Identification of sesamol byproducts produced by plasma treatment with inhibition of advanced glycation endproducts formation and ONOO? scavenging activities

Article abstract of DOI:10.1016/j.foodchem.2020.126196

Little is known of plasma-mediated relations between major food components and their biological capacities. In the present work, the effects of dielectric barrier discharge (DBD) plasma irradiation on pure sesamol and sesame oil were investigated using sp

Full text of DOI:10.1016/j.foodchem.2020.126196

Journal Pre-proofs
Identification of sesamol byproducts produced by plasma treatment with inhib-
ition of advanced glycation endproducts formation and ONOO – scavenging
activities
Yun Hee Jeong, Gyeong Han Jeong, Yong-Ha Jeong, Tae Hoon Kim
PII:
S0308-8146(20)30043-1
DOI:
https://doi.org/10.1016/j.foodchem.2020.126196
FOCH 126196
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Food Chemistry
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16 September 2019
2 January 2020
9 January 2020
Please cite this article as: Hee Jeong, Y., Han Jeong, G., Jeong, Y-H., Hoon Kim, T., Identification of sesamol
byproducts produced by plasma treatment with inhibition of advanced glycation endproducts formation and
ONOO – scavenging activities, Food Chemistry (2020), doi: https://doi.org/10.1016/j.foodchem.2020.126196
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Identification of sesamol byproducts produced by plasma treatment with
inhibition of advanced glycation endproducts formation and ONOO–
scavenging activities
Yun Hee Jeong a,b, Gyeong Han Jeong a,b, Yong-Ha Jeong a, Tae Hoon Kim a,*
a Department of Food Science and Biotechnology, Daegu University, Gyeongsan 38453, Republic of Korea
* Corresponding Author.
E-mail address: skyey7@daegu.ac.kr (T.H.Kim).
b These authors contributed equally to this work.

ABSTRACT
Little is known of plasma-mediated relations between major food components and their
biological capacities. In the present work, the effects of dielectric barrier discharge (DBD)
plasma irradiation on pure sesamol and sesame oil were investigated using spectroscopic (LC-
MS, NMR) and bioassay methods. Sesamol was degraded when subjected to plasma irradiation
for 40 min, and the exposed products exhibited improved anti-glycation capacities against
advanced glycation end products (AGEs) formation and better ONOO–scavenging ability.
Structures of newly formed compounds were determined spectroscopically. Quantitative LC-
MS analysis of the major products generated in sesamol and sesame oil was achieved using
isolates 1–4 of purified sesamol plasma treated for 40 min. These results indicate that the
predominant chemical changes induced in sesamol and sesame oil by DBD plasma treatment
might enhance biological properties.
Keywords: Sesamol, Sesame oil, Dielectric barrier discharge plasma, Dimerization, Anti-diabetic complications

1. Introduction
Naturally occurring secondary metabolites exhibit substantial structural diversity and
frequently have unique biologic effects (Kinghorn, Pan, Fletcher, & Chai, 2011). Research
interest in extracts of terrestrial plants, microorganisms, and marine life forms has been
maintained efforts to identify bioactive constituents. Interest in pharmacologically active
constituents of medicinal plants led to the isolation of several drugs, such as morphine, codeine,
and digitoxin, in the 19th century, and these drugs are still widely used (Balunas & Kinghorn,
2005). Among naturally occurring bioactive polyphenolics, lignans are a class of diphenolic
secondary metabolites that are well distributed in the plant kingdom and are which can be
biosynthesized by the oxidative dimerization of two phenylpropanoid units (Saleem, Kim, Ali,
& Lee, 2005). This class of natural polyphenols exhibits broad structure diversity and have
been shown to possess anti-tumor, antioxidant, anti-inflammatory, anti-neurodegenerative,
antiviral, and other effects (Zálešák, Denis Bon, & Pospíšil, 2019). Sesame lignans in particular
are identified from Sesamum indicum in many countries in the east. Sesame oil is the main
source of important antioxidant lignans such as sesamin, sesamolin, sesaminol and sesamol
(Dar, & Arumugam, 2013). Current attention in novel lignans in foods continues because of
their abilities to prevent disease and promote health.
Glycation is a non-enzymatic reaction between reducing sugars and the free amino residues
of proteins, lipids, and nucleic acids, and involves rearrangement, oxidation, dehydration, and
polymerization and the generation of advanced glycation-end products (AGEs) (Singh, Barden,
Mori, & Beilin, 2001). Interestingly, AGEs accumulation has been shown to be closely related
to aging-associated diseases like diabetes, arteriosclerosis, osteoporosis, and Alzheimer’s
disease (Nagai, Mori, Yamamoto, Kaji, & Yonei, 2010). Thus, it appears the inhibition of AGE
formation offers a promising strategy for preventing the progress of several age-associated

diseases.
Non-thermal technologies have emerged as alternative means of minimizing the negative
influences of conventional thermal treatments on food (Putnik P, Barba, Lucini, Rocchetti, &
Montesano, 2019). Recently, cold plasma treatment is recognized as a non-thermal technology
that provides kills microbes in foods (Misra et al., 2014) and indicated the other characteristic
applications such as benzopyrene degradation and anthocyanin yield increasing (Lee,
Puligundla, & Mok, 2019; Bursać Kovačević et al., 2016). Plasma is known as causing reactive
nitrogen and oxygen species associated chemical reactions (Gaunt, Beggs, & Georghiou, 2006).
However, the chemical and biological impacts on plasma irradiation of major food ingredients
have not been well documented, and in particular, optimizations of exposure parameters are
required. Recently, we found dielectric barrier discharge (DBD) plasma treatment results in the
generation of structurally modified food components with improved biological properties (Kim
et al., 2014; Jeong et al., 2017). In the present study, we investigated the influences of DBD
plasma irradiation on the chemical structures and bioactivities of sesamol and sesame oil. In
addition, we explored underlying mechanisms and suggested a plausible mechanism for the
dimerization and oxidation of sesamol.
2. Materials and methods
2.1. Chemicals
Sesamol, sesamin, sesamolin, aminoguanidine, L-penicillamine, MeCN, MeOH, HCOOH
(HPLC grade), EtOAc deuterated MeOH, D-(–)-fructose, D-(+)-glucose, and bovine serum
albumin (BSA) were obtained from Sigma-Aldrich CO. (St. Louis, MO, USA). Peroxynitrite
was purchased from Cayman Chemical (ANN Arbor, MI, USA). All other chemicals and
reagents used for bioassays and analyses were of analytical grade. Ultraviolet (UV) spectra
were obtained using a Hitachi U-2000 spectrophotometer (Hitachi, Tokyo, Japan). Nuclear

magnetic resonance (NMR) data were recorded at room temperature using a Varian VNS600
instrument at 600 MHz (Varian, Palo Alto, CA, USA). Chemical shifts are recorded in  (ppm)
using acetone-d6 (H 2.04; C 29.8) and CD3OD (H 3.35; C 49.0) as points of reference versus
tetramethylsilane. Standard programmed pulse sequences were used for two-dimensional
measurements. JCH was set at 8 Hz in heteronuclear multiple bond connectivity (HMBC)
spectra. Fast atom bombardment mass spectra (FABMS) were obtained using a Micro Mass
Auto Spec OA-TOF spectrometer (Micromass, Manchester, UK) in positive ion mode. Column
chromatography was conducted using a YMC GEL ODS AQ 120-50S (YMC Co., Kyoto,
Japan).
2.2. Plasma irradiation procedure
The non-thermal dielectric-barrier discharge (DBD) device used in the present experiments
was installed on the inner walls of a rectangular, parallelepiped plastic container (137 mm ×
104 mm × 53 mm) (Jeong, Park, & Kim, 2019). The instrument was prepared by a
polytetrafluoroethylene sheet and copper electrodes attached to the inner walls of the bottle.
Two linear jet plasma sources (LJPS, Plasmapp Co., Ltd.) were built into the plasma source
chamber and attached in parallel to the power supply. Plasma treatment was carried out in the
instrument under ambient air condition.
The DBD plasma source provided uniform laminar flow of the process ambient air for a
glow-like discharge. A bipolar square-waveform voltage at 15 kHz was applied to one plasma
electrode and the other electrode was grounded. Plasma was produced inside the chamber using
an input power of 250 W at 40% relative humidity and 25°C. Sample solutions (1.0 g sample
in 2.0 L EtOH) were located in a glass dish at the bottom of the chamber and exposed to DBD
plasma for 20, 40, and 60 min. The chamber is 30 cm in interior diameter and the distance
between the bottom of the chamber and the surface of sample solution 12 cm. Control was

prepared in the same humidity conditions and temperature for the duration of the irradiation.
Exposed ethanol solutions containing sesamol and sesame oil were directly evaporated to
dryness using a vacuum evaporator. Sesame oil is the rich source of antioxidant lignans such
as sesamin, sesamolin, sesaminol and major sesamol. The main aim of this comparison analysis
between pure sesamol and sesame oil was to determine the influence of different chemical
change and biological properties by plasma treatment.
2.3. HPLC analysis of newly generated products
A Shimadzu HPLC system SPD-M20A (Shimadzu C., Kyoto, Japan) equipped with a
diode-array detector was used to isolate compounds generated by DBD plasma irradiation from
sesamol. Analytical HPLC was performed using a YMC-Pack ODS A-302 column (4.6 mm
i.d. × 150 mm, 5 m particle size; YMC Co., Kyoto, Japan). The mobile phase consisted of
mixes of H2O containing 0.1% HCOOH (A) and MeCN (B), using a gradient mode of 8–100%
B over 30 min at a flow rate of 1 mL/min and mobile phase and an injection volume of 5 L.
The diode-array detector was set at 280 nm and the column temperature at 40oC. Sesamol
products were detected by comparing retention times with that of sesamol, and quantification
by HPLC analysis using the external standard method and standard curves.
2.4. Purification and structure elucidation of byproducts
A solution of sesamol (1.0 g) in EtOH (2.0 L) in a plastic container was exposed to DBD
plasma radiation for 20, 40, and 60 min, and the degraded pattern were monitored by reverse-
phase HPLC. Dried sesamol solution exposed for 40 min exhibited most inhibitory activity
with an IC50 value of 22.0 ± 2.2 g/mL in the AGE formation assay (Table 1). Sesamol
irradiated for 40 min was evaporated and suspended in 10% MeOH (200 mL) and this mixture
was sequentially partitioned with ethylacetate (EtOAc) (3 × 200 mL) to yield a dried EtOAc-

soluble layer (860.2 mg). A portion of this EtOAc extract (300 mg) was subjected to column
chromatography on a YMC GEL ODS AQ 120-50S column (1.1 cm i.d. × 40 cm) (YMC Co.,
Kyoto, Japan) using aqueous MeOH as eluent, to yield compounds 1 (tR 16.9 min, 5.9 mg), 2
(tR 20.7 min, 60.6 mg), 3 (tR 19.6 min, 5.9 mg), and 4 (tR 7.8 min, 2.1 mg). Chromatographic
purification was monitored by reversed-phase HPLC using the above-mentioned analytical
conditions. Structures of generated byproducts were determined using spectroscopic data (1H,
13CNMR, 2D NMR, and MS), and their purities were checked by HPLC.
2.5. LC–MS analysis of plasma treated sesame oil
UPLC–ESI-MS was conducted using an ACQUITY UPLC system (Waters Co., MA, USA),
prepared with a binary solvent delivery mode. Chromatographic separation was achieved using
an ACQUITY UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm particle size) (Waters Co.,
MA, USA) at a column temperature of 40℃ and using a mobile phase consisting of mixes of
0.1% HCOOH in H2O (solvent A) and MeCN (solvent B). Separation was achieved using a
linear gradient of 95–5% A over 25 min at a flow rate of 0.6 mL/min. The injection volume
was 3 μl. Mass spectrometry was conducted using a Xevo TQ-S micromass spectrometer
(Waters Co., MA, USA). Electrospray ionization (ESI) mass spectra were acquired in positive
ion electrospray ionization mode over the m/z range 50–1000. The ESI capillary voltage was
set at 1.5 kV, and the temperatures of the electrospray source and desolvation gas were 100℃
and 300℃, respectively. N2 was used as the nebulizing gas, desolvation gas, and cone gas at
the flow-rates of 60, 550 and 50 L/h, respectively. Cone voltage was varied over the range 50-0
V to investigate the intensities and distribution of ions in the mass spectra of newly generated
sesamol derivatives.
2.6. Inhibitions of AGEs formation
To evaluate the abilities of sesamol derivatives to inhibit AGEs formation, we used a

previously reported method (Vinson & Howard, 1996) with minor modification. Briefly, an
AGEs reaction solution was prepared by adding 50 mM sodium phosphate buffer (pH 7.4)
containing bovine serum albumin (10 mg/mL), and 0.02% sodium azide to inhibit bacterial
growth to 0.2 M glucose and 0.2 M fructose. This reaction mixture (950 L) was then added
to samples (50 L, final concentration 200 g/mL) dissolved in 5% DMSO. After incubation
for 7 days at 37 oC, fluorescence intensities were measured by spectrofluorometry (Infinite
F200; Tecan Austria GmBH, Grödig, Austria) using excitation and emission wavelengths of
350 and 450 nm, respectively. The percentage inhibition was calculated from a graphical plot
of the data and is expressed as the mean ± S.D. of triplicate experiments. Aminoguanidine was
used as a positive control in the AGE assay.
2.7. ONOO– scavenging activity assay
The ONOO− scavenging capacity used as described previously with minor modification
(Kooy et al., 1994), by monitoring highly rhodamine 123 produced from non-fluorescent DHR
123 in the presence of ONOO−. The rhodamine buffer (pH 7.4) consisted of 50 mM disodium
phosphate, 50 mM monosodium phosphate, 90 mM sodium chloride, 5.0 mM potassium
chloride, and 100 μM DTPA. The final DHR 123 concentration was 5.0 μM. The assay buffer
was prepared prior to use and kept on ice. Test samples were dissolved in 10% DMSO (final
concentration 100 μM). Background and final fluorescence intensities were measured 5 mins
after treatment with or without the addition of ONOO− (10 μM) dissolved in 0.3 N NaOH.
Fluorescence intensities of oxidized DHR123 were measured using a fluorescence microplate
reader (Infinite F200; Tecan Austria GmBH, Grödig, Austria) at excitation and emission
wavelengths of 480 and 530 nm, respectively. Scavenging activities were calculated after
subtracting background fluorescence. L-Penicillamine was used as the positive control.

2.8. Statistical analysis
All experiments were performed in triplicate. In vitro inhibition of AGE formation results
and ONOO− scavenging activities were analyzed using Proc GLM procedure of SAS software
(version 9.3, SAS Institute Inc., Cary, NC, USA). Results are reported as least square mean
values and standard deviations. Statistical significance was accepted for p values < 0.05.
3. Results and discussion
3.1. Isolation and characterization of the compounds produced by plasma irradiation
Polyphenols are a group of major plant constituents with potent antioxidant capacities, and
have recently attracted considerable attention as functional ingredients in foods that improve
human health and protect against diseases (Valduga, Conçalves, Magri, & Delalibera Finzer,
2019). Furthermore, some polyphenolics act as antioxidants a property closely linked with
beneficial effects in man. However, some polyphenols are chemically unstable under oxidative
conditions and this can result in the accumulation of various oxidation products in foods
(Masuda et al., 2010), though the biological properties of these accumulated products have not
been examined in detail (Zhou et al., 2008). Sesamol is a well-known natural phenol with
antioxidant properties that are at least partly responsible for the high stability of sesame oil
(Yoshida & Kajimoto, 1994). However, comparatively little is known about the products of
sesamol oxidation under food processing conditions. Thus, in the present study, we investigated
and compared the chemical and biological properties of plasma irradiated and non-irradiated
sesamol and sesame oil.
Sesamol dissolved in EtOH was irradiated with plasma for 20, 40, and 60 min and chemical
changes were investigated by reversed-phase HPLC. Sesamol exposed for 40 min exhibited
most antioxidant activity in with an IC50 value of 22.0 ± 2.2 g/mL as determined by the AGEs
formation assay, and thus, this sample was selected for further purification. HPLC showed the

sesamol irradiated for 40 min exhibited four new HPLC peaks (Fig. 1). Successive
chromatographic separation of this sample resulted in the isolation of a novel dimerized product
1 and three known compounds 2–4.
Compound 1 was obtained as a brown amorphous powder with a pseudomolecular ion peak
at m/z 274.0478 [M]+ observed in its positive HRFABMS spectrum that corresponded to a
molecular formula of C14H10O6. 1H NMR of 1 exhibited resonances for 1,2,4,5-tetrasubstituted
aromatic rings at H 6.68 (1H, s, H-6) and 6.56 (1H, s, H-3), and a methylenedioxy group at H
5.94 (2H, s, H-7), which suggested the presence of the original sesamol moiety (Singh et al.,
2010). Additional analysis of the 13C NMR spectrum at C 186.4 (C-4ꞌ), 182.0 (C-5ꞌ), 158.5 (C-
2ꞌ), 144.7 (C-1'), 107.8 (C-3ꞌ) and a heteronuclear single quantum coherence (HSQC)
experiment based on the 1H NMR spectroscopic data of two olefinic protons at H 6.79 (1H, s,
H-6ꞌ) and 6.07 (1H, s, H-3ꞌ), and a methoxyl group at H 3.85 (3H, s, 2ꞌ-OCH3) indicated the
presence of a unusual oxidized sesamol moiety. Careful interpretation of these NMR
characteristics and of the peak at m/z 274 in the HRFAB mass spectrum suggested compound
1 contained a sesamol and a 4-methoxy-1,2-benzoquinone moiety (Saito & Kawabata, 2005)
connected through a C-C linkage. The linkage positions of sesamol and oxidized sesamol
residues between C-1 and C-1', and a methoxyl group at C-2' of 1 were unambiguously
elucidated using HMBC associations (Fig. 2). Thus, the structure of compound 1 was
elucidated as shown, and this novel substance has been accorded the trivial name sesaplasmin.
Sesaplasmin 1: brown amorphous powder; UV (MeOH) max (log ): 205 (3.53), 298 (2.42)
nm; FABMS m/z 274 [M]+, HRFABMS m/z 274.0478 [M]+ (calcd. for C14H10O6, 274.0477);
1H NMR (acetone-d6+D2O, 600 MHz): δ 6.79 (1H, s, H-6ꞌ), 6.68 (1H, s, H-6), 6.56 (1H, s, H-
3), 6.07 (1H, s, H-3ꞌ), 5.94 (2H, s, H-7), 3.85 (3H, s, 2ꞌ-OCH3); 13C NMR (acetone-d6+D2O,
150 MHz): δ 186.4 (C-4ꞌ), 182.0 (C-5ꞌ), 158.5 (C-2ꞌ), 151.4 (C-2), 149.3 (C-4), 144.7 (C-1'),

140.4 (C-5), 132.1 (C-6ꞌ), 112.0 (C-6), 110.1 (C-1), 107.8 (C-3ꞌ), 101.4 (C-7), 97.8 (C-3), 55.8
(2ꞌ-OCH3) (Supporting information).
Isolated known byproducts were characterized as 6,6'-methylenebis-1,3-benzodioxol-5-ol
(2), 5,5'-bi-1,3-benzodioxole-6,6'-diol (3), and 1,3-benzodioxole-5,6-dione (4), by comparing
their spectroscopic data (NMR, MS and []D) with literature values (Constantin et al., 2012;
Hellberg et al., 2004; Mibu & Sumoto, 2000).
1
Compound 2: yellow amorphous powder, FABMS m/z 288 [M]+; H NMR (CD3OD, 600
MHz): δ 6.53 (1H, s, H-3, 3ꞌ), 6.36 (2H, s, H-6, 6ꞌ), 5.76 (4H, s, OCH2O, OCH2ꞌO), 3.68 (2H,
s, -CH2-); 13C NMR (CD3OD, 150 MHz): δ 149.9 (C-2, 2ꞌ), 147.5 (C-4, 4ꞌ), 142.1 (C-5, 5ꞌ),
120.9 (C-1, 1ꞌ), 110.5 (C-3, 3ꞌ), 101.9 (OCH2O, OCH2ꞌO), 98.5 (C-6, 6ꞌ), 30.4 (-CH2-)
(Supporting information). All spectral data were consistent with the data of 6,6'-methylenebis-
1,3-benzodioxol-5-ol (Fig. 2) (Mibu & Sumoto, 2000).
1
Compound 3: brown amorphous powder, FABMS m/z 274 [M]+; H NMR (CD3OD, 600
MHz): δ 6.64 (1H, s, H-3, 3ꞌ), 6.46 (2H, s, H-6, 6ꞌ), 5.94 (4H, s, OCH2O, OCH2ꞌO); 13C NMR
(CD3OD, 150 MHz): δ 149.7 (C-2, 2ꞌ), 148.9 (C-4, 4ꞌ), 142.8 (C-5, 5ꞌ), 119.3 (C-1, 1ꞌ), 111.3
(C-3, 3ꞌ), 102.4 (OCH2O, OCH2ꞌO), 99.4 (C-6, 6ꞌ) (Supporting information). All spectral data
were consistent with the data of 5,5'-bi-1,3-benzodioxole-6,6'-diol (Fig. 2) (Constantin et al.,
2012).
Compound 4: brown amorphous powder. FABMS: m/z 152 [M]+; 1H NMR (acetone-d6+D2O,
600 MHz): δ 6.31 (2H, s, H-3, 6), 5.96 (2H, s, OCH2O); 13C NMR (acetone-d6+D2O, 150 MHz):
δ 178.1 (C-1, 2), 162.4 (C-4, 5), 105.8 (C-3, 6), 100.4 (OCH2O) (Supporting information). All
spectral data were consistent with the data of 1,3-benzodioxole-5,6-dione (Fig. 2) (Hellberg et
al., 2004).
3.2. Inhibition of AGEs formation and ONOO– scavenging activities

Of the proposed mechanisms responsible for the pathogenesis of diabetic complications,
AGEs formation is viewed as a primary contributor to oxidative damage in some tissues such
as eye lenses and nerves (Nugroho et al., 2013). Therefore, oxidative stress is considered to be
closely associated with AGE formation, and antioxidant substances that inhibit AGEs
formation are considered potential therapeutics for diabetic complications (Masuda et al., 2003).
In the present study, dried sesamol exposed for 40 min exhibited most inhibitory activity, with
an IC50 value of 22.0 ± 2.2 g/mL in the AGEs formation assay.
Furthermore, the inhibition of AGEs formation inhibitory ability of sesamol was improved
by exposure to plasma for 40 min with value of IC50 22.0 ± 2.2 g/mL. Plasma exposure
sesamol in ethanol for 60 min showed slightly decreased inhibitory capacity, with an IC50 value
of 27.8 ± 2.3 g/mL compared to plasma irradiated sesamol for 40 min (Table 1). All isolated
byproducts produced by irradiating sesamol for 40 min were assessed for their anti-diabetic
complication property against AGEs formation using aminoguanidine as a positive control.
The AGEs formation inhibitory activity of novel sesamol dimer 1, which possessed a cyclic
1,2-diketone moiety was greatest potent in this bioassay system with IC50 value of 1.2 ± 0.1
M, compared to the positive control aminoguanidine (IC50, 831.3 ± 7.6 M). On the other
hand, the structurally related dimeric compounds 2 and 3 were relatively less potent with IC50
values of 3.1 ± 1.2 and 19.9 ± 1.7 M, respectively (Table 1). Oxidized sesamol monomer 4
bearing a cyclic 1,2-diketone substituent showed no discernible activity with IC50 value of >
300 M (Table 1).
In addition, the radical scavenging capacities of the purified byproducts from plasma treated
sesamol for 40 min were also investigated based on the previously reported in vitro ONOO–
scavenging assay (Kooy et al., 1994). Plasma exposed sesamol for 40 min displayed slightly
enhanced radical scavenging activity, with an IC50 value of 21.3 ± 1.0 g/mL in comparison

with the standard sesamol. Among them from the isolated compounds from 40 min treated
sesamol, unusual sesamol dimers 1 and 2 showed more potent ONOO– scavenging activities
with IC50 values of 4.1 ± 0.3 and 7.6 ± 0.5 M, respectively. A symmetric dimer of sesamol 3
showed relatively moderate ONOO– scavenging activities as shown in Table 1. Unprecedented
dimeric and trimeric sesamol derivatives produced by Fe ion and laccase have also been
reported to exhibit potent cytotoxic effects (Constantin et al., 2012; Masuda et al., 2009;
Masuda et al., 2010). However, naturally occurring dimeric sesamols are rare and their effects
of anti-diabetic complication capacity on oxidative dimerization of sesamol by plasma
irradiation have not been investigated yet. These newly generated oxidized compounds might
contribute to potent AGEs formation inhibition and ONOO–scavenging effects after plasma
treatment because of the formation of unusual compounds 1–3 due to oxidative dimerization
of standard sesamol.
3.3. Quantitative analysis of the major products generated by the plasma treatments of sesamol
and sesame oil
An LC-MS analysis method was developed that provided good separation of compounds 1,
2, 3, and 4 (Fig. 1). By comparing the retention times, UV profiles, and [M+H]+
pseudomolecular ion peaks with those of authentic standards (Table 2 & Supporting
information), these four compounds were unambiguously identified in sesame oil irradiated for
40 min. Sesaplasmin (1) (tR 16.9 min), 6,6'-methylenebis-1,3-benzodioxol-5-ol (2) (tR 20.7
min), 5,5'-bi-1,3-benzodioxole-6,6'-diol (3) (tR 19.6 min), 1,3-benzodioxole-5,6-dione (4) (tR
7.8 min), sesamol (tR 13.2 min), sesamin (tR 26.8 min), and sesamolin (tR 27.8 min) (Table 2)
were detected at 280 nm in plasma treated sesamol and sesame oil. Five concentrations were
used to plot calibration curves, which were effectively linear (R2 > 0.999). Quantitative analysis
exhibited that the contents of the most potent 6,6'-methylenebis-1,3-benzodioxol-5-ol (2) in

two plasma treated samples for 40 min were 581.1±2.4 and 24.1±0.7 mg/g, respectively (Table
3). On the other hand, sesamol contents were decreased to 202.8 ± 1.8 mg/g after 40 min of
plasma treatment (Table 3).
Reactive oxygen species (ROS) generated in plasma exposed to air under ambient conditions
have been shown to be composed of ozone, peroxide, atomic oxygen, superoxide, and hydroxyl
radicals (Gaunt, Beggs, & Georghiou, 2006). Recent studies have suggested that ROS
generated by DBD plasma might be conveniently transformed to dimerization linked through
characteristic methylene bridge under alcoholic conditions with potent biological properties
(Jeong, Cho, Kim, & Kim, 2017; Jeong, Cho, & Kim, 2019; Jeong, Park, & Kim, 2019).
Despite the distinctive advantages of non-thermal plasma in terms of inducing structural
modifications and enhancing the bioactivities, few studies have investigated the chemical
influences of food extract existing various dietary components. In the present study,
dimerization, hydroxylation, methoxylation, and dehydrogenation (Fig. 3) of sesamol and
sesame oil induced by DBD plasma irradiation under ethanolic condition improved the
inhibition of AGE and ONOO– scavenging activities. The chemical change of naturally
occurring dietary lignans by DBD plasma irradiation is closely associated with human health
and it is necessary to evaluate their levels under plasma treatment conditions because of
possible biological capacities and safety. These finding can be useful for food industry in
relation to plasma treatment parameters and enlargement of safety and quality as well as
increase of biological capacities.
4. Conclusion
The work presented herein, we first established that sesamol could be readily dimerized into
a new compound, sesaplasmin (1), as well as known 6,6'-methylenebis-1,3-benzodioxol-5-ol
(2), 5,5'-bi-1,3-benzodioxole-6,6'-diol (3), and 1,3-benzodioxole-5,6-dione (4). The structures

of the newly oxidized compounds were elucidated by detailed 1D- and 2D-NMR experiments
as well as HRFABMS data interpretation. The AGEs formation inhibitory and ONOO–
scavenging capacities of newly generated novel sesamol dimer 1 was found to be significantly
improved the activities with an IC50 value of 1.2 ± 0.1 and 4.1 ± 0.3 M, respectively.
Interestingly, this study also revealed the successful dimerization of potential anti-glycative
lignans of sesame oil using a DBD plasma apparatus. Further systematic investigation
employing DBD plasma of major food ingredients is essential for advanced food industry in
improvement of food safety and bioactivity.
Conflict of interest
The authors have no conflict of interest to declare.
Acknowledgements
This research was supported by the Daegu University Research Grant, 2019.
Appendix A. Supplementary data
Supplementary data associated with this article can be found in the online version at
doi:10.1016/j.foodchem. 2020.
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Figure captions
Table 1. Effects on AGEs formation inhibition and ONOO– scavenging activities of newly generated 1—4
from plasma treated sesamol for 40 min.
Table 2. LC−MS data of the major oxidized products identified in DBD plasma treated sesamol and sesame
oil for 40 min.
Table 3. Quantitative analysis of the major oxidized products in plasma treated sesamol and sesame oil for
40 min.
Fig. 1. HPLC chromatograms of DBD plasma irradiation treated sesamol and sesame oil. For analytical
conditions refer to Materials and Methods. (A) sesamol; (B) sesamol treated for 40 min; (C) sesame oil; (D)
sesame oil treated for 40 min.
Fig. 2. Chemical structures of compounds 1–4 obtained by DBD plasma irradiation of sesamol and key
HMBC correlations
Fig. 3. Suggested mechanism for the oxidation of sesamol by DBD plasma irradiation in ethanol.

Fig. 1. HPLC chromatograms of DBD plasma irradiation treated sesamol and sesame oil. For analytical
conditions refer to Materials and Methods. (A) sesamol; (B) sesamol treated for 40 min; (C) sesame oil;
(D) sesame oil treated for 40 min.

HO
O
O
O
O
HO
O
O
O
H2C
O
O
O
OH
Sesamol
4
2
HO
H3CO
O
O
O
O
H3CO
O
O
2'
O
O
O
1
O
7
1'
2
O
OH
OH
O
OH
(HMBC)
3
1
1
Fig. 2. Chemical structures of compounds 1–4 obtained by DBD plasma irradiation of sesamol and key
HMBC correlations.

OH HO
O
O
O
O
O
6-(((6-Hydroxybenzo[1,3]dioxol-5-yl)
-methoxy)methyl)benzo[1,3]dioxol-5-ol
- CH2O
- H2O
HO
O
O
HO
HO
O
O
HO
O
O
O
O
O
H2C
n
o
i
t
O
a
l
O
o
HOH2C
l
y
h
t
e
H
M
O
6-(Hydroxymethyl)benzo
-[1,3]dioxol-5-ol
O
C
4
OH
H
Benzo[1,3]dioxole-5,6-diol
+
HO
O
2
O
HO
O
O
-
Sesamol
H +
HO
O
O
H3CO
O
O
O
O
C-C coupling
O
O
O
O
O
O
O
OH
OH
4-Hydroxy-5-(6-hydroxybenzo
-[1,3]dioxol-5-yl) cyclohexa-3,5
-diene-1,2-dione
OH
3
1
Fig. 3. Suggested mechanism for the oxidation of sesamol by DBD plasma irradiation in EtOH.

Table 1
Effects on AGEs formation inhibition and ONOO– scavenging activities of newly generated 1—4
from plasma treated sesamol for 40 min.
IC50 value (M )a
Compound
Inhibition of AGEs
formation
ONOO–
scavenging
Sesamol
>700
>300
Plasma treated sesamol (20 min)
156.8 ± 5.5b
22.0 ± 2.2b
27.8 ± 2.3b
1.2 ± 0.1
3.1 ± 1.2
19.9 ± 1.7
>300
109.0 ± 3.1b
21.3 ± 1.0b
26.9 ± 1.3b
4.1 ± 0.3
7.6 ± 0.5
28.8 ± 2.5
>300
Plasma treated sesamol (40 min)
Plasma treated sesamol (60 min)
1
2
3
4
Aminoguanidineb
L-Penicillamineb
831.3 ± 7.6
—
—
12.2 ± 0.7
a All experiments were performed in triplicate.
b Results are expressed as IC50 value in g/mL.
c Used as positive controls.

Table 2
LC−MS data of the major oxidized products identified in DBD plasma treated sesamol and sesame oil
for 40 min.
tR (min)
UV λmax (nm)
241, 291
MF
[M+H]+
139
Identification
Sesamol
1
13.2
C7H6O3
C14H10O6
16.9
250, 296
275
20.7
19.6
7.8
240, 303
254, 311
248, 293
C15H12O6
C14H10O6
C7H4O4
289
275
153
2
3
4
26.8
27.8
242, 285
243, 288
C20H18O6
C20H18O7
355
371
Sesamin
Sesamolin

Table 3
Quantitative analysis of the major oxidized products in plasma treated sesamol and sesame oil for 40
min.
Regression equationa
(Y = aX + b, R2)
Content (mg/g)b
Linear range
(mg/mL)
Compounds
Sesamol
tR (min)
Sesamol
Sesame oil
13.2
Y=0.233084X+7.8, 0.9998
Y=0.442774X+1.3, 0.9998
Y=0.675208X+9.0, 0.9996
Y=0.892509X +6.3, 0.9999
Y=0.343001X +1.2, 0.9997
Y=0.130459X +8.0, 0.9999
Y=0.274158X +2.1, 0.9998
50−500
50−500
50−500
50−500
50−500
50−500
50−500
202.8±1.8
10.4±0.5
581.1±2.4
93.6±1.3
3.6±0.2
-
10.6±0.4
1
16.9
20.7
19.6
7.8
0.8±0.1
24.1±0.7
18.3±0.5
0.6±0.1
2
3
4
Sesamin
Sesamolin
26.8
52.3±1.0
21.0±0.8
27.8
-
a Y = peak area and X = concentration.
b Mean ± SD (n = 3).
CRediT author statement
Yun Hee Jeong: Conceptualization, methodology. Gyeong Han Jeong and Yong-Ha
Jeong: Experiments of structure elucidation a biological evaluation - Original draft preparation.
Tae Hoon Kim: Supervision, writing- reviewing and editing, design and interpretation of
research.
.
Declaration of interests

☒
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence
the work reported in this paper.
☐The authors declare the following financial interests/personal relationships which may
be considered as potential competing interests:
Highlights:
• Dimerization of sesamol was accelerated in ethanol solution induced by DBD plasma.
• Newly generated sesamol derivatives were elucidated by spectroscopic interpretation.
• Novel sesamol byproducts showed the enhanced anti-diabetic complication capacities.
• Quantitative analysis of plasma treated sesame oil using the sesamol derivatives was
achieved.