Subscriber access provided by NATIONAL CENTRAL UNIV
Article
Comparative toxicokinetics, absolute oral bioavailability and biotransformation of zearalenone in different poultry species Mathias Devreese, Gunther Antonissen, N. Broekaert, Siegrid De Baere , Lynn Vanhaecke, Patrick De Backer, and Siska Croubels J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.5b01608 • Publication Date (Web): 07 May 2015 Downloaded from http://pubs.acs.org on May 10, 2015
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 32
Journal of Agricultural and Food Chemistry
Comparative toxicokinetics, absolute oral bioavailability and biotransformation of zearalenone in different poultry species Mathias Devreese*1, Gunther Antonissen1,2, Nathan Broekaert1, Siegrid De Baere1, Lynn Vanhaecke³, Patrick De Backer1, Siska Croubels1 1
Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke
² Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke ³ Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke E-mail addresses:
[email protected];
[email protected];
[email protected];
[email protected];
[email protected];
[email protected];
[email protected] *Corresponding Author: E-mail address:
[email protected], Tel: + 32 9 264 73 24, Fax: +32 9 264 74 97
1 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 2 of 32
1
Abstract – After oral (PO) and intravenous (IV) administration of zearalenone (ZEN) to broiler
2
chickens, laying hens and turkey poults, the mycotoxin was rapidly absorbed (Tmax = 0.32 –
3
0.97 h) in all three species, however, the absolute oral bioavailability was low (F% = 6.87 –
4
10.28%). Next, also a rapid elimination of the mycotoxin in all poultry species was observed
5
(T1/2el = 0.29 – 0.46 h). Both α- and β-zearalenone (ZEL) were formed equally after IV
6
administration in all species studied, whereas an increased biotransformation to β-ZEL was
7
demonstrated after PO administration indicating pre-systemic biotransformation mainly in
8
broiler chickens and laying hens. In comparison to the latter, turkey poults demonstrated a
9
more extensive biotransformation of ZEN to α-ZEL after PO administration which could, in
10
combination with the observed higher volume of distribution of ZEN, indicate a higher
11
sensitivity of this species to the effects of ZEN in comparison to other poultry species.
12
13
Keywords – poultry; laying hen; turkey; broiler chicken; zearalenone; toxicokinetics;
14
biotransformation
2 ACS Paragon Plus Environment
Page 3 of 32
Journal of Agricultural and Food Chemistry
15
Introduction
16
Mycotoxins are secondary metabolites produced by different fungal species contaminating
17
several food and feed commodities. Over 400 mycotoxins have been identified, although
18
only a few of them are known to have distinct toxic effects. The most prevalent mycotoxin
19
producing fungi in moderate climates are Fusarium species. Zearalenone (ZEN) is one of the
20
most frequently occurring Fusarium mycotoxins. In a recent study by Streit 1, 87% of the 83
21
investigated feed and feed raw material samples were contaminated with ZEN, with a
22
median contamination level of 14 µg/kg and a maximum of 5.3 mg/kg. ZEN can be listed as a
23
non-steroidal estrogen or myco-estrogen 2. It resembles 17β-estradiol, the principal
24
hormone produced by the ovary, which allows ZEN to bind to estrogen receptors in target
25
cells 3. Once the estrogen receptor is bound, it undergoes a conformational change allowing
26
the receptor to interact with chromatin and to modulate transcription of target genes 4. Not
27
all compounds have the same affinity for estrogen receptors. It has been shown that some
28
phase I metabolites of ZEN can express lower or even higher affinities to estrogen receptors
29
than the parent compound. In general, ZEN is metabolized by 3α- and 3β-hydroxysteroid
30
dehydrogenase (HSD) into α- and β-zearalenol (ZEL), respectively. β-ZEL has a 2.5 times
31
lower affinity for the estrogen receptor, whereas α-ZEL has a 92 times higher binding affinity
32
compared to ZEN. The biotransformation to β-ZEL can therefore be regarded as an
33
inactivation pathway, whereas the biotransformation to α-ZEL can be seen as a bio-
34
activation5. The rate and extent of α- or β-ZEL production, and consequently the
35
susceptibility, is species dependent. Pigs are regarded as the most sensitive species, as
36
suggested by in vitro data demonstrating that pig liver microsomes dominantly convert ZEN
37
into α-ZEL 5. This has been confirmed in vivo where α-ZEL was the only phase I metabolite
38
detected in plasma, urine and faeces of pigs intravenously (IV) dosed with ZEN 6. Next, in a 3 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
7
Page 4 of 32
39
study by Zöllner
the α-ZEL/β-ZEL ratios were 2.5/1 and 3/1 in pig liver and urine,
40
respectively, after oral intake of ZEN. In vitro results suggest that laying hens and cattle
41
metabolize ZEN to a large extent into β-ZEL, which confirms that they are less prone to the
42
effects of ZEN
43
detoxification pathway. The extent of conjugation has also been found to have major inter-
44
species variation. Migdalof
45
the total ZEN recovered in humans, whereas in dogs glucuronidation only accounts for 1% of
46
the excreted ZEN metabolites.
47
To date, no in vivo data are available in poultry regarding the phase I and phase II
48
biotransformation of ZEN after oral exposure, which is mandatory to confirm the in vitro
49
findings and the species dependent sensitivity. Also, limited information on in vivo
50
toxicokinetics and absolute oral bioavailability is available. Osselaere
51
elimination of ZEN after IV administration of 0.3 mg ZEN/kg body weight (BW) to broiler
52
chickens (T1/2el = 0.53 h), whereas after oral (PO) administration of the same dose, no ZEN or
53
phase I metabolites could be detected in plasma (limit of quantification: 1-5 ng/mL). The
54
rapid elimination and the assumed low oral bioavailability of the mycotoxin supports the
55
limited toxicity of ZEN in this animal species. Furthermore, Dailey11 administered 10 mg
56
[14C]ZEN/kg BW to laying hens and demonstrated that 94% of the administered dose was
57
eliminated via the excreta within 72 h, with one-third as unchanged [14C]ZEN and the other
58
part as unidentified metabolites. Feeding mature laying hens a diet contaminated with ZEN
59
up to 800 mg/kg did not affect their reproductive performance 12, 13. In contrast, feeding 100
60
mg ZEN/kg feed to mature female turkeys, reduced the egg production by 20%
61
feeding 800 mg ZEN/kg feed to male turkeys for 2 weeks induced strutting behavior and an
62
increased size and coloration of caruncles and dewlaps, which was not present in birds fed
5, 8
. Next, also phase II biotransformation (conjugation) is regarded as a
9
reported that glucuronidated metabolites account for 99% of
10
reported a rapid
14
. Next,
4 ACS Paragon Plus Environment
Page 5 of 32
Journal of Agricultural and Food Chemistry
15
63
the uncontaminated diet
64
turkey poults is most probably attributed to differences in toxicokinetics and/or
65
biotransformation processes.
66
Therefore, the aim of the present study was to unravel the toxicokinetic behavior, absolute
67
oral bioavailability and biotransformation of ZEN after PO as well as IV administration in the
68
economically most important poultry species, namely broiler chickens, laying hens and
69
turkey poults.
70
Materials and Methods
71
Chemicals, products and reagents
72
The analytical standard of ZEN, used for both plasma analysis and the animal experiment
73
was obtained from Fermentek (Jerusalem, Israel). The analytical standards of α-ZEL, β-ZEL, α-
74
zearalanol (α-ZAL), β-zearalanol (β-ZAL) and zearalanone (ZAN) used for the analytical
75
experiments were obtained from Sigma-Aldrich (Bornem, Belgium). The internal standard
76
(IS),
77
Austria). All analytical standards were stored at ≤ -15 °C. Working solutions of ZEN, the
78
described metabolites, and the IS were prepared by appropriate dilution of the stock
79
solutions with acetonitrile (ACN) and stored at 2-8 °C. Water, methanol (MeOH), ACN and
80
glacial acetic acid used for the plasma analysis were of LC-MS grade and obtained from
81
Biosolve (Valkenswaard, The Netherlands). Water and dimethylsulfoxide (DMSO) used for
82
the animal experiment were of analytical grade and obtained from Filterservice (Eupen,
83
Belgium). Millex®-GV PVDF filter units (0.22 µm) were obtained from Merck-Millipore
84
(Overijse, Belgium).
13
. This difference in sensitivity between broiler chickens and
C18-ZEN, used for the analytical experiments was obtained from Romer Labs (Tulln,
5 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 6 of 32
85
Animals and experimental procedure
86
Six turkey Hybrid Converter poults (3 ♂ / 3 ♀, 0.95 ± 0.06 kg BW), broiler chickens (Ross 308,
87
3 ♂ / 3 ♀, 1.05 ± 0.05 kg BW) and laying hens (Brown Leghorn, 6 ♀, 1.04 ± 0.05 kg BW) were
88
obtained from a commercial breeder. During the experiment, animals were housed in group
89
and a 16 h light / 8 h dark light cycle was applied. Feed and water were given ad libitum
90
throughout the one week acclimatization period. Subsequently, twelve hours before the
91
start of the experiment, the animals were deprived of feed. After this period, three birds per
92
species were administered ZEN (3 mg/kg BW) by oral gavage (PO) whereas the other 3
93
birds/species were injected the same dose of ZEN in the wing vein (IV). The PO and IV bolus
94
solution was prepared by dissolving the ZEN standard in DMSO (10 mg/mL) and further
95
diluted with water (PO) or physiological saline (IV) up to a volume of 1 mL. Following
96
administration of the mycotoxin, 0.5 mL of blood was drawn from the leg vein at various
97
time points: 0 (just before administration) and 2, 5, 10, 20, 30, 40, 50, 60, 120, 180 and 240
98
min post-administration. Samples were centrifuged (2851 x g, 10 min, 4 °C) and aliquots of
99
plasma (150 µL) were stored at ≤ -15 °C until analysis. After a two-day wash-out period, the
100
protocol was repeated in a two-way cross-over design. The birds that received an IV injection
101
of the mycotoxin then received a PO bolus and vice versa. The dosing, blood collection and
102
sample storage was performed in the same way as the first administration. The animal
103
experiment was approved by the Ethical Committee of the Faculty of Veterinary Medicine
104
and Bioscience Engineering of Ghent University (EC 2014/118).
105
LC-MS/MS analysis
106
Sample treatment and quantification of ZEN, and its phase I metabolites (α-ZEL, β-ZEL, α-
107
ZAL, β-ZAL and ZAN, see Supplementary Figure 1), in poultry plasma was performed as 6 ACS Paragon Plus Environment
Page 7 of 32
Journal of Agricultural and Food Chemistry
108
previously described by De Baere et al. (2012) with minor modifications. Briefly, 50 µL of IS
109
working solution (50 ng/mL) were added to 150 µL of plasma, followed by the addition of
110
ACN up to 1 mL. Next, the sample was vortex mixed (15 sec) and centrifuged (8517 x g, 10
111
min, 4 °C). The supernatant was evaporated to dryness using nitrogen (N2, 45 ± 5 °C). The dry
112
residue was reconstituted in 200 µL of water/MeOH (85/15, v/v), vortex mixed (15 sec),
113
filtered through a Millex® GV-PVDF syringe filter and transferred into a conical autosampler
114
vial. An aliquot (5 µL) was injected onto the LC-MS/MS instrument.
115
Chromatographic separation was achieved on a Hypersil® Gold column (50 mm x 2.1 mm i.d.,
116
dp: 1.9 µm) in combination with a guard column of the same type (10 mm x 2.1 mm i.d., dp:
117
3 µm), both from ThermoFisher Scientific (Breda, The Netherlands). Mobile phase A
118
consisted of 0.1% acetic acid in water whereas mobile phase B was ACN. Following gradient
119
elution program was run: 0-0.5 min (70% A, 30% B), 0.5-5.0 min (linear gradient to 70% B),
120
5.0-6.4 min (30% A, 70% B), 6.4-6.5 min (linear gradient to 30% B), 6.5-8.5 min (70% A, 30%
121
B). Flow rate was set at 300 µL/min and the temperature of the column oven and
122
autosampler tray were set at 45 and 5 °C, respectively.
123
Detection was performed on a Waters Xevo® TQ-S triple quadrupole mass spectrometer by
124
means of electrospray ionization (ESI) in the negative ionization mode. The instrument was
125
tuned by direct infusion of a 10 ng/mL working solution of ZEN, the metabolites and the IS.
126
The following parameters were retained for optimal detection: capillary voltage: 2.5 kV,
127
cone voltage: 15 V, source temperature: 150 °C, desolvation temperature: 600 °C, cone gas
128
flow: 150 L/h, desolvation gas flow: 1000 L/h. Acquisition was performed in the selected
129
reaction monitoring (SRM) mode. Following transitions (m/z) were used as quantifier and
130
qualifier ion, respectively, for ZEN: 317.1 > 175.0 and 317.1 >131.0, for α-ZEL: 319.0 > 275.0
7 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 8 of 32
131
and 319.0 > 159.9, for β-ZEL: 319.0 > 159.9 and 319.0 > 275.0, for ZAN: 319.0 > 205.0 and
132
319.0 > 275.0, for α-ZAL: 321.1 > 277.1 and 321.1 > 303.0, for β-ZAL: 321.1 > 277.1 and 321.1
133
> 303.0 and for the IS: 335.2 > 168.9 and 335.2 > 185.0. The method was validated for the
134
compounds listed above according to a validation protocol described by De Baere
135
on European
136
following parameters: linearity (correlation coefficient and goodness-of-fit), within- and
137
between-run accuracy and precision, carry-over, limit of quantification (LOQ) and limit of
138
detection (LOD). The LOQ was set at 0.5 ng/mL for ZEN, 0.2 ng/mL for α-ZEL and α-ZAL and
139
0.1 ng/mL for β-ZEL, β-ZAL and ZAN.
140
UHPLC-HRMS analysis
141
The extracted samples were also analyzed by UHPLC coupled to HRMS analysis for
142
identification and semi-quantification of the glucuronide conjugates of ZEN and of its phase I
143
metabolites as previously described by De Baere 19. This was performed based on the peak
144
area ratios of the metabolites, versus the IS. The UHPLC system consisted of an Accela® type
145
1250 High Speed LC and autosampler both from ThermoFisher Scientific. The same HPLC
146
column and mobile phases were used as described above. The UHPLC was interfaced to an
147
Exactive Orbitrap® HR mass spectrometer, equipped with a heated ESI probe operating in the
148
negative ionization mode (ThermoFisher Scientific). Accurate masses were based on the
149
predicted masses (m/z; [M-H]-) described by De Baere 19 and Stevenson 20: ZEN-glucuronide
150
(ZEN-GlcA, C24H30O11): 493.17153; ZAN-GlcA, α-ZEL-GlcA and β-ZEL-GlcA (C24H32O11, no
151
chromatographic separation or distinction between these compounds based on accurate
152
masses possible): 495.18718; α-ZAL-GlcA, β-ZAL-GlcA (C24H34O11, no chromatographic
153
separation or distinction between these compounds based on accurate masses possible):
17
and international
18
16
based
guidelines. The validation protocol encompassed
8 ACS Paragon Plus Environment
Page 9 of 32
Journal of Agricultural and Food Chemistry
154
497.20283. Confirmation of the GlcA peaks observed in the extracted ion chromatogram
155
(EIC) was performed by comparing the theoretically calculated 13C/12C isotope ratios for the
156
[M-H]- ion with the corresponding isotope ratios detected in the analyzed samples, as
157
described by De Baere 19.
158
Toxicokinetic analysis
159
Non compartmental toxicokinetic analysis of ZEN, α- and β-ZEL was performed with
160
WinNonlin 6.3 (Pharsight, St-Louis, MI, USA). For ZEN, following toxicokinetic parameters
161
were calculated for IV and PO administration: maximal plasma concentration for PO (Cmax),
162
plasma concentration at time 0 for IV (C0), time to maximal plasma concentration (Tmax), area
163
under the plasma concentration-time curve from time 0 to 3 h (AUC0-t), area under the
164
plasma concentration-time curve from time 0 to infinite (AUC0-inf), elimination rate constant
165
(kel), elimination half-life (T1/2el), total body clearance (Cl), volume of distribution (Vd) and
166
mean residence time (MRT).
167
The absolute oral bioavailability (F, expressed as %, F%) for each individual bird was
168
calculated according to the formula:
169
F% = AUC0-inf PO / AUC0-inf IV x 100
170
The Cl and Vd after PO administration was calculated by multiplying the data generated by
171
the toxicokinetic software (i.e. Vd/F and Cl/F) by the F from each individual bird.
172
The mean absorption time (MAT) was calculated according to the formula:
173
174
MAT = MRTPO – MRTIV The absorption rate constant (ka) and absorption half-life (T1/2a) were derived from the MAT:
9 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
175
ka = MAT-1
176
T1/2a = 0.693 / ka
Page 10 of 32
177
For α- and β-ZEL, the Cmax, Tmax, AUC0-t (from time 0 to the last time point above the LOQ, i.e.
178
2 or 3 h) and AUC0-inf were determined after both IV and PO administration of ZEN. Next,
179
ZEL/ZEN ratios were calculated according to the formulas:
180
α-ZEL/ZEN = (AUC0-inf α-ZEL) / (AUC0-inf ZEN)
181
β-ZEL/ZEN = (AUC0-inf β-ZEL) / (AUC0-inf ZEN)
182
ZEL/ZEN = (AUC0-inf α-ZEL + AUC0-inf β-ZEL) / (AUC0-inf ZEN)
183
184
Finally, the α-ZEL/β-ZEL ratio was calculated according to the formula: α-ZEL/β-ZEL = (AUC0-inf α-ZEL) / (AUC0-inf β-ZEL)
185
Statistical analysis
186
All toxicokinetic parameters from each compound (ZEN, α- and β-ZEL) and each
187
administration route were compared between animal species using one-way analysis of
188
variance (ANOVA) (SPSS 21, IBM, USA). The level of significance was set at 0.05.
189
Results and Discussion
190
The goal of this study was to unravel the toxicokinetic behavior, absolute oral bioavailability
191
and biotransformation of ZEN in different poultry species in order to assess potential species
192
dependent sensitivity to this mycotoxin. During the animal experiment, no clinical symptoms
193
were observed after PO or IV administration of ZEN to the birds. Furthermore, no sex
194
differences in toxicokinetic parameters were observed for broiler chickens and turkey poults.
10 ACS Paragon Plus Environment
Page 11 of 32
Journal of Agricultural and Food Chemistry
195
In figure 1A, B and C, the plasma concentration-time profiles of ZEN, α- and β-ZEL after IV
196
and PO administration of ZEN to broiler chickens, laying hens and turkey poults are
197
presented, respectively. Only trace amounts of α- and β-ZAL and ZAN were detected but
198
none above the LOQ of 0.2, 0.1 and 0.1 ng/mL, respectively. As can be seen in these figures
199
and Table 1, ZEN is rapidly absorbed in all studied poultry species, namely broiler chickens
200
(Tmax = 0.35 h, MAT = 0.37 h), laying hens (Tmax = 0.32 h, MAT = 0.35 h) and turkey poults
201
(Tmax = 0.97 h, MAT = 0.44 h). However, the F% is low in all studied poultry species, 8.34%,
202
10.28% and 6.87%, in broiler chickens, laying hens and turkey poults, respectively. This might
203
indicate either a low extent of absorption and/or extensive pre-systemic biotransformation,
204
and attributes to the generally accepted high tolerance of poultry to ZEN since F is a
205
measurement for systemic exposure. Next to rapid absorption, the mycotoxin is rapidly
206
eliminated in all species as well with T1/2el between 0.34 – 0.36 h and 0.29 – 0.46 h after PO
207
and IV administration, respectively. Osselaere
208
administration of 0.3 mg ZEN/kg BW to broiler chickens. Furthermore, a high Vd is observed
209
after PO and IV administration in all animal species (Vd = 3.21 – 10.65 L/kg). For broiler
210
chickens, an even higher Vd has been reported previously by Osselaere
211
L/kg, however this value was reported with a high uncertainty (15.15 L/kg). Of interest here
212
is that turkey poults have a significant higher Vd (9.03 – 10.65 L/kg) compared to broiler
213
chickens (3.21 – 4.16 L/kg) and laying hens (6.18 – 6.24 L/kg) which supports the hypothesis
214
of a higher sensitivity to ZEN of this species. Furthermore, the higher Vd explains why the C0
215
is significantly lower in turkey poults (C0 = 700.5 ng/mL) compared to broiler chickens (C0 =
216
2607.0 ng/mL) and laying hens (C0 = 2789.2 ng/mL) although they were administered the
217
same dose of ZEN (3 mg/kg BW). Also pigs display a high Vd of ZEN, comparable to turkey
218
poults, after IV administration, namely 10.84 L/kg, leading to a high tissue distribution of the
10
reported a similar T1/2el of 0.53 h after IV
10
, namely 22.26
11 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 12 of 32
219
mycotoxin 6. Besides a higher Vd in turkey poults, also a significantly higher Cl in turkeys (Cl =
220
16.57 – 19.66 L/h/kg) compared to broiler chickens (Cl = 9.06 – 11.1 L/h/kg) and laying hens
221
(Cl = 9.39 – 11.38 L/h/kg) was noticed. Since both Vd and Cl are higher in turkey poults, this
222
leads to a comparable T1/2el between the latter (T1/2el = 0.35 – 0.38 h) and broiler chickens
223
(T1/2el = 0.29 – 0.34 h) and laying hens (T1/2el = 0.36 – 0.46 h). Next, due to the higher Cl in
224
turkey poults and comparable F, the AUC0-inf is significantly lower in this species after both
225
administration routes (AUC0-inf PO = 10.21 h.ng/mL, AUC0-inf IV = 183.12 h.ng/mL) compared to
226
broiler chickens (AUC0-inf PO = 23.59 h.ng/mL, AUC0-inf IV = 292.10 h.ng/mL) and laying hens
227
(AUC0-inf PO = 30.04 h.ng/mL, AUC0-inf IV = 324.93 h.ng/mL). Similarly, also the AUC0-t was
228
significantly lower.
229
As described above, species dependent biotransformation of ZEN has a distinct impact on
230
sensitivity to this mycotoxin, and the in vitro estrogenic potency of its phase I metabolites is
231
as follows: α-ZAL > α-ZEL > β-ZAL > ZEN > β-ZEL 21. Phase I biotransformation of ZEN consists
232
of reduction of the ketone group of ZEN to its corresponding alcohol by 3α-/3β-HSD, thereby
233
forming α/β-ZEL, and aromatic hydrogenation of α/β-ZEL to α/β-ZAL by cytochrome P450
234
(CYP450) enzymes. Finally, α/β-ZAL can be oxidized by 3α-/3β-HSD to ZAN. The
235
biotransformation of ZEL to ZAL and ZAN has been reported for pigs and humans, however,
236
the extent is negligible 21. Also in the present study only trace amounts of α/β-ZAL and ZAN
237
were detected demonstrating that formation of α- and β-ZEL is also the predominant phase I
238
biotransformation in poultry. In all three poultry species both α- and β-ZEL could be detected
239
although the extent differed between species and routes of administration (Figure 1 and
240
Table 2). Turkey poults have a more efficient biotransformation of ZEN to α- and β-ZEL
241
compared to broiler chickens and laying hens, with higher α-ZEL/ZEN and β-ZEL/ZEN ratios
242
after both PO and IV administration (although not significant for β-ZEL/ZEN after PO), 12 ACS Paragon Plus Environment
Page 13 of 32
Journal of Agricultural and Food Chemistry
243
whereas these ratios are comparable between broiler chickens and laying hens (Table 2).
244
Consequently, also the ZEL/ZEN ratio in turkey poults is significantly higher after PO
245
(ZEL/ZENPO = 5.226) as well as IV administration (ZEL/ZENIV = 0.152) compared to broiler
246
chickens (ZEL/ZENPO = 1.149, ZEL/ZENIV = 0.032) and laying hens (ZEL/ZENPO = 2.086,
247
ZEL/ZENIV = 0.042). Furthermore, the biotransformation of ZEN to α- and β-ZEL occurs to a
248
greater extent after PO than after IV administration in all animal species. This difference in
249
ZEL formation between both administration routes indicates pre-systemic biotransformation
250
of ZEN in the gut and/or the liver. After IV administration, the α-ZEL/β-ZEL ratio is not
251
statistically different between bird species and is around 1 (α-ZEL/β-ZELIV = 1.073 to 1.629).
252
In contrast, after PO administration the β-ZEL isomer is predominantly formed in broiler
253
chickens (α-ZEL/β-ZELPO = 0.153) and laying hens (α-ZEL/β-ZELPO = 0.027), but this is
254
significantly different in turkey poults (α-ZEL/β-ZELPO = 0.749). Again, this indicates pre-
255
systemic formation of mainly β-ZEL, especially in broiler chickens and laying hens. These data
256
confirm the in vitro findings in laying hens, namely a predominant β-ZEL formation 5. Since
257
the α-ZEL/ZEN ratio after PO and IV ZEN administration is significantly higher in turkey poults
258
compared to both other bird species, this supports the hypothesis of increased sensitivity of
259
turkey poults to the estrogenic effects of the mycotoxin.
260
Phase II biotransformation of ZEN and its phase I metabolites comprises glucuronidation
261
which is catalyzed by uridine 5’-diphosphate glucuronosyltransferase (UGT)
262
analytical standards of glucuronidated ZEN (ZEN-GlcA) nor glucuronidated α- or β-ZEL (ZEL-
263
GlcA) are commercially available, no accurate quantitative analysis could be performed.
264
However, a semi-quantitative using HR-MS was done (Figure 2). After IV administration of
265
ZEN, ZEN-GlcA is the predominant phase II metabolite in all three bird species. Although the
266
ZEL/ZEN ratio is higher in turkey poults, namely 0.152, compared to broiler chickens and
22
. Since no
13 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 14 of 32
267
laying hens, 0.032 and 0.042 respectively, no ZEL-GlcA could be detected in this species after
268
IV administration, which is in contrast to the other species. After oral ZEN administration, a
269
comparable amount of ZEN-GlcA and ZEL-GlcA was detected in broiler chickens and laying
270
hens, whereas in turkey poults only ZEL-GlcA was detected, attributed to the high ZEL/ZEN
271
ratio in this species after PO administration (ZEL/ZEN = 5.226). This confirms the phase I
272
biotransformation data, namely a pre-systemic ZEL formation and consequent predominant
273
ZEL glucuronidation. Differences in phase II biotransformation might also account for
274
differences in sensitivity. For the mycotoxin DON, for instance, limited sulfation was
275
described for turkeys in contrast to broiler chickens, which might explain the increased
276
sensitivity of turkeys to deoxynivalenol
277
turkeys are more sensitive compared to other poultry and animal species based on
278
differences in biotransformation of AFB1. In turkeys, the phase I bio-activation of AFB1 to
279
AFB1-8,9-epoxide, is highly efficient and the epoxide metabolite is held responsible for the
280
hepatotoxic and carcinogenic effects of AFB1 24. Furthermore, turkeys have a glutathione-S-
281
transferase deficiency (phase II biotransformation) which adds to the sensitivity of this
282
species 25.
283
In conclusion, this paper describes – for the first time – the toxicokinetic behavior, absolute
284
oral bioavailability and comparative phase I and II biotransformation of ZEN in broiler
285
chickens, laying hens and turkey poults. ZEN is rapidly absorbed in all studied poultry
286
species, but the absolute oral bioavailability of the mycotoxin is low. Furthermore, it is
287
rapidly eliminated as well after both PO and IV administration. Both α- and β-ZEL were
288
formed equally after IV administration in all bird species, whereas an increased
289
biotransformation to β-ZEL was demonstrated after oral administration indicating pre-
290
systemic biotransformation processes, primarily in broiler chickens and laying hens. Finally,
23
. Also for the mycotoxin aflatoxin B1 (AFB1),
14 ACS Paragon Plus Environment
Page 15 of 32
Journal of Agricultural and Food Chemistry
291
the presented data suggest that turkey poults might be more sensitive to the effects of ZEN
292
based on the higher Vd of ZEN and the more extensive pre-systemic biotransformation of
293
ZEN to α-ZEL in comparison to the two other poultry species.
15 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 16 of 32
294
Supporting Information Available
295
Chemical structure and phase I biotransformation pathways of zearalenone (adapted from
296
Mukherjee21). This material is available free of charge via the Internet at http://pubs.acs.org.
297
References
298
1.
299
mycotoxin screening reveals the occurrence of 139 different secondary metabolites in feed
300
and feed ingredients. Toxins (Basel) 2013, 5, 504-23.
301
2.
302
and deoxynivalenol on different non-reproductive and reproductive organs in female pigs: A
303
review. Food Addit Contam 2007, 24, 306-314.
304
3.
305
mycotoxins with estradiol binding sites in the mouse uterus. J Toxicol Environ Health 1979, 5,
306
593-8.
307
4.
308
P. T.; van der Burg, P.; Gustafsson, J. A., Interaction of estrogenic chemicals and
309
phytoestrogens with estrogen receptor beta. Endocrinology 1998, 139, 4252-4263.
310
5.
311
hepatic biotransformation of zearalenone. Vet J 2006, 172, 96-102.
312
6.
313
deoxynivalenol (DON) in the pig. Archives of Animal Nutrition-Archiv Fur Tierernahrung 2004,
314
58, 169-180.
315
7.
316
Lindner, W., Concentration levels of zearalenone and its metabolites in urine, muscle tissue,
Streit, E.; Schwab, C.; Sulyok, M.; Naehrer, K.; Krska, R.; Schatzmayr, G., Multi-
Tiemann, U.; Danicke, S., In vivo and in vitro effects of the mycotoxins zearalenone
Greenman, D. L.; Mehta, R. G.; Wittliff, J. L., Nuclear interaction of Fusarium
Kuiper, G. G. J. M.; Lemmen, J. G.; Carlsson, B.; Corton, J. C.; Safe, S. H.; van der Saag,
Malekinejad, H.; Maas-Bakker, R.; Fink-Gremmels, J., Species differences in the
Dänicke, S.; Valenta, H.; Doll, S., On the toxicokinetics and the metabolism of
Zollner, P.; Jodlbauer, J.; Kleinova, M.; Kahlbacher, H.; Kuhn, T.; Hochsteiner, W.;
16 ACS Paragon Plus Environment
Page 17 of 32
Journal of Agricultural and Food Chemistry
317
and liver samples of pigs fed with mycotoxin-contaminated oats. J Agr Food Chem 2002, 50,
318
2494-2501.
319
8.
320
metabolism, detoxification, regulations and intake of zearalenone: an oestrogenic
321
mycotoxin. Food Chem Toxicol 2007, 45, 1-18.
322
9.
323
Biotransformation of zeranol: disposition and metabolism in the female rat, rabbit, dog,
324
monkey and man. Xenobiotica 1983, 13, 209-21.
325
10.
326
Backer, P.; Croubels, S., Toxicokinetic study and absolute oral bioavailability of
327
deoxynivalenol, T-2 toxin and zearalenone in broiler chickens. Food Chem Toxicol 2013, 51,
328
350-5.
329
11.
330
Hens. J Agr Food Chem 1980, 28, 286-291.
331
12.
332
Chickens. Poultry Sci 1980, 59, 1577-1577.
333
13.
334
of Dietary Zearalenone on Reproduction of Chickens. Poultry Sci 1981, 60, 1165-1174.
335
14.
336
2-Toxin, and Zearalenone on Reproduction of Turkey Females. Poultry Sci 1983, 62, 282-289.
337
15.
338
Concentrations of Dietary Zearalenone by Young Male Turkey Poults. Poultry Sci 1986, 65,
339
1905-1910.
Zinedine, A.; Soriano, J. M.; Molto, J. C.; Manes, J., Review on the toxicity, occurrence,
Migdalof, B. H.; Dugger, H. A.; Heider, J. G.; Coombs, R. A.; Terry, M. K.,
Osselaere, A.; Devreese, M.; Goossens, J.; Vandenbroucke, V.; De Baere, S.; De
Dailey, R. E.; Reese, R. E.; Brouwer, E. A., Metabolism of [Zearalenone-C-14 in Laying
Allen, N. K.; Aakhusallen, S.; Mirocha, C. J., Effect of Zearalenone on Reproduction of
Allen, N. K.; Mirocha, C. J.; Aakhusallen, S.; Bitgood, J. J.; Weaver, G.; Bates, F., Effect
Allen, N. K.; Peguri, A.; Mirocha, C. J.; Newman, J. A., Effects of Fusarium Cultures, T-
Olsen, M.; Mirocha, C. J.; Abbas, H. K.; Johansson, B., Metabolism of High-
17 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 18 of 32
340
16.
De Baere, S.; Goossens, J.; Osselaere, A.; Devreese, M.; Vandenbroucke, V.; De
341
Backer, P.; Croubels, S., Quantitative determination of T-2 toxin, HT-2 toxin, deoxynivalenol
342
and deepoxy-deoxynivalenol in animal body fluids using LC-MS/MS detection. Journal of
343
Chromatography B 2011, 879, 2403-2415.
344
17.
345
Volume 8: Notice to applicants and guideline on the establishment of maximum residue limits
346
(MRLs) for residues of veterinary medicinal products in foodstuffs of animal origin. 2005 weblink:
347
http://ec.europa.eu/health/files/eudralex/vol-8/pdf/vol8_10-2005_en.pdf
348
May 4, 2015).
349
18.
350
Kinetics of Veterinary Drugs in Food-Producing Animals: Validation of Analytical Methods Used in
351
Residue Depletion Studies. 2015 weblink:
352
http://www.fda.gov/downloads/AnimalVeterinary/GuidanceComplianceEnforcement/GuidanceforIn
353
dustry/UCM207942.pdf (consulted on May 4, 2015).
354
19.
355
Quantitative determination of zearalenone and its major metabolites in animal plasma using
356
LC-MS/MS and (U)HPLC-HR-MS detection. Analytica Chimica Acta 2012, 756, 37-48.
357
20.
358
Miles, C. O., Preparative enzymatic synthesis of glucuronides of zearalenone and five of its
359
metabolites. J Agr Food Chem 2008, 56, 4032-4038.
360
21.
361
V.; Zarbl, H.; Georgopoulos, P. G., Physiologically-Based Toxicokinetic Modeling of
362
Zearalenone and Its Metabolites: Application to the Jersey Girl Study. Plos One 2014, 9.
European Union. The rules governing medicinal products in the European Union
(consulted
on
VICH GL49(R). Guidance for Industry Studies to Evaluate the Metabolism and Residue
De Baere, S.; Osselaere, A.; Devreese, M.; Van Haecke, L.; De Backer, P.; Croubels, S.,
Stevenson, D. E.; Hansen, R. P.; Loader, J. I.; Jensen, D. J.; Cooney, J. M.; Wilkins, A. L.;
Mukherjee, D.; Royce, S. G.; Alexander, J. A.; Buckley, B.; Isukapalli, S. S.; Bandera, E.
18 ACS Paragon Plus Environment
Page 19 of 32
Journal of Agricultural and Food Chemistry
363
22.
Pfeiffer, E.; Hildebrand, A.; Mikula, H.; Metzler, M., Glucuronidation of zearalenone,
364
zeranol and four metabolites in vitro: Formation of glucuronides by various microsomes and
365
human UDP-glucuronosyltransferase isoforms. Mol Nutr Food Res 2010, 54, 1468-1476.
366
23.
367
De Backer, P.; Croubels, S., Toxicokinetic study and oral bioavailability of deoxynivalenol in
368
turkey poults, and comparative biotransformation between broilers and turkeys World
369
Mycotoxin J 2015, in press.
370
24.
371
the relative roles of cytochromes P450 1A5 and 3A37. Toxicol Appl Pharmacol 2011, 254,
372
349-54.
373
25.
374
Springer Publishers, New York, USA.
Devreese, M.; Antonissen, G.; Broekaert, N.; De Mil, T.; De Baere, S.; Vanhaecke, L.;
Rawal, S.; Coulombe, R. A., Jr., Metabolism of aflatoxin B1 in turkey liver microsomes:
Chen, C-H. Activation and Detoxification Enzymes: Functions and Implications. 2012,
19 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 20 of 32
375
Figure Captions
376
Figure 1. Plasma concentration-time profile of zearalenone (ZEN), α-zearalenol (α-ZEL) and
377
β-zearalenol (β-ZEL) after intravenous (IV) and oral (PO) administration of 3 mg ZEN/kg body
378
weight to broiler chickens (A), laying hens (B) and turkey poults (C) (n=6). Values are
379
presented as mean + SD.
380
Figure 2. Ratio of the peak area detected by ultra-high performance liquid chromatography
381
coupled to high resolution-mass spectrometry of zearalenone (ZEN) or its metabolites,
382
namely α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), ZEN-glucuronide (ZEN-GlcA) and ZEL-
383
glucuronide (ZEL-GlcA), and the internal standard (13C18-ZEN) plotted against the time after
384
intravenous (IV) or oral (PO) administration (p.a.) of 3 mg ZEN/kg body weight to broiler
385
chickens (A), laying hens (B) or turkey poults (C) (n=6). Values are presented as mean + SD.
20 ACS Paragon Plus Environment
Page 21 of 32
Journal of Agricultural and Food Chemistry
21 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 22 of 32
Table 1. Main Toxicokinetic Parameters Of Zearalenone After Oral (PO) And Intravenous (IV) Administration (3 mg/kg BW) To Broiler Chickens, Laying Hens And Turkey Poults (n=6). Values Are Presented As Mean ± SD. Broiler chickens Laying hens Turkey poults PO
IV
PO
IV
PO
IV
39.17 ± 18.67 a,b
2607.0 ± 506.03 a
54.12 ± 22.90 a
2789.2 ± 189.78 a
8.33 ± 2.21 b
700.5 ± 301.18 b
Tmax (h) e
0.35 ± 0.16 a
/
0.32 ± 0.08 a
/
0.97 ± 0.36 b
/
AUC0-t (h.ng/mL) f
21.87 ± 12.12 a,b
290.9 ± 72.78 a
29.31 ± 6.78 a
322.8 ± 37.27 a
8.53 ± 3.07 b
180.0 ± 21.12 b
AUC0-inf (h.ng/mL) g
23.59 ± 15.62 a
292.1 ± 72.50 a
30.04 ± 6.45 a
324.9 ± 35.94 a
10.21 ± 5.57 b
183.1 ± 18.92 b
ka (h-1) h
3.36 ± 1.52 a
/
3.50 ± 1.41 a
/
3.68 ± 2.28 a
/
T1/2a (h) i
0.26 ± 0.10 a
/
0.24 ± 0.09 a
/
0.30 ± 0.19 a
/
MRT (h) j
0.53 ± 0.13 a
0.16 ± 0.02 a
0.53 ± 0.07 a
0.22 ± 0.04 a,b
0.68 ± 0.19 a
0.33 ± 0.09 b
MAT (h) k
0.37 ± 0.14 a
/
0.35 ± 0.13 a
/
0.44 ± 0.27 a
/
Cl (L/h/kg) l
9.06 ± 4.61 a
11.1 ± 2.91 a
11.38 ± 3.03 a
9.39 ± 1.08 a
19.66 ± 3.87 b
16.57 ± 1.64 b
kel (h-1) m
2.14 ± 0.35 a
2.86 ± 1.06 a
1.98 ± 0.37 a
1.72 ± 0.07 a
2.04 ± 0.57 a
1.83 ± 0.10 a
T1/2el (h) n
0.34 ± 0.07 a
0.29 ± 0.11 a
0.36 ± 0.07 a
0.46 ± 0.12 a
0.35 ± 0.10 a
0.38 ± 0.02 a
Cmax (PO) c or C0 (IV) d (ng/mL)
22
ACS Paragon Plus Environment
Page 23 of 32
Journal of Agricultural and Food Chemistry
Vd (L/kg) o
3.21 ± 2.13 a
4.16 ± 0.75 a
6.18 ± 2.52 a
6.24 ± 0.92 a
10.65 ± 1.05 b
9.03 ± 1.43 b
F (%) p
8.34 ± 5.96 a
100 a
10.28 ± 2.53 a
100 a
6.87 ± 3.54 a
100 a
A different superscript (a or b) denotes a significant difference between animal species for each administration route at p < 0.05 Cmax: maximal plasma concentration, d C0: plasma concentration at time 0, e Tmax: time to maximal plasma concentration, f AUC0-t: area under the plasma concentration-time curve from time 0 to 3 h; g AUC0-inf: area under the plasma concentration-time curve from time 0 to infinite, h ka: absorption rate constant, i T1/2a: absorption half-life, j MRT: mean residence time, k MAT: mean absorption time, l Cl: total body clearance, m kel: elimination rate constant, n T1/2el: elimination half-life, o Vd: volume of distribution, p F: absolute oral bioavailability c
23
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 24 of 32
Table 2. Main Toxicokinetic Parameters Of α- And β-zearalenol (α-/β-ZEL) After Oral (PO) And Intravenous (IV) Administration Of Zearalenone (3 mg/kg BW) To Broiler Chickens, Laying Hens And Turkey Poults (n=6). Values Are Presented As Mean ± SD. Broiler chickens Laying hens Turkey poults PO
IV
PO
IV
PO
IV
Cmax (ng/mL) c
3.99 ± 2.53 a
30.31 ± 10.23 a
3.20 ± 1.99 a
37.91 ± 10.07 a
6.45 ± 0.33 a
27.32 ± 2.21 a
Tmax (h) d
0.63 ± 0.11 a
0.03 ± 0.00 a
0.27 ± 0.08 a
0.03 ± 0.00 a
0.58 ± 0.08 a
0.09 ± 0.03 b
AUC0-t (h.ng/mL) e
2.44 ± 0.80 a
5.68 ± 1.61 a
1.57 ± 0.87 a
6.81 ± 1.80 a
11.60 ± 0.14 b
17.71 ± 2.35 b
AUC0-inf (h.ng/mL) f
2.79 ± 1.37 a
5.93 ± 1.68 a
1.63 ± 0.89 a
6.99 ± 1.75 a
15.58 ± 8.39 b
20.04 ± 5.12 b
Cmax (ng/mL) c
25.25 ± 13.96 a
13.30 ± 6.48 a
96.16 ± 38.95 b
38.92 ± 16.14 b
28.52 ± 15.36 a
15.14 ± 1.61 a
Tmax (h) d
0.61 ± 0.11 a
0.07 ± 0.19 a
0.42 ± 0.08 a,b
0.03 ± 0.00 a
0.37 ± 0.14 b
0.15 ± 0.03 b
AUC0-t (h.ng/mL) e
24.55 ± 15.09 a
3.50 ± 1.51 a
58.48 ± 14.60 a
6.64 ± 2.81 b
29.66 ± 13.43 a
9.83 ± 1.43 b
AUC0-inf (h.ng/mL) f
27.36 ± 17.51 a
4.09 ± 1.87 a
58.84 ± 14.54 a
6.90 ± 2.71 a
38.83 ± 20.04 a
15.36 ± 3.42 b
α-ZEL/ZEN g
0.138 ± 0.073 a
0.020 ± 0.001 a
0.057 ± 0.026 a
0.021 ± 0.004 a
1.015 ± 0.369 b
0.109 ± 0.033 b
β-ZEL/ZEN h
1.607 ± 1.159 a
0.018 ± 0.011 a
2.029 ± 0.262 a
0.021 ± 0.006 a
4.888 ± 3.124 a
0.089 ± 0.028 b
α-ZEL
β-ZEL
24
ACS Paragon Plus Environment
Page 25 of 32
Journal of Agricultural and Food Chemistry
ZEL/ZEN i
1.149 ± 0.525 a
0.032 ± 0.009 a
2.086 ± 0.271 a
0.042 ± 0.009 a
5.226 ± 2.898 b
0.152 ± 0.040 b
α-ZEL/β-ZEL j
0.153 ± 0.049 a
1.629 ± 0.566 a
0.027 ± 0.013 a
1.073 ± 0.151 a
0.749 ± 0.292 b
1.076 ± 0.243 a
A different superscript (a or b) denotes a significant difference between animal species for each administration route at p < 0.05 c Cmax: maximal plasma concentration, d Tmax: time to maximal plasma concentration, e AUC0-t: area under the plasma concentration-time curve from time 0 to 2 or 3 h, f AUC0-inf: area under the plasma concentration-time curve from time 0 to infinite, g α-ZEL/ZEN = (AUC0-inf α-ZEL) / (AUC0-inf ZEN), h β-ZEL/ZEN = (AUC0-inf β-ZEL) / (AUC0-inf ZEN), i ZEL/ZEN = (AUC0-inf α-ZEL + AUC0-inf β-ZEL) / (AUC0-inf ZEN), j α-ZEL/β-ZEL = (AUC0-inf α-ZEL ) / (AUC0-inf β-ZEL)
25
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 26 of 32
Figure 1 (A)
Plasma concentration (ng/mL)
IV 10000.0 1000.0 100.0 ZEN 10.0
α-ZEL β-ZEL
1.0 0.1 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
Plasma concentration (ng/mL)
PO 100.00
10.00
1.00
ZEN α-ZEL
0.10
β-ZEL
0.01 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
26 ACS Paragon Plus Environment
Page 27 of 32
Journal of Agricultural and Food Chemistry
(B)
Plasma concentration (ng/mL)
IV 10000.0 1000.0 100.0 ZEN 10.0
α-ZEL β-ZEL
1.0 0.1 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
Plasma concentration (ng/mL)
PO 1000.00 100.00 10.00 ZEN 1.00
α-ZEL β-ZEL
0.10 0.01 0.0
0.5
1.0
1.5
2.0
Time p.a. (h)
27 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 28 of 32
(C)
Plasma concentration (ng/mL)
IV 1000
100 ZEN α-ZEL
10
β-ZEL 1 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
Plasma concentration (ng/mL)
PO 100.00
10.00
1.00
ZEN α-ZEL
0.10
β-ZEL
0.01 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
28 ACS Paragon Plus Environment
Page 29 of 32
Journal of Agricultural and Food Chemistry
Figure 2 (A)
IV 1000.000
Area ratios
100.000 10.000
ZEN
1.000
α-ZEL
0.100
β-ZEL ZEN-GlcA
0.010
ZEL-GlcA 0.001 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
PO 10.000
Area ratios
1.000 ZEN 0.100
α-ZEL β-ZEL
0.010
ZEN-GlcA ZEL-GlcA
0.001 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
29 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 30 of 32
(B)
IV 1000.000
Area ratios
100.000 10.000
ZEN
1.000
α-ZEL
0.100
β-ZEL ZEN-GlcA
0.010
ZEL-GlcA 0.001 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
PO 10.000
Area ratios
1.000 ZEN 0.100
α-ZEL β-ZEL
0.010
ZEN-GlcA ZEL-GlcA
0.001 0.0
0.5
1.0
1.5
2.0
Time p.a. (h)
30 ACS Paragon Plus Environment
Page 31 of 32
Journal of Agricultural and Food Chemistry
(C)
IV Area ratios
100.00 10.00 ZEN
1.00
α-ZEL β-ZEL
0.10
ZEN-GlcA 0.01 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
PO Area ratios
10.000 1.000 ZEN
0.100
α-ZEL β-ZEL
0.010
ZEL-GlcA 0.001 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time p.a. (h)
31 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 32 of 32
Graphic for Table Of Contents (TOC)
32 ACS Paragon Plus Environment