Subscriber access provided by UNIVERSITY OF ADELAIDE LIBRARIES
Article
Cellular Transport of Esculin and its Acylated Derivatives in Caco-2 Cell Monolayers and their Antioxidant Properties in Vitro Mengmeng Zhang, Xuan Xin, Furao Lai, Xiaoyuan Zhang, Xiao-Feng Li, and Hui Wu J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b02525 • Publication Date (Web): 14 Aug 2017 Downloaded from http://pubs.acs.org on August 17, 2017
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 41
Journal of Agricultural and Food Chemistry
1
Cellular Transport of Esculin and its Acylated Derivatives in Caco-2
2
Cell Monolayers and their Antioxidant Properties in Vitro
3
Mengmeng Zhang†, Xuan Xin†, Furao Lai†, Xiaoyuan Zhang§, Xiaofeng Li*#, and Hui Wu*†
4 5 6
Affiliation
7
†College of Food Science and Engineering, South China University of Technology,
8
Guangzhou, Guangdong, 510640, China
9
§Research Institude of Shaoguan Huagong High-tech Industry, South China
10
University of Technology, Guangzhou, Guangdong, 510640, China
11
#State Key Laboratory of Pulp and Paper Engineering, South China University of
12
Technology, Guangzhou, Guangdong , 510640, China
13
Short title: Bioavailability and Antioxidant Properties of Esculin and its Acylated
14
Derivatives
15
Corresponding authors:
16
*Xiaofeng Li, State Key Laboratory of Pulp and Paper Engineering, South China
17
University of Technology, Wushan Road 381, Guangzhou, Guangdong, China.
18
Tel: (+86)20-22236819; E-mail:
[email protected] ; Fax: (+86)20-87112853
19
*Hui Wu, College of Food Science and Engineering, South China University of
20 21
Technology, Wushan Road 381, Guangzhou, Guangdong, China. Tel: (+86)20-87112853; E-mail:
[email protected]; Fax: (+86)20-87112853 1
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
22
ABSTRACT: Esculin has many pharmacological effects, but these are difficult to
23
observe after oral administration owing to poor lipid solubility. In our previous study,
24
five acylated derivatives with different acyl chain lengths (EA, EP, EO, EL, and EM)
25
were synthesized to improve the lipophilicity of esculin. In this study, the
26
bioavailability and antioxidant activity of the five derivatives were investigated. The
27
logP of esculin, EA, EP, EO, EL, and EM were -1.1±0.1, -0.3±0.14, 0.1±0.17,
28
1.6±0.09, 2.4±0.11 and 2.8±0.18, and their Papp were 0.71±0.02, 1.24±0.18,
29
1.74±0.11, 11.6±3.6, 4.11±1.03 and 2.64±0.97 ×10−6 cm/s, respectively. Besides, the
30
bioavailability of EO, EL, and EM were seriously affected by carboxylesterase. The
31
results of ABTS, ORAC, and DPPH assays indicated that the antiradical ability of
32
the five derivatives did not exceed that of esculin. However, EA, EP, and EO showed
33
more effective inhibition of AAPH-induced oxidative hemolysis than esculin did
34
(p
220
0.05) before and after the experiment, which indicated that the monolayers retained
221
good integrity, and the used exposure times and concentrations of all samples were
222
appropriate for the experiment. Table 2 showed the results of the transport experiment.
223
It was found that for all samples, the Papp of AP to BL transport was close to that of
224
BL to AP transport. This indicated the efficiency of transport from AP and BL sides
225
were similar for each compound. Uptake ratio (UR) was defined as the quotient of the
226
absorptive permeability and the secretory permeability (Papp AP−BL/Papp BL−AP). A
227
value of UR or ER (efflux ratio, Papp BL−AP/Papp AP−BL) higher than 1.5 suggests
228
the participation of an active transport mechanism; if the values are close to 1.0, this is
229
a passive transport.20 All UR were approximately 1.0 in this result, which indicated
230
that passive transport occurred for all samples.
231
Propranolol is a high permeability-high solubility lipophilic drug, which can be
232
absorbed almost completely after oral consumption. Furosemide is a low
233
permeability-high solubility hydrophilic compound with very low bioavailability.19
234
On the basis of these two extremes for the estimation of bioavailability, it was
235
determined that esculin has a much lower bioavailability than furosemide. The
236
bioavailability of EA and EP was better than that of esculin but similar to that of 11
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
237
furosemide. EO had a much better bioavailability than EA and EP did, but it was still
238
lower than that of propranolol. These results agreed with the prediction of logP values.
239
However, EL and EM had a much lower bioavailability than EO did, which was
240
similar to that of EA and EP. It is very different from the prediction of logP values.
241
This difference was not caused by the molecular weight. Although the molecular
242
weights of EL and EM were greater than 500 g/mol, they were only 56 and 85 g/mol
243
more than that of than EO (Mw = 466 g/mol), respectively. Thus, there must be other
244
explanations for the huge difference.
245
The results in Table 2 showed that the recovery of esculin, EA, and EP was
246
greater than 90%. However, EO, EL, and EM had a very low recovery. A recovery
247
of >80% gives an acceptable approximation of the Papp value. A lower recovery will
248
result in the underestimation of the Papp values;20 thus, the practical Papp values of EO,
249
EL, and EM were greater than the measured values. The reason may be that the
250
compound was retained inside the cells or that the compound was metabolized.20 Then,
251
the cells were lysed and the cellular concentrations of these esters were determined.
252
As shown in Table 3, these esters were detected in the lysate. However, compared
253
with the initial concentrations (100 nmol), the concentration of the esters in cells was
254
so low that the loss could not be offset. This means that EO, EL, and EM were
255
metabolized. In fact, vast amounts of esculin were detected in the samples of the AP
256
and BL sides of EO, EL, and EM (Table 3). This indicated that the ester bonds of EO,
257
EL, and EM were broken, and EO, EL, and EM were metabolized back to esculin. In
258
addition, almost no esculin was detected in the samples of EA and EP. This may have 12
ACS Paragon Plus Environment
Page 12 of 41
Page 13 of 41
Journal of Agricultural and Food Chemistry
259
occurred because the enzyme breaking the ester bond was mainly present in the
260
cytoplasm. The poor permeability of EA and VP would make it hard for these
261
compounds to enter the cytoplasm. Even if EA and VP were hydrolyzed, the
262
concentration of the product was too low to be detected. Interestingly, for EO, EL,
263
and EM, the amount of esculin molecules on the AP side was 2-3 times higher than
264
that on the BL side, which appeared to indicate that the enzyme was mainly situated
265
in the cytomembrane of the AP side.
266
Transport of Esculin and its Esters Across Caco-2 Cell Monolayers without
267
CES-mediated Hydrolysis CES are members of the α/β hydrolase fold family and
268
show ubiquitous tissue expression profiles with high levels in the liver, small intestine
269
and lung. They are the most important hydrolases for ester-containing drugs.21 Caco-2
270
cells were reported to have sufficient CES.21, 33 Thus, it was speculated that CES
271
hydrolyzed EO, EL, and EM. To demonstrate this speculation, BNPP, a specific CES
272
inhibitor was used to inhibit CES-mediated hydrolysis. After pretreatment with BNPP,
273
the Papp of EA and EP was unchanged, whereas the Papp of EO, EL, and EM increased
274
significantly (Table 4); especially, the Papp of EO was close to that of propranolol.
275
Additionally, the recoveries of EO, EL, and EM were greater than 90% (Table 4).
276
These results demonstrated that CES led to the main hydrolysis of EO, EL, and EM.
277
However, a small amount of esculin was detected (data not shown), which indicated
278
that other esterases existed.17 CES is predominantly located in the endoplasmic
279
reticulum membrane,34 which explained the low levels of hydrolysis of EA and EP.
280
However, it is difficult to determine why the mole number of esculin in the AP side 13
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
281
was much greater than that in the BL side. In fact, the efflux of drugs was dependent
282
on the relative size of the AP and BL membranes in Caco-2 cells. It is already
283
accepted that the brush border membrane has a larger surface area than the BL
284
membrane owing to the presence of microvilli.21 Thus, after the hydrolysis, the
285
produced esculin would be apt to flow to the AP side. The process of transport is
286
shown in Figure 3, and the amounts of each part are shown in Table 3. In addition, the
287
Papp of EO was close to that of EL and EM after the treatment with BNPP, but the Papp
288
of EO was higher than that of EL and EM without BNPP treatment. These results
289
suggested that the esters with a longer acyl chain were more easily hydrolyzed by
290
CES; this may be another explanation for the low levels of hydrolysis of EA and EP.
291
There are five subfamilies of CES: CES1–CES5. The major CES isozyme in
292
human intestine is human CES2 isozyme (hCE2), whereas the human CES1 isozyme
293
(hCE1) is predominant in Caco-2 cells. The substrate specificities of hCE1 and hCE2
294
are different, with hCE2 mainly hydrolyzing drugs in which an alcohol group of the
295
pharmacologically active parent drug has been modified with a simple acyl group. In
296
contrast, drugs in which the carboxyl group of the pharmacologically active drug is
297
modified with small alcohol groups are preferentially hydrolyzed by hCE1. hCE1 is
298
also capable of hydrolyzing substrates of hCE2 at low levels of activity, whereas
299
hCE2 is unable to hydrolyze substrates of hCE1.21 Esculin esters appeared to be
300
substrate of hCE2, which suggested that they may undergo more extensive hydrolysis
301
in the human intestine. Besides CES, there are other enzymes or proteins affecting the
302
bioavailability of esters in the human intestine, such as, UGT, cytochrome P450, 14
ACS Paragon Plus Environment
Page 14 of 41
Page 15 of 41
Journal of Agricultural and Food Chemistry
303
multidrug resistance-associated protein 2, breast cancer resistance protein.35 The
304
colonic microflora also can hydrolyze the ester drugs.36 Even food microstructure
305
affects the bioavailability.37 Thus, for the bioavailability of esculin and its esters in
306
body, more research is needed.
307
Antiradical Ability of Esculin and its Esters Scavenging free radicals is an
308
essential ability for most antioxidants. The antioxidant activities of esculin and its
309
esters were measured by the ABTS, ORAC, and DPPH assays. Like most of the
310
acylated derivatives and their parent compounds,14,
311
esculin esters was similar to or lower than that of esculin (Table 5 and Figure 4).
312
However, one report indicates that the antiradical ability of acylated derivatives was
313
higher than that of parent compounds.40 That study may be explained by the location
314
at which the acylation occurred, which was the phenolic hydroxyl group. The
315
phenolic hydroxyl group of polyphenols is closely related to their antioxidant
316
activity.41 The incorporated fatty acid chains caused electronic and steric effects in the
317
benzene ring and improved the antioxidant activity.40 In our study, the acylation
318
occurred at the stable glycosidic moiety and had little effect on the active site of
319
esculin. Thus, the antiradical ability of the acylated derivatives could not exceed that
320
of esculin. As shown in Table 5 and Figure 4, in the ABTS and ORAC assays, the
321
antiradical ability of esculin esters decreased with an increase in the acyl chain length.
322
The values for EA and EP were close to those for esculin, but those of EO, EL, and
323
EM were much lower than that of esculin. The cause of these differences is shown in
324
Figure 5. At the same concentration, the distribution of antioxidants in Figure 5A
38, 39
15
ACS Paragon Plus Environment
the antiradical ability of
Journal of Agricultural and Food Chemistry
325
provided more contact with free radicals than that in Figure 5B. Therefore, the
326
antioxidants in Figure 5A would exhibit more effective antiradical ability than those
327
in Figure 5B. The logP values of EA and EP indicated a relatively high hydrophilicity.
328
The ABTS and ORAC assays occur in a hydrophilic environment. Thus, EA and EP
329
could be evenly distributed in the system, whereas EO, EL, and EM had higher
330
lipophilicity and would form micelles. This structure will decrease the contact
331
between the active site of esculin and free radicals. In the DPPH assay, the antioxidant
332
activity of EO was similar to that of esculin, because that the solvent in the reaction
333
system was methanol. EO is more soluble in methanol and a homogeneous
334
distribution can be achieved. This result was in agreement with some previous
335
studies.39, 42 However, EL and EM had a lower DPPH free radical scavenging ability.
336
This may be explained by the hydrophobicity of EL and EM, which was much higher
337
than that of methanol and still led to a low solubility in methanol.43
338
Attenuation of Erythrocyte Hemolysis by Esculin and its Esters Although
339
many reports have indicated that the antiradical ability of acylated derivatives was
340
lower than that of their parent compounds, these new compounds exhibited more
341
remarkable antioxidant capacities when tested in food matrices, such as oils and
342
oil-in-water emulsions.25 This phenomenon can be explained by the polar paradox
343
theory, whcih can be applied to cells.9, 25 However, there are only a few studies that
344
use cells to evaluate the antioxidant activity of these acylated derivatives.39, 42 The cell
345
lines used in those studies may possess esterases. As previously mentioned, the esters
346
may be hydrolyzed by certain esterases in cells. Thus, to exclude the effect of 16
ACS Paragon Plus Environment
Page 16 of 41
Page 17 of 41
Journal of Agricultural and Food Chemistry
347
esterases on these esters, the erythrocytes were used as a model to explore the
348
antioxidant activities of esculin and its esters, because the metabolic networks in
349
erythrocytes are relatively simple. The esterases are not included in metabolic
350
networks of erythrocytes.16 The hemolysis of erythrocytes has been used extensively
351
as an ex vivo model for the study of the antioxidant activity. In the erythrocyte
352
hemolysis assay, free radicals induced by AAPH can cause lipid peroxidation and loss
353
of erythrocyte membrane integrity, which can ultimately lead to hemolysis.16
354
As shown in Figure 6A, erythrocyte hemolysis was effectively attenuated by
355
esculin and its esters. Their activity was in the order EO > EP ≈ EA > esculin > EL ≈
356
EM. The samples without AAPH supplementation did not induce hemolysis (data not
357
shown). AAPH-induced ROS generation can cause membrane lipid peroxidation and
358
result in the release of MDA. As seen in Figure 6B, the level of MDA in erythrocytes
359
was in accordance with the result of the hemolysis.
360
The structure of an erythrocyte is similar to a micro-balloon with a lipid bilayer
361
surface. Therefore, its interaction with water is similar to an oil-in-water emulsion. An
362
oil-in-water emulsion generally consists of three essential parts: lipid droplets, the
363
continuous aqueous phase, and the oil-water interface. According to the polar paradox
364
theory, nonpolar antioxidants are more effective than their polar homologs in
365
oil-in-water emulsions.44 Nonpolar antioxidants are mainly concentrated at the
366
oil-water interface, the optimum location for shielding the oil droplets from oxidation;
367
therefore, they would inhibit lipid oxidation more efficiently.25 In fact, lipophilicity
368
has been viewed as an important factor with respect to the effectiveness of the 17
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
45
Page 18 of 41
369
anti-hemolytic substances in hemolytic studies.16,
370
hydrophilicity of esculin was high and it was mainly distributed in the aqueous phase.
371
The mechanism of the inhibitory effect on hemolysis is only dependent on the ability
372
of scavenging free radicals produced by AAPH. For EA, EP, and EO which have a
373
relatively higher lipophilicity; the mechanism is not only dependent on the antiradical
374
ability, but also the location on the “oil-water interface” (Figure 7B). The increased
375
lipophilicity of the esters made it easier to form a shield around the cells; thus, the
376
inhibition of hemolysis occurred in the order: EO > EP ≈ EA > esculin
As shown in Figure 7A, the
377
However, the polar paradox theory has faced some challenges in recent years. One
378
such challenge is the “cutoff effect”, which means that a nonlinear relationship
379
existed between polarity and the antioxidant efficacy in emulsions for antioxidants.
380
There is a threshold for the antioxidant activity conferred by the increased alkyl
381
chain lengths; with further chain length extension, the activity will drastically
382
decrease. Several studies have revealed that short-medium-chain lipophilic esters
383
were able to improve the efficacy of antioxidants in emulsions better than long-chain
384
esters.9 This phenomenon also was observed in this study. The reason may be that if
385
the lipophilicity of the antioxidants was too high, they would most likely be placed at
386
the interior of the emulsion dissolved in the oil droplet, or aggregate readily in the
387
aqueous phase rather than orienting themselves at the interfacial layer.9,
388
indicated that the low inhibitory effects of EL and EM on hemolysis may be a result
389
of the ease of entering the cell and forming micelles (Figure 7C).
390
25
This
Some reports have deemed that a good antioxidant for oil-in-water emulsions 18
ACS Paragon Plus Environment
Page 19 of 41
Journal of Agricultural and Food Chemistry
391
should be an effective surfactant. At certain hydrophilic-lipophilic balance (HLB)
392
values (between 8 and 11), the lipophilic antioxidants can be located in the oil-water
393
interface. The cutoff effect appears when HLB values are lower than 8.25 However, all
394
HLB values of esculin esters were greater than 11 (EA, 16.9; EP, 16.3; EO, 13.9; EL,
395
12.3; EM, 11.7), and the cutoff effect appeared at 12.3. The explanation for the
396
different cutoff chain lengths may be that an effective surfactant depends on different
397
parameters that may vary for each specific series of phenolipids, such as the optimum
398
HLB value or the specific polarity and geometry of the polar head.25 Although
399
erythrocytes could be approximately regarded as the emulsion or oil droplets, the
400
structure of the cytomembrane is quite different from that of oil droplets.
401
The Role of “Oil-Water Interface” in Inhibiting Hemolysis A “shield” around
402
the cells was supposed to exist according to the polar paradox theory. The existence of
403
the “shield” was dependent on the “oil-water interface”. To further demonstrate the
404
role of “oil-water interface”, erythrocyte hemolysis was performed in cold ultrapure
405
water. The water was then treated with AAPH and esculin or esculin esters according
406
to the method described in the assay for erythrocyte hemolysis. The level of MDA
407
showed that esculin was a potent inhibitor of membrane lipid peroxidation. The
408
activity of the esters was in the order, EA ≈ EP > EO > EL ≈ EM (Figure 8), which
409
was similar to the order of the antiradical abilities. This indicated that the inhibitory
410
effect of the esters on membrane lipid peroxidation was dependent on the intact closed
411
structure of the cytomembrane. The structure of cytomembrane was destroyed and, as
412
there was not the “oil-water interface”, the esters could not aggregate. Thus the 19
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
413
“shield” cannot be formed, and the esters cannot show an improved inhibition of lipid
414
peroxidation.
415
In conclusion, this study investigated the bioavailability and antioxidant activity of
416
esculin and its acylated derivatives. It was found that all derivatives had a better
417
bioavailability than esculin. However, the bioavailability of derivatives with short or
418
long alkyl chain still was low. The derivative with medium alkyl chain had a much
419
better bioavailability. Besides, derivatives with medium and long alkyl chain were
420
hydrolyzed by CES, which significantly decreased the bioavailability of esters.
421
These results hinted that the acylation was an effectual method to improve the
422
bioavailability of polyphenols with poor lipophilicity. However, certain factors should
423
be considered in choosing acyl donors, such as the suitability between the lipotropism
424
of the acyl donor and hydrophilicity of these polyphenols and relationship between
425
the structure of the acyl donor and the substrate specificity of CES. The antioxidant
426
activity analysis showed that although the antiradical ability of the acylated esculin
427
was not improved, the protective effect on cells under the oxidative stress conditions
428
was enhanced. These results indicated that the antioxidant activity of these acylated
429
derivatives was dependent on not only the antioxidant properties of their parent
430
compound, but also their distribution in the reaction system of the antioxidant activity
431
assays. Compared with other research, our study proposed that acyl donors should be
432
chosen according to the purpose of acylation. For example, if the acylated derivatives
433
will be used as drug or prodrug, the acyl donor should help the derivatives cross the
434
intestinal wall and vascular wall. If the derivatives were used to protect the fatty or 20
ACS Paragon Plus Environment
Page 20 of 41
Page 21 of 41
Journal of Agricultural and Food Chemistry
435
oily foods from oxidation, the acyl donor should help the derivatives locate in the
436
oil-water interface; thus, this study provides the guidance for the acylation of
437
polyphenols with poor lipophilicity.
438
Funding This work was financially supported by the National Natural Science
439
Foundation of China (Nos. 31270636, 21676105), Self Determined Research Fund
440
of SCUT from the College Basic Research and Operation of MOE (No. 2015ZZ111),
441
and Science and Technology Planning Project of Guangdong Province (Nos.
442
2016A040402020, 2016B010121014).
443
Supporting Information Standard curves, limit of quantification and limit of
444
detection; Intra- and inter-day accuracy and precision; HPLC chromatograms of
445
blank HBSS and HBSS spiked with standard compounds.
21
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
446
REFERENCES
447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488
1. Yeh, W.-J.; Hsia, S.-M.; Lee, W.-H.; Wu, C.-H., Polyphenols with antiglycation activity and mechanisms of action: A review of recent findings. J Food Drug Anal 2016. 2. Patti, A.; Piattelli, M.; Nicolosi, G., Use of Mucor miehei lipase in the preparation of long chain 3-O-acylcatechins. J Mol Catal B: Enzym 2000, 10, 577-582. 3. Kang, K. S.; Lee, W.; Jung, Y.; Lee, J. H.; Lee, S.; Eom, D.-W.; Jeon, Y.; Yoo, H. H.; Jin, M. J.; Song, K. I., Protective effect of esculin on streptozotocin-induced diabetic renal damage in mice. J Agr Food Chem 2014, 62, 2069-2076. 4. Rehman, S. U.; Kim, I. S.; Kang, K. S.; Yoo, H. H., HPLC Determination of Esculin and Esculetin in Rat Plasma for Pharmacokinetic Studies. J Chromatogr Sci 2015, bmv014. 5. Kong, L.; Zhou, J.; Wen, Y.; Li, J.; Cheng, C. H., Aesculin possesses potent hypouricemic action in rodents but is devoid of xanthine oxidase/dehydrogenase inhibitory activity. Planta Med 2002, 68, 175-178. 6. Chen, Q.; Hou, S.; Zheng, J.; Bi, Y.; Li, Y.; Yang, X.; Cai, Z.; Song, X., Determination of aesculin in rat plasma by high performance liquid chromatography method and its application to pharmacokinetics studies. J Chromatogr B 2007, 858, 199-204. 7. Hu, Y.; Guo, Z.; Lue, B.-M.; Xu, X., Enzymatic synthesis of esculin ester in ionic liquids buffered with organic solvents. J Agr Food Chem 2009, 57, 3845-3852. 8. Bernini, R.; Carastro, I.; Palmini, G.; Tanini, A.; Zonefrati, R.; Pinelli, P.; Brandi, M. L.; Romani, A., Lipophilization of Hydroxytyrosol-Enriched Fractions from Olea europaea L. Byproducts and Evaluation of the in Vitro Effects on a Model of Colorectal Cancer Cells. J Agr Food Chem 2017. 9. Shahidi, F.; Zhong, Y., Revisiting the Polar Paradox Theory: A Critical Overview. J Agr Food Chem 2011, 59, 3499-3504. 10. Vavříková, E.; Langschwager, F.; Jezova-Kalachova, L.; Křenková, A.; Mikulová, B.; Kuzma, M.; Křen, V.; Valentová, K., Isoquercitrin Esters with Mono-or Dicarboxylic Acids: Enzymatic Preparation and Properties. Int J Mol Sci 2016, 17, 899. 11. Milisavljević, A.; Stojanović, M.; Carević, M.; Mihailović, M.; Veličković, D. a.; Milosavić, N.; Bezbradica, D., Lipase-catalyzed esterification of phloridzin: acyl donor effect on enzymatic affinity and antioxidant properties of esters. Ind Eng Chem Res 2014, 53, 16644-16651. 12. Wang, Z.; Bi, Y.; Yang, R.; Zhao, X.; Jiang, L.; Zhu, C.; Zhao, Y.; Jia, J., Enzymatic Synthesis of Sorboyl-Polydatin Prodrug in Biomass-Derived 2-Methyltetrahydrofuran and Antiradical Activity of the Unsaturated Acylated Derivatives. BioMed Res Int 2016, 2016. 13. Weng, T.; Qi, J.; Lu, Y.; Wang, K.; Tian, Z.; Hu, K.; Yin, Z.; Wu, W., The role of lipid-based nano delivery systems on oral bioavailability enhancement of fenofibrate, a BCS II drug: comparison with fast-release formulations. J Nanobiotecg 2014, 12, 39. 22
ACS Paragon Plus Environment
Page 22 of 41
Page 23 of 41
Journal of Agricultural and Food Chemistry
489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532
14. Ma, X.; Yan, R.; Yu, S.; Lu, Y.; Li, Z.; Lu, H., Enzymatic acylation of isoorientin and isovitexin from bamboo-leaf extracts with fatty acids and antiradical activity of the acylated derivatives. J Agr Food Chem 2012, 60, 10844-10849. 15. Mbatia, B.; Kaki, S. S.; Mattiasson, B.; Mulaa, F.; Adlercreutz, P., Enzymatic synthesis of lipophilic rutin and vanillyl esters from fish byproducts. J Agr Food Chem 2011, 59, 7021-7027. 16. Zhang, M.; Zhang, H.; Li, H.; Lai, F.; Li, X.; Tang, Y.; Min, T.; Wu, H., Antioxidant Mechanism of Betaine without Free Radical Scavenging Ability. J Agr Food Chem 2016, 64, 7921-7930. 17. Ohura, K.; Sakamoto, H.; Ninomiya, S.-i.; Imai, T., Development of a Novel System for Estimating Human Intestinal Absorption Using Caco-2 Cells in the Absence of Esterase Activity. Drug Metab Dispos 2010, 38, 323-331. 18. Xu, J.; Qian, J.; Li, S., Enzymatic acylation of isoorientin isolated from antioxidant of bamboo leaves with palmitic acid and antiradical activity of the acylated derivatives. Eur Food Res Techn 2014, 239, 661-667. 19. Chen, X.-M.; Dai, Y.; Kitts, D. D., Detection of Maillard Reaction Product [5-(5, 6-Dihydro-4 H-pyridin-3-ylidenemethyl) furan-2-yl] methanol (F3-A) in Breads and Demonstration of Bioavailability in Caco-2 Intestinal Cells. J Agr Food Chem 2016, 64, 9072-9077. 20. Hubatsch, I.; Ragnarsson, E. G.; Artursson, P., Determination of drug permeability and prediction of drug absorption in Caco-2 monolayers. Nature Protoc 2007, 2, 2111-2119. 21. Ohura, K.; Nozawa, T.; Murakami, K.; Imai, T., Evaluation of transport mechanism of prodrugs and parent drugs formed by intracellular metabolism in Caco‐2 cells with modified carboxylesterase activity: Temocapril as a model case. J Pharm Sci-US 2011, 100, 3985-3994. 22. Chen, P. X.; Tang, Y.; Zhang, B.; Liu, R.; Marcone, M. F.; Li, X.; Tsao, R., 5-Hydroxymethyl-2-furfural and derivatives formed during acid hydrolysis of conjugated and bound phenolics in plant foods and the effects on phenolic content and antioxidant capacity. J Agr Food Chem 2014, 62, 4754-4761. 23. Ma, Q.; Xie, H.; Li, S.; Zhang, R.; Zhang, M.; Wei, X., Flavonoids from the Pericarps of Litchi chinensis. J Agr Food Chem 2014, 62, 1073-1078. 24. Su, C.; Xia, X.; Shi, Q.; Song, X.; Fu, J.; Xiao, C.; Chen, H.; Lu, B.; Sun, Z.; Wu, S., Neohesperidin dihydrochalcone versus CCl4-induced hepatic injury through different mechanisms: the implication of free radical scavenging and Nrf2 Activation. J Agr Food Chem 2015, 63, 5468-5475. 25. Lucas, R.; Comelles, F.; Alcantara, D.; Maldonado, O. S.; Curcuroze, M.; Parra, J. L.; Morales, J. C., Surface-Active Properties of Lipophilic Antioxidants Tyrosol and Hydroxytyrosol Fatty Acid Esters: A Potential Explanation for the Nonlinear Hypothesis of the Antioxidant Activity in Oil-in-Water Emulsions. J Agr Food Chem 2010, 58, 8021-8026. 26. Zhu, S.; Li, Y.; Li, Z.; Ma, C.; Lou, Z.; Yokoyama, W.; Wang, H., Lipase-catalyzed synthesis of acetylated EGCG and antioxidant properties of the acetylated derivatives. Food Res Int 2014, 56, 279-286. 23
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576
27. Purser, S.; Moore, P. R.; Swallow, S.; Gouverneur, V., Fluorine in medicinal chemistry. Chem Soc Rev 2008, 37, 320-330. 28. Rothwell, J. A.; Day, A. J.; Morgan, M. R., Experimental determination of octanol− water partition coefficients of quercetin and related flavonoids. J Agr Food Chem 2005, 53, 4355-4360. 29. Wang, Z.-Y.; Bi, Y.-H.; Yang, R.-L.; Zhao, X.-J.; Jiang, L.; Ding, C.-X.; Zheng, S.-Y., Highly efficient enzymatic synthesis of novel polydatin prodrugs with potential anticancer activity. Process Biochem 2017, 52, 209-213. 30. Rubas, W.; Jezyk, N.; Grass, G. M., Comparison of the permeability characteristics of a human colonic epithelial (Caco-2) cell line to colon of rabbit, monkey, and dog intestine and human drug absorption. Pharm Res-Dordr 1993, 10, 113-118. 31. Hou, T.; Wang, J.; Zhang, W.; Xu, X., ADME evaluation in drug discovery. 6. Can oral bioavailability in humans be effectively predicted by simple molecular property-based rules? J Chem Inf Model 2007, 47, 460-463. 32. Lipinski, C. A.; Lombardo, F.; Dominy, B. W.; Feeney, P. J., Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings. Adv Drug Deliver Rev 1997, 23, 3-25. 33. Lu, Y.; Bao, N.; Borjihan, G.; Ma, Y.; Hu, M.; Yu, C.; Li, S.; Jia, J.; Yang, D.; Wang, Y., Contribution of Carboxylesterase in Hamster to the Intestinal First-Pass Loss and Low Bioavailability of Ethyl Piperate, an Effective Lipid-Lowering Drug Candidate. Drug Metab Dispos 2011, 39, 796-802. 34. Hakamata, W.; Tamura, S.; Hirano, T.; Nishio, T., Multicolor Imaging of Endoplasmic Reticulum-Located Esterase As a Prodrug Activation Enzyme. Acs Med Chem Lett 2014, 5, 321-325. 35. Brodie, B. B.; Gillette, J. R.; La Du, B. N., Enzymatic metabolism of drugs and other foreign compounds. Annu Rev Biochem 1958, 27, 427-454. 36. Manach, C.; Scalbert, A.; Morand, C.; Rémésy, C.; Jiménez, L., Polyphenols: food sources and bioavailability. Am J Clin Nutrt 2004, 79, 727-747. 37. Parada, J.; Aguilera, J., Food microstructure affects the bioavailability of several nutrients. J Food Sci 2007, 72. 38. Trujillo, M.; Gallardo, E.; Madrona, A.; Bravo, L.; Sarria, B.; Gonzalez-Correa, J. A.; Mateos, R.; Luis Espartero, J., Synthesis and Antioxidant Activity of Nitrohydroxytyrosol and Its Acyl Derivatives. J Agr Food Chem 2014, 62, 10297-10303. 39. Bernini, R.; Crisante, F.; Barontini, M.; Tofani, D.; Balducci, V.; Gambacorta, A., Synthesis and Structure/Antioxidant Activity Relationship of Novel Catecholic Antioxidant Structural Analogues to Hydroxytyrosol and Its Lipophilic Esters. J Agr Food Chem 2012, 60, 7408-7416. 40. Zhong, Y.; Shahidi, F., Lipophilized Epigallocatechin Gal late (EGCG) Derivatives as Novel Antioxidants. J Agr Food Chem 2011, 59, 6526-6533. 41. Kurek-Górecka, A.; Rzepecka-Stojko, A.; Górecki, M.; Stojko, J.; Sosada, M.; Świerczek-Zięba, G., Structure and antioxidant activity of polyphenols derived from propolis. Molecules 2013, 19, 78-101. 24
ACS Paragon Plus Environment
Page 24 of 41
Page 25 of 41
Journal of Agricultural and Food Chemistry
577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592
42. Tofani, D.; Balducci, V.; Gasperi, T.; Incerpi, S.; Gambacorta, A., Fatty Acid Hydroxytyrosy Esters: Structure/Antioxidant Activity Relationship by ABTS and in Cell-Culture DCF Assays. J Agr Food Chem 2010, 58, 5292-5299. 43. Medina, I.; Alcantara, D.; Gonzalez, M. J.; Torres, P.; Lucas, R.; Roque, J.; Plou, F. J.; Morales, J. C., Antioxidant Activity of Resveratrol in Several Fish Lipid Matrices: Effect of Acylation and Glucosylation. J Agr Food Chem 2010, 58, 9778-9786. 44. Panya, A.; Laguerre, M.; Bayrasy, C.; Lecomte, J.; Villeneuve, P.; McClements, D. J.; Decker, E. A., An Investigation of the Versatile Antioxidant Mechanisms of Action of Rosmarinate Alkyl Esters in Oil-in-Water Emulsions. J Agr Food Chem 2012, 60, 2692-2700. 45. Ximenes, V. F.; Lopes, M. G.; Petronio, M. S.; Regasini, L. O.; Siqueira Silva, D. H.; da Fonseca, L. M., Inhibitory Effect of Gallic Acid and Its Esters on 2,2 '-Azobis(2-amidinopropane)hydrochloride (AAPH)-Induced Hemolysis and Depletion of Intracellular Glutathione in Erythrocytes. J Agr Food Chem 2010, 58, 5355-5362.
25
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
593
FIGURE CAPTIONS
594
Figure 1 Chemical structure of esculin and its esters.
595
Figure 2 LogP values of esculin and its esters. Different letters indicate significant
596
differences (p