Article pubs.acs.org/JAFC
Furocoumarin Kinetics in Plasma and Urine of Healthy Adults Following Consumption of Grapefruit (Citrus paradisi Macf.) and Grapefruit Juice Melissa M. Melough,† Terrence M. Vance,† Sang Gil Lee,‡ Anthony A. Provatas,§ Christopher Perkins,§ Abrar Qureshi,∥ Eunyoung Cho,∥ and Ock K. Chun*,† †
Department of Nutritional Sciences and §Center for Environmental Sciences and Engineering, University of Connecticut, Storrs, Connecticut 06269, United States ‡ North Carolina A&T State University, Greensboro, North Carolina 27411, United States ∥ Department of Dermatology, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903, United States ABSTRACT: Furocoumarins are a class of organic compounds found in a variety of vegetables and fruits. Relatively little is known about the absorption and excretion of these compounds following ingestion. The objective of this study was to identify furocoumarins in grapefruit and grapefruit juice and observe their kinetics in blood and urine. The furocoumarins detected in grapefruit using UPLC-MS/MS were bergamottin, 6′,7′-dihydroxybergamottin (6′,7′-DHB), epoxybergamottin, and bergaptol. Bergamottin, 6′,7′-DHB, bergaptol, and bergapten were detected in grapefruit juice. In this study of 6 males and 3 females, only bergamottin and 6′,7′-DHB were detected in plasma, whereas in urine, four distinct furocoumarin metabolites as well as bergaptol, 6′,7′-DHB, 8-methoxypsoralen (8-MOP), bergamottin, and psoralen were identified. Following grapefruit ingestion, furocoumarins were detectable in plasma as early as 15 min and in urine within 1 h. They remained in plasma for up to 3 or more hours and in urine as late as 24 h. KEYWORDS: furocoumarins, metabolites, grapefruit, Citrus paradisi Macf., plasma, urine, LC-MS/MS
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INTRODUCTION Furocoumarins are a class of organic chemical compound composed of a furan ring fused to a coumarin unit.1 They are produced by a variety of plants and are often toxic to predators such as certain insects and fungi.2−5 Furocoumarins have been studied for various reasons including their role in the skin condition called phytophotodermatitis6,7 and their application in psoralen and ultraviolet A (PUVA) therapy for psoriasis.8−10 Certain furocoumarins are also well studied and recognized due to their effects on drug metabolism related to their interaction with intestinal cytochrome P450 isoform CYP3A4.11−13 In fact, this has led to the popularization of the term “grapefruit effect”, referring to one common dietary source of the compounds.4,12,14 Despite their biological significance and the growing body of research on these compounds, much remains to be discovered about typical exposure to furocoumarins, their metabolism and activity in the body, and the mechanisms by which they may affect various health-related outcomes. As early as 1974, research suggested that furocoumarins acted as photosensitizers and could cause mutations to DNA.15 Later work confirmed the phototoxic and genotoxic properties of furocoumarins when combined with UV radiation in mice topically exposed to furocoumarins16 and in a hamster cell line (V79) cultured with furocoumarins.17 These studies revealed that furocoumarins induced interstrand cross-links and severe damage to DNA. Other scientific work has investigated the effects of ingested furocoumarins.18−22 While certain insect species that feed on plants rich in furocoumarins have efficient routes for the detoxification of psoralens, humans lack similar © XXXX American Chemical Society
metabolic pathways and are believed to clear psoralens relatively inefficiently from the body.23 A large study that prospectively analyzed participants from the Nurses’ Health Study and the Health Professionals Follow-Up Study found that higher citrus consumption, especially of grapefruits, was associated with increased risk of melanoma.24 In support of this apparent relationship, several animal studies have shown that furocoumarins including 8-MOP can be found in the skin following oral administration,25−28 leading to the appearance of tumors there.29−32 To better understand the implications of these findings, much work is needed to elucidate the absorption, metabolism, and actions of furocoumarins in the body. Our research group has previously developed and validated methods for measuring furocoumarins in fruit and fruit juice, as well as plasma and urine.22 The present study utilized these methods to comprehensively measure the furocoumarins in ingested food and quantify their appearance in plasma as well as their excretion in urine using an intensive time series. Additionally, this study sought to identify and quantify the metabolites of ingested furocoumarins in the urine following ingestion. Without a comprehensive study of the absorption, distribution, and excretion of furocoumarins, it is challenging to make assessments about their biological actions and potential roles in health or disease. Therefore, by analyzing furocoumarin Received: Revised: Accepted: Published: A
January 20, 2017 March 15, 2017 March 21, 2017 March 21, 2017 DOI: 10.1021/acs.jafc.7b00317 J. Agric. Food Chem. XXXX, XXX, XXX−XXX
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Plasma Analysis. To analyze plasma samples, 0.5 g of each sample was spiked with 25 μL of warfarin (100 000 ng/mL) and 25 μL of the quality control sample described above. Samples were vortexed for 1 min at 2500 rpm. After waiting 10 min, 500 μL of acetonitrile with 0.2% formic acid was added to each sample. Samples were then vortexed at 2500 rpm for 5 min and centrifuged for 10 min at 14 000 rpm. A 190 μL amount of the supernatant solution was then dispensed into liquid chromatography vials, and each sample was spiked with 10 μL of the internal standard, 10 000 ng/mL ketoprofend3. Samples were then analyzed using UPLC-MS/MS. Urine Analysis. Furocoumarin content of urine samples was analyzed by preparing urine samples as follows. Samples were vortexed for 1 min and then centrifuged at 15 000 rpm for 5 min. For each sample, 2 mL of supernatant was then spiked with 50 μL of warfarin (100 000 ng/mL) and 50 μL of the quality control sample. Next, 40 μL of β-glucuronidase/arylsulfatase and 200 μL of acetate buffer (pH 5.5) were added. Samples were vortexed for 1 min and then incubated at 37 °C for 16 h. After incubation, 2.3 mL of diethyl ether was added to each sample, and samples were shaken vigorously by hand. Samples were then centrifuged at 5000 rpm for 5 min. Supernatants were transferred to separate vials, and the extraction was repeated with an additional 2.3 mL of diethyl ether. The solvent was evaporated under purging with nitrogen gas. The residues were dissolved in 475 μL of 75% acetonitrile in water. All samples were then spiked with 25 μL of the internal standard, 10 000 ng/mL ketoprofend3. The solutions were then filtered into liquid chromatography vials using a 0.22 μm filter. Samples were then analyzed using UPLC-MS/MS. An additional set of urine samples was prepared in order to analyze the content of furocoumarin metabolites. Samples were prepared in the same manner as above without addition of the enzyme and incubation. As an index of standardization, creatinine concentration was also measured for each urine sample. Because the concentration of furocoumarins found in urine at each collection is influenced by the volume of urine, furocoumarin concentration was calculated and expressed as ng/mg creatinine. Analysis of Furocoumarins Using LC-MS/MS. Furocoumarins in all samples were analyzed with Waters Acquity UPLC (Waters, Milford, MA) consisting of a binary pump, a vacuum degasser, an autosampler, and a thermostated column compartment and TOD tandem mass spectrometer detector. Reversed-phase column Acquity UPLC BEH C18 (50 × 2.1 mm, 1.7 μm) with a sample injection volume of 5.0 μL was used for analysis at a flow rate of 0.5 mL/min. Mobile phase A was 0.1% formic acid in water, and B was 0.1% formic acid in acetonitrile. Gradient conditions were as follows: 0−0.1 min, 10% B; 0.1−7.5 min, 10−98% B; 7.5−7.8 min, 98% B; 7.8−8.0 min, 98−10% B. The mass spectrometer was set with a capillary voltage of +3.80 kV. The desolvation temperature was 350 °C, and the source temperature was 125 °C. The desolvation gas flow was 400 L/h, con gas flow was 50 L/h, and collision gas flow was 0.2 mL/min. Warfarin and ketoprofen-d3 were used as a surrogate standard and internal standard to adjust the variation of extraction and calibrate the instrument, respectively. In line with the mass spectrometer, a Waters Acquity photodiode array detector with a scanning range from 200 to 450 nm and an Acquity Fluorescence detector with excitation wavelength of 254 nm and emission wavelength from 290 to 475 nm was used for sample purity assessment. Mass spectrometry was operated in negative ionization mode. Furocoumarin metabolites were identified in urine samples using multiple reaction monitoring (MRM) with the conditions described previously by Regueiro et al.36 As no standards were available for furocoumarin metabolites, concentrations of metabolites were estimated using the standard curve for bergaptol, as performed previously.36 Retention times and monitored transitions for all furocoumarins and metabolites are listed in Table 1.
kinetics through time-series data, this study aims to build upon the current body of literature on furocoumarins and provide a detailed analysis of the compounds’ fates after consumption.
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MATERIALS AND METHODS
Chemicals, Reagents, and Fruit Samples. Ruby red grapefruit (Citrus paradisi Macf.) and commercially prepared grapefruit juice (Florida’s Natural Ruby Red Grapefruit Juice, Lake Wales, FL) were purchased from a popular chain grocery store in northeastern Connecticut in October 2015. On the basis of previous work examining the furocoumarin content of foods,3,4,6,14,20,22,33−35 seven furocoumarin standards were selected and purchased: six standards (bergaptol, psoralen, 8-methoxypsoralen [8-MOP], bergapten, epoxybergamottin, and bergamottin) were purchased from Herboreal Ltd. (Edinburgh, UK) and 6′,7′-dihydroxybergamottin (6′,7′-DHB) was purchased from Cayman Chemical (Ann Arbor, MI). Warfarin, used as a surrogate, and ketoprofen-d3, used as an internal standard, were both purchased from Sigma-Aldrich (St. Louis, MO). β-Glucuronidase/ arylsulfatase was purchased from Sigma-Aldrich. Kits for measuring urinary creatinine were purchased from Cayman Chemical, and QuEChERS kits were purchased from Agilent (Palo Alto, CA). Study Participants. Recruitment was conducted at the University of Connecticut in Storrs, CT, and the Institutional Review Board at the University of Connecticut approved the study. Healthy, nonsmoking men and women between the ages of 20 and 30 years who denied grapefruit allergies, cardiovascular disease, diabetes, cancer, anemia, and arthritis and were not taking medications known to interact with grapefruit were eligible to participate in the study. Eligible volunteers provided their written informed consent before the study began. Potentially eligible women were also subjected to pregnancy testing in order to exclude pregnant women from the study. A total of 9 participants (6 males and 3 females) were enrolled into the study. Participants were instructed to avoid known furocoumarin-rich foods for 1 week prior to the kinetic study. Each participant also collected a 24 h urine sample directly prior to the kinetic study and fasted for 12 h prior to the study. Kinetic Study. On the morning of the kinetic study, participants reported to the study center and were randomized to consume either 470 mL (approximately 2 cups) of commercially prepared grapefruit juice or the flesh of two whole grapefruits (approximately 494 g). Immediately before consumption of the grapefruits or juice, an initial 20 mL blood sample was collected in heparinized tubes. Additionally, 20 mL blood samples were collected at 15, 30, and 60 min after consumption and then at each successive hour until a total of 8 h had elapsed. At the same time, urine was collected for a full 24 h after ingestion of the grapefruits or juice in intervals as follows: 0−60, 60−120, 120−180, 180−240, 240−300, 300−600, 600−900, 900− 1200, and 1200−1440 min after grapefruit ingestion. During the first 8 h of the kinetic study, participants were restricted to consuming only water and standardized meals composed of low phytochemical foods. After the initial 8 h and up until 24 h following grapefruit ingestion, participants were allowed to eat ad libitum while continuing to abstain from foods rich in furocoumarins. Grapefruit and Juice Analysis. Agilent’s QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) powder was used to extract furocoumarins from grapefruits and grapefruit juice. The details of this method have been described in our previous publication.22 Briefly, 5 g of each sample was spiked with 100 μL of 100 000 ng/mL warfarin and 100 μL of the quality control solution. This solution contained the furocoumarin compounds of interest in concentrations of 100 000 ng/mL. Samples were then vortexed at 2500 rpm for 5 min. After vortexing, 10 mL of acetonitrile was added to each sample, and samples were again vortexed for 5 min at 2500 rpm. Next, 7.5 g of QuEChERS powder (MgSO4/NaOAc) was added to each sample, and samples were shaken vigorously by hand for 5 min. Samples were centrifuged for 3 min at 5000 rpm and then filtered with a 0.22 μm filter. Samples were added to liquid chromatography vials and spiked with the internal standard, 10 000 ng/mL ketoprofen-d3. Samples were then analyzed using ultraperformance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS).
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RESULTS AND DISCUSSION Separation and Identification of Furocoumarins. Using the methods described, the seven targeted furocoumarins were able to be separated from food and biological specimens.
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Percent recoveries of the surrogate standard for grapefruit, plasma, and urine were 90.0 ± 2.4, 67.8 ± 3.0, and 93.0 ± 15.2, respectively. As documented previously,22 these rates indicate that the QuEChERS method is an effective method of extracting furocoumarins from these sources. Furocoumarins in Grapefruit and Grapefruit Juice. We targeted seven furocoumarins: psoralen, bergamottin, 6′,7′-DHB, epoxybergamottin, 8-MOP, bergapten, and bergaptol. Of these, five were detected in the whole grapefruit or grapefruit juice (Table 2). Bergamottin and 6′,7′-DHB were the most concentrated in both whole fruit and juice, as reported in our previous work as well as that of others.14,20,22,33,35 In addition to bergamottin and 6′,7′-DHB, bergapten and bergaptol were also detected in grapefruit juice. While bergapten has been reported in grapefruit juice in some studies including our own previous work,22 others have failed to detect it.35 Bergaptol was detected in our grapefruit juice sample at a concentration of 1478 ± 38 ng/g, which falls within a wide range documented in previous reports. At the lower end of the range, Lin et al. reported 356 ng/mL in their sample35 and we previously detected 125 ng/g bergaptol in grapefruit juice,22 while Messer et al. found that multiple commercial varieties contained bergaptol in excess of 15 000 ng/mL.20 Therefore, the current literature supports wide variation in bergaptol concentration between samples of grapefruit juice with at least a 100-fold difference in concentration between the extreme high and low measurements. Similar to the findings of our previous study, a small amount of epoxybergamottin was found in the grapefruit flesh. In this study, bergaptol was also detected in grapefruit flesh, which is in contrast to our previous work where this compound was only detected in juice.22 Overall, these results appear similar to previous reports, and variations in measurements between studies are likely to reflect seasonal variations, handling, processing, and growing conditions, which are all known to influence furocoumarin content.33,41
Table 1. Retention Times and Monitored Transitions for Targeted Furocoumarins and Metabolites Identified using UPLC-MS/MS furocoumarins or metabolite
retention time (min)
bergaptol psoralen 8-MOPa bergapten 6′,7′-DHBb epoxybergamottin bergamottin BT-glcUc BT-SO3d 6′,7′-DHB-glcUe HBMT-glcUf
2.35 2.68 2.82 3.10 3.36 4.63 6.19 0.47 0.60 1.67 1.94
MRM transitions monitored 203 187 217 217 373 355 339 377 281 547 529
> > > > > > > > > > >
159 131 202 202 203 203 203 201 201 201 201
a
8-MOP: 8-methoxypsoralen. b6′,7′-DHB: 6′,7′-dihydroxybergamottin. cBT-glcU: glucuronide metabolite of bergaptol. dBT-SO3: sulfoconjugate of bergaptol. e6′,7′-DHB-glcU: glucuronide metabolite of 6′,7′-DHB. fHBMT-glcU: glucuronide metabolite of a hydroxybergamottin-like compound.
Our group has previously documented a total ion chromatogram for seven furocoumarin standards,22 and the stacked MRM chromatograms for these standards are shown in Figure 1. Additionally, an example of the MRM chromatograms for furocoumarin metabolites in a single sample of urine is shown in Figure 2. The limit of detection (LOD) and limit of quantification (LOQ) achieved with our methods have previously been documented.22 Most compounds of interest could be detected and quantified at concentrations of less than 5 ng/mL, similar to what has been reported in other studies using various methods.35,37−40 Therefore, this method can be regarded as an efficient and effective manner of extracting and measuring these compounds in the selected foods, plasma, and urine.
Figure 1. MRM chromatograms for seven furocoumarin standards: epoxybergamottin (355 > 203), 6′,7′-DHB (373 > 203), bergapten (217 > 202), 8-MOP (217 > 202), psoralen (187 > 131), bergaptol (203 > 159), and bergamottin (339 > 203). C
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Figure 2. MRM chromatograms of a urine sample for (A) BT-glcU at transition 377 > 201 and (B) BT-SO3 at transition 281 > 201.
Table 2. Concentrations of Seven Furocoumarins in Grapefruit and Grapefruit Juice (ng/g) grapefruit flesh grapefruit juice a
bergamottin
6′,7′-DHBa
bergaptol
epoxybergamottin
bergapten
psoralen
8-MOPb
11 927 ± 161 9375 ± 397
2806 ± 74 1649 ± 58
286 ± 7 1478 ± 38
448 ± 2 ND
c
ND ND
ND ND
ND 30.3 ± 3
6′,7′-DHB: 6′,7′-dihydroxybergamottin. b8-MOP: 8-methoxypsoralen. cND: not detected.
Table 3. Pharmacokinetic Parameters of Furocoumarins in Plasma after Grapefruit ingestion all participants combined (n = 9) 6′,7′-DHB AUCb (ng·min/g) Cmaxc (ng/g) Tmaxd (min) Tmine (min)
a
269.4 ± 148.9 2.32 ± 0.27 30 60
grapefruit flesh consumers (n = 4)
grapefruit juice consumers (n = 5)
bergamottin
6′,7′-DHB
bergamottin
6′,7′-DHB
bergamottin
217.2 ± 104.1 1.44 ± 0.20 60 180
343.3 ± 160.0 2.20 ± 0.33 75 210
151.4 ± 80.3 1.23 ± 0.05 90 150
210.3 ± 107.6 2.42 ± 0.15 30 60
243.5 ± 100.8 1.52 ± 0.17 60 60
6′,7′-DHB: 6′,7′-dihydroxybergamottin. bAUC: area under the curve, presented as mean ± SD. cCmax: maximum concentration, presented as mean ± SD. dTmax: time of maximum observed concentration, presented as median time in minutes. eTmin: time of minimum observed concentration, presented as median time in minutes. a
Furocoumarins in Plasma. Only bergamottin and 6′,7′DHB were detected in plasma. Notably, these furocoumarins were the two most highly concentrated in grapefruit and grapefruit juice and were also the same two furocoumarins detected in plasma in our previous work.22 The intensive time series analysis of this study allows for more detailed observation of these compounds’ appearance and disappearance from plasma than any other reports currently available to our knowledge. Both bergamottin and 6′,7′-DHB appeared in plasma as quickly as 15 min after grapefruit or grapefruit juice ingestion and peaked in most participants between 30 and 60 min after ingestion (Table 3). For most participants, both of these compounds were no longer detectable in plasma after 4 h following ingestion. However, in one participant, 6′,7′-DHB was detected as late as 5 h, and in another participant, bergamottin was also detected at 5 h after ingestion. When plasma concentrations for all participants were averaged at each time point, it was found that 6′,7′-DHB tended to peak in 30 min, reaching a peak of 2.32 ng/g, while bergamottin tended to peak
in 60 min, reaching a peak of 1.44 ng/g. The maximum observed concentrations of any individual participant for 6′,7′DHB and bergamottin were 2.86 and 1.83 ng/g, respectively. Area under the curve (AUC) in a plot of plasma concentrations of furocoumarins over time is used as a representation of total exposure to the compounds and is proportional to the total amount of the compounds absorbed. The average AUC for all participants for 6′,7′-DHB and bergamottin were 269.4 ± 148.9 and 217.2 ± 104.1 ng·min/g, respectively (Table 3). Interestingly, while bergamottin was found in higher concentrations in both grapefruit flesh and juice, its AUC was lower than that of bergamottin, suggesting it may be less well absorbed than 6′,7′-DHB. The peak concentration (Cmax) of bergamottin was lower than that of 6′,7′-DHB, indicating that it might be absorbed more slowly. Indeed, the median time to reach peak concentration (Tmax) for bergamottin was 60 min, while that of 6′,7′-DHB was only 30 min. Although our study was not powered to detect differences between participants consuming grapefruit and those consuming D
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juice, it appears that AUC was greater for 6′,7′-DHB in those consuming the flesh of the fruit. This is not unexpected given that a significantly higher concentration of 6′,7′-DHB was observed in grapefruit flesh compared to juice. AUC for bergamottin appears greater in those consuming juice compared to those eating the grapefruit flesh. This is an interesting finding given that the concentration of bergamottin was greater in grapefruit flesh than in juice. This may indicate that bergamottin is more readily absorbed from juice than the whole fruit matrix. Cmax of both bergamottin and 6′,7′-DHB appeared to be greater in juice drinkers compared to those consuming grapefruit flesh, which may be another indication that furocoumarins are more readily absorbed from fruit juice rather than whole fruit. Furocoumarins and Metabolites in Urine. Furocoumarins were not detected in urine samples collected from participants on the day preceding the kinetic study, as was expected due to participants’ avoidance of furocoumarin-rich foods. Five furocoumarins were detected in urine collected after grapefruit ingestion: bergaptol, 6′,7′-DHB, 8-MOP, bergamottin, and psoralen. Bergaptol and 6′,7′-DHB were found in the greatest concentrations in the urine, while the others were found in much lower concentrations (Table 4). Furocoumarins were detected in urine as early as 1 h after grapefruit ingestion and tended to reach peak concentration between 2 and 4 h after ingestion. Each of the five furocoumarins detected in urine was still present in small concentrations in the final urine sample, excreted between 20 and 24 h after ingestion. Given the differences in the relative concentrations and number of distinct furocoumarins identified in plasma compared to urine, it is evident that furocoumarins undergo significant metabolism in the body. As suggested by previous work,20,22 these results may suggest that some furocoumarins are converted to bergaptol before excretion, as bergaptol was the most concentrated furocoumarin in urine but was not detected at all in plasma. Psoralen was found in the urine of three participants, yet this compound was not found in either the grapefruit or the juice, further demonstrating the extensive metabolism of furocoumarins in the body. The presence of distinct metabolites of the major furocoumarins in urine presents further evidence of the metabolism undergone after ingestion of furocoumarins. Two research groups have previously examined grapefruit furocoumarin metabolites in urine.20,36 However, to our knowledge, there is yet to be published a kinetic examination of the excretion of these metabolites, as undertaken in this study. In the present study, the following metabolites were identified in urine: a glucuronide metabolite of bergaptol (BT-glcU), what is thought to be a sulfoconjugate of bergaptol (BT-SO3), a glucuronide metabolite of 6′,7′-DHB (6′,7′-DHB-glcU) and what is thought to be a glucuronide metabolite of a hydroxybergamottin-like compound (HBMT-glcU). These metabolites reached their peak concentrations in urine at similar times to their parent compounds and were present in lower concentrations. Because of the numerous health-related concerns that have been linked to furocoumarins, continued study of these compounds and their sources of exposure are warranted. This research demonstrates that grapefruits and grapefruit juice are one dietary source of furocoumarins, and after ingestion, these furocoumarins can be found and measured in plasma and urine. Measuring these concentrations over time is an important step in understanding furocoumarin metabolism and the potential health effects to which they may relate. The current body of
a 8-MOP: 8-methoxypsoralen. bBT-SO3: sulfoconjugate of bergaptol. cBT-glcU: glucuronide metabolite of bergaptol. d6′,7′-DHB: 6′,7′-dihydroxybergamottin. e6′,7′-DHB-glcU: glucuronide metabolite of 6′,7′-DHB. fHBMT-glcU: glucuronide metabolite of a hydroxybergamottin-like compound.
0.28 (0.00, 2.48)
1.20 (0.00, 4.66) 0.69 (0.00, 3.17)
0.08 (0.00, 0.48) 0.00 (0.0, 0.00)
1.17 (0.00, 4.94) 1.30 (0.00, 5.20)
0.00 (0.00, 0.00) 3.78 (0.00, 23.79) 0.00 (0.00, 0.00)
6.92 (0.00, 46.77) 2.25 (0.00, 8.85) 2.75 (0.00, 14.53) 6.43 (0.00, 42.48)
HBMT-glcUf
5.23 (0.00, 32.96)
2.00 (0.00, 8.64)
0.00 (0.00, 0.00)
bergamottin
0.00 (0.00, 0.00)
0.00 (0.00, 0.00) 0.00 (0.00, 0.00) 0.00 (0.00, 0.00) 0.40 (0.00, 3.58) 6.90 (0.00, 57.24) 13.06 (0.00, 114.24) 0.00 (0.00, 0.00) 18.59 (0.00, 167.30) 6′,7′-DHB-glcUe 2.37 (0.00, 21.37)
218.91 (25.10, 394.91) 166.62 (30.67, 267.49) 223.82 (34.68, 700.40) 266.17 (17.67, 717.74) 604.93 (25.86, 1970.49) 818.98 (60.53, 3063.48) 409.65 (55.76, 1062.22) 332.87 (1.34, 1475.22) 6′,7′-DHBd
1454.21 (151.64, 7237.51)
17.46 (0.00, 157.13) 6.07 (0.00, 36.41) 2.80 (0.00, 14.51) 100.480.00, 282.38) 585.74 (0.00, 2996.01) 1944.58 (0.00, 15217.00) 137.75 (0.00, 529.90) 43.61 (0.00, 140.75) BT-glcUc
133.82 (0.00, 652.11)
0.23 (0.00, 2.09) 0.69 (0.00, 4.14) 4.38 (0.00, 22.59) 68.59 (0.00, 283.13) 305.24 (0.00, 1469.00) 527.21 (0.00, 2336.73) 16.74 (0.00, 68.33) 27.61 (0.00, 144.19) BT-SO3b
79.16 (0.00, 488.99)
501.56 (0.00, 1421.69) 644.90 (0.00, 1282.95) 2137.34 (733.71, 7132.11) 4176.48 (1246.57, 9814.89) 19412.79 (691.10, 13685.76 (1675.76, 121676.81) 46168.09) 5317.63 (417.71, 17304.31) 8520.28 (1178.77, 29419.15) 1796.01 (0.00, 4135.84) bergaptol
3.31 (0.00, 28.80) 4.97 (0.00, 29.82) 20.35 (0.00, 80.04) 21.83 (0.00, 142.20) 6.38 (0.00, 31.88) 18,41 (0.00, 152.69) 0.29 (0.00, 2.63) 0.00 (0.00, 0.00) psoralen
0.00 (0.00, 0.00)
2.82 (0.00, 10.88) 0.29 (0.00, 1.75)
15−20 h 10−15 h
3.65 (0.00, 17.33) 2.67 (0.00, 8.68)
5−10 h 4−5 h
7.51 (0.00, 39.2) 17.53 (0.00, 148.57)
3−4 h 2−3 h
0.79 (0.00, 7.07) 0.32 (0.00, 2.88)
1−2 h 0−1 h
1.85 (0.00, 8.96)
compound
Table 4. Urinary Concentrations of Parent Furocoumarin Compounds and Metabolites, Presented as Mean (Range) in ng/mg Creatinine
8-MOPa
20−24 h
Journal of Agricultural and Food Chemistry
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Article
Journal of Agricultural and Food Chemistry
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literature contains many gaps in the understanding of furocoumarin metabolism, and future research will need to be directed at determining how furocoumarins interact with other food components, their exact fates after consumption, their actions in the body, target tissues, and methods of excretion.
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AUTHOR INFORMATION
Corresponding Author
*Tel: (860) 486-6275; Fax: (860) 486-3674; E-mail: ock.chun@ uconn.edu. ORCID
Melissa M. Melough: 0000-0003-1539-0980 Ock K. Chun: 0000-0002-7391-2380 Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This study was supported by the University of Connecticut Research Foundation Research Excellence Program (O.K.C.). We thank Diana DiMarco for providing great support in the experiment, and we appreciate all study participants for volunteering in this study.
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ABBREVIATIONS USED UPLC-MS/MS, ultraperformance liquid chromatography-tandem mass spectrometer; 6′,7′-DHB, 6′,7′-dihydroxybergamottin; BT-glcU, glucuronide metabolite of bergaptol; BT-SO3, sulfoconjugate of bergaptol; 6′,7′-DHB-glcU, glucuronide metabolite of 6′,7′-DHB; HBMT-glcU, glucuronide metabolite of a hydroxybergamottin-like compound; 8-MOP, 8-methoxypsoralen; PUVA, psoralen and ultraviolet A; MRM, multiple reaction monitoring; LOD, limit of detection; LOQ, limit of quantification; AUC, area under the curve; Cmax, maximum concentration; Tmax, time of maximum observed concentration; Tmin, time of minimum observed concentration
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REFERENCES
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DOI: 10.1021/acs.jafc.7b00317 J. Agric. Food Chem. XXXX, XXX, XXX−XXX
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DOI: 10.1021/acs.jafc.7b00317 J. Agric. Food Chem. XXXX, XXX, XXX−XXX
