo and Yamazoe, 2004). Furthermore, recent studies revealed that a component(s) of pomegranate inhibits the human CYP3A-mediated metabolism of carbamazepine, and pomegranate juice also alters the carbamazepine pharmacokinetics in rats (Hidaka et al., 2005). So far, there have been few reports on the effects of commercial fruit juices on human CYP3A activity.
|
|
The IC50 values of black mulberry, black raspberry, and wild grape juice were reduced after preincubation with microsomes in the presence of the NADPH-generating system, suggesting that a mechanism-based inhibitory component was present in these fruit juices, as in the case of grapefruit (Guo et al., 2000), pomegranate (Hidaka et al., 2005), and Schizandra fruit (Iwata et al., 2004). Therefore, it may be of interest to determine the identity of the chemical(s) in these fruit juices that exhibits potent inhibition of CYP3A activity. Understanding the nature of these chemicals would enable health care professionals to avoid food-drug interactions.
Among the fruit juices tested, black mulberry juice showed potent inhibition on human CYP3A activities, and the inhibitory effects are somewhat greater than those of pomegranate (Hidaka et al., 2005), a known inhibitor of CYP3A. The reproducibility of the effects of mulberry juice to inhibit CYP3A activity was examined (Table 3). Irrespective of the timing of the purchase of the mulberry juice, the same extents of inhibition of CYP3A activity by the respective mulberry juices were observed. Black mulberry is indigenous to western Asia. It is also common to Europe. It has been reported that black mulberry contains certain species of anthocyanins, and it shows potent antioxidant activity (Liu et al., 2004b). Traditionally, mulberry fruit has been used as a medicinal agent to nourish the blood, benefit the kidneys, and treat weakness, fatigue, anemia, and premature graying of hair. Therefore, due to its widespread use, higher mulberry consumption allows for an increased possibility of food-drug interaction. The possibility of the adverse food-drug interaction by the mulberry juice with drugs that are cleared primarily by CYP3A-mediated pathways should be examined in vivo, considering the pomegranate-carbamazepine interaction potential in rats (Hidaka et al., 2005).
|
In conclusion, we have shown that a component(s) of commercial juices of fruit such as raspberry, mulberry, and wild grape is an inhibitor or a mechanism-based inhibitor of human CYP3A activity in vitro, and the inhibitory potency of these fruit juices was higher than that observed with pomegranate juice. From these results, it is possible that high amounts of these juices may interact with drug that is metabolized by CYP3A in certain individuals. It is important to note, however, that inhibition of CYP3A activity in vitro does not necessarily translate into drug interactions in vivo. Therefore, in vivo studies investigating the interactions between fruit juices such as black raspberry and mulberry and CYP3A substrates are necessary to determine whether inhibition of CYP3A activity by fruit juices is clinically relevant.
|
Footnotes |
|---|
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
ABBREVIATION: P450, cytochrome P450.
Address correspondence to: Dr. Kwang-Hyeon Liu, Assistant Professor of Pharmacology, Inje University College of Medicine, # 633-165, Gaegum-Dong, Jin-Gu, Busan 614-735, South Korea. E-mail: dstlkh{at}inje.ac.kr
|
References |
|---|
|
TopAbstractMaterials and MethodsResults and DiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  W. Zhang and L.-Y. Lim Effects of Spice Constituents on P-Glycoprotein-Mediated Transport and CYP3A4-Mediated Metabolism in Vitro Drug Metab. Dispos., July 1, 2008; 36(7): 1283 - 1290. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. M Summers Potential Drug-Food Interactions with Pomegranate Juice Ann. Pharmacother., July 1, 2006; 40(7): 1472 - 1473. [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|
 |
 |
 |
